In this study, we aimed to improve the performance of the photovoltaic-thermal (PV/T) system by incorporating phase change material (PCM) into the heat exchanger. A new design for the finned tube heat exchanger layout was introduced, and a comprehensive mathematical model was developed to analyze the heat transfer process and operational efficiency of the PV/T system. The temperature variation of the PV/T system was simulated and validated using real climatic conditions in Baghdad and Tehran. To conduct our analysis, we utilized the OpenFOAM software and enhanced our solver to accurately capture the melting process in the PCM. We also investigated the effects of wind velocity and atmospheric pressure on the performance of the PV/T system. Our findings showed that an increase in wind velocity led to an increase in PV/T efficiency, while an increase in atmospheric pressure resulted in a decrease in efficiency. Additionally, we observed that the Baghdad climate was more sensitive to variations in wind velocity compared to Tehran. In Baghdad and Tehran, the highest obtained water temperatures were 54.3 and 50.1 °C, respectively. Furthermore, a study was conducted to assess the viability of using PV/T (photovoltaic-thermal) technology for hot water production in the Multi-Effect Desalination and Adsorption Desalination cycle. The proposed PV/T system demonstrated an average performance improvement of 26% compared to traditional PV/T systems. During warmer months, the system was capable of producing 0.11 and 0.10 m3/h of potable water per month in Baghdad and Tehran, respectively. Furthermore, the system had the potential to generate 170 and 140 kW h of electricity for the respective cities.

The global utilization of renewable energy is steadily surging, with the electricity sector at the forefront of this transformation. The adoption of renewable energy has experienced substantial growth in the past ten years, with double-digit rates, and this trend is poised to persist until 2035. The focus of this growth lies in harnessing renewable energy sources for electricity, heat, and transportation purposes. The performance of photovoltaic (PV) solar panel installations hinges on the level of solar radiation they receive. Regions in closer proximity to the tropics tend to receive more abundant solar radiation compared to wind energy, resulting in advantageous daily and seasonal power generation for PV panels.1–3 On sunny days, solar radiation follows a characteristic bell-shaped pattern, with the zenith occurring around midday. Presently, the energy conversion efficiency of PV panels ranges from 10% to 20%. Nonetheless, remarkable technological advancements in PV panel technology have transpired over the last decade, yielding significant improvements. The manufacturing of PV panels has become more economically viable, particularly with the integration of thin-film technology for PV materials. This cutting-edge technology is gaining a larger market share and holds the potential for further cost reductions.4,5

Photovoltaic systems, also known as solar power systems, are active solar systems that generate electricity by utilizing the photovoltaic effect. This natural phenomenon enables the conversion of sunlight into electrical energy through the use of photovoltaic cells. These cells employ special semiconductor materials to transform photons, which are particles of light, into useable electricity. However, the conversion process is not perfect, and a portion of the absorbed solar radiation is converted into heat instead of electricity. The efficiency of PV panels typically falls within the range of 15%–20%, meaning that only a fraction of the solar energy received can be converted into electricity, while the remaining energy is lost as heat. The temperature of the PV panels is a critical factor in their efficiency because higher surface temperatures can lead to a decrease in the conversion efficiency. Scientific studies have demonstrated that for each degree of temperature increase, the conversion efficiency can drop by ∼0.4%–0.65%. Therefore, it is crucial to regulate the surface temperature of PV panels to maximize their electrical efficiency.6–8 

To ensure optimal performance and durability of PV systems, it is crucial to regulate their thermal energy. Excessive heat can raise the surface temperature of PV panels, potentially compromising their efficiency and longevity. To tackle this issue, various cooling mechanisms have been developed to effectively dissipate heat. Extensive research has focused on monitoring and controlling the surface temperature of PV panels to keep them within optimal operating conditions. One innovative approach is the integration of PV/thermal (PV/T) technology, where heat extraction components are incorporated into the PV module itself. This integration enhances performance and boosts power output. Another promising technique involves using phase change materials (PCMs) to cool PV panels. PCM panels are integrated alongside the PV panels, enabling them to absorb excess heat through a phase change process. PCM possesses the unique ability to store and release thermal energy during phase transitions, effectively dissipating heat and preventing excessive temperature rise in the PV panels. By implementing PCM panels, the overall solar energy conversion efficiency of the PV system can be significantly enhanced.9–11 

The PCM-based cooling method provides several benefits. First, it helps maintain the ideal surface temperature of PV panels, resulting in improved electrical efficiency. Additionally, PCM panels have a high thermal energy storage capacity, enabling them to absorb a significant amount of heat. This stored heat can be released as needed, serving as a potential source of thermal energy for various applications. The integration of PCM technology with PV panels has the potential to significantly enhance the overall performance and efficiency of PV systems. Ongoing research and development in this area aim to optimize the design and implementation of PV-PCM systems for widespread adoption in the renewable energy sector. The PV-PCM system comprises a PV panel and a container filled with PCM. The PV panel is affixed to the front plate of the housing, which is constructed from a material that facilitates efficient heat conduction. The container itself is insulated with polystyrene. When solar radiation strikes the PV panel, a portion of the energy is converted into electricity, while the remaining energy is transformed into heat. This heat is then transferred to the PCM container. To facilitate heat dissipation, an air cavity is created between the container and the building walls, allowing for natural convection to dissipate the heat.12–15 

Kalkan et al.16 developed a numerical model to analyze the performance of a solar photovoltaic/thermal domestic hot water system. Their results showed that the air-based system had a higher solar fraction than the water-based system, and the addition of fins improved the solar fraction for both systems. Deymi-Dashtebayaz et al.17 conducted a study on a concentrated photovoltaic thermal (CPV/T) system coupled with a domestic heat pump (CPV/T-HP) that utilized Al2O3 nanofluid flow in a porous channel. Their findings revealed that increasing the nanofluid mass flow rate resulted in lower temperatures for both the PV cell and the nanofluid outlet, leading to improved PV cell efficiency and CPV/T energy efficiency but decreased exergy efficiency. The researchers determined that the optimal performance of the porous channel collector was achieved with a pore diameter of 0.9 mm and a porosity of 95%. Through energy-exergy-economic analysis and the Pareto method, they identified the optimal nanofluid mass flow rate for the integrated CPV/T-HP system to be 0.013 82 kg/s. Samiezadeh et al.18 conducted a study on a parabolic trough solar collector with a porous receiver tube and internal longitudinal fins using a hybrid nanofluid as the heat transfer medium. They found that increasing the volume fraction of Cu nanoparticles improved temperature gain and thermal efficiency, with Cu nanoparticles being more effective than Al2O3 nanoparticles. The temperature gradient in the collector cross-section increased with decreasing solar irradiance. Increasing the volume fraction of Cu and Al2O3 nanoparticles improved thermal efficiency with a slight increase in the friction factor. Higher permeability had a minor adverse effect on thermal efficiency but significantly reduced the friction factor. These findings provide insights for enhancing the efficiency of solar collectors.

Researchers have recognized the significance of operating temperature in photovoltaic (PV) modules. Exceeding the optimal temperature can negatively impact the open-circuit voltage by decreasing the semiconductor bandgap. To counter this, scientists have proposed cooling methods to maintain lower temperatures and prevent degradation. These techniques, such as nanoparticles, electrical magnetic fields, PCM, and micro-jet impingement cooling, have shown promise in increasing power production and extending the lifespan of PV modules. Implementing efficient cooling methods improves the overall efficiency and reliability of PV systems. Bassam et al.19 conducted a study on photovoltaic thermal collectors (PV/T) using nanophase change material (PCM) and micro-fins tube nanofluid. They utilized water and a nanofluid containing 0.6 vol. % SiC as working fluids in the PV/T system. The nano-PCM included 1% SiC nanoparticles, which improved the electrical, thermal, and overall efficiency of the PV/T system. Their findings showed that the PV/T system achieved an electrical efficiency of 9.6%. The highest thermal efficiency of 77.5% was observed in the PV/T system with micro-fins, nanofluids, and nano-PCM. Alsaqoor et al.20 investigated the impact of phase change material on photovoltaic thermal (PV/T) systems. Their results indicated that the PV/T system with PCM achieved a higher electrical efficiency of 14%, compared to 13.75% in the PV/T system without PCM. Additionally, the maximum achievable electrical power in the PV/T system with PCM was 21 kW, while it was 18 kW in the PV/T system without PCM. Sun et al.21 analyzed the performance of a combined heat and power photovoltaic-thermal module integrated with phase change material-water storage. They found that the position of the packed-bed did not significantly affect the performance of the PV/T module. However, increasing the amount of PCM led to higher water temperature stratification in the storage tank, resulting in improved PV/T module efficiencies, particularly in the afternoon. Applications of heat exchangers with PV modulus have been investigated by various Refs. 22–25 to increase the temperature. The main concept of this work revolves around utilizing a unique configuration of phase change material (PCM), rectangular fins, and pipes. Additionally, we incorporated the novel concept of PV/T in the Multi-Effect Desalination and Adsorption Desalination (MEDAD) cycle to produce potable water. In a study conducted by Meng et al.,26 the impact of different PCM properties on measuring the latent heat of low-temperature was investigated. Recent studies have also explored the use of PCM or other active methods to enhance the performance of simple photovoltaic panels.27–29 

At present, there is a lack of comprehensive research on the performance of rectangular fins within the phase change material (PCM) container in a photovoltaic/thermal (PV/T) system used in multi-effect distillation and adsorption desalination systems. Additionally, there is a lack of guidance on the number of people that can benefit from the potable water produced by the MEDAD system and the amount of auxiliary heat required to meet the water demand. This study aims to fill these gaps by conducting a thorough investigation into the efficiency of PV/T coupled with MEDAD in a novel and efficient manner. Computational Fluid Dynamics (CFD) tools will be employed to analyze the energy, exergy, exergo-environment, and exergo-economic concepts of the proposed cycle for two cities, Tehran and Iraq. The study will focus on optimizing the design and minimizing waste heat during different months. The results of this research will provide valuable insights for designers of fresh water systems, enabling them to create suitable plants for various geographical locations. The methods employed in this study include modeling the innovative PV/T system, creating a spatial mesh, formulating governing equations, and validating the results through multiple case studies. The impact of different design parameters on production will be discussed in Sec. III, and the final section will summarize the findings and draw conclusions.

The climate of Baghdad and Tehran, two major cities in the Middle East, exhibits both similarities and differences in terms of pressure at sea level, wind velocity, and solar irradiation. Baghdad, located in Iraq, experiences a desert climate with high temperatures and low humidity during the summer months.30 The pressure at sea level in Baghdad averages around 1013 mbar, and the city generally experiences light to moderate winds, although occasional dust storms can occur. Baghdad receives abundant solar irradiation, with an average of 3000 h of sunlight per year, making it suitable for solar energy utilization. Tehran, the capital city of Iran, has a semi-arid climate with distinct seasons. The pressure at sea level in Tehran is similar to that in Baghdad, but due to its higher elevation, the climate is generally cooler. Tehran experiences moderate to strong winds, especially in the spring and early summer months, which can provide relief from the heat and aid in the dispersion of air pollutants. Solar irradiation in Tehran is also significant, with an average of 4.5 kW h per square meter per day and ∼2800 h of sunlight per year. Both cities have favorable conditions for harnessing solar energy due to their high solar irradiation levels. The abundant sunlight can be harnessed through photovoltaic systems, contributing to sustainable development and reducing reliance on fossil fuels in these urban areas.

The aim of this study is to investigate novel photovoltaic systems that can generate both hot water and electricity. The specific conditions of Baghdad and Tehran are taken into account to achieve optimal performance of PV/T systems. Both cities are currently facing energy crises due to unreliable electricity supplies. Baghdad's crisis is caused by outdated infrastructure, insufficient power generation capacity, and neglect, while Tehran’s crisis is a result of high population growth, urbanization, and increasing energy consumption. Both cities are investing in new power facilities and upgrading the grid, but sustainable improvements require long-term planning, substantial investments, and political stability. The study recommends the use of high-performance solar farms to generate electricity and hot water. The hot water can be utilized in a multi-effect distillation system to produce potable water, while the electricity can be used in a reverse osmosis system to obtain even more drinkable water. Several parameters, such as solar irradiance, temperature, shading, orientation and tilt angle, system capacity and configuration, maintenance and cleaning, grid connection and integration, and monitoring and control, are important in the design and operation of photovoltaic farms. Optimizing these parameters can maximize energy production and efficiency in PV farms.

The main steps and work configurations are depicted in Fig. 1. First, the climate conditions of both cities were analyzed, including data on sun radiation, wind patterns, and atmospheric pressure. The second step involved designing new PV modules and incorporating a finned heat exchanger within the cooling system. This innovative heat exchanger features a long-curved tube that efficiently transfers heat from the cells to water. Another aspect that enhances the novelty of this work is the application of PCM within the fins, increasing heat capture during PV operation. This work introduces a novel PV system that paves the way for future improvements. Following that, mesh and time step independent tests were conducted. The final step focused on analyzing various influential parameters such as wind velocity and atmospheric pressure. Atmospheric pressure, particularly at different altitudes, plays a significant role in the amount of solar irradiation that reaches the Earth’s surface. At sea level, where atmospheric pressure is highest, the denser air causes sunlight to scatter and be absorbed more, resulting in a diffuse component of solar irradiation. Conversely, at higher altitudes with lower atmospheric pressure and air density, there is less scattering and absorption, allowing for a larger portion of direct solar irradiation to reach the surface. Understanding these variations in atmospheric pressure is crucial for optimizing the performance of solar energy systems in different locations and altitudes. In this study, the locations of Baghdad and Tehran were analyzed to determine the highest altitude within these cities, which would provide the highest efficiency for solar energy systems. For each month of the year, the PV/T system produces different outlet temperatures. These temperatures were inputted into the EES software to calculate four thermodynamic parameters: energy, exergy, exergo-environment, and exergo-economic analysis. Each of these parameters was thoroughly investigated and validated individually.

FIG. 1.

Main steps of the present work and summary of work configurations.

FIG. 1.

Main steps of the present work and summary of work configurations.

Close modal

The PCM melting and fluid flow problems were resolved using the finite element method in OpenFOAM with discretized equations. The flow was simulated through the use of the two-phase mixing technique, while the enthalpy method was applied to address the PCM melt front. Machine learning was employed to explore the optimal conditions for a solar panel with the lowest temperature and pressure drop, and the impact of various parameters on the results was thoroughly investigated. Design Expert software was utilized for this analysis. For the investigation, Salome software (version 6) and the SnappyHexMesh utility were utilized to generate and discretize the photovoltaic module equipped with a heat exchanger containing finned and PCM materials. Due to the complex geometry, an unstructured grid was employed to accommodate various geometric structures. The results of a mesh-independent test are presented in Fig. 2(c), with 3 × 106 cells found to be the appropriate grid resolution for a single module case. Figure 2(c) displays the three mesh configurations for the case study. To validate the numerical method used for calculating the exit temperature of the novel PV/T system, the CFD simulations were compared with Alqaed et al.’s study on a PV module with PCM and nanoparticles. Figures 2(a) and 2(b) illustrate the comparison of maximum and middle temperature distributions between the two studies, respectively. Alqaed et al.31 conducted experiments and numerical simulations to observe PCM melting and its impact on increasing the electricity production efficiency of the panel. The maximum relative deviations of the maximum and middle temperatures between the two cases in Figs. 2(a) and 2(b) were ∼0.6% and 1.1%, respectively.

FIG. 2.

(a) and (b) Validation of CFD results with Alqaed et al.31 work; (c) mesh independent test; (d) time independent test.

FIG. 2.

(a) and (b) Validation of CFD results with Alqaed et al.31 work; (c) mesh independent test; (d) time independent test.

Close modal

In this section of the article, we present the temperatures obtained from the proposed PV/T system for each month. We also examine the impact of using phase change material (PCM) and rectangular fins in the PV modules. Additionally, we provide the thermodynamic results and analyze how different parameters affect the overall cycle. Moreover, we discuss the requirement for an auxiliary heat source in both Baghdad and Tehran. Figure 3 illustrates the variations in solar irradiation and temperature over the months in both cities. It is observed that the highest temperatures occur in May, June, and July. This figure is included to improve understanding of the temperature and irradiation patterns throughout the year. These temperatures are used as boundary conditions in the CFD simulation, and subsequently, we extract the outlet temperature from the PV/T system. To achieve significant production of drinkable water and electricity, the numerical work considers the actual climate conditions of Baghdad and Tehran. When solar radiation reaches the PV surface, it is directed toward a heat exchanger that is equipped with pipes. These pipes transfer the thermal energy from the collectors to the water that is flowing through them. Another advantage of this study is the utilization of the hot water flow in a multi-effects distillation and adsorption desalination cycle to produce drinkable water. To understand the affordability and environmental impact of the proposed cycle, we conducted an analysis of exergo-environmental and exergo-economic factors.

FIG. 3.

Solar irradiations and temperatures variations over the month for both cities of Baghdad and Tehran: (a) solar irradiations and (b) temperature.

FIG. 3.

Solar irradiations and temperatures variations over the month for both cities of Baghdad and Tehran: (a) solar irradiations and (b) temperature.

Close modal

Using phase change materials (PCMs) in cooling PV systems is essential for enhancing efficiency and preventing overheating. PCMs absorb excess heat from PV modules and undergo a phase change to regulate temperature, resulting in stable temperatures, increased electrical efficiency, and a sustainable and cost-effective cooling solution. The highest temperatures obtained from PV/T systems in Baghdad and Tehran are shown in Figs. 4 and 5, respectively, with June having the highest temperatures due to increased solar irradiation. In Baghdad, June temperatures are over 31.8% higher than December, while in Tehran, they are 37.9% higher. An important assumption is that the PCM can completely melt in peak summer or solidify in peak winter, allowing for system design considerations such as starting water circulation early in the summer months to extract heat from melted PCM and provide extended time for solidification.

FIG. 4.

Various exit temperatures from the PV/T system over the month for Baghdad.

FIG. 4.

Various exit temperatures from the PV/T system over the month for Baghdad.

Close modal
FIG. 5.

Various exit temperatures from the PV/T system over the month for Tehran.

FIG. 5.

Various exit temperatures from the PV/T system over the month for Tehran.

Close modal

In our study, we compared three types of PCM to determine their effectiveness in increasing the exit temperature. Figure 6 illustrates the impact of different PCM materials on the PV/T system. Paraffin wax, salt hydrates, and organic component PCMs are commonly used for energy storage. Paraffin wax, as a solid PCM, has a high latent heat capacity, enabling it to absorb and release significant thermal energy during phase transitions. It is cost-effective and easily accessible. However, its thermal conductivity is relatively low, which limits its ability to transfer heat efficiently. Salt hydrates, such as sodium sulfate decahydrate, have a high latent heat capacity and good thermal conductivity, making them suitable for various applications. However, they can be corrosive and require careful handling. Organic component PCMs, such as fatty acids or alcohols, offer advantages like a wide range of phase change temperatures and good thermal conductivity. They can be customized to specific temperature requirements and are compatible with other materials. However, organic PCMs can be more expensive compared to paraffin wax or salt hydrates. The choice of PCM depends on the specific application, temperature requirements, and cost considerations. Paraffin wax is commonly used for low-temperature applications, while salt hydrates and organic component PCMs offer more flexibility in terms of temperature range and performance. In our study, we found that paraffin wax performed better at increasing the exit temperature due to its higher heat capacity. Paraffin wax exhibited temperature variations of 4.6% and 10.6% for the month of June in Baghdad compared to salt hydrates and organic components. Figure 7 depicted the surface temperature variation over time. As the PCM reached its melting point, it underwent phase change, resulting in constant and stable temperature variations over time. The surface temperature of paraffin wax was lower than in the other cases due to its effective heat absorption. It can be observed that the paraffin wax PCM experienced a lower temperature drop compared to the other cases in Baghdad. In June, the peak and average temperature drops were 11 and 5.1 °C, respectively, which decreased to 8.6 and 2.3 °C in January. These temperatures in Tehran were slightly higher, around 2%, compared to the reported values in Baghdad.

FIG. 6.

Exit temperatures from the PV/T system and PV surface temperature vs time in June month of Baghdad and Tehran for three types of PCM: (a) and (d) paraffin wax, (b) and (e) salt hydrate, and (c) and (f) organic components.

FIG. 6.

Exit temperatures from the PV/T system and PV surface temperature vs time in June month of Baghdad and Tehran for three types of PCM: (a) and (d) paraffin wax, (b) and (e) salt hydrate, and (c) and (f) organic components.

Close modal
FIG. 7.

Max temperature vs time for three PCMs of paraffin wax, salt hydrate, and organic component.

FIG. 7.

Max temperature vs time for three PCMs of paraffin wax, salt hydrate, and organic component.

Close modal

In this phase of our analysis, we focused on evaluating how wind velocity affects the performance of our proposed system in Baghdad and Tehran. To gather data, we conducted experiments and recorded the wind conditions on a daily basis for both cities. Utilizing the average wind velocity as the boundary condition, we employed the Swak4Foam utility to apply a CFD approach. Our analysis revealed that the average wind velocity in Baghdad is 3.1 m/s, while in Tehran it is 1.8 m/s. To assess the system's sensitivity, we considered a range of 2.5–4 m/s for Baghdad and 1.5–3 m/s for Tehran. It is worth noting that the performance of the PCM coupled finned tube within the PV/T system may be influenced by solar radiation at different wind velocities. Wind velocity can have direct and indirect effects on solar irradiation and the performance of photovoltaic (PV) systems. Directly, wind can impact solar irradiation by influencing cloud movement. When wind blows, it can disperse or break up clouds, allowing more sunlight to reach the earth’s surface. This increases the amount of direct solar irradiation available for PV systems, leading to higher energy production. Indirectly, wind affects PV system performance by regulating the temperature of solar panels. When wind blows over the panels, it helps dissipate heat and prevent overheating, improving efficiency and longevity. However, strong winds can also increase convective heat loss, slightly reducing efficiency. Mechanically, wind can exert force on PV panels and supporting structures, potentially causing damage. Proper design and installation, with consideration for wind loads and structural integrity, are crucial. Site-specific assessments and analyses of wind patterns and obstructions help optimize PV system performance. Wind data can determine average wind speed and direction, aiding in selecting appropriate system designs and orientations. Overall, wind velocity impacts solar irradiation and PV system performance, necessitating careful consideration for optimal performance and durability. In Fig. 8, we observe the variation of PV surface temperature over time in the month of June for Tehran (a) and Baghdad (b), considering three different wind velocities. Our findings indicate that as the wind velocity increases in both cities, the PV surface temperature decreases and stabilizes quickly. In Tehran, wind velocities of 1.5 and 2.25 m/s yield similar results. Figure 8(c) displays the PV efficiency for all wind velocities in both cities. It is worth noting that Baghdad's weather conditions exhibit higher sensitivity, as evidenced by the steeper slope of the line.

FIG. 8.

(a) PV surface temperature vs time in June month of Tehran; (b) Baghdad for three types of wind velocity; (c) PV efficiency for both cities.

FIG. 8.

(a) PV surface temperature vs time in June month of Tehran; (b) Baghdad for three types of wind velocity; (c) PV efficiency for both cities.

Close modal

In this stage of our analysis, our focus was on examining the impact of atmospheric pressure, which is determined by the elevation above sea level, on the performance of our proposed system in Baghdad and Tehran. This impact was taken into account through the boundary condition of pressure. Our findings indicated that Baghdad is situated at an elevation of 47 m above sea level, while Tehran is located at an elevation of 1147 m. To assess the system’s sensitivity, we considered a pressure range of 0.9–1.2 bar for Baghdad and 0.7–1 bar for Tehran. It is important to note that the performance of the PCM coupled finned tube within the PV/T system can be influenced by solar radiation under varying atmospheric pressures. The altitude above sea level, which determines the atmospheric pressure, can affect the performance of photovoltaic (PV) systems. As altitude increases, atmospheric pressure decreases, leading to changes in air density and solar irradiation reaching the PV panels. Comparing the altitudes from sea level of Baghdad and Tehran, Baghdad is at a lower altitude of ∼47 m above sea level, while Tehran is at a higher altitude of around 1147 m above sea level. Due to its higher altitude, Tehran experiences lower atmospheric pressure compared to Baghdad. This may result in slightly higher operating temperatures for PV panels in Tehran, potentially reducing the efficiency of PV systems compared to those in Baghdad. However, the lower air density at higher altitudes in Tehran allows for more direct sunlight to reach the PV panels, leading to higher solar irradiance and increased energy production compared to PV systems in Baghdad. It’s important to consider that atmospheric pressure and altitude are just some of the factors influencing PV system performance. Other factors like temperature, humidity, shading, and system design also play significant roles. A comprehensive evaluation of all these factors is necessary to accurately assess the performance of PV systems in different locations. In Fig. 9, we present the variation in water outlet temperature for Tehran and Baghdad across different months, considering three levels of atmospheric pressure. The results indicate that lower atmospheric pressure can enhance the thermal efficiency of the PV/T system. As depicted in Figs. 9(a) and 9(b), a decrease in atmospheric pressure leads to higher outlet temperatures. This elevated temperature can be utilized in the MEDAD system to reduce the need for additional heat sources during evaporation. Moreover, lower pressure results in higher electricity production efficiency. Additionally, both cities exhibit equal sensitivity to changes in pressure.

FIG. 9.

(a) Water outlet temperature of Tehran; (b) Baghdad vs months for three types of atmospheric pressure; (c) PV efficiency for both cities.

FIG. 9.

(a) Water outlet temperature of Tehran; (b) Baghdad vs months for three types of atmospheric pressure; (c) PV efficiency for both cities.

Close modal

During this phase of our research, we utilized monthly temperature data to preheat water for the auxiliary heater in the MEDAD cycle. As mentioned earlier, we selected paraffin wax PCM as the primary cooling material for the PV system. This material has the ability to absorb a significant amount of waste heat from the modules and effectively transfer it to the coiled pipe with the help of fins. It reaches a steady-state temperature quickly, allowing for efficient heat transfer, which is ideal for our proposed cycle. Our study implemented the MEDAD cycle to improve potable water production in both Baghdad and Tehran. Comparing the two systems, we found that integrating an Adsorption–Desorption (AD) stage into the Multi-Effect Distillation (MED) system offers several advantages. Unlike the MED system, where the final stage is limited by the condensation temperature of the environment, the MEDAD system’s final stage is controlled by the adsorption unit. This allows for a greater number of stages and results in a remarkable 2.68-fold increase in desalinated water production compared to an independent MED system. Additionally, the AD unit’s low energy consumption contributes to a significantly reduced Specific Energy Consumption (SEC) in the MEDAD system, achieving a notable 52.3% reduction compared to the MED system. This decrease in energy consumption leads to a higher Performance Ratio (PR) for the MEDAD system, with respective values of 4.68 and 11.09 for the MED and MEDAD systems.

These findings were obtained under the same conditions, including a seawater temperature of 25 °C, a seawater Total Dissolved Solids (TDSs) of 42 000 ppm, a seawater mass flow rate of 0.0035 kg/s per stage, and a heat transfer fluid mass flow rate of 0.2 kg/s. It’s worth noting that Ref. 16 also reports consistently high average Performance Ratios (PRs = 7–8) for the hybrid 8-stage MEDAD desalination system compared to the MED system. Our study aligns with these findings and highlights the advantages of the MEDAD system, including higher total desalinated water production (m3/h), lower specific energy consumption (kW h/m3), and an elevated Performance Ratio (PR). The performance results for the proposed cycle in Baghdad are presented in Table I, with the highest performance achieved in June. To determine the number of solar panels required for a photovoltaic farm, various factors such as panel wattage and the energy requirements of the farm are considered. The number of panels needed is calculated by multiplying the hourly energy requirement of the farm by the peak sunlight hours for the specific area and then dividing by the wattage of a single panel. In this specific installation, there are 23 photovoltaic (PV) arrays installed on 15 building terraces, with the properties of the selected PV detailed in Table II. The calculations for Tables I and II were performed using the same heat source. Specifically, the outlet pipe temperatures for each month were calculated and then applied to a fixed value of 450 kW h for the auxiliary chamber to produce potable water through MEDAD. In another phase of the study, a fixed volumetric flow rate of desalinated water was chosen for the proposed system, and calculations were recalibrated to determine the required auxiliary heat.

TABLE I.

Results of performance for the proposed cycle for Baghdad.

MonthsVolumetric flow rate of desalinated water (m3/h)Required power for the desalination (kW)Specific energy consumption SEC (kW h/m3)Performance ratio PRProduced electricity power (kW h)
January 0.0821 5.5412 55.78 10.00 121 
February 0.0891 5.8961 57.45 10.85 135 
March 0.0991 6.0325 61.04 11.09 141 
April 0.1145 6.1541 65.41 12.01 150 
May 0.1345 6.3544 67.32 12.45 161 
June 0.1400 7.1457 70.35 13.01 172 
July 0.1452 7.8519 72.24 13.24 175 
August 0.1357 6.2454 65.45 12.45 165 
September 0.1314 6.0145 60.25 12.01 150 
October 0.1247 5.4561 58.87 11.78 145 
November 0.1198 5.0145 56.35 10.54 131 
December 0.0871 4.4751 54.21 10.21 121 
MonthsVolumetric flow rate of desalinated water (m3/h)Required power for the desalination (kW)Specific energy consumption SEC (kW h/m3)Performance ratio PRProduced electricity power (kW h)
January 0.0821 5.5412 55.78 10.00 121 
February 0.0891 5.8961 57.45 10.85 135 
March 0.0991 6.0325 61.04 11.09 141 
April 0.1145 6.1541 65.41 12.01 150 
May 0.1345 6.3544 67.32 12.45 161 
June 0.1400 7.1457 70.35 13.01 172 
July 0.1452 7.8519 72.24 13.24 175 
August 0.1357 6.2454 65.45 12.45 165 
September 0.1314 6.0145 60.25 12.01 150 
October 0.1247 5.4561 58.87 11.78 145 
November 0.1198 5.0145 56.35 10.54 131 
December 0.0871 4.4751 54.21 10.21 121 
TABLE II.

Results of performance for the proposed cycle for Tehran.

MonthsVolumetric flow rate of desalinated water (m3/h)Required power for the desalination (kW)Specific energy consumption (SEC) (kW h/m3)Performance ratio (PR)Produced electricity power (kW h)
January 0.0771 6.04 59.28 09.85 106 
February 0.0841 6.44 60.95 10.64 119 
March 0.0941 6.45 64.54 10.90 125 
April 0.1095 6.64 68.91 11.86 135 
May 0.1295 6.95 70.89 12.20 146 
June 0.1342 7.71 74.00 12.71 158 
July 0.1442 8.34 75.75 13.09 162 
August 0.1324 6.76 69.11 12.34 149 
September 0.1241 6.34 63.84 11.75 135 
October 0.1202 5.94 62.41 11.59 130 
November 0.0914 5.52 60.35 10.39 115 
December 0.0871 4.98 58.57 10.25 100 
MonthsVolumetric flow rate of desalinated water (m3/h)Required power for the desalination (kW)Specific energy consumption (SEC) (kW h/m3)Performance ratio (PR)Produced electricity power (kW h)
January 0.0771 6.04 59.28 09.85 106 
February 0.0841 6.44 60.95 10.64 119 
March 0.0941 6.45 64.54 10.90 125 
April 0.1095 6.64 68.91 11.86 135 
May 0.1295 6.95 70.89 12.20 146 
June 0.1342 7.71 74.00 12.71 158 
July 0.1442 8.34 75.75 13.09 162 
August 0.1324 6.76 69.11 12.34 149 
September 0.1241 6.34 63.84 11.75 135 
October 0.1202 5.94 62.41 11.59 130 
November 0.0914 5.52 60.35 10.39 115 
December 0.0871 4.98 58.57 10.25 100 

Table III displays the properties of the silica gel Regular Density (RD) in the proposed adsorption desalination cycle. By incorporating adsorption desalination into the multi-effect distillation system, we can improve the quality of water by reducing salt concentration and increasing water production. Baghdad, in comparison to Tehran, faces more severe climate change in the Middle East, has polluted rivers near the city, limited water resources, and struggles to provide accessible water to its residents. Iraq relies heavily on water sources such as the Tigris and Euphrates rivers, making it crucial for the country to adopt this proposed water system. In addition, we suggest utilizing the surplus electricity generated by the photovoltaic system in a reverse osmosis system to further increase water production. Tehran also experiences water scarcity, particularly the during summer months. The proposed cycle could serve as a valuable source of potable water for the city. The Caspian Sea, located nearby, can be utilized as a water source. Our estimates indicate that the proposed system could provide potable water for ∼10% of Tehran’s population and 12% of Baghdad’s population.

TABLE III.

Silica gel RD properties for the proposed cycle inside adsorption desalination.

ParametersValues
Regeneration temperature (°C) 55–140 
Maximum acceptable temperature (°C) 400 
Specific heat capacity (kJ/kg K) 0.921–1.09 
Bulk density (kg/m3704.8–897.0 
Average pore diameter (nm) 2.2 
Pore volume (cm3/g) 0.37 
Surface area (m2/g) 750 
ParametersValues
Regeneration temperature (°C) 55–140 
Maximum acceptable temperature (°C) 400 
Specific heat capacity (kJ/kg K) 0.921–1.09 
Bulk density (kg/m3704.8–897.0 
Average pore diameter (nm) 2.2 
Pore volume (cm3/g) 0.37 
Surface area (m2/g) 750 

As the energy requirements for desalination technologies continue to decrease, it becomes increasingly important to consider the auxiliary power consumption in thermal desalination processes, especially when utilizing waste heat sources where thermal energy costs are minimal or nonexistent. The impact of auxiliary power on overall operational costs becomes more significant in such cases. In this analysis, we have conducted calculations to determine the auxiliary energy needed to produce a specific mass flow rate of water, providing insights into the energy requirements for freshwater production in Baghdad and Tehran. For our proposed system, we have chosen a constant volumetric flow rate of desalinated water at 0.15 m3/h and adjusted our calculations accordingly to determine the auxiliary heat required. Additionally, we have separately calculated the energy output from the photovoltaic/thermal (PV/T) system and utilized it as a preheater. By increasing the inlet temperature from the PV/T system to the MEDAD system, the need for auxiliary heat decreases. The boosted MEDAD system, which utilizes preheated water from the PV/T system, demonstrates a significant reduction in additional auxiliary power demand as temperatures rise. Figure 10 illustrates the required auxiliary heat source for each month in Baghdad and Tehran. The month of June, with its high temperatures, requires fewer additional heat sources for the MEDAD system. The utilization of phase change material (PCM) in the cycle further reduces this requirement. Additionally, on average, Tehran requires more than 8% additional heat source compared to Baghdad, with the warmest months necessitating a lower amount of extra heat source.

FIG. 10.

Auxiliary energy needed for both cities of Baghdad and Tehran.

FIG. 10.

Auxiliary energy needed for both cities of Baghdad and Tehran.

Close modal

By analyzing the specific cost of water production, we can effectively demonstrate the parameters previously mentioned. The actual cost can vary greatly depending on the specific application, but by comparing cost parameters from existing plants, we can estimate the cost reasonably accurately. The cost of electrical power is particularly important as it affects auxiliary power consumption. In the surveyed range of applications, the additional capital investment for MEDAD with feed pre-heating is relatively small, but the increased auxiliary power consumption negates the advantages, resulting in comparable water production costs to a basic MEDAD plant. Only when there are high heating medium temperatures and cost-effective electrical power available can we observe a preliminary cost reduction compared to a basic MED plant. On the other hand, the proposed MEDAD for the month of June shows a significant reduction in production cost, up to 10%, with a low heating auxiliary heat source.

The implementation of PV/T systems offers significant long-term cost savings, potentially reducing energy costs by more than 51%. These systems have the advantage of producing more water at temperature levels that would not be economically viable with a basic MEDAD system. By incorporating pre-heating and coupled MEDAD schemes, costs can be further reduced by generating more water from the same energy source. The specific electricity and potable water costs for both Baghdad and Tehran make the installation of PV/T systems economically feasible in both cities. Economic analysis demonstrates that the utilization of PV thermal systems, which harness solar energy for electricity and heat, can lead to long-term cost savings. Additionally, coupling a multi-effect desalination system with adsorption desalination shows potential for significant returns. The timeframe for achieving economic benefits varies, with PV thermal systems typically taking 2–3 years, while multi-effect desalination systems have varying durations. To determine the precise timeframe for economic performance, a comprehensive cost–benefit analysis considering factors such as system efficiency, lifespan, maintenance requirements, and market prices is necessary. Furthermore, it is important to consider environmental benefits, such as reduced carbon emissions and water conservation, in the overall assessment.

Figures 11(c) and 11(d) depict the exergy destruction in the proposed system. The auxiliary heat source stands out as having a higher rate of exergy destruction compared to other parameters. This is because the use of floating technology in potable water production introduces additional irreversibility. Several factors contribute to the high exergy destruction in the auxiliary energy system. These factors include lower thermodynamic efficiencies in energy conversion processes, operation at smaller scales and lower temperatures, higher pressure drops and heat transfer inefficiencies, as well as suboptimal design and operation. Consequently, there is a loss of exergy, making auxiliary energy systems less efficient than the main energy source. The PV/T heat exchanger component of the system also experiences significant exergy destruction due to temperature differences in the heat exchange process and losses from solar energy. These values are all illustrated in figures. In terms of exergy destruction in the auxiliary energy system, Baghdad has a lower rate compared to Tehran, with a difference of around 18%. This difference can be attributed to the higher availability of solar energy in Baghdad. Additionally, the Multi-Effect Distillation (MED) part of the proposed system has the highest environmental impact rate among the components, as indicated by the results in Figs. 11(e) and 11(f). One of the main reasons for this is the availability of free water during the installation. The second highest environmental impact rate is associated with the PV component, which faces challenges related to accessing phase change material (PCM), leading to greater environmental effects.

FIG. 11.

Exergo-environment and exergo-economic results for both the cities of Baghdad and Tehran.

FIG. 11.

Exergo-environment and exergo-economic results for both the cities of Baghdad and Tehran.

Close modal

The present study focuses on the effectiveness of a proposed PV/T system in reducing temporal fluctuations. The aim was to enhance the efficiency of the PV/T system in the climates of Baghdad and Tehran through a novel design. We utilized the OpenFOAM software, written in C++, to simulate various environmental conditions to achieve our objectives. Our specific focus was on investigating the impact of wind velocity and atmospheric pressure to comprehend the system's sensitivity. The system employed a combination of traditional phase change material (PCM) and a novel finned curved tube heat exchanger within the modules, which had a unique design that efficiently collected heat with the aid of PCM. Additionally, we utilized the waste heat generated by the PV/T system as a preheater in the multi-effect distillation and adsorption desalination systems. Our evaluation of the proposed system’s performance was based on four key parameters: energy, exergy, economic, and environmental analysis. This design allowed for the capture of heat dissipated from the PV surface, which was then used to increase the temperature of the water inside the tubes. The PCM near the PV surface absorbed the dissipated heat and transferred it to the water inside the tubes. The inclusion of finned tubes extended the heat transfer surface area, improving efficiency. Notably, the study analyzed the system’s performance for each month and compared the numerical results with experimental data, adding to the robustness of the findings. The following are our key findings:

  1. The proposed PV/T system demonstrates a significant increase in electricity production, with a boost of ∼26% compared to traditional systems.

  2. The month of June yields higher water outlet temperatures and power output.

  3. Baghdad exhibits a greater potential for utilizing solar irradiation.

  4. In our study, paraffin wax is recommended as the phase change material (PCM) for the PV/T system.

  5. Higher wind velocities contribute to increased efficiency in the PV/T system, with Baghdad displaying higher sensitivity to variations in wind velocity.

  6. Conversely, an increase in atmospheric pressure leads to a decrease in the efficiency of the PV/T system.

  7. The proposed system can produce an average of 0.11 and 0.10 m3/h of potable water for each month in Baghdad and Tehran, respectively.

  8. The proposed system has the potential to generate 170 and 140 kW h of electricity for the mentioned cities.

We express our gratitude to the Environmental Committee of Iraq for their contribution to sharing valuable data and engaging in productive discussions. This study received complete financial support from the Environmental Committee of Iraq (Grant No. 457863-d), located in Baghdad, Iraq. The experimental aspects of this work were conducted at the Research Institute of Petroleum Industry (RIPI) in Tehran, Iran. We extend our gratitude to the laboratory members for their assistance in providing the sample of PCM and the supplementary data on the photovoltaic surface. We also appreciate their valuable contributions to the discussions related to this study.

The authors have no conflicts to disclose.

Hassan Abdal Haidy Al-Hamzawi: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Funding acquisition (equal); Investigation (equal); Methodology (equal); Project administration (equal); Resources (equal); Software (equal); Supervision (equal); Validation (equal); Visualization (equal); Writing – original draft (equal); Writing – review & editing (equal). Mohammad Hassan Shojaeefard: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Funding acquisition (equal); Investigation (equal); Methodology (equal); Project administration (equal); Resources (equal); Software (equal); Supervision (equal); Validation (equal); Visualization (equal); Writing – original draft (equal); Writing – review & editing (equal). Mohammad Mazidi Sharfabadi: Conceptualization (equal); Data curation (equal); Formal analysis (equal); Funding acquisition (equal); Investigation (equal); Methodology (equal); Software (equal); Validation (equal); Visualization (equal); Writing – original draft (equal); Writing – review & editing (equal).

The data that support the findings of this study are available from the corresponding authors upon reasonable request.

In the following, the introduction of equations governing the problem, such as phase-changing materials, is discussed. Therefore, in this section of the research, the presentation and investigation of equations governing a system composed of photovoltaic panels and phase-changing materials are mentioned. The governing equations for the fluid phase in photovoltaic panels, heat transfer by convection and conduction, the thermophysical model, and the method of electricity generation for the photovoltaic system with phase-changing materials are discussed and examined. Equations (A1) and (A2) represent the continuity and momentum equations, respectively. They include two additional terms, Boussinesq and Darcy,32,33
ρt+(ρu)=0,
(A1)
ρt+(ρu)u=(μ(u))p +SDarcy+SBoussinesq,
(A2)
SDarcy=C(1fl)2fl3+εu
(A3)
SBoussinesq=ρgβ(TTm).
(A4)
The parameter C in Eq. (A3) represents the transfer between the solid and liquid. The highest possible value has been considered in this research. In the above-mentioned equation, the liquid phase is considered. Additionally, in this equation, α is a constant value. On the other hand, in Eq. (A2), the Boussinesq approximation is also taken into account. In Eq. (A5), the energy equation is shown to consider the melting process of the phase-changing material,34,35
(ρcpT)t+(ρcpuT)=(kT)(ρflhsf)t.
(A5)
In Eq. (A6), the energy equation for the solid phase is also considered,35 
(ρcpT)t=(kT)+Pout+Qout.
(A6)
Furthermore, in Eq. (A6), Pout and Qout represent the volumetric power generation in the cell and the energy source for solar radiation absorption, respectively, which are further illustrated in their respective formulas31,
Pout=ηpv×(αpvτglassIsolar)tpv,
(A7)
Qout=(1ηpv)×(αpvτglassIsolar)tpv.
(A8)
In the above-mentioned equation, ηpv represents the electrical energy conversion efficiency, which is dependent on the cell temperature and is calculated using the ηpv = ηref × (1 − βref(TpvTref)) equation.31–34 This formula represents the electrical efficiency of the cell, and the values of the constant parameters in it, such as βref = 0.003 82, Tref = 25 °C, and ηref = 0.2, have been considered. The Boussinesq approximation simplifies fluid dynamics by assuming constant density, except for small temperature variations. It is useful for analyzing fluids with slight temperature differences, such as in a photovoltaic panel with a phase change material (PCM). The PCM can absorb and release thermal energy during phase transitions. By applying the Boussinesq approximation, density variations within the PCM can be disregarded, allowing for simpler analysis of fluid flow and heat transfer in the panel. In this research, we utilized OpenFOAM version 5, a widely used open-source computational fluid dynamics (CFD) software package, for numerical simulations. OpenFOAM, implemented in the C++ programming language, employs a finite-volume method to solve the Reynolds-averaged forms of mass, energy, momentum equations, and equation of state. The chtMultiRegionFoam solver was used to model the transient fluid flow of PCM and water, as well as the solid heat conduction of the photovoltaic layers. To account for the Darcy term in Eq. (A2), the fvOption utility in OpenFOAM was incorporated as a source of momentum/thermal term. Convective terms were handled using a Gaussian upwind scheme, while diffusion terms were addressed using a Gaussian linear-limited approach. The PIMPLE algorithm was employed to couple pressure and velocity. The convergence criteria for pressure, velocity, and temperature were set at maximum residuals of 10−5, 10−8, 10−7, and 10−8, respectively. The k-ω SST (Shear Stress Transport) turbulence model has been used in the present work.
The paper discusses a hybrid desalination cycle called MEDAD that can increase water production by approximately three times at the same boiling temperature. The authors provide a numerical simulation and modeling of the MEDAD cycle, along with a detailed design of the heat exchangers used in the system. The rate of heat transfer in the heat exchangers can be determined using Eq. (B1), which takes into account the overall heat transfer coefficient, heat transfer area, and logarithmic mean temperature difference,36,
Q̇=U×A×LMTD.
(B1)
The process of heat transfer in the evaporator involves overcoming three types of resistances, namely the heat transfer coefficient on the cold side, the heat transfer coefficient on the hot side, and tube wall resistance. These resistances are resolved to calculate the overall heat transfer coefficient, U, using Eq. (B3),36 
Q̇Ev,k=ms,khfg,s,k=mF,kCpF(TB,kTF,k)+Dkhfg,k,
(B2)
1UA=1(hA)c+Rf,cAcRc+1(hA)h+Rf,hAhRh+Rw.
(B3)
The correlations for hh, hc, and RW used in falling film evaporators and preheaters are presented. For the evaporators, the values for Rf,c and Rf,h are 88 × 106 and 1.7 × 106 m2 K/W, respectively. For the brine preheater, the values are 17 × 106 and 52 × 106 m2 K/W, while for the distillate preheaters, the values are 52 × 106 and 1.7 × 106 m2 K/W, respectively. Other design parameters for the preheaters are obtained from the literature. The flow rate of cooling water is derived from the following equation:
Q̇cond=ṁ1Cp(T2T1)=ṁ6Cp(T6T7)+ṁ6hfg.
(B4)
The formula used to compute the logarithmic mean temperature difference (LMTD) for heat exchangers operating in a counterflow arrangement is as follows:36,
LMTD=(Th,oTc,i)(Th,iTc,o)ln(Th,oTc,i)(Th,iTc,o).
(B5)
The heat transfer areas of all Heat exchangers (HXs), including evaporators, condensers, adsorption desalination evaporators, and adsorption desalination condensers, are determined individually using Eq. (B3). Consequently, the overall specific area of the entire system is obtained,36,37
Aspc=AEV+AEV,AD+ACD,AD+ACDṁD.
(B6)
To determine the boiling point elevation (BPE) caused by the effect temperature and brine salinity, Eqs. (B7) and (B8) are utilized to calculate the brine salinities for all effects,37,
BkSB,k=FkSF,k,
(B7)
Bk=FkDk,
(B8)
BPE=TB,kTV,k.
(B9)
To consider the adsorption desalination formulation for MED, the present work uses the proposed heat exchanger designs for AD, as shown below. The required energy for the desorption process in the AD stage,36,37
QAD=des,timeQdes×msg×cp,des+ads,timeQads×msg×cp,ads+msg×csg×(TAD,2TAD,1)t.
(B10)
The amount of adsorbate in the adsorbent, which is the water vapor in silica gel, is shown in Eqs. (B11) and (B12). At the beginning of the desorption process, the Qdes is used as36,37
Qdes=Pevap×k0×expQisosRv×TAD,1.
(B11)
At the beginning of the adsorption process, Qads is used as36,37
Qads=Pcond×k0×expQisosRv×TAD,2.
(B12)
The mass of the adsorbent for two beds that is required to adsorb the vapor exiting the last MED stage in one cycle,36,37
msg=mv,n×tQdesQads.
(B13)
In Eqs. (B10)(B13), t is the simulation time for water production, k0 is the adsorption constant, Rv is the gas constant of water vapor, and Qisos refers to the heat transfer of the isosteric process. The heat transfer of an isosteric process refers to the transfer of heat in a system where the pressure remains constant. The power needed by the pumps, which corresponds to the work performed, can be computed as follows:37,
Ẇpump=j=1nV̇jΔPjηpump.
(B14)
Here, V̇j represents the volume flow rate passing through the jth pump, measured in m3/s, and ΔPj denotes the pressure gradient of the relevant pump in kPa. The efficiency of a designed system is often described using GOR, which is a widely accepted performance parameter. GOR is determined using Eq. (B15), where D represents the total distillate flow rate in kg/s and ṁs represents the mass flow rate of inlet steam in kg/s,37 
GOR=Dṁs.
(B15)
Specific heat consumption (SHC) is a significant performance parameter that represents the amount of heat energy necessary to produce 1 kg of distillate. It is calculated by dividing the vapor enthalpy (kJ/kg) at a saturation temperature of steam (usually around 50 °C) by GOR and is expressed as the following equation:37 
SHC=2330GOR.
(B16)
To analyze the input energies of a desalination system, the concept of specific energy consumption is utilized. It combines energies of different grades and provides a single value, denoted as Win,37 
Ẇin=Ẇpump.
(B17)
In a PV/T system, the thermal energy is converted into equivalent electrical energy, which can be added to the pumps’ power Ẇpump. Finally, the energy in kW is converted to kW h/m3,37,
SEC=Ẇin3600V̇p.
(B18)
The second law analysis relies on an exergy balance and asserts that the difference between the summation of fuel and product exergy is equal to the sum of exergy destruction and exergy loss,38,
ẊProduct=ẊfuelXDXLXout,
(B19)
where Xout = XelXth. Where Xout, Xel, and Xth are the exergy of output, electrical (power), and thermal, respectively. Xth can be defined by Xth = Q × (1 − Ta/Tc). Ta is the ambient temperature achieved from experimental data. The solar panel temperature (Tc) is determined using a CFD approach, and the heat transfer (Q) from the glass cover to the heat exchanger is calculated through CFD work. The exergy of the inlet stream represents the fuel for the auxiliary heat source chamber, while the useful product’s exergy is solely the distillate. Exergy destruction refers to the work lost due to irreversibility, while exergy loss describes the work lost from rejected streams carrying exergy. The second law of efficiency is determined by comparing the exergy of the useful product to the total exergy input, which includes thermal and electrical inputs,
ηII=ẊProductẊauxiliary+Ẋin,
(B20)
where Ẋin=Gt×A×[143×(TaTsun)+13×(TaTsun)4] with Tsun = 6000 K. The exergoeconomic analysis is performed on each component in both configurations. The cost flow method is used to calculate the cost of each flow stream through all components, considering fixed and stream costs. The exergoeconomic model takes inputs such as interest rate, amortization factor, cost index factor, and electricity cost. Stream costs are determined based on the exergy of the flow, and after calculating the fixed cost, all costs are converted into a fixed cost rate. These values are then incorporated into the exergetic costs of each stream,38 
ZAnnual=ZcompAF,
(B21)
where
AF=i(1+i)t(1+i)t1.
(B22)
In this equation, t denotes the plant life in years, and i represents the interest rate. The cost of each component is expressed in $/year (annual fixed cost). However, since the current MED system is based on cost in $/s, the actual cost is calculated using the following equation:38 
Zactual=ZAnnual365×24×3600×Availability.
(B23)
The final product cost in $/s is calculated by summing up the exergo-economic costs of distillate C8, brine C10, cooling water C2, chemical cost, input steam cost C9, operational and maintenance cost (OM), and labor cost (LB), as presented in the following equation:
ĊD=Ċ7+Ċ5+Ċ2+V̇7Cchem+Ċ9+OM+LB.
(B24)
The following equation is used to compute the final product cost in $/m3:
Ċp=ĊDV̇D,$m3.
(B25)
Exergoenvironmental analysis is a technique that uses exergy principles to assess the environmental impact of energy conversion systems. It involves conducting an exergy analysis for each process stream and evaluating the environmental effects of manufacturing. A life cycle assessment (LCA) is used to quantify the environmental aspects of the system. The analysis assumes a 20 year lifetime and 10 000 working hours per year at full capacity. The process involves three phases: exergy analysis, evaluation of manufacturing effects, and prediction of environmental impact using exergo-environmental equations,
Ḃp,k=ḂF,kḂL,k+ϒ̇k,
(B26)
eḂe,k+Ḃω,k=Ḃq,kiḂi,k+ϒ̇k,
(B27)
Ḃi=ḃiẊi.
(B28)
The environmental impact rate associated with the exergy destruction of each system component is given by the following equation:39,
ḂD,k=bF,kXdi.
(B29)
The exergo-environmental factor for each piece of equipment can be calculated using the following equation:39,
fbk=ϒ̇kϒ̇k+bF,k.Xdi.
(B30)
The environmental impact of each piece of equipment can be determined by the following equation:39 
yk=ωkbmk.
(B31)

The environmental impact of the equipment, measured in points (pts), is denoted as yk, while the weight of the equipment in tons is represented by ωk. The environmental impact per mass unit of the equipment, measured in pts/ton, is indicated by bmk. This value is determined by the material utilized in the manufacturing process of the various components of the system.

Our study validated the thermodynamic analysis by comparing it with previous research, showing close agreement and consistent calculations (Tables IVVI). The integration of the Multi-Effect Distillation (MED) and Adsorption–Desorption (AD) systems in the MEDAD system significantly increased desalinated water production compared to the MED system alone. Our proposed system, incorporating a PV/T system for electricity production and water preheating, enhanced the existing configuration for potable water production. The model assumed steady-state operation with minimal losses and negligible energy losses to the environment.

TABLE IV.

Validation of results for MED with Ghenai et al.36 

ParameterReference 36, MEDPresent work, MED
Number of stages 
HTF inlet temperature to the desalination unit (°C) 80 80 
Volumetric flow rate of desalinated water (m3/h) 0.0369 0.0370 
Required power for the desalination (kW) 5.3311 5.3141 
Specific energy consumption SEC (kW h/m3144.4743 145.1254 
Performance ratio PR 4.67 4.68 
ParameterReference 36, MEDPresent work, MED
Number of stages 
HTF inlet temperature to the desalination unit (°C) 80 80 
Volumetric flow rate of desalinated water (m3/h) 0.0369 0.0370 
Required power for the desalination (kW) 5.3311 5.3141 
Specific energy consumption SEC (kW h/m3144.4743 145.1254 
Performance ratio PR 4.67 4.68 
TABLE V.

Validation of results for MEDAD with Ghenai et al.36 

ParameterReference 36, MEDADPresent work, MEDAD
Number of stages 
HTF inlet temperature to the desalination unit (°C) 80 80 
Volumetric flow rate of desalinated water (m3/h) 0.0989 0.0991 
Required power for the desalination (kW) 6.0313 6.0325 
Specific energy consumption SEC (kW h/m360.98 61.04 
Performance ratio PR 11.0783 11.09 
ParameterReference 36, MEDADPresent work, MEDAD
Number of stages 
HTF inlet temperature to the desalination unit (°C) 80 80 
Volumetric flow rate of desalinated water (m3/h) 0.0989 0.0991 
Required power for the desalination (kW) 6.0313 6.0325 
Specific energy consumption SEC (kW h/m360.98 61.04 
Performance ratio PR 11.0783 11.09 
TABLE VI.

Validation of results for MED exergy-economic parameters with Abid et al.38 

ParameterReference 38, MEDPresent work, MED
Distillate production (D) (kg/s) 50.49 50 
Gain output ratio (GOR) 3.595 3.421 
Brine flow (B) (kg/s) 98.006 98.51 
Feed flow (F) (kg/s) 148.5 148.5 
Specific heat consumption (SHC) (kJ/kg) 648.1 645.2 
Specific energy consumption (SEC) (kW h/m310.22 10.53 
Second law efficiency (%) 7.405 7.421 
Product cost ($/m32.823 2.921 
System exergy destruction (kW) 2859 2858 
ParameterReference 38, MEDPresent work, MED
Distillate production (D) (kg/s) 50.49 50 
Gain output ratio (GOR) 3.595 3.421 
Brine flow (B) (kg/s) 98.006 98.51 
Feed flow (F) (kg/s) 148.5 148.5 
Specific heat consumption (SHC) (kJ/kg) 648.1 645.2 
Specific energy consumption (SEC) (kW h/m310.22 10.53 
Second law efficiency (%) 7.405 7.421 
Product cost ($/m32.823 2.921 
System exergy destruction (kW) 2859 2858 
1.
K.
Krisciunas
, “
How solar panels work, in theory and in practice
,”
AIP Adv.
13
(
8
),
085222
(
2023
).
2.
D.
Parajuli
,
G. S.
Gaudel
,
D.
KC
,
K. B.
Khattri
, and
W. Y.
Rho
, “
Simulation study of TiO2 single layer anti-reflection coating for GaAs solar cell
,”
AIP Adv.
13
(
8
),
085002
(
2023
).
3.
L. A.
Omeiza
,
M.
Abid
,
A.
Dhanasekaran
,
Y.
Subramanian
,
V.
Raj
,
K.
Kozak
,
U.
Mamudu
, and
A. K.
Azad
, “
Application of solar thermal collectors for energy consumption in public buildings—An updated technical review
,”
J. Eng. Res.
(
published online, 2023
).
4.
M.
Boussaid
,
A.
Belghachi
,
K.
Agroui
, and
N.
Djarfour
, “
Mathematical models of photovoltaic modules degradation in desert environment
,”
AIMS Energy
7
(
2
),
127
140
(
2019
).
5.
R. K.
Koech
,
R.
Ichwani
,
J. L.
Martin
,
D. O.
Oyewole
,
O. V.
Oyelade
,
Y. A.
Olanrewaju
,
D. M.
Sanni
,
S. A.
Adeniji
,
R. L.
Grimm
,
A.
Bello
,
O. K.
Oyewole
,
E.
Ntsoenzok
, and
W. O.
Soboyejo
, “
A study of the effects of a thermally evaporated nanoscale CsBr layer on the optoelectronic properties and stability of formamidinium-rich perovskite solar cells
,”
AIP Adv.
11
(
9
),
095112
(
2021
).
6.
M.
Miyoshi
,
T.
Nakabayashi
,
K.
Yamamoto
,
P.
Dalapati
, and
T.
Egawa
, “
Improved epilayer qualities and electrical characteristics for GaInN multiple-quantum-well photovoltaic cells and their operation under artificial sunlight and monochromatic light illuminations
,”
AIP Adv.
11
(
9
),
095208
(
2021
).
7.
S. M.
Sulthan
et al
, “
Development and analysis of a two stage hybrid MPPT algorithm for solar PV systems
,”
Energy Rep.
9
,
1502
1512
(
2023
).
8.
L.
Kunjuramakurup
,
S. M.
Sulthan
,
M. S.
Ponparakkal
,
V.
Raj
, and
M.
Sathyajith
, “
A high-power solar PV-fed TISO DC-DC converter for electric vehicle charging applications
,”
Energies
16
(
5
),
2186
(
2023
).
9.
S.
Bandyopadhyay
,
K.
Dasgupta
,
V.
Arya
,
S.
Mathew
,
I.
Petra
, and
A.
Alias
, “
PV potential in oil and sun rich nations: An experimental case study from Brunei
,” in
Proceedings of the Eighth International Conference on Future Energy Systems
(E-ENERGY,
2017
), pp.
264
265
.
10.
K. M.
Chung
,
T.
Feng
,
J.
Zeng
,
S. R.
Adapa
,
X.
Zhang
,
A. Z.
Zhao
,
Y.
Zhang
,
P.
Li
,
Y.
Zhao
,
J. E.
Garay
, and
R.
Chen
, “
Thermal conductivity measurement using modulated photothermal radiometry for nitrate and chloride molten salts
,”
Int. J. Heat Mass Transfer
217
,
124652
(
2023
).
11.
H.
Ramenah
,
P.
Casin
,
M.
Ba
,
M.
Benne
, and
C.
Tanougast
, “
Accurate determination of parameters relationship for photovoltaic power output by augmented dickey fuller test and Engle Granger method
,”
AIMS Energy
6
(
1
),
19
48
(
2018
).
12.
X.
Yang
,
Z.
Li
,
Y.
Shen
, and
R.
Kuang
, “
Review of studies on enhancing thermal energy grade in the open ocean
,”
J. Renewable Sustainable Energy
14
(
6
),
062701
(
2022
).
13.
J.
Hazra
,
K.
Dasgupta
,
P.
Manikandan
,
A.
Verma
,
S.
Mathew
, and
I.
Petra
, “
Solar PV integration considering grid stability—A case study for the Temburong district in Brunei
,” in
2016 IEEE Power and Energy Society Innovative Smart Grid Technologies Conference (ISGT)
(
IEEE
,
2016
), pp.
1
5
.
14.
I.
Altarawneh
,
M.
Batiha
,
S.
Rawadieh
,
M.
Alnaief
, and
M.
Tarawneh
, “
Solar desalination under concentrated solar flux and reduced pressure conditions
,”
Sol. Energy
206
,
983
996
(
2020
).
15.
A.
El Mansouri
,
M.
Hasnaoui
,
A.
Amahmid
, and
S.
Hasnaoui
, “
Feasibility analysis of reverse osmosis desalination driven by a solar pond in Mediterranean and semi-arid climates
,”
Energy Convers. Manage.
221
,
113190
(
2020
).
16.
C.
Kalkan
,
J.
Duquette
, and
M.
Akif Ezan
, “
Development of a novel computational fluid dynamics-based model for a solar photovoltaic/thermal collector-assisted domestic hot water system with sensible heat storage
,”
Appl. Therm. Eng.
228
,
120424
(
2023
).
17.
M.
Deymi-Dashtebayaz
,
M.
Rezapour
, and
M.
Farahnak
, “
Modeling of a novel nanofluid-based concentrated photovoltaic thermal system coupled with a heat pump cycle (CPVT-HP)
,”
Appl. Therm. Eng.
201
,
117765
(
2022
).
18.
S.
Samiezadeh
,
R.
Khodaverdian
,
M. H.
Doranehgard
,
H.
Chehrmonavari
, and
Q.
Xiong
, “
CFD simulation of thermal performance of hybrid oil-Cu-Al2O3 nanofluid flowing through the porous receiver tube inside a finned parabolic trough solar collector
,”
Sustainable Energy Technol. Assess.
50
,
101888
(
2022
).
19.
A. M.
Bassam
,
K.
Sopian
,
A.
Ibrahim
,
M. F.
Fauzan
,
A. B.
Al-Aasam
, and
G. Y.
Abusaibaa
, “
Experimental analysis for the photovoltaic thermal collector (PVT) with nano PCM and micro-fins tube nanofluid
,”
Case Stud. Therm. Eng.
41
,
102579
(
2023
).
20.
S.
Alsaqoor
,
A.
Alqatamin
,
A.
Alahmer
,
Z.
Nan
,
Y.
Al-Husban
, and
H.
Jouhara
, “
The impact of phase change material on photovoltaic thermal (PVT) systems: A numerical study
,”
Int. J. Thermofluids
18
,
100365
(
2023
).
21.
V.
Sun
,
A.
Asanakham
,
T.
Deethayat
, and
T.
Kiatsiriroat
, “
Performance analysis on combined heat and power of photovoltaic-thermal module integrated with phase change material-water storage
,”
J. Energy Storage
47
,
103614
(
2022
).
22.
M.
Hemmat Esfe
,
M. H.
Kamyab
, and
M.
Valadkhani
, “
Application of nanofluids and fluids in photovoltaic thermal system: An updated review
,”
Sol. Energy
199
,
796
818
(
2020
).
23.
M. F.
Suzuki Valenzuela
,
F.
Sánchez Soto
,
M. M.
Armendáriz-Ontiveros
,
I. M.
Sosa-Tinoco
, and
G. A.
Fimbres Weihs
, “
Improving thermal distribution in water-cooled PV modules and its effect on RO permeate recovery
,”
Water
13
(
2
),
229
(
2021
).
24.
A.
Khelifa
,
K.
Touafek
,
H.
Ben Moussa
,
I.
Tabet
,
H.
Ben cheikh El hocine
, and
H.
Haloui
, “
Analysis of a hybrid solar collector photovoltaic thermal (PVT)
,”
Energy Procedia
74
,
835
843
(
2015
).
25.
A.
Herez
,
H.
El Hage
,
T.
Lemenand
,
M.
Ramadan
, and
M.
Khaled
, “
Review on photovoltaic/thermal hybrid solar collectors: Classifications, applications and new systems
,”
Sol. Energy
207
,
1321
1347
(
2020
).
26.
F.
Meng
,
Z.
Jiang
, and
M.
Yan
, “
A novel method for measuring latent heat of low-temperature PCM phase transition by oxygen bomb calorimeter
,”
AIP Adv.
12
(
8
),
085120
(
2022
).
27.
J.
Allan
,
H.
Pinder
, and
Z.
Dehouche
, “
Enhancing the thermal conductivity of ethylene-vinyl acetate (EVA) in a photovoltaic thermal collector
,”
AIP Adv.
6
(
3
),
035011
(
2016
).
28.
M. S. H.
Choudhury
,
S. E.
Ahmed Himu
,
M. U.
Khan
,
M. Z.
Hasan
,
M. S.
Alam
, and
T.
Soga
, “
Analysis of charge transport resistance of ZnO-based DSSCs because of the effect of different compression temperatures
,”
AIP Adv.
13
(
9
),
095129
(
2023
).
29.
R. M.
Ko
,
S. J.
Wang
,
S. J.
Huang
,
C. H.
Wu
,
W. H.
Chen
, and
H. C.
Cheng
, “
Enhancing photodetection performance of UV photodetectors with stacked Pt/NiO dual capping layers on IGZO thin-film transistors
,”
AIP Adv.
13
(
7
),
075307
(
2023
).
30.
S. A.
Kadhim
,
M. K.
Al-Ghezi
, and
W. Y.
Shehab
, “
Optimum orientation of non-tracking solar applications in Baghdad city
,”
Int. J. Heat Technol.
41
(
1
),
125
(
2023
).
31.
S.
Alqaed
,
J.
Mustafa
,
F. A.
Almehmadi
,
M. A.
Alharthi
,
M.
Sharifpur
, and
G.
Cheraghian
, “
Machine learning-based approach for modeling the nanofluid flow in a solar thermal panel in the presence of phase change materials
,”
Processes
10
(
11
),
2291
(
2022
).
32.
A.
Nazari
,
M.
Jafari
,
N.
Rezaei
,
F.
Taghizadeh-Hesary
, and
F.
Taghizadeh-Hesary
, “
Jet fans in the underground car parking areas and virus transmission
,”
Phys. Fluids
33
(
1
),
013603
(
2021
).
33.
Y. S.
Ranjbaran
,
M. H.
Shojaeefard
, and
G. R.
Molaeimanesh
, “
Thermal performance enhancement of a passive battery thermal management system based on phase change material using cold air passageways for lithium batteries
,”
J. Energy Storage
68
,
107744
(
2023
).
34.
M. H.
Shojaeefard
,
N. B.
Sakran
,
M. M.
Sharfabadi
,
O. A.
Hussein
, and
H. A.
Mohammed
, “
Experimental and numerical investigation of the effect of water cooling on the temperature distribution of photovoltaic modules using copper pipes
,”
Energies
16
(
10
),
4102
(
2023
).
35.
H. M.
Taqi Al-Najjar
and
J. M.
Mahdi
, “
Novel mathematical modeling, performance analysis, and design charts for the typical hybrid photovoltaic/phase-change material (PV/PCM) system
,”
Appl. Energy
315
,
119027
(
2022
).
36.
C.
Ghenai
,
D.
Kabakebji
,
I.
Douba
, and
A.
Yassin
, “
Performance analysis and optimization of hybrid multi-effect distillation adsorption desalination system powered with solar thermal energy for high salinity sea water
,”
Energy
215
,
119212
(
2021
).
37.
M. A.
Jamil
and
S. M.
Zubair
, “
Effect of feed flow arrangement and number of evaporators on the performance of multi-effect mechanical vapor compression desalination systems
,”
Desalination
429
,
76
87
(
2018
).
38.
A.
Abid
,
M. A.
Jamil
,
N. u.
Sabah
,
M. U.
Farooq
,
H.
Yaqoob
,
L. A.
Khan
, and
M. W.
Shahzad
, “
Exergoeconomic optimization of a forward feed multi-effect desalination system with and without energy recovery
,”
Desalination
499
,
114808
(
2021
).
39.
M. H.
Khoshgoftar Manesh
,
R. S.
Ghadikolaei
,
H. V.
Modabber
, and
V. C.
Onishi
, “
Integration of a combined cycle power plant with MED-RO desalination based on conventional and advanced exergy, exergoeconomic, and exergoenvironmental analyses
,”
Processes
9
(
1
),
59
(
2020
).