Abstract:
This research aims to study the spreading out of the soil temperature at each level of depth by using mathematical model. In this study, a set of soil temperature tester was designed. It consisted of aluminium box. The aluminium box is placed on the top of the soil box; it creates heat source for soil. Meanwhile, under the box there is heat sink; it takes the heat from the top in order to make the heat flow easier. The experiment started by placing hot water at 60?C, 70 ?C and 80 ?C into the top of aluminium box by using temp control for controlling the temperature of hot water steadily. Subsequently, measured the temperature of soil at the different levels of depth until the equilibrium point was reached. From the experiment, the thermal conductivity of the tested soil was found to be 0.844 W/maC. The results of studying the spreading out of the'soil temperature at the levels of 0, 5, 10, 15, 20, and 25 centimeters showed that at the primary stage, the temperature of soil depended on duration of time and level of deepness. Namely, the soil temperature increased with the time and the temperature of soil surface was highest, while the temperature decreased when the level of depth was getting higher. When the equilibrium point was reached, the soil temperature depended only on the deepness. The higher temperature of hot water placed to the system resulted in higher soil temperature, depending on the level of depth. In the experiment, soil temperature had changed at the depth of 0-15 centimeters mainly, while at the depths of 20 and 25 centimeters, it changed slightly. The changing of soil temperature resulted from two processes, heat conduction and latent heat. When comparing the results gained from measuring and calculating of model, it was found that at the primary stage, the different value was about 0.8'~-3.5'~ due to value of latent heat, but when the time went by, The values of both cases were nearly similar.