Performance of solar-assisted hybrid air-conditioning liquid desiccant system in Beirut

摘要

In this work a model of a solar-operated liquid desiccant system (using calcium Chloride) for air dehumidification is developed. The desiccant system model is integrated with a solar heat source for performance evaluation at a wide range of recorded ambient conditions for Beirut city. The desiccant system of the current study is part of a hybrid desiccant-vapor compression system for a high latent load application, namely a small restaurant with an estimated cooling load of 11.39 TR (40 kW), including reheat. The relevant parameters of the desiccant system are optimized at peak load, and it is found out that there is an important energy saving if the ratio of the air flow rate in the regenerator to that in the dehumidifier is about 0.3 to 0.4. The COP of the desiccant unit is 0.45 for the restaurant. The size of the vapor compression unit of the restaurant is reduced to eight TR when supplemented by a desiccant system. The transient simulation of the solar desiccant system is performed for the entire cooling season. The solar fraction for the restaurant is 0.19, 0.38, and 0.54, for a collector area of 28.72, 57.44, and 86.16 m~2, respectively. The economic benefit of the desiccant system is positive. For a gas price of 0.5638 $/kg, the payback period for the restaurant turned out to be immediate if the energy is supplied solely by natural gas, and 11 years if an 86.16 m~2 solar collector is implemented to reduce the fuel consumption.