Performance study on modularized ultra-low-grade-heat-driven desiccant-coated oblique tube banks in tropics

In hot and humid subtropical and tropical climates where the latent cooling load significantly impacts the fresh air and total cooling load, substantial energy can be consumed in the air dehumidification process. This study delves into solid desiccant-assisted dehumidification employing ultra-low-grade waste heat (as low as 38.1 °C), investigated through both experimental and numerical analyses of an internally cooled desiccant-coated oblique tube bank configuration. This novel heat exchanger design eliminates the thermal contact resistance in some tube-fin heat exchangers, enhancing the efficient utilization of waste condensation heat in air conditioning systems. Comparative analysis against a circular tube bank with identical tube surface area and tube pitches demonstrates a remarkable reduction of more than 90 % in air pressure drop, accompanied by a significant 73 % enhancement in flow uniformity in the main direction. The experimental results demonstrate an electrical coefficient of performance ranging from 30 to 108 for the proposed desiccant-coated heat exchanger, highlighting its potential for energy-efficient air dehumidification. Furthermore, the study examines the influence of key operational parameters on the capacity and performance of the proposed desiccant-coated heat exchanger in tropical climates, indicating that even with a minimum 7.9 °C temperature difference between warm water and cool water, the heat exchanger maintains a 3.0 g/kg dehumidification ratio. The effect of water flow rate, air flow rate, inlet air specific humidity, cool water temperature, warm water temperature, and desiccant thickness on the performance of the proposed DCHX system are discussed in detail.