Discussion on wastewater heat recovery and energy conservation for public bathrooms in Xihua University

摘要

Based on a lot of researches on public bathrooms of universities in Chengdu and massive amounts of data, the temperature of hot water only drops 10°C in bathing. After bathing, the wastewater at 30°C is directly discharged, which causes great thermal pollution to the environment. For this case, a heat recycling device was proposed in the air source heat pump water heaters to recycle most of the waste heat. The impact on the Coefficient Of Performance (COP) and power consumption of the air source heat pump water heaters was analyzed at different inlet-water temperature for the different heat recovery efficiency. The Coefficient Of Performance (COP) and power consumption reduces with the increasing heat recovery efficiency, but while the former is not obvious; the latter is significantly lower. Therefore, adding heat recovery in air source heat pump hot water system, the heat of the wastewater was exchanged with the potable water to reduce the power consumption and save the costs. According to the calculation of Public Bathrooms in Xihua University, the higher the heat recovery efficiency of the air source heat pump water heaters is the lower annual operating cost. Therefore, a high recovery efficiency device shall be selected under reasonable conditions.