Experimental studies on perforated plate matrix heat exchanger surfaces with different plate thickness and spacer thickness using modified maximum slope method

Abstract

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.The design of perforated-plate heat exchanger is combined with a high thermal conductance in transverse direction with a low thermal conductance in axial direction. Perforated plate matrix heat exchangers (MHE) essentially consist of a stack of perforated plates made of high thermal conductivity material alternating with spacers made of low thermal conductivity material. The single blow transient test is most appropriate for determining the heat transfer coefficients of perforated plate MHEs. Dimensionless temperature and dimensionless time are determined from the exit temperature history of the single blow transient test. The slope is determined from the dimensionless temperature and time plot. The maximum slope and time at which the maximum slope occurs is used in this method for the determination of ntu and longitudinal heat conduction factor simultaneously. The experimentation in this work is to examine the effect of plate thickness to perforation diameter ratio (l/d) and spacer thickness to plate thickness ratio (s/l) on the heat transfer characteristics. The heat transfer and the flow friction characteristics data are presented in the form of Colburn factor (j) and fanning friction factor (f) vs. Reynolds number (Re) respectively. The j and f increase as the l/d value increases. The value of j and f decrease as the s/l value of the plate increases for MHE.