Experimental Investigation to Determine The Effect of Laminated Evaporator's Tank Position on Heat Transfer and Pressure Drop

Experiments were conducted on laminate evaporator to determine the effect of the tank position on the evaporator heat transfer and pressure drop. The experiments were conducted on the evaporator calorimeter facility that is fully instrumented per ASHRAE specifications. A typical 4 pass laminate evaporator was used for testing. The refrigerant used for this investigation was R-134a. An oil circulation ratio of 2% was used for this study. The test conditions were: air inlet state was maintained at 27°C of dry bulb temp and 50% RH; average condensing and evaporation pressures were maintained at 15.5 & 1.96 kg/cm² G, respectively with 5°C evaporator superheat and 5°C condenser subcooling; and air flow rate was varied from 120 to 480 m³/hr.

The result shows that there is a significant impact of the tank position on the evaporator heat transfer rate and pressure drop. The heat transfer rate for an evaporator with the tank at the bottom is greater by 15-27% in comparison to an evaporator with the tank on the top; and the refrigerant pressure drop is also greater (max 28%) for an evaporator with the tank at the bottom. The results from this study can be used in designing better evaporators, and hence, cooling units.