This work pertains to the transient modeling and comparative study of active solar thermal space and water heating systems using liquid and air-type solar thermal collectors as the main energy source. The study utilizes TRNSYS to simulate the two systems in the context of Taxila's weather data (located at 33.74°N, 72.83°E), with the goal of meeting peak space and domestic water heating demands of 20 kW and 200 lit/day, respectively. The liquid water-based system (S-1) is primarily composed of a liquid solar collector, thermal storage, an auxiliary heater, connections to the hot water supply, and the space heating load through a water–air heat exchanger. In contrast, the air-based system (S-2), employs a pebble bed storage to store heat extracted from the solar thermal air collector. The heated air is subsequently used directly for space heating and passed through an air–water heat exchanger for water heating. Dynamic simulations of both systems span the entire winter season, and various performance metrics, including solar fraction, primary energy savings, and solar collector thermal efficiency, are computed. The results revealed that at the same collector area, the liquid water-based system (S-1) shows a higher solar fraction than the air-based systems (S-2) while the primary energy savings of the S-1 resulted in lower values than S-2 at smaller collector areas (< ∼30 m2) but surpasses the S-2 with increasing collector size. The optimal collector tilt for both systems is determined to be 50°, while specific storage volumes corresponding to maximum primary energy savings are estimated to be 100 and 40 L/m2 for S-1 and S-2, respectively.

1.
Abdullah
,
Zhou
,
D.
,
Shah
,
T.
,
Jebran
,
K.
,
Ali
,
S.
,
Ali
,
A.
, and
Ali
,
A.
, “
Acceptance and willingness to pay for solar home system: Survey evidence from Northern Area of Pakistan
,”
Energy Rep.
3
,
54
60
(
2017
).
2.
Assareh
,
E.
,
Mousavi Asl
,
S. S.
,
Ahmadinejad
,
M.
,
Parvaz
,
M.
, and
Ghodrat
,
M.
, “
Optimization of a solar energy system integrating cooling, hot water, and power units in Australian cities: A climate-based analysis and cost-efficiency investigation
,”
Int. J. Hydrogen Energy
(published online 2023).
3.
Bellos
,
E.
,
Tzivanidis
,
C.
,
Moschos
,
K.
, and
Antonopoulos
,
K. A.
, “
Energetic and financial evaluation of solar assisted heat pump space heating systems
,”
Energy Convers. Manage.
120
,
306
319
(
2016
).
4.
Borhani
,
S.
,
Kasaeian
,
A.
,
Pourmoghadam
,
P.
, and
Omid
,
M.
, “
Regional performance evaluation of solar combined cooling heating and power systems for household demands
,”
Appl. Therm. Eng.
230
(
PA
),
120666
(
2023
).
5.
Duffie
,
J. A.
and
Beckman
,
W. A.
,
Solar Engineering of Thermal Processes
, 4th ed. (
John Wiley & Sons
,
2013
), Vol.
9
.
6.
Farooq
,
A. S.
and
Zhang
,
P.
, “
Technical assessment, economic viability, and environmental impact of a solar-driven integrated space and water heating system in various configurations
,”
Energy Sustainable Dev.
71
,
330
340
(
2022
).
7.
Flynn
,
C.
and
Sirén
,
K.
, “
Influence of location and design on the performance of a solar district heating system equipped with borehole seasonal storage
,”
Renewable Energy
81
,
377
388
(
2015
).
8.
Fong
,
K. F.
,
Chow
,
T. T.
,
Lee
,
C. K.
,
Lin
,
Z.
, and
Chan
,
L. S.
, “
Comparative study of different solar cooling systems for buildings in subtropical city
,”
Sol. Energy
84
(
2
),
227
244
(
2010
).
9.
Furbo
,
S.
,
Wang
,
Z.
, and
Deng
,
J.
, “
Simulation and optimization study on a solar space heating system residential houses in Beijing
,”
Energy Build.
126
,
2
13
(
2016
).
10.
Guo
,
S.
,
Zhao
,
J.
,
Wang
,
W.
,
Yan
,
J.
,
Jin
,
G.
, and
Wang
,
X.
, “
Techno-economic assessment of mobilized thermal energy storage for distributed users: A case study in China
,”
Appl. Energy
194
,
481
486
(
2017
).
11.
Jaber
,
J. O.
,
Jaber
,
Q. M.
,
Sawalha
,
S. A.
, and
Mohsen
,
M. S.
, “
Evaluation of conventional and renewable energy sources for space heating in the household sector
,”
Renewable Sustainable Energy Rev.
12
(
1
),
278
289
(
2008
).
12.
Ji
,
J.
,
Luo
,
C.
,
Chow
,
T-t.
,
Sun
,
W.
, and
He
,
W.
, “
Thermal characteristics of a building-integrated dual-function solar collector in water heating mode with natural circulation
,”
Energy
36
(
1
),
566
574
(
2011
).
13.
Li
,
H.
,
Sun
,
L.
, and
Zhang
,
Y.
, “
Performance investigation of a combined solar thermal heat pump heating system
,”
Appl. Therm. Eng.
71
(
1
),
460
468
(
2014
).
14.
Li
,
T.
,
Liu
,
Q.
,
Liu
,
L.
,
Li
,
Y.
,
Yu
,
J.
, and
Wang
,
X.
, “
Case studies in thermal engineering feasibility study on solar coupled gas-fired boiler heating system retrofit in residential buildings in the HSCW zone of China
,”
Case Stud. Therm. Eng.
42
,
102698
(
2023
).
15.
Ma
,
Y.
,
Xi
,
J.
,
Cai
,
J.
, and
Gu
,
Z.
, “
TRNSYS simulation study of the operational energy characteristics of a hot water supply system for the integrated design of solar coupled air source heat pumps
,”
Chemosphere
338
,
139453
(
2023
).
16.
Mahfuz
,
M. H.
,
Anisur
,
M. R.
,
Kibria
,
M. A.
,
Saidur
,
R.
, and
Metselaar
,
I. H.
, “
Performance investigation of thermal energy storage system with phase change material (PCM) for solar water heating application
,”
Int. Commun. Heat Mass Transfer
57
,
132
139
(
2014
).
17.
Mazarrón
,
F. R.
,
Porras-prieto
,
C. J.
,
Luis García
,
J.
, and
Benavente
,
R. M.
, “
Feasibility of active solar water heating systems with evacuated tube collector at different operational water temperatures
,”
Energy Convers. Manage.
113
,
16
26
(
2016
).
18.
Minh
,
N.
,
Ba
,
P.
, and
Van Hap
,
N.
, “
Effective efficiency assessment of a solar air heater having baffles spaced with different successive ratios
,”
Case Stud. Therm. Eng.
28
,
101486
(
2021
).
19.
Mohammad
,
A. T.
, “
Design and analysis of solar space heating system in Iraq
,”
Int. J. Therm. Environ. Eng.
15
(
1
),
51
56
(
2017
).
20.
Nemś
,
M.
,
Kasperski
,
J.
,
Nemś
,
A.
, and
Bać
,
A.
, “
Validation of a new concept of a solar air heating system with a long-term granite storage bed for a single-family house
,”
Appl. Energy
215
,
384
395
(
2018
).
21.
Product Overview FPC-A
, see https://www.apricus.com/upload/userfiles/downloads/Apriucs_FPC-A_Collector_Inst_Manual.pdf
for “
Product overview FPC-A flat plate solar collector delivering sustainable hot water solutions
(
2013
),”
22.
Siampour
,
L.
,
Vahdatpour
,
S.
,
Jahangiri
,
M.
,
Mostafaeipour
,
A.
,
Goli
,
A.
,
Alidadi
,
A.
, and
Atabani
,
A.
, “
Techno-enviro assessment and ranking of turkey for use of home-scale solar water heaters
,”
Sustainable Energy Technol. Assess.
43
,
100948
(
2021
).
23.
Sohani
,
A.
,
Rezapour
,
S.
, and
Sayyaadi
,
H.
, “
Comprehensive performance evaluation and demands' sensitivity analysis of different optimum sizing strategies for a combined cooling, heating, and power system
,”
J. Cleaner Prod.
279
,
123225
(
2021
).
24.
Sparber
,
W.
,
Besana
,
F.
,
Streicher
,
W.
, and
Henning
,
H-M.
, “
Introduction/monitoring procedure
,” in
1st International Conference on Solar Heating, Cooling and Buildings, Lisbon
, 7–10 October 2008 (Eurosun, 2008), Vol. 6, pp.
1
54
.
25.
Stanciu
,
C.
and
Stanciu
,
D.
, “
Optimum tilt angle for flat plate collectors all over the world—A declination dependence formula and comparisons of three solar radiation models
,”
Energy Convers. Manage.
81
,
133
143
(
2014
).
26.
TRNSYS
, “
TRNSYS 18 manual
,” in
A Transient System Simulation Program
(
Solar Energy Laboratory, University of Wisconsin
,
Madison, WI
,
2018
).
27.
Tzivanidis
,
C.
,
Bellos
,
E.
,
Mitsopoulos
,
G.
,
Antonopoulos
,
K. A.
, and
Delis
,
A.
, “
Energetic and financial evaluation of a solar assisted heat pump heating system with other usual heating systems in Athens coefficient of performance
,”
Appl. Therm. Eng.
106
,
87
97
(
2016
).
28.
Vengadesan
,
E.
,
Bharathwaj
,
D.
,
Kumar
,
B. S.
, and
Senthil
,
R.
, “
Experimental study on heat storage integrated flat plate solar collector for combined water and air heating in buildings
,”
Appl. Therm. Eng.
216
,
119105
(
2022
).
29.
Wan
,
K. K. W.
,
Li
,
D. H. W.
,
Liu
,
D.
, and
Lam
,
J. C.
, “
Future trends of building heating and cooling loads and energy consumption in different climates
,”
Build. Environ.
46
(
1
),
223
234
(
2011
).
30.
Xi
,
C.
,
Lin
,
L.
, and
Hongxing
,
Y.
, “
Long term operation of a solar assisted ground coupled heat pump system for space heating and domestic hot water
,”
Energy Build.
43
(
8
),
1835
1844
(
2011
).
31.
Zhao
,
D. L.
,
Li
,
Y.
,
Dai
,
Y. J.
, and
Wang
,
R. Z.
, “
Optimal study of a solar air heating system with pebble bed energy storage
,”
Energy Convers. Manage.
52
(
6
),
2392
2400
(
2011
).
32.
Zhao
,
Y.
,
Zhang
,
X.
, and
Xu
,
X.
, “
Application and research progress of cold storage technology in cold chain transportation and distribution
,”
J. Therm. Anal. Calorim.
139
(
2
),
1419
1434
(
2020
).
33.
Zhou
,
X.
,
Sui
,
Z.
, and
Wang
,
X.
, “
Research on the performance of solar space heating systems using photovoltaic-thermal collectors
,”
Appl. Sol. Energy
59
(
1
),
48
63
(
2023
).
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