Energy and exergy analyses of GAX and GAX hybrid absorption refrigeration cycles

In this paper, the GAX and GAX hybrid absorption refrigeration cycles are studied and compared from the viewpoint of both first and second law of thermodynamics. Exergy analyses were performed in order to calculate the total exergy destruction rate within the cycles and also reveal the contribution of different components to the destructions. In order to evaluate the efficiencies of the cycles at different working conditions, particularly from the viewpoint of the second law, parametric studies were also performed. It was found that in both cycles the generator temperature (Tgen) has more influence on the second law efficiency whereas, the coefficient of performance (COP) of the cycles are comparatively less affected by this temperature. An increase of about 75% in the second law efficiency of the GAX cycle was found as the generator temperature was varied from 400 to 440 K. With this variation of the generator temperature, the increase in the corresponding COP was around 5%. In addition, compared to that in the GAX cycle, the maximum value of exergetic efficiency in the GAX hybrid cycle occurs at a slightly higher value of Tgen.

Research highlights
► In this paper, the GAX and GAX hybrid absorption refrigeration cycles are studied and compared from the view point of both first and second law of thermodynamics.
► It was found that in both cycles the generator temperature (Tgen ) has more influence on the second law efficiency whereas, the coefficient of performance (COP) of the cycles are comparatively less affected by this temperature.
► In addition, compared to that in the GAX cycle, the maximum value of exergetic efficiency in the GAX hybrid cycle occurs at a slightly higher value of Tgen.