Simulation of Heat and Moisture Transfer in the Greenhouse Substrate due to a Heating System by Buried Pipes

The paper presents a mathematical model of the greenhouse substratum heating process, which occurs when tubes are positioned in the substratum. The model includes the processes of transpiration, evaporation and infiltration. The mass of water consumed by roots of cultivated vegetables was calculated as a transpiration model, treated as a source function and presented as a diffusion equation, which describes water flow in the substrate. The undoubted advantage of this approach is the ability to use diffusion and heat transfer theory to solve the problems posed. The processes in the substratum being studied were analysed by applying heat and mass transport coefficients calculated from the correlation equations widely used in chemical engineering. The tests demonstrated a high correlation between the predicted values (numerical calculations) and the measured values: coefficients of correlation r of 0·94 (for temperature) and 0·91 (for moisture content).