THERMAL-ANALYSIS OF LOW-TEMPERATURE GROUN D-LEVEL HEATING-SYSTEMS IN GREENHOUSES - RADIANT MULCH AND BURIED PIPES

Greenhouse heating can be achieved using various systems, for the gene rator as well as for the exchanger. The exchanger characteristics invo lve quite different modes of energy distribution, with differing agron omic and economic consequences. This paper focuses on two ground-level heating systems with low temperature (20-40-degrees-C) water circulat ion : a << radiant mulch >> exchanger, composed of a network of ground -level heating hoses, and a << buried pipes >> exchanger, composed of a network of under-ground pipes. The first part of the paper develops a model for these exchangers and its integration into a previously des cribed greenhouse global model. The second part compares the effects o f these exchangers on the greenhouse energetical behaviour with those of classic aerial metallic pipes with hot (50-70-degrees-C) water circ ulation.