548 / 2019-01-16 17:48:43

Effect of heat pump recycling technology on evaporative loss in a natural draft counter-flow wet cooling tower

NDCFWCT; mathematical method; evaporation loss; heat pump recycling technology.

全体主题 > 数值模拟、建模与CFD

Abstract: The amount of water lost by evaporative heat dissipation during cooling is an important part of the draft counter-flow wet cooling tower (NDCFWCT) water loss. Moreover, the "white smoke" from the top of the tower will pollute the surrounding environment. Therefore, taking measures to reduce the impact of evaporation loss in the NDCFWCT has important implications for water conservation and emissions reduction. In this study, the effect of heat pump recycling technology on evaporative water loss in the NDCFWCT was studied. Based on heat and mass transfer theory and the balance between NTU and the cooling characteristic number theory, a mathematical model for predicting the evaporation loss of the NDCFWCT was established. The calculated values obtained by the mathematical method were in good agreement with field experiment. The calculation results showed, when the heat transfer of condenser was constant, the evaporation loss didn’t change significantly with the change of the inlet tower water volume. Therefore, in the conventional cold end system, water saving cannot be achieved by the measure to change water volume. The relationship between evaporation loss and inlet tower heat load was determined. With the decrease of inlet tower heat load, evaporation loss decreased gradually. Based on this Law, the measure of saving water by recycling waste heat of circulating cooling water to reduce inlet tower heat load was put forward. For the parallel arrangement, when the heat load of the evaporator was fixed, quantity of water saving decreased with the increase of the temperature drop of circulating water which passed through the evaporator; when circulating water passing through the evaporator was fixed, the larger the temperature drop of the circulating water passing through the evaporator, the less water saving. When the heat load of evaporator was fixed, the water saving effect of the parallel arrangement was better than that of series arrangement in winter condition, but it was uncertain in summer condition.