An Investigation of the Air-Side Forced Convection Heat Transfer from Saw-Tooth Shaped, Multi-Layer, Wire-On-Tube Condensers

This investigation focuses on determining the relative air-side heat transfer performance of several wire-on-tube condensers with multiple layers at high angles-of-attack with respect to a forced air flow. During each experiment, a wind tunnel containing a variable height test section was used to draw air, with free stream velocities ranging from 0.2 mls to 2.0 mls (0.66 ftls to 6.56 ftls), through the wire and tube matrix of a multi-layer condenser. The total heat transfer rate from each condenser layer was determined by performing an overall energy balance on the fluid (water for purposes of this study) flowing through the serpentine tube of the condenser. The contribution of radiation to the overall heat transfer rate was estimated and accounted for, as were the influences of the fin efficiency of the condenser wires and the thermal constriction resistance resulting from heat flow to locations on the tube surface at which wires are welded. Over the course of the study, influences of the free stream air velocity, condenser angle-ofattack (45??~ a ~ 90??), condenser orientation ('II = 0 for air flow normal to the wires of the condenser and 'II = 7th for air flow normal to the serpentine tube), and geometric differences between condensers (Ow == wire diameter, Sw == wire spacing, St == tube spacing, and SL == layer spacing) on the air-side convection heat transfer performance were examined. In addition, alternative condenser designs such as (i) staggered-wire condenser layers, (ii) one-sided condenser layers, and (iii) staggered-tube condensers were also studied.Air Conditioning and Refrigeration Project 6