An advanced GAX cycle for waste heat recovery WGAX cycle

The objectives of this paper are to develop an advanced generator absorber heat exchanger cycle (WGAX) to reduce the generator exit temperature as low as possible using waste heat sources, and to compare it with the standard GAX cycle (SGAX). This paper performed parametric analysis to study the effects of the waste heat source temperature (T-w) and the outlet temperature of a gas fired desorber (GFD), T-g, on the cycle performance. Three different WGAX cycles (type A, type B and type C) were compared from the viewpoint of performance improvement. It was found that the effect of the waste heat source temperature (T-w) on coefficient of performance (COP)s was negligible for a given GFD outlet temperature in the WGAX cycles. The GFD outlet temperature could be reduced down to 172 degrees C with a higher COPbeta of WGAX cycle than the COP of the SGAX cycle. Therefore, the corrosion problem in the SGAX cycle at a higher T-g than 200 degrees C will be solved by adopting the WGAX cycles with a comparable COP. Type A had a merit from the viewpoint of the GAX effect while Type B had a merit from the viewpoint of exergy loss effect. In the WGAX cycles developed in this study, the GAX effect was dominant for a lower temperature than 181 degrees C while the effect of exergy loss was dominant for a higher temperature than 181 degrees C. It is found that the solution heated desorber should be placed below the GAXD to improve the cycle performance in the WGAX cycles. It is strongly recommended that there be a subcooling effect in the weak solution for cycle performance enhancement in the WGAX systems. (C) 1999 Elsevier Science Ltd. All rights reserved.