Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
645283 | Applied Thermal Engineering | 2015 | 12 Pages |
Abstract
Integrated-average temperature difference (ÎTave) was proposed to connect with exergy destruction (Ieva) in heat exchangers. Theoretical expressions were developed for ÎTave and Ieva. Based on transcritical pressure ORCs, evaporators were theoretically studied regarding ÎTave. An exact linear relationship between ÎTave and Ieva was identified. The increased specific heats versus temperatures for organic fluid protruded its T-Q curve to decrease ÎTave. Meanwhile, the decreased specific heats concaved its T-Q curve to raise ÎTave. Organic fluid in the evaporator undergoes a protruded T-Q curve and a concaved T-Q curve, interfaced at the pseudo-critical temperature point. Elongating the specific heat increment section and shortening the specific heat decrease section improved the cycle performance. Thus, the system thermal and exergy efficiencies were increased by increasing critical temperatures for 25 organic fluids. Wet fluids had larger thermal and exergy efficiencies than dry fluids, due to the fact that wet fluids shortened the superheated vapor flow section in condensers.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
Chao Yu, Jinliang Xu, Yasong Sun,