Abstract
A finite difference model of a heat exchanger (HX) considered maldistribution, axial conduction, heat leak, and the edge effect, all of which are needed to model a high effectiveness HX. An HX prototype was developed, and channel height data were obtained using a computerized tomography (CT) scan from previous work along with experimental results. This study used the core geometry data to model results with the finite difference model, and compared the modeled and experimental results to help improve the expanded microchannel HX (EMHX) prototype design. The root mean square (RMS) error was 3.8%. Manifold geometries were not put into the model because the data were not available, so impacts of the manifold were investigated by varying the temperature conditions at the inlet and exit of the core. Previous studies have not considered the influence of heat transfer in the manifold on the HX effectiveness when maldistribution is present. With no flow maldistribution, manifold heat transfer increases overall effectiveness roughly as would be expected by the greater heat transfer area in the manifolds. Manifold heat transfer coupled with flow maldistribution for the prototype, however, causes a decrease in the effectiveness at high flow rate, and an increase in effectiveness at low flow rate.
Highlights
Heat exchangers (HXs) are ubiquitous in modern life [1] and have a market size predicted to reach over $20 billion U.S dollars by 2024 [2]
The present paper addresses this analysis by varying the boundary conditions at the HX core based on different manifold heat transfer characteristics to examine the effect on each fluid path in the core
The overall conclusion for varying the temperature boundary conditions with no flow maldistribution is that manifold heat transfer increases overall effectiveness roughly what would be expected by the greater heat transfer area in the manifolds
Summary
Heat exchangers (HXs) are ubiquitous in modern life [1] and have a market size predicted to reach over $20 billion U.S dollars by 2024 [2]. An emerging application, solar water pasteurization, demands low-cost HX and has the potential to save the lives of thousands of children a day [7,8,9]. Another important application can be found in absorption cycles, which can utilize waste heat from diesel engines, such as those found on ships [10]. An open-source polymer laser welder has been developed [15], heat transfer in polymer HX using it was studied [16] and recent work [17] has provided a low-cost method of making a polymerbased expanded microchannel HX (EMHX). A paper [32] developed a finite difference model that can be applied to this EMHX that was scanned, allowing for a comparison between modeled and experimental heat transfer characteristics when maldistribution is present
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