Reconciling thermal performance and power-saving performance of counter-flow spray heating towers

Abstract Heating tower heat pumps are increasingly used in subtropical areas due to their frost-free characteristics. The spray heating tower (SHT) solves the fouling problem suffered by the packing heating tower and ensures thermal performance. However, the heat and mass transfer characteristics of SHT have not been fully revealed and the power consumption of SHT is higher than that of packing heating towers. In the present study, the effects of tower height, air temperature, solution concentration/type, and liquid to gas ratio on the thermal performance of SHT were analyzed using a mathematical model. The heat and mass transfer characteristics of SHT with 100% thermal efficiency and/or 100% tower effectiveness were investigated. The results showed that when thermal efficiency approached 100% and liquid to gas mass ratio was 0.28, evaporation and condensation occurred at the bottom and top of the tower, respectively. Based on the parametric analysis results, a parameter design strategy to reduce pump power consumption while ensuring thermal performance was determined, which reconciled the contradiction between power consumption and thermal performance of SHT. The results of this investigation may provide a reference for the design and operation of SHT.