In studies using computational fluid dynamics software, very often a uniform air stream is applied as inlet boundary condition of a heat exchanger. In actual applications, however, the inlet flow conditions are not uniform. Therefore, the effect of non-uniformities on the thermal performance is characterized in a wind tunnel for a commercially available plate water/air heat exchanger. Three non-uniform flow conditions are investigated. The heat exchanger is 275 mm wide and 295 mm high. Three non-uniformities are created by placing a plate 10 cm upstream of the heat exchanger: the first one covers the right-hand side of the heat exchanger, the second one covers the top half of the heat exchanger and the last obstruction consists of a circular hole of 150 mm diameter in the middle of a plate. Only the circular obstruction has a significant influence on the heat transfer rate: the external convective resistance is up to 25% higher compared to the uniform case. The measurement results presented in this study can be used by other researchers to validate numerical simulations with non-uniform inlet conditions.
展开▼
