Plate heat exchanger; end plate effect
Steady-state heat transfer data for single-phase (water) in both frame-and-plate (FPHE) and brazed plate heat exchangers (BPHE) are presented with various number of chevron plates in U-type flow arrangement. Analysis of the experimental results indicates that the end plates, instead of being adiabatic, function as fins due to the contact with adjacent plates. The experimental data is used to validate a thermal conduction model in ANSYS, which indicates that the end plates fin efficiency is a function of fluid convective heat transfer coefficient and conductive thermal resistance. In the frame-and-plate heat exchanger, the pressing force of the frame may affect the contact thermal resistance, thus change the fin efficiency. In brazed plate heat exchanger, the fin efficiency is much higher due to the larger contact area and higher conductivity of the brazing material. Although the effect of end plates is quickly diluted by the increased number of plates in real applications, it could be significant when plate number is small, as is often the case in laboratory settings for the development of heat transfer correlations.