Performance analysis of advanced hybrid GAX cycles: HGAX

The objectives of this paper are to develop advanced hybrid GAX cycles (HGAX) using NH3–H2O by combining absorption and vapor compression cycles, and to perform parametric analysis of system pressures and component sizes for performance enhancement. Four different HGAX cycles are developed—Type A (Performance improvement), Type B (Low temperature applications) Type C (Reduction of desorption temperature) and Type D (Hot water temperature applications). A compressor is placed between the evaporator and the absorber in Type A and Type B, and placed between the desorber and the condenser in Type C and Type D. It is found that the COP can be improved by 24% compared with the standard GAX cycle (in Type A) and the evaporation temperature of as low as −80 °C can be obtained from the HGAX cycle (Type B). In Type C, the maximum desorption temperature can be reduced down to 164 °C. Therefore, the corrosion problem, which becomes severe at higher temperature 200 °C, can be completely removed. The maximum desorption temperature for the standard GAX cycle ranges 190–200 °C. In Type D, the hot water temperature of as high as 106 °C could be obtained. Therefore, Type D can be applied for space heating and panel or floor heating applications.