A comprehensive analysis of capacitive signals of two-phase R134a characteristics in a microchannel heat exchanger header with and without a distributor

IF 3.5 2区工程技术 Q1 ENGINEERING, MECHANICAL

International Journal of Refrigeration-revue Internationale Du Froid Pub Date : 2025-04-08 DOI:10.1016/j.ijrefrig.2025.04.005

Jiajia Song , Hequn Liu , Shenghan Jin , Chao Yuan , Jinqing Peng , Houpei Li

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引用次数: 0

Abstract

The maldistribution of refrigerant in header has a serious impact on the performance of the microchannel heat exchanger (MCHX). This study investigated using to obtain an improved flow distribution distributor in a MCHX. The tested inlet vapor quality covered from 0.2 to 0.6. Mass flow rate was 10 g/s. In the heat exchanger header, the two-phase distribution was quantified using a capacitance sensor for with and without distributor cases. The capacitive signals were comprehensively analyzed in the time, amplitude and frequency domains. Probability density function (PDF) and Fast Fourier Transform (FFT) of the capacitive signals were used to characterize flow patterns. The local vapor qualities calculated by the correlation was used to quantify two-phase distribution. This comprehensive analysis improved the accuracy of capacitive signal processing of two-phase flow characteristics. In the Fast Fourier Transform of capacitive signals, the more violent the two-phase flow, the greater fluctuation on the amplitude. The improvement of two-phase distribution by distributor and the two-phase flow characteristics at the distribution hole were discussed. At low inlet vapor quality

(x_{i n} \leq 0.3)

, the distributor had a better effect on the maldistribution. At high inlet vapor quality

(x_{i n} = 0.6)

, alternate vapor-liquid distribution would occur at the distribution hole. In this paper, the capacitive signals were comprehensively analyzed in the time, amplitude and frequency domains in the MCHX header for the first time. The two-phase flow state was specifically evaluated through the capacitive signal characteristics.

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带分配器和不带分配器的微通道换热器集管中两相R134a电容性信号的综合分析

冷媒在集箱内的不均匀分布严重影响微通道换热器的性能。本文研究了一种改进的MCHX气流分布器。测试的进口蒸汽质量范围从0.2到0.6。质量流量为10 g/s。在热交换器集箱中，使用电容传感器对有和无分电器箱的两相分布进行了量化。对电容信号进行了时域、幅域和频域的综合分析。利用电容信号的概率密度函数（PDF）和快速傅里叶变换（FFT）来表征流型。利用相关计算得到的局部汽相质量来量化两相分布。这一综合分析提高了电容信号处理两相流特性的准确性。在电容信号的快速傅里叶变换中，两相流越剧烈，振幅波动越大。讨论了分布器对两相分布的改善及分布孔的两相流动特性。在进口汽质较低（xin≤0.3）时，分布器对不均匀分布的处理效果较好。当进口汽质较高（xin=0.6）时，配气孔处出现气液交替分布。本文首次对MCHX标头中的电容信号进行了时域、幅域和频域的综合分析。通过电容信号特性具体评价了两相流状态。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

International Journal of Refrigeration-revue Internationale Du Froid 工程技术-工程：机械

CiteScore

7.30

自引率

12.80%

发文量

363

审稿时长

3.7 months

期刊介绍： The International Journal of Refrigeration is published for the International Institute of Refrigeration (IIR) by Elsevier. It is essential reading for all those wishing to keep abreast of research and industrial news in refrigeration, air conditioning and associated fields. This is particularly important in these times of rapid introduction of alternative refrigerants and the emergence of new technology. The journal has published special issues on alternative refrigerants and novel topics in the field of boiling, condensation, heat pumps, food refrigeration, carbon dioxide, ammonia, hydrocarbons, magnetic refrigeration at room temperature, sorptive cooling, phase change materials and slurries, ejector technology, compressors, and solar cooling. As well as original research papers the International Journal of Refrigeration also includes review articles, papers presented at IIR conferences, short reports and letters describing preliminary results and experimental details, and letters to the Editor on recent areas of discussion and controversy. Other features include forthcoming events, conference reports and book reviews. Papers are published in either English or French with the IIR news section in both languages.