Abstract:

Recently, the extensive use of heating, ventilation and air conditioning systems contribute 50% of building consumption, which causes the rapid growth of building consumption. Absorption cycle, which uses low grade energy likes solar heat energy and industrial heat to generate cooling effect, could lower the large amount of high grade electric power for cooling demand in summer. The most common working pair used in absorption chiller, i.e. LiBr-H₂O, owes the highest COP but has narrow evaporation temperature range and high crystallization risk, making the limitation for miniaturization and air-cooled design. Although the NH₃-H₂O can operate in wide range of evaporation temperature, the rectifier is indispensable for increasing the concentration of ammonia gas, that is disadvantageous to performance. The new working pair NH₃-LiNO₃ has a crystallization temperature which is much higher than that of LiBr-H₂O. And the chiller uses it as working medium operates without rectifier. In addition, the high pressure of ammonia gas makes the cycle using it is more suitable to coupled with compressor for performance improvement and operation temperature widening. Therefore, the performance analysis of absorption heat recovering cycle with high-pressure booster using NH₃-LiNO₃ as the working pair was carried out in this paper, to deeply research the improvement effect of the compressor introduction. As shown in results, with the assist of compressor, the driven temperature of the new cycle can decline to 34℃, and the evaporation temperature decreases to -34℃ as well. Furthermore, the circulating ratio reduced by 52.16%, which means the adaptability for miniaturization and air-cooled design.

Key words: NH₃-LiNO₃, pressure booster, performance analysis, absorption, numerical analysis, compressor

摘要：

近年来，日益增长的暖通空调系统能耗已接近50%的建筑能源消费量。吸收式循环可使用太阳能热能、工业废热等低品位能源产生制冷效果，进而降低夏季制冷负荷对高品味电能的大量需求。当前常用于吸收制冷循环的LiBr-H₂O工质对虽然COP较高，但由于物性限制了其蒸发温度范围以及存在较高的结晶风险，使得系统小型风冷设计存在限制。氨水工质对具有较宽的制冷温区，但由于需要精馏以提高氨气浓度造成COP较低。NH₃-LiNO₃工质对无须增设精馏器，结晶温度远高于LiBr-H₂O，且氨气压力较高适合在耦合压缩机循环以提升循环性能，扩宽运行温区。因此，本研究提出压缩机辅助的增压型回热吸收循环使用NH₃-LiNO₃工质对，并对其进行热力分析，研究压缩机的引入对循环性能的改进作用。结果显示，压缩机辅助作用下循环驱动温度下降至34℃，蒸发温度亦可降低至-34℃，且循环倍率降低了52.16%，更适于小型风冷设计。

关键词: NH₃-LiNO₃, 增压, 性能分析, 吸收, 数值分析, 压缩机