Performance evaluation of a plate type condenser for heat pump water heater

Abstract

This study deals with an application of blazed plate heat exchangers to a condenser used in a heat pump water heater. The heat transfer performance was experimentally evaluated by using a pump driven two-phase flow loop in the operating condition for water heating at the environmental temperature. The effects of number of refrigerant paths and setting orientation, such as a vertical orientation with downward refrigerant flow or a horizontal orientation, were evaluated. HFC134a was used as the refrigerant. Superheated vapor was supplied to the condenser, and heated water, and then subcooled liquid was exhausted. Water was supplied to form a counter flow heat exchange. Three kinds of heat exchangers with different refrigerant paths of 6, 10, and 14 were used. Refrigerant temperatures at the exit of each path were measured by inserted thermocouples to evaluate the flow distribution. As a result, it was shown that vertical orientation produced higher heat transfer rate than the horizontal orientation. For the horizontal orientation, heat transfer rate decreased with an increase of refrigerant channels from 10 to 14. The reason would be due to a maldistribution of the refrigerant. The deterioration in heat transfer performance for the horizontal orientation could be improved by the inclination of 15° of the heat exchanger.