Paper No 385 – Techno-environmental evaluation of a river-source heat pump system using a hot gas bypass valve – 14th IEA Heat Pump Conference, Chicago, USA
River water-source heat pumps show higher energy efficiency than conventional air-source heat pumps because water has better thermal characteristics than air. However, as the river water temperature decreases in winter, there is a risk of freezing in heat exchangers during the heating season. In this study, the performance of a hybrid heat pump system using a hot gas bypass valve (HBHPS) was compared analytically to that of a conventional hybrid heat pump system (CHHPS). In the HBHPS, the refrigerant flow rate can be controlled by the hot gas bypass valve to decrease the heating capacity, hence reducing the temperature difference of the secondary fluid on the evaporator side. Accordingly, it can increase the heat pump operation time in winter. Mechanical components of the HBHPS were modeled analytically. The performances of the two energy conversion systems were compared through transient simulations based on a water temperature measurement in Han River, South Korea. As a result, the HBHPS showed higher life cycle climate performance than the CHHPS owing to the increase in the heat pump operation time.