具有相变的三介质换热器的分析

具有混合能源的暖通空调与制冷（heating, ventilation, air conditioning & refrigerating, HVAC&R）系统通常需要在3种或多种流体之间传递热量。三介质换热器能满足多流体换热需求，在该领域具有应用前景，其优化具有重要意义。对于具有相变的三介质换热器，现有的热阻定义不能很好地发挥作用，而最新提出的理论提供了另一种方法。本文采用分布参数法建立了翅片管三介质换热器的仿真模型，并用实验结果进行了验证。此外，还推导了三介质换热器中基于耗散的的热阻。根据传热量和理论，分析了不同结构和空气流量下的三介质换热器的换热性能。结果表明，采用基于耗散的热阻作为评价标准与采用传热量为评价标准相比，改变管路排布方式获得的优化结果不同，改变管径或风量获得的优化结果相同。以基于耗散的热阻为标准，考虑不同流体侧之间的传热和压降的匹配，以获得最佳的管路排布方式。本文的实验结果有利于制冷空调系统中三介质换热器的优化以及理论新应用领域的拓展。

Entransy analysis on a three-fluid heat exchanger with phase change

HVAC&R(heating, ventilation, air conditioning & refrigerating) systems with hybrid energy sources need to transfer heat among three or more fluids. Three-fluid heat exchanger has application potential in this field and its optimization shows great significance. For three-fluid heat exchangers with phase change, existing definition of thermal resistance does not work well while the recent developed entransy theory offers an alternative way. In this paper, a fin-tube three-fluid heat exchanger is simulated with distributed parameter method and validated by experimental results. Entransy-dissipation-based thermal resistance for three-fluid heat exchanger with phase change is derived. The performance of different structures and air flow rate is analyzed on the basis of both heat transfer rate and entransy theory. The results show that using entransy-dissipation-based thermal resistance as the criterion achieves different results with maximizing heat transfer rate when circuit arrangement type is varied, while same results when tube diameter or air flow rate is varied. Optimal circuit arrangement is obtained by using entransy-dissipation-based thermal resistance as criterion, which can take heat transfer matching between different sides and pressure drop into consideration. This paper provides useful results on the optimization of three-fluid heat exchangers in HVAC&R systems and a new application field of entransy theory.