Detailed heat transfer measurements of impinging swirling and non-swirling jet arrays emitted from grooved orifice plate

An innovative type of heat exchanger with heat transfer benefits from jet impingements is proposed. The increase of surface area to volume ratio for the heat exchanger requires the minimization of the separation distance for the impinging jets, which motivates the present study to comparatively examine the heat transfer performances between the non-swirling and swirling impinging jet arrays emitted from the orifice plate with vertical and horizontal grooves at small separation distances less than one orifice diameter. As demonstrated by the selective experimental results, either the grooves on the orifice plate or the swirling jets can effectively alleviate the unfavorable crossflow effect to boost the heat trasnfer rates at small separation distances. After analyzing the isolated and coupled Re_j and separation-distance effects on the local and area-averaged heat transfer properties for the non-swirling and swirling impinging jet arrays, two sets of physically consistent heat transfer and friction factor correlations are devised for practical applications.