Thermo‐flow behavior of air-channel heat exchanger with nonidentical baffle lengths: computational analysis

Previous research assumed the same baffle size across a heat exchanger with two baffles although the flow characteristics change along the channel. This present work suggests a novel design of using nonidentical baffle lengths along the channel because the best baffle length is not the same for both baffles. The main objective of this suggested design is to enhance the thermal enhancement factor (TEF) of a regular heat exchanger with baffles. After studying 16 cases of different baffle sizes using a two-dimensional channel in ANSYS Fluent software, it is found that the baffles with the same length do not always achieve the best TEF. When the second baffle is half the length of the first baffle, TEF increases by 3%, and the upper wall friction factor decreases by about 50%. In addition, it is found that the average Nusselt number of the upper wall is sensitive to the length of both baffles. From these results, the assumption that the baffles inside the channel should not be identical in length is authentic.