An experimental investigation on the heat transfer and friction coefficients of a small plate heat exchanger with chevron angle

摘要

In the present study, a small brazed and commercial plate heat exchanger (PHE) with chevron angle 60 degrees and symmetrical layout, was experimentally investigated. New correlations for calculating heat transfer and friction coefficients of hot flow channels were presented. Few studies have been done on the small PHEs and due to the industrial needs, it is necessary to conduct new researches in this field. For this purpose, an experimental model was designed to calculate the single-phase water flow, heat transfer, and friction coefficients. The previously presented correlations were not successful in predicting the mentioned coefficients for the small PHEs and showed a 34% difference with the results of this study. Chevron grooves on the PHE plate can enhance the heat transfer as well as increasing the pressure drop. Defining mml:mfenced close=")" open="("mml:mfracjfmml:mfracmml:mfenced factor, it was revealed that with the increase of Reynolds number, heat transfer increased more than friction. In previous studies, with increasing Reynolds, mml:mfenced close=")" open="("mml:mfracjfmml:mfracmml:mfenced factor is almost constant in large PHEs but the results of the present study showed that this increase may be 5-fold higher in the small PHEs as compared with the larger ones. As there was no temperature and heat transfer coefficient value in the hot flow channels of PHE, the Nusselt number was calculated by the modified Wilson plot method.