Energy consumption of solar-assisted desiccant dehumidification air conditioning system in Beirut

The performance of a solar-assisted desiccant air conditioner is numerically investigated. The main feature of the system is that it employs a rotary desiccant dehumidification wheel to perform the task of air dehumidification while utilizing available solar energy to regenerate the wheel. The case study of a typical high latent load application of a restaurant is presented. The desiccant system model is evaluated for a total cooling load of 23.8 kW (6.78 Tons of Refrigeration (TOR)) under a wide range of recorded ambient conditions of Beirut city. Numerical transient simulation of the solar desiccant system is performed on an hourly basis for the cooling season to predict energy consumption and then perform economic analysis. The relevant parameters of the desiccant wheel are selected to meet the required humidity ratio at peak load with the minimum regeneration temperature that can be reached in the storage tank. It is found that for a given rotational speed of the wheel, minimum regeneration temperature occurs if the regeneration area is twice the dehumidification area. The size of the vapor compression unit of the restaurant is reduced to 4.74 kW (1.35 TOR) when supplemented by a desiccant system. When compared to the use of a vapor compression system, the life cycle savings of using the solar-assisted desiccant system with the down-sized conventional unit were positive when natural gas was available at a cheap price. The pay back period ranged from 3.1 to 7.5 years depending on the market price of the solar assisted system and the input energy (gas) price.