露点蒸发冷却换热器的优化与仿真分析

发布时间：2018-05-20 10:16

本文选题：蒸发冷却技术 + 露点效率　；参考：《天津工业大学》2016年硕士论文

【摘要】：空调能耗是建筑能耗中最重要的一项,现有的机械压缩式制冷不仅消耗大量的能量,并且其使用的制冷剂工质还会对大气产生严重的破坏作用。间接蒸发冷却作为目前一种新型的制冷方式,以其更节能、更环保的优势而获得更多的关注,其处理后空气温度降低,同时湿度保持不变。但该方式最多可将空气处理至其湿球温度,不能满足室内热舒适需求。露点冷却技术是在原来间接蒸发冷却技术上的改进新发展,可以将空气冷却到湿球温度以下,至露点温度附近,较原有间接蒸发技术能实现更大的降温效果。但目前该技术大多应用于中央空调的预冷却,体积庞大,多安装在室外,因此不能广泛应用于家庭制冷。本文针对以上若干问题,设计小型露点蒸发冷却换热器,优化冷却换热器的结构,构造多级冷却,研究影响露点冷却器换热效率的各项参数,进而指导该冷却方式在实际中的应用。首先,本文对比普通蒸发冷却技术和露点冷却技术,证明露点冷却技术在环境保护等方面节能节排的效能。其次,本文从理论角度,分析板式换热器和流体逆流流动在换热方面的诸多优势,构造板式逆流式冷却换热器,增强流体间的换热效果；对比间接蒸发冷却器和传统露点冷却器,本文在结构上主要提出以间壁换热面上多种不同的穿孔形式,以及空气通道组轴对称和周期性的布置方式等优化手段构造芯体的多级冷却,同时,对冷却器的整机结构进行设计,包括其进出口的设计改良。以室外空气为工作介质,在预期工况下,计算得到初始设计数据。运用CAD-Pro/E辅助设计完成冷却器模型1：1比例的三维建模。针对本文露点冷却器的结构优化,给出本文露点冷却器理论分析的基本假设和热力分析方法,分析了热力设计参数间的影响关系,研究了蒸发冷却的数学模型,完成露点冷却的热力理论分析。利用CFD-FLUENT仿真软件对三维冷却器芯体内部温度场、浓度场、速度场等场变化进行模拟分析,分别对穿孔类型、单通道高度以及空气进口流速、进气温度和相对湿度等因素进行分析研究,并整合分析结果进一步完成预期工况条件下露点冷却换热器的优化和仿真计算,验证本文露点蒸发冷却换热器的优化方案可行。本文优化的露点冷却换热器,冷却性能优良,在预期稳定工况下露点效率同比传统结构的预期效率提高2.4%。
[Abstract]:The energy consumption of air conditioning is one of the most important items in building energy consumption. The existing mechanical compression refrigeration not only consumes a lot of energy, but also uses refrigerant refrigerants to destroy the atmosphere seriously. Indirect evaporative cooling, as a new refrigeration method, has gained more attention because of its advantages of more energy saving and more environmental protection. After treatment, the air temperature decreases and the humidity remains unchanged. However, the air can be treated to its wet bulb temperature at most, which can not meet the indoor thermal comfort requirements. Dew point cooling technology is a new development of indirect evaporative cooling technology, which can cool air below the wet bulb temperature and near the dew point temperature, which can achieve greater cooling effect than the original indirect evaporation technology. But at present, most of the technology is used in central air conditioning pre-cooling, large volume, mostly installed outdoors, so it can not be widely used in home refrigeration. Aiming at the above problems, this paper designs a small dew point evaporative cooling heat exchanger, optimizes the structure of the cooling heat exchanger, constructs multi-stage cooling, and studies the parameters that affect the heat transfer efficiency of the dew point cooler. Furthermore, the application of the cooling method in practice is guided. Firstly, the efficiency of dew-point cooling technology in environmental protection is proved by comparing with conventional evaporative cooling technology and dew point cooling technology. Secondly, from the theoretical point of view, this paper analyzes many advantages of plate heat exchanger and countercurrent flow in heat transfer, and constructs plate countercurrent cooling heat exchanger to enhance the heat transfer effect between fluids. Compared with indirect evaporative cooler and traditional dew point cooler, in this paper, many different perforations on the interwall heat transfer surface are proposed. As well as the air passage group axisymmetric and periodic arrangement and other optimization means to construct the core multi-stage cooling, at the same time, the whole structure of the cooler is designed, including the design improvement of the inlet and outlet of the cooler. Using outdoor air as working medium, the initial design data are calculated under the expected working conditions. The 1:1 scale three-dimensional model of the cooler model was built with CAD-Pro/E aided design. In view of the structural optimization of dew point cooler in this paper, the basic assumptions and thermal analysis methods of the theoretical analysis of dew point cooler are given, the influence relationship between the thermal design parameters is analyzed, and the mathematical model of evaporative cooling is studied. The thermodynamic analysis of dew point cooling is completed. The temperature field, concentration field, velocity field and so on are simulated and analyzed by CFD-FLUENT software. The perforation type, the height of single channel and the inlet velocity of air are analyzed respectively. The factors such as inlet air temperature and relative humidity are analyzed and analyzed, and the optimization and simulation of dew point cooling heat exchanger under expected working conditions are further completed by integrating the results of the analysis. It is proved that the optimization scheme of dew point evaporative cooling heat exchanger in this paper is feasible. The optimized Dew Point cooling Heat Exchanger has excellent cooling performance and the dew-point efficiency is 2.4% higher than that of the traditional structure under the expected stable working conditions.
【学位授予单位】：天津工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB657.5

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