Study And Numerical Simulation Of Hydrothermal Coupled Environment Inside Solar Greenhouse

Hydrothermal coupling is very obvious inside the solar greenhouse. Crop and soil are generally endothermic and exothermic heat during daytime and nighttime, and the crop canopy and evapotranspiration thermal coupling makes crop growth environment become more complexity. Solar radiation is the main source of solar greenhouse anti-season production and especially vital for cold-arid regions winter greenhouse production. Temperature and soil moisture are the main factors for crops normal growth, but too much of the crop and soil water evaporates reduced ambient air temperature, this is not conducive to cold-arid regions greenhouse production. In order to explore the hydrothermal coupling mechanism of the inside greenhouse, the research on the outskirts of Hohhot in Inner Mongolia were tested greenhouse temperature and humidity, soil moisture and indoor solar radiation, and by Penman-Monteith evapotranspiration formula to calculate the greenhouse moisture latent heat exchange capacity of water transpiration and evaporation. Finally, in this study using CFD methods to simulate the inside greenhouse hydrothermal coupling environment for experimental greenhouse.During the test, the choice of a high-precision calibrated AM2305 temperature and humidity sensors, and invented temperature and humidity test system based on single-chip STC11F04E. The testing of soil temperature and moisture content system using MS 10 soil temperature (moisture) sensor, and they are arranged in -30cm.15cm and 0cm (soil surface) soil layer testing the relationship between soil temperature and moisture content in a day.The test results show that, with daytime soil temperatures increase the soil moisture content are increased. The reason is the high temperature and strong surface evaporation will increase the occurrence of wet-dry surface soil unsaturated hydraulic conductivity. The calculating of the latent heat exchange capacity based on Penman-Monteith evapotranspiration formula found that the crop canopy transpiration latent heat of water use are greater than soil evaporation during the day. The analysis of convection currents wind generated inside greenhouse at 0:00 and 7:00 found that, it is a mainly cooling mode for in the greenhouse forming a natural convection. In order to reduce the greenhouse air convection heat transfer quantity should be installed air flow baffle above the crop to obstruct air convection heat transfer.