Comparative analysis between constant pressure and constant temperature absorption processes for an intermittent solar refrigerator

•Comparing constant pressure & temperature intermittent solar absorption systems.•Constant pressure system has 20% higher COP than constant temperature system.•Optimum generator temperature for constant pressure system is 12% higher.•Constant pressure & temperature systems have same COP below critical temperature.

This paper presents a detailed comparative analysis between constant pressure and constant temperature aqua-ammonia absorption processes for an intermittent solar refrigerator. The results of the analysis indicate that constant pressure processes results in as high as 20% increase in coefficient of performance compared to constant temperature processes. Also, the results indicate that there is a critical temperature below which both the constant pressure and constant temperature processes exhibit the same performance. Furthermore, it has been observed that the optimum generator temperature for constant pressure processes is approximately 12% higher than constant temperature processes. Finally, the effect of maintaining a constant temperature or constant pressure absorption processes on the heat duties of both, the absorber and the evaporator, is addressed in the paper.