An air-source hybrid absorption-compression heat pump with large temperature lift

Abstract

High-temperature heat pump is gaining more and more research attention due to the efficient heat supply for industrial uses, which includes waste heat-source, water-source, and air-source types. Although air heat source has lower energy grade, its superior availability is attractive. However, large temperature lift is necessary to fill in the gap between the low temperature ambient air and high temperature supply, which cannot be fulfilled by current heat pumps. In this study, a novel air-source hybrid absorption-compression heat pump is proposed to address this issue, in which the compression sub-cycle and absorption sub-cycle are thermally coupled for stepped temperature lift. Compared with the conventional air-source heat pump, a large temperature lift (over 90 °C) and relatively good thermodynamic perfectibility (0.34) are obtained. As the temperature lift increases from 70 °C to 110 °C, the coefficient of performance changes from 1.7 to 1.2. Moreover, heat recovery between the two sub-cycles is achieved to reduce the heat exchange capacity with air, thus saving air–liquid heat exchanger area and cost. Via the integration of relatively mature technologies, the proposed system provides a feasible and efficient way to upgrade ambient heat for industrial uses, and it is technologically available in different capacities.