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Wet surface heat exchangers such as cooling towers and wet plate heat exchangers are important in air conditioning. A linear approximate model of wet surface heat exchangers is proposed. The equations of the model are rearranged, enabling solutions for wet bulb depression and wet bulb temperature to be obtained independently, by analogy from published solutions for dry bulb temperature in dry surface heat exchangers. Performance predictions by this method for a crossflow cooling tower are found to agree with those from a prevous finite difference solution. Published performance measurements for a crossflow wet plate heat exchanger are lower than predicted by the method possibly due to poor wetting or excessive water flow. Excellent performance is predicted for a proposed regenerative evaporative cooler using such an exchanger.

Solid desiccant, open cooling cycles use low temperature heat efficiently making them attractive for solar air conditioning. Advanced cycles using nearly reversible evaporative coolers have previously been proposed and shown to have high ideal performance. This parametric study shows that, with real components comparable to those used in studies of classical cycles, these open cycles can give more than twice the thermal coefficient of performance of a ventilation cycle.

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