Experimental Investigation Of Superficial Soil Thermal Release-storage (By Water) Combined With Heat Pump In Solar Greenhouse

In this study, the solar energy is used as heat source, the water is used as heat storage medium and the shallow soil in greenhouse is used for heat storage. The heat was collected and stored in shallow soil through water circulation during the day, and the greenhouse temperature increased at night due to the soil heat releasing. The results showed that: this method increased the heat storage of greenhouse. The temperature difference began to increase after covered the insulation. The average air temperature in experiment greenhouse is 4.0℃higher than in normal greenhouse. The soil temperature at 0cm,30cm,60cm in the experiment greenhouse is 3.0℃,3.0℃, 5.0℃higher than in the normal greenhouse respectively. Therefore, this method not only increased the air temperature, but also increased the temperature of soil around which crops grow.Comparing the measured data of environment factors in greenhouse with the simulated values, IA of indoor air temperature in CG was 0. 92, IA of indoor air temperature in TG was 0.79, IA of north wall surface temperature in TG was 0.58, IA of air layer temperature in TG was 0.79, IA of soil surface temperature in TG was 0.94。It was shown that model could simulate the temperature change generally.In the sunny days, the solar energy is used as heat source, the water is used as heat storage medium and the shallow soil in greenhouse is used for heat storage. The heat was collected and stored in shallow soil through water circulation during the day, and the greenhouse temperature increased at night due to the soil heat releasing. The results showed that: this method increased the heat storage of greenhouse. The temperature difference began to increase after covered the insulation. The average air temperature in experiment greenhouse is 4.0℃higher than in normal greenhouse. The soil temperature at 0cm,30cm,60cm in the experiment greenhouse is 3.0℃,3.0℃, 5.0℃higher than in the normal greenhouse respectively. Therefore, this method not only increased the air temperature, but also increased the temperature of soil around which crops grow.In the cloudy days, the temperature in the greenhouse is low, During the first half of the night,the energy stored in the north wall and soil will release to the air. After midnight, the heat pump is opened, the heat stored in the black wall released to the air from the north to the south. So the temperature distribution in the greenhouse is uneven.The influence of different depth on crop root is caculated by model, the result showed that: When the pipes at the depth of 36~ 60cm, soil temperature at 30cm increased lower. So pipes at 36cm are better. This can not only ensures soil temperature at 30cm, but also reduces unnecessary labor costs.