A WET PLATE HEAT-EXCHANGER FOR CONDITIONING CLOSED GREENHOUSES

In the design of new greenhouse production systems, one of the objectives is to reduce emissions (such as pesticides and CO2) which are hazardous to the environment. This necessitates the use of air conditioning instead of natural ventilation. In this paper an air conditioner for closed greenhouses is proposed in which the functions of a cooling tower and a heat exchanger have been integrated. A simulation model of the heat transfer process in the proposed design shows an increase of the heat transfer per unit area of heat exchanging surface compared to traditional heat exchangers. The simulations show that the heat exchanger is able to transfer large quantities of both sensible and latent heat from the greenhouse. Under Dutch design conditions the transferred sensible and latent heat is about 100W/m2 and 115 W/m2 respectively, for a heat transfer coefficient of 30W/m2K in the exchanger. © 1993 Silsoe Research Institute.