J.Y. Zhang’s research while affiliated with Shanghai Jiao Tong University and other places

In this paper, composite silica gel and potassium formate as typical organic weak acid salts is proposed to use in desiccant coated heat exchanger (DCHE). An experimental study on dynamic adsorption performance of desiccant coated metal sheet samples is conducted to obtain results with different proportions of silica gel and potassium format. A DCHE testing platform is then used to compare thermodynamic performance between single silica gel coated heat exchanger (SCHE) and composite potassium formate and silica gel coated heat exchanger (PSCHE). It is found that impregnating potassium formate into porous silica gel is an effective method to improve adsorption capacity, and 75% saturated potassium formate solution is recommended to constitute composite desiccant under experimental conditions. Compared with SG coated sheet, on average the maximum adsorption mass of SG&0.75PF coated sheet increases 2–3 times. Besides, PSCHE can obtain about 20% higher moisture removal capacity compared with SCHE under experimental condition, meaning the utilization of composite silica gel and potassium formate desiccant can effectively improve dehumidification capacity. PSCHE also can obtain 50% higher total cooling capacity compared with SCHE.

In this paper, a desiccant coated heat exchanger system is installed and tested under typical winter condition at Shanghai. Effects of hot water temperature, hot water mass flow rate and regeneration air flow flux are discussed as vital factors impacting system performance. It is found that the optimum regeneration hot water temperature and mass flow rate is 40℃ and 0.4 kg/s, when the regeneration air mass flow flux is 400 m³/h. Under this operation condition, average humidity ratio of supply air is 5.15 g/kg, and COPth can reach 1.78. For different humidify ratios of ambient air, a strategy of appropriate mass flow fluxes of air is implemented to balance thermal comfort and system thermal efficiency.

In this paper, a desiccant coated heat exchanger (DCHE) system driven by solar energy is built and tested under winter condition. The purpose of this experimental research is to explore the heating and humidification performance of DCHE system. Effects of hot water temperature, hot water mass flow rate and regeneration air flow flux are discussed as vital factors impacting system performance. Results show that increasing of heat water temperature as well as of hot water mass flow rate both have positive effects on humidification capacity and thermal coefficient of performance (COP) of the DCHE system. Moreover, the latter has a more remarkable influence. When a tradeoff is made between the performance of DCHE system and the thermal comfort of supply air, 40oC and 0.4 kg/s are selected as optimum hot water condition. Under this operation condition, average humidity ratio of supply air is 5.15 g/kg, almost twice of ambient air. COP can reach 1.78 with a comfortable average temperature of supply air (28.3 oC). To provide a better supply air state under low humidify ratio of ambient air, small regeneration air flow flux is implemented, which effectively increases the humidity ratio of supply air with the decrease of COP.