The plate-type heat exchanger is found to be well suited for the application of a transcritical CO_2 heat pump water heater (HPWH). A CO_2 HPWH test facility was used to evaluate the performance of a high-pressure plate-type heat exchanger. The performance characteristics of heat exchanger effectiveness, capacity, and pressure drop were evaluated over a range of operating CO_2 GC inlet pressures and temperatures. For the ambient temperature range of 10 to 30°C, the maximum observed capacities ranged from 4.46 kW to 5.34 kW, with the capacity increasing approximately linearly with increasing ambient temperature. Over this maximum capacity range, the effectiveness of the gas cooler ranged from 98.7% to 99.4%, with the effectiveness increasing with decreasing ambient temperature. The largest gas cooler pressure drop was approximately 130 kPa at a volumetric flow rate of about 128 cm~3/s; which is the flow rate resulting from the standard system operating conditions at an ambient temperature of 30°C.
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