Analysis of the thermodynamic performance of a solar-assisted heat pump using a condenser with recirculation

Abstract

This research studied a direct-expansion solar-assisted heat pump with a water recirculation system. The installed heat exchangers were a copper collector/evaporator of 0.75 m2 and a coil condenser built in copper pipe with a length of 2.49 m and
8 turns, submerged in a tank with 5 liters of water.

It was used a centrifuge pump of 20 L/min at 110 V was used for the water recirculation. The installed compressor is a variable speed one at 12-24 V DC that uses R600a as working fluid. The throttling device installed was an electronic expansion valve.

The experimental tests were carried out for a water recirculation setup and without recirculation, considering similar weather conditions. In this manner, it can be determined which configuration gives a higher performance to the system. To obtain data about incident solar radiation, wind speed and ambient temperature, a WS-1201 climatological station was employed.

The system provided domestic hot water at 45 °C, delaying between 40 to 50 minutes, depending of the weather conditions. The maximum COP of the recirculation system was 9.83 an 8.04 % higher than the non-recirculation system. The heating time lasted 10 minutes less for the recirculation system, 16.67 % less than using the non-recirculation system.