The efficiency of biomass heating networks has become an increasingly important issue in recent years. Studies have shown that the most effective measure for increasing efficiency is to install a heat pump along with a flue gas condenser in the boiler of a biomass heating system. With a view to further enhancing efficiency, this study focuses on the thermodynamic analysis and optimization of a heat pump design used for heat recovery in a biomass heating network and its impact on the overall system. The study demonstrates that the choice of target exhaust gas temperature has a significant impact on both heat pump sizing and overall system efficiency. There is an optimum exhaust gas temperature at which the maximum overall system efficiency can be achieved. The supply temperature of the heat pump and the choice of refrigerant have little effect on the system overall, but they do affect the size of the heat pump. The supply temperature should be as low as possible. R600a is recommended as a refrigerant for the heating networks studied, due to its physical properties and beneficial behavioral characteristics at different temperatures.
Keywords biomass district heating, heat pump design, integration, heat recovery