Ground Thermal Diffusivity Calculation by Direct Soil Temperature Measurement. Application to very Low Enthalpy Geothermal Energy Systems

Abstract

This paper presents a methodology and instrumentation system for the indirect measurement of the thermal diffusivity of a soil at a given depth from measuring its temperature at that depth. The development has been carried out considering its application to the design and sizing of very low enthalpy geothermal energy (VLEGE) systems, but it can has many other applications, for example in construction, agriculture or biology. The methodology is simple and inexpensive because it can take advantage of the prescriptive geotechnical drilling prior to the construction of a house or building, to take at the same time temperature measurements that will allow get the actual temperature and ground thermal diffusivity to the depth of interest. The methodology and developed system have been tested and used in the design of a VLEGE facility for a chalet with basement at the outskirts of Huelva (a city in the southwest of Spain). Experimental results validate the proposed approach.

An Empirical Estimation of Underground Thermal Performance for Malaysian Climate

“…the soil could cause the soil to become isothermal after it reaches certain depth. These findings are consistent with those reported by previous researchers [3][4][5][6]. …”

“…In other words, at a sufficient depth, the soil temperature is lower than the surface air temperature during daytime (the trend is opposite during night-time). Therefore, soil temperature is seemingly a key factor in affecting the heat transfer of an underground building and the thermal storage for new sources of renewable energy [3][4][5][6][7]. Therefore, the investigation of soil temperature at different depths is necessary to calculate the heat flux through the building surface.…”

“…Soil temperature has been investigated for different geographical locations [8], geothermal assessments [3,9] and soil depths [9][10][11]. Also, research work on Ground Heat Exchanger (GHE) implementation [12,13], underground building [5,6,14] and underground wine cellar [2,15] have been performed as well.…”

uhuMEB: Design, Construction, and Management Methodology of Minimum Energy Buildings in Subtropical Climates

“…To take advantage of the available room on the plot and the compulsory excavation to locate the basement of the house, a LEGE system has been designed [62]. This system can replace the conventional external air intake set by the mandatory regulations in Spain (window aerators, wall aerators, etc.)…”

“…Regarding the LEGE system design, Figure 16 represents the measures of a temperature probe buried in the ground of the Casa Zaranda plot [62]. Note that the temperature of the ground tends to remain constant as the depth increases.…”