A new modeling and analysis method of the indirect evaporative heat exchanger based on the heat current perspective

Abstract Indirect evaporative cooling technology has increasing importance and significance because of its high cooling efficiency and environment-friendly feature. The paper introduces a new parameter named moisture-temperature ratio that unifies the temperature difference and humidity difference and then proposes the heat current model to reveal the coupled heat and mass transfer process. For an indirect evaporative heat exchanger, the driven potential of the coupled heat and mass transfer processes is considered and can be modified as the difference between the inlet temperature of the hot fluid and the inlet wet-bulb temperature of the cold wet air. On this basis, we derive and obtain the thermal resistance expressions of parallel-flow, counter-flow and other complex flow arrangements indirect evaporative heat exchangers. Finally, the comparison with the experimental data shows that the discrepancy of the outlet temperature of the hot air obtained by the heat current model is less than less than 0.85 °C. Besides, the proposed heat current model is feasible and convenient for analyzing the influences of inlet humidity, inlet temperature, and channel height on the overall performance of heat exchanger, and provides an effective solution for the indirect heat exchanger design and performance analysis.