反冲洗降膜式污水源热泵机组供热性能实验测试

Experimental test on heating performance of backwash falling film sewage source heat pump unit

污水源热泵供热是城市污水热能利用的重要途径。为提高原生污水源热泵机组回收城市污水余热的能效,本文提出反冲洗降膜式污水源热泵机组供热系统,建立了污水源热泵机组供热性能实验系统,可与满液式污水热泵机组的供热性能进行比较研究,为解决直接换热式污水源热泵系统遇到的原生污水堵塞问题,本文还设计了污水反冲洗系统,并测试了反冲洗频率和时长对机组换热性能的影响。实验结果表明:降膜式污水蒸发器的平均传热系数要显著高于满液式污水蒸发器,降膜式污水蒸发器的平均传热系数比满液式污水蒸发器高了60.17%;在文中工况下,利用降膜式污水蒸发器的污水源热泵机组的供热性能系数要显著高于满液式污水蒸发器的污水源热泵机组,降膜式污水源热泵机组的供热性能系数比满液式污水蒸发器高了9.52%;污水反冲洗方式可以有效解决直接换热式原生污水源热泵系统的堵塞问题,在使用反冲洗模式时,反冲洗的时间间隔应尽可能短,以确保平均传热系数不会减小。因此,利用反冲洗降膜式蒸发器的污水源热泵机组可以更加高效地利用污水热能。

Heating by wastewater source heat pump(WWSHP)is an important way for urban sewage heat utilization.In order to improve the energy efficiency of the original WWSHP unit in recovering urban sewage waste heat,the heating system of the backwash falling film WWSHP unit was proposed,which can be compared with the heating performance of the full liquid WWSHP unit.The sewage backwash system was also designed to reduce primary sewage blockage in the direct heat exchange WWSHP.Experimental results showed that the average overall heat transfer coefficient(OHTC)of the wastewater falling film evaporator(WFFE)was significantly higher than that of the wastewater flooded evaporator(WFE).The average OHTC of the WFFE was 60.17%higher than that of the WFE.Under the working conditions tested,the heating performance coefficient of the WWSHP with WFFE was significantly higher than that with WFE.The average coefficient of performance in falling film mode was 9.52%higher than that in the flooded mode.The wastewater backwash can solve the blocking problem of direct heat exchange primary WWSHP unit.When using the backwash mode,the time interval for backwashing should be as short as possible to ensure that the average heat transfer coefficient will not decrease.Therefore,the WWSHP unit using the backwash falling film evaporator can use the sewage heat more efficiently.