Investigation of Geometry Effects of Channels of a Silica-gel Desiccant Wheel

Abstract

Desiccant evaporative cooling systems are potential environment-friendly alternative to energy-intensive vapour compression chillers. They operate on an open heat-driven cycle consisting of a combination of a dehumidifier, a sensible heat exchanger and evaporative coolers. A desiccant wheel is the heart of the heat-driven cooling system and it uses a solid desiccant for dehumidification. The desiccant material is coated onto the supporting rotor structure. The matrix consists of multiple channels in the direction of the axis of the wheel rotation. The flow passage of the desiccant wheel is usually of sinusoidal shape. The performance of the whole cooling system largely depends on the dehumidification ability of the desiccant wheel and mathematical models are an effective tool to predict the heat and mass transfer behaviour of moisture transport in air dehumidification applications with rotary desiccant wheels. In this paper, a heat and mass transfer model incorporating both solid-side and gas-side resistances is presented and compared with experimental data. This model is used to investigate the effect of the geometry and shape of element channels on the transport process and the performance of the wheel.