地热驱动氨水吸收式动力/制冷复合循环参数优化分析

Optimization and Analysis of Ammonia-Water Absorption Power/Cooling Integrated Cycle with Geothermal Energy

针对中低品位地热驱动的氨水吸收式动力/制冷复合循环的热力学性能展开分析与优化,在Kalina循环的基础上利用氨水变温蒸发的特性,将正向动力子过程与逆向制冷子过程耦合,对外实现动力与冷量的联供。本文对影响复合循环热力性能的工质对浓度xw/xb、氨水发生温度(露点温度)t14、循环倍率K以及分流比n四个重要参数展开了分析优化。研究表明,在xw/xb=0.50/0.32、t14=180℃、K=2.80和n=0.505的优化工况下,复合循环的热效率和?效率分别可达19.38%和59.77%,较氨水动力循环分别高出3.71%和4.74%,较水蒸气朗肯循环分别高出8.54%和35.81%。

Analysis and optimization on thermodynamic performance of the ammonia-water absorption power/coolingintegrated cycle driven by mid- or low-grade geothermal energy were conducted in this study. Based on the Kalina cycle,by applying the evaporation characteristic of ammonia-water, the forward power sub-process was combined with thereverse refrigeration sub-process, which realized the hybrid generation of power and cooling capacity simultaneously. Fourmain parameters were analyzed on their effect on the thermal performance of the integrated cycle, including the workingfluid concentration xw/xb, ammonia dew-point temperature t14, circulation ratio K, and chilling fraction n. The result showedthat under the optimal condition, (xw/xb=0.50/0.32, t14=180℃, K=2.80 and n=0.505), the thermal efficiency of theintegrated cycle could reach up to 19.38%, which is 3.71% higher than that of ammonia-water power cycle and 8.54% thanthat of Rankine cycle, repectively. Besides, the integrated cycle presented much higher exergy efficiency of 59.77%comparing with the other two cycles.