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本文提出了自然循环复合回路太阳热水系统的数学模型。将系统的模型予示结果与实测数据进行了比较。用该数学模型研究了系统运行的过程机理,并探讨了换热器的设计因素对系统热性能的影响。由于系统运行的非稳态性质引起复合回路中传热过程的“自调节”的结果,对于一确定的系统,在一定的运行条件下,其换热面积有一固有的“临界值”,若设计的换热面积超过此值,则所增加的面积无助于系统热性能的改善。根据“临界面积”的概念,选定最佳换热面积,并确定最佳组合尺寸,为合理设计换热器提供了依据。
This paper presents a mathematical model of natural circulation solar hot water system. The results of the system model are compared with the measured data. The mathematical model was used to study the process of system operation, and the influence of the design factors of heat exchanger on the thermal performance of the system was discussed. As a result of the “self-tuning” of the heat transfer process in the composite circuit due to the unsteady nature of the system operation, there is an inherent “critical value” for the heat transfer area of a given system under certain operating conditions, Of the heat transfer area exceeds this value, the increase of the area does not help improve the thermal performance of the system. According to the concept of “critical area”, the optimal heat exchange area is selected and the optimal combination size is determined, which provides the basis for designing the heat exchanger reasonably.