Experimental research of heating by fire-pit and underground heating exchange system in a solar greenhouse

In order to raise soil temperature and air temperature in solar greenhouse,fire-pit and undergroundheating exchange system which connected the fire-pit with underground heating exchange system were designed. The average temperatures of three different test points of soil(350 mm below the earth surface) in length of solar greenhouse arebasically uniform, which are 15.5℃, 15.6℃ and 15.5℃, increasing by 1.9℃, 2.0℃ and 1.9℃, respectively, in width of solar greenhouse, which are 15.2℃, 15.6℃ and 14.7℃, increasing by 2.7℃, 2.0℃ and 3.7℃. The average temperature in the solar greenhouse reaches 21.4℃ with the increase of 2.6℃; the temperature difference between inside and outside reaches 34.0℃. The results show that,during the winter seasons, using the fire-pit and underground heating exchangesystem has better efficiency to raise thesoil temperature and the air temperature.