Thermodynamic analysis of mass and heat recovery adsorption refrigeration cycles and scheme selection

doi:10.11949/j.issn.0438-1157.20151803

Abstract

Abstract:

Adsorption refrigeration is an energy-saving and environmental-friendly refrigerating method, which can utilize low-grade thermal energy. Under air-conditioning working conditions, silica gel-water mass and heat recovery systems are most often used. In order to understand which kind of cycle can improve the performance of the system under specific working conditions, the evaluating indicators of the first and the second laws of thermodynamics were adopted to analyze the COP, the exergetic efficiency and the cycle entropy production of the basic cycle, mass recovery cycle and mass and heat recovery cycle. The analysis showed that only when the heating source temperature was relatively low, the COP of mass recovery cycle was remarkably higher than that of basic cycle. The COP of mass and heat recovery cycle was significantly higher than that of mass recovery cycle only when the heating source temperature was relatively high. Consequently, the mass recovery cycle had its recommended highest heating source temperature and optimum heating source temperature, while the mass and heat recovery cycle had its recommended lowest heating source temperature and optimum heating source temperature. For example, under the typical air-conditioning working condition in summer of 90℃ heating source temperature, 10℃ evaporating temperature and 40℃ condensing temperature, the recommended highest heating source temperature of mass recovery cycle was 93℃, which is higher than the heating source temperature of 90℃. As a result, the mass recovery cycle was more suitable under this working condition and should be chosen rather than the mass and heat recovery cycle. Finally, the analysis of a chiller indicated that the given method and recommended working temperature intervals could provide guidance or advice on the scheme selection and system control for real systems.

Key words: adsorption refrigeration, mass and heat recovery, thermodynamics, entropy, exergy

摘要：

吸附式制冷是一种能利用低品位热能的节能环保的制冷方式。在空调工况下,硅胶-水回质回热系统应用最多。为了解在特定工况下选择何种循环能提升系统性能,应用热力学第一与第二定律评价指标分析了基本循环、回质循环、回质回热循环的COP、(火用)效率、循环熵产。分析表明,回质循环存在推荐最高热源温度和最优热源温度,回质回热循环存在推荐最低热源温度和最优热源温度。例如对于典型夏季空调工况热源温度90℃、蒸发温度10℃、冷凝温度40℃,回质循环的推荐最高热源温度为93℃,高于实际热源温度90℃,选用回质循环更合适而非回质回热循环。最后,对制冷机组的分析表明给出的方法和推荐工作温度区间能针对实际系统给出方案优选和系统控制的指导性建议。

关键词: 吸附式制冷, 回质回热, 热力学, 熵, (火用)

CLC Number:

TB61⁺1

XU Shengzhi, WANG Liwei, WANG Ruzhu. Thermodynamic analysis of mass and heat recovery adsorption refrigeration cycles and scheme selection[J]. CIESC Journal, 2016, 67(6): 2202-2210.

徐圣知, 王丽伟, 王如竹. 回质回热吸附式制冷循环的热力学分析与方案优选[J]. 化工学报, 2016, 67(6): 2202-2210.

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