Study On Soil Temperature Field Of Greenhouse With Buried Pipe Heating

As one of the growth places for off-season vegetables and fruits in northern China,the greenhouse provides suitable temperature for planting plants in the cold season.Indoor temperature and soil temperature have a great impact on the growth and development of seed plants,but also affect the use effect of greenhouses and the production benefit of farmers,which is a practical value direction in greenhouse research.When the indoor temperature reaches the appropriate temperature of the plant soil temperature will be low,to create a suitable plant soil temperature environment,geothermal energy as heat source,change the water supply temperature and pipe diameter,depth,spacing to determine the soil temperature under different working conditions,layout parameters,so as to determine the suitable water supply temperature and buried pipe layout parameters,through buried pipe heating soil to improve the ground temperature.First of all,this thesis combined with the actual project of Zhangjiakou greenhouse,determines the heat load of the greenhouse through thermal calculation.Selection and layout of heat dissipation equipment according to the heat load of the greenhouse.Through calculation,the heat load of the greenhouse is 13.29 KW,and the annual heat consumption is 134.3GJ.Then,the influence of water supply temperature,pipe diameter,pipe depth and pipe layout spacing on the soil temperature field is studied.First,the mathematical model of soil temperature field is established through the theoretical analysis of soil heat transfer research to determine the soil temperature distribution function.At the same time,the physical model of the buried pipe in the greenhouse was established.By changing the water supply temperature and the layout parameters of the buried pipe,the FLUENT software in the ANSYS was used to simulate the soil temperature field in the greenhouse under different conditions.Finally,combined with the economy and energy conservation and environmental protection requirements,to determine the greenhouse water supply temperature and buried pipe layout parameters.Research found that the suitable water supply temperature is 35℃,40℃ and 45℃,buried pipe diameter of 25 mm,25cm,pipe length of 10 m,greenhouse soil temperature field under different buried depth,the greenhouse soil temperature is improved,meet the suitable temperature of different temperature requirements and different root depth,and provide theoretical reference for soil layout and operation of buried pipe heating.