太阳能有机朗肯-闪蒸循环工质选择

摘要

近年来,太阳能低温热发电技术作为可再生能源领域的研究热点受到越来越多的关注.文章针对太阳能平板集热器驱动的有机朗肯-闪蒸循环(solar binary-flashing cycle,SBFC),基于EES(engineering equation solver)软件建立数学模型,分析了7种制冷剂包括R601、R601a、R1233zd(E)、R600、R1234ze(Z)、R600a和R1234ze作为循环工质在SBFC系统中的应用潜力,并在系统净输出功最大的工况下,研究了集热器出口热水温度(80~100℃)对SBFC系统热力性能的影响规律.选用的性能指标参数有净输出功、热效率、第二定律效率、不可逆损失、换热器热导(UA,总传热系数与传热面积的乘积)和单位太阳能集热器面积净输出功.结果表明,在所研究的工况范围内,随着集热器出口热水温度的增大,SBFC系统的热力性能得到显著的提高,且工质的标准沸点温度越高,SBFC热力性能越好,其中R601具有较高的净输出功、热效率和第二定律效率,并且系统的不可逆损失较小,是一较理想的SBFC系统循环工质.%As a research hotspot in the renewable energy field,low-temperature solar thermal power technologies have attracted more and more attention in recent years. A mathematical model for the binary-flashing cycle(SBFC)driven by flat-plate solar collectors was developed based on EES (engineering equation solver)software. The potential of seven refrigerants,including R601,R601a, R1233zd(E),R600,R1234ze(Z),R600a and R1234ze,used as working fluid in the SBFC had been examined. The effect of hot water temperatures at solar collector outlet ranging from 80℃ to 100℃ on the thermodynamic performance of the SBFC had also been analyzed under the conditions of maximum net power output. In the analysis,the net power output,thermal efficiency,exergy efficiency,exergy loss,thermal conductivity of heat exchanger(UA,the product of overall heat transfer coefficient and heat transfer area),and the net power output per unit solar collector area were selected as performance indicators. Results showed that under the given working conditions,the increase in the hot water temperature at solar collector outlet can significantly improve the thermodynamic performance of the SBFC system. The systems with the working fluids having higher normal boiling temperature would yield the better thermodynamic performance. Among the working fluids examined, R601 produced relatively high net power output,thermal efficiency as well as exergy efficiency and had relatively low total exergy loss. So it is recommended to use R601 as an ideal working fluid for the SBFC system.