基于可及处理区域的溶液除湿循环热力完善度分析

来源期刊:中南大学学报(自然科学版)2020年第12期

论文作者:殷勇高 陈博闻 程小松

文章页码:3528 - 3537

关键词:溶液除湿;热力完善度;可及处理区域;热力分析

Key words:liquid desiccant dehumidification; thermal perfection; accessible handling region; thermodynamic analysis

摘    要:提出一种基于空气和溶液热湿交换可及处理区域的溶液除湿循环热力完善度分析方法。通过对溶液除湿循环的热力分析以及等效分解再生过程,定义再生过程的热湿角γ为再生器进出口再生空气连线与等含湿量线的夹角,分析热湿角随溶液除湿循环各主要参数的变化规律,指出热湿角达到某工况下理论最大值时溶液除湿循环应满足的条件,从而得到溶液除湿循环的理想化描述。在此基础上,基于叉流式溶液除湿/再生器的NTU-Le计算模型,计算再生器传质单元数和溶液-溶液换热器效率等设备参数,并分析循环溶液浓度差和再生空气流量等运行参数对实际溶液除湿系统热力完善度的影响。研究结果表明:热湿角γ越大,理想溶液除湿循环的性能系数COP,max越高。理想溶液除湿循环热湿角γ的影响因素为室外空气状态、热源温度和除湿器出口空气含湿量;室外空气温度越高,含湿量越低,热源温度越高,除湿器出口空气含湿量越高,热湿角γ越大,COP,max越高。对于实际的溶液除湿循环,再生器传质单元数越大,溶液-溶液换热器效率越高,再生空气流量越小,循环溶液浓度差越小,系统热力完善度越高。在室外空气温度为34.8 ℃、含湿量为21.4 g/kg,热源温度为75 ℃的工况下,溶液除湿系统的热力完善度为0.7左右。

Abstract: An analysis method of the thermal perfection of LDD cycle based on the accessible handling region was proposed. The heat and humidity angle γ of the regeneration process was defined by conducting analysis of the thermodynamic process of the LDD cycle and the equivalent decompostion of the air regeneration process. In addition, the variation law of the γ with the main parameters of the solution dehumidification cycle was analyzed. The conditions that the solution dehumidification cycle should meet when the γ reaches the theoretical maximum under certain working condition were pointed out. Moreover, the ideal description of the solution dehumidification cycle was obtained. Based on this, the influence of the equipment parameters, such as the number of mass transfer units and efficiency of the solution–solution heat exchanger, and the operation parameters (e.g., the concentration difference of the circulating solution and the regeneration air mass flow rate) on the thermal perfection of the actual LDD system was evaluated. The results show that the greater the value of γ, the higher the coefficient of performance of the ideal LDD cycle (COP, max). The influencing factors of γ of the ideal LDD cycle are outdoor air status, heat source temperature, and outlet air humidity of the dehumidifier. Higher outdoor air temperature, lower outdoor air moisture content, higher heat source temperature and moisture content of dehumidifier outlet air lead to greater γ, and higher COP, max. For the actual LDD cycle, the system''''s thermal perfection is higher. When the number of mass transfer units of the regenerator is larger, the efficiency of the solution-solution heat exchanger is higher, and the regeneration air mass flow rate and the concentration difference of the circulating solution are smaller. If the outdoor air temperature is 34.8 ℃, the moisture content is 21.4 g/kg, and the heat source temperature is 75 ℃, the thermal perfection of the solution dehumidification system is around 0.7.

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