Effects of Header Configuration on Flow Maldistribution in Plate-Fin Heat Exchangers

Abstract

Non-uniform flow distribution among the channels of a heat exchanger (HX) can adversely affect its thermo-hydraulic performance. In this research, various header designs for a plate-fin heat exchanger (PFHX) and a flow data acquisition system were constructed to study the water flow distribution among the channels of the PFHX. These different header configurations were installed at the entrance of the PFHX operating under different flow conditions to evaluate the impact of header structure on flow distribution within the HX and its thermal-hydraulic performance. The conventional header was found to cause severe flow maldistribution at the inlet of the PFHX. The Reynolds number based on channel flow and geometry was seen to significantly affect the flow distribution, which in turn drastically reduced its effectiveness. To improve the conventional header, new headers with different perforated plates were designed and built. Experimental results showed that an improved version of the header is very effective in mitigating the flow maldistribution in the PFHX and thereby enhancing its thermal performance. Engineering correlations relating the flow distribution non-uniformity, HX effectiveness, and the Reynolds number for different header designs were also developed.