Substrate heating system with solar energy for greenhouse

Aiming at solving the problem of lower temperature, which restrains plant development, production and quality in greenhouse during wintertime, a system was introduced which could store solar energy in substrate maintain the soil temperature to meet the crop requirement for growing well. This research was conducted mainly by mathematical simulation and the regression analysis in the SAS Software. The result showed that the system could efficiently increase the soil temperature and reduce range of soil temperature fluctuation in the greenhouse during wintertime. And there was a transition layer of the substrate temperature between the storing one and heating one, in which the temperature did not vary with the time, but the others did. The research proved that the simulation result showed good agreement with the measured one. The difference method was used to calculate the heat diffusion coefficient and it was accurate enough. It was also confirmed that the optimizing areas ratio of solar collector of the system to cultivation field is 1∶5, which could meet crop growth requirement all the year round in the study situation. In a word, the system could accomplish the goal of storing solar energy in summer and utilizing in winter, storing it in daytime and utilizing in nighttime, storing it in sunshiny day and utilizing in cloudy day, for raising substrate temperature to meet the plant growth requirement without any other energies.