Abstract:
Adsorption chillers are a favorable choice for solar based cooling system because of driving
lower range of 50-85°C temperatures and therefore simple inexpensive flat plate solar
collectors (FPC’s) can also furnish the desired energy. In this study three system
configurations are analyzed to achieve 13 TR cooling demand load for an Islamabad (33.71°
N, 73.06° E) located building for office. In configuration-I (C-I) returning fluid from
adsorption chiller moves towards the hot water storage tank (HWST) connected to solar
thermal collector whereas in configuration-II (C-II) returning fluid from adsorption chiller
may be diverted from collector-HWST loop if temperature of water in HWST is less than the
required temperature (i.e. 85°C). In third configuration C-III, HWST is not used. Therefore
hot water from the outlet of solar collector directly enters in the auxilary heater (which will
be switched on if required else off) and return water from adsorption chiller will become inlet
of solar collector. The three system configurations are modeled and simulated in TRNSYS
for the whole summer season to investigate the optimum collector tilt, least collector area for
maximum solar fraction (SF), fractional primary energy savings (ƒPES) and monthly solar
collector’s thermal efficiency. Simulation results showed that C-I gives comparatively higher
collector thermal efficiency and ƒPES. For configurations C-I and C-II, the minimum required
collector’s area for FPC is estimated to be 250 m² which is reduced to 150 m² for evacuated
tube collector (ETC) and corresponding to those areas optimized size of HWST is estimated
to be 10000 and 4500 liters for FPC and ETC respectively. For both collectors maximum
seasonal solar fraction is obtained at a collector tilt of approximately 13°. C-III gives
comparatively higher solar collector’s thermal efficiency as compare to C-I and C-II but C-III
has comparatively low values of SF and ƒPES as compare to configuration-II and
configuration-I for same FPC and ETC areas of 250 m² and 150 m² respectively.
