Absorption refrigeration systems powered by solar energy increasingly attract research interests in the last years. In this study, thermodynamic analyses for different working fluid pairs are performed.
A computer simulation model has been developed to predict the performance of solar absorption refrigeration system using different working fluid. The model is based on detailed mass and energy balance and heat and mass transfer for the cycle component.
Detailed thermodynamic properties for ammonia-water, ammonia-lithium nitrate and ammonia-sodium thiocyanate are expressed in polynomial equations and used in cycle simulation. The performances of these three cycles against various generator, evaporator, and condenser temperatures are compared. The results show that the ammonia-lithium nitrate and ammonia-sodium thiocyanate cycles give better performance than the ammonia-water cycle.
The ammonia-sodium thiocyanate cycle cannot operate at evaporator temperatures below -10°C for the possibility of crystallization. Increasing condenser temperatures cause a decrease in system performance for each cycle. With the increase in evaporator temperature, the COP values for each cycle increase.
These results can serve as a source of reference for developing new cycles and searching for new working fluids pairs. They can also be used in selecting operating conditions for existing systems and achieving automatic control for maintain optimum operation of the system.
Source: North Atlantic University Union
Authors: Jasim M. Abdulateef, Kamaruzzaman Sopian, M. A. Alghoul, Mohd Yusof Sulaiman, Azami Zaharim and Ibrahim Ahmad