DEHUMIDIFYING GREENHOUSE AIR BY DIRECT CR OSS-CURRENT CONTACT WITH ANORGANIC DESICCANT LIQUID

Greenhouse air can be dehumidified by direct contact with a desicant f luid on a trickle exchanger. The water vapour extraction rate depends on the hygroscopicity of the fluid and on the exchanger efficiency. An organic fluid, the triethylene glycol (TEG) at 90% concentration, has been tested. Cross corrugated cellulosic pads, of the type used in co oling, irrigated with TEG, were placed in a wind channel to dehumidify air at various speeds and temperatures. A semi-analytical model, base d on energy and mass conservation, correctly reproduces the water vapo r extraction rate and the enthalpy change of both fluids. It is shown that TEG trickling through a ventilated pad of 1 m(2) area and 0.1 m t hickness can be used to extract 3 to 5 kg of water vapor per hour in g reenhouse climate control applications. Several pads arranged in serie s can be used to decrease more efficiently the absolute humidity of th e air, for other applications like food drying or industrial compresse d air.