Operating Performance of Combined Heat Systems Based on Surface Water Heat Pump and Peak Shaving Boiler

摘要

It plays a significant role in energy conservation, environmental protection and system efficiency when using the surface water heat pump for building heating, but auxiliary heat source is necessary for the winter surface water temperature is often too low to satisfy the peaking heat load. Here pre-positioned and the postpositioned combined heat systems based on surface water heat pump and peak shaving boiler are introduced. On the different climate conditions, the combined heating systems run at different modes. For pre-positioned form, at the first stage with high air temperature and surface water temperature, it can satisfy the heat load by only running the heat pump unit; at the second stage with low air temperature and surface water temperature, the peak shaving boiler will put into operation with the heat pump, and the water temperature out of the evaporator will be above the limit of antifreeze protection; at the third stage with lower air temperature and surface water temperature, the water temperature into the evaporator will be below the limit of antifreeze protection in some cases, then peak heat source needs to heat the surface in accordance with the user heat load and drain it at limit temperature to minimize peak power consumption. Similarly, for post-positioned form, at the first stage, it runs only with the heat pump unit; at the second stage, the peak shaving boiler puts into operation with the heat pump, and the water temperature out of the evaporator will be above the limit of antifreeze protection; at the third stage, it runs only with the peak heat source and Heat Pump and surface water pumps stopped together.The heating performance has been deducted on theory at the peak load. With an example, their operating performance is compared. The results indicate that the post-positioned combined system is better on performance and efficiency than the pre-positioned one, and in the example it may save 6.65 Yuan/m2 on the operating cost, so it is the priority at design.