往复脉动流对板式换热器的性能强化实验研究

Experiment of the pulsation strengthen heat transfer in plate heat exchanger

首先,搭建了脉动流强化换热实验台架,针对板式换热器,研究了脉动流和稳态流下的换热性能对比,探究了脉动振幅、脉动频率与其换热特性之间的关系。热沉室设计采用3层结构,包括加热铜块、热沉室盖板和热沉室底座,加热铜块表面分别加工为平板流道和周期性矩形凹槽流道。实验结果表明,随着雷诺数的增大,无论稳态流动或是脉动流动下板式换热器的总传热系数均呈现增大现象,换热增强因子呈现逐渐降低的态势,这与热沉室实验中得到的规律基本相同;同时,在各雷诺数条件下,随着脉动频率的增大,换热增强因子出现了先减小后增大的现象,最低值出现在脉动频率0.66 Hz附近,换热增强因子的最大值为1.598,出现在雷诺数3 774、脉动频率0.55 Hz附近。

Firstly, an experimental bench of the the pulsating flow enhancing heat transfer is designed, target for plate heat exchangers, a comparison is carried out for the efficiency of heat transfer in the condition of pulsating flow and steady flow, which study the relationship among the pulsation amplitude, pulse frequency and the characteristics of heat transfer.Meanwhile, three layer structure of heat sink chamber is designed including the heating copper, cover plate and chamber base. The pulsation heat transfer for both kinds of channels are discussed, which are the rectangular flat plate and periodicvariation grooved plate. The results show that with the increasing of the Reynolds number, regardless of the steady flow or pulsating flow, the total heat transfer coefficient of plate heat exchanger has increased, the heat transfer efficiency has a gradually decreasing trend, which are almost coexistent with the rule in the experiment in heat sink chamber. At the same time, under the condition of the Reynolds number, with the increase of pulse frequency, the heat exchange efficiency appeared first decreases and then increases, the lowest value appeared in the vicinity of the pulsation frequency f=0.66 Hz, the maximum value of the thermal efficiency is 1.598, appear in the vicinity of the Reynolds number Re=3 774, pulsation frequency f=0.55 Hz.