Heat pump driven by a gas engine for heating and domestic hot water generation

International audienceAir source heat pumps driven by a gas engine is a known technology. In this paper, we describe a Heat Pump driven by a gas engine that uses grey waters as the cold source producing domestic hot water and heat for the hydronic system. Grey waters are coming exclusively from kitchen’s and bathrooms’ wastewater and their average temperature is about 30°C. This temperature is constant all along the year. The recovered lukewarm water is stored at atmospheric pressure in a tank. The domestic hot water and the heating water are produced instantaneously by the heat pump and stored in a tank, and hot water is delivered at 58 °C. The paper presents the architecture resulting from a heat integration and exergy analysis study. It allows the heat recovery from the grey waters for the generation of domestic hot water while heat recovery from the engine is used for heating the building. A sensitivity analysis is performed on the ratio between the heat recovered from the grey waters and the heat recovered from the engine when the thermal efficiency of the engine varies. Simulations show also how to handle the engine operation during the heating period and in summer conditions for the climatic conditions of France. The seasonal energy efficiency of the system is calculated based on simulations; they predict a seasonal energy efficiency of 2.1 for generating hot water at 58 °C