Abstract
This paper is focused on the resort to geothermal energy, through the employment of an Earth-to-Air-Heat Exchanger (EAHX) positioned upstream of the air-handling unit of an air conditioning system, for an office building in Naples (South Italy). The aim is to evaluate the energy performances of this unusual system compared to the common solution of external air directly entering the air-handling unit. The EAHX is extensively designed and two-dimensionally modeled, and the analysis is solved with finite element method. The model is validated with experimental data and this comparison shows good agreement. With the requirement of providing the building with 1300 m3 h−1 of external airflow, different design solutions for the EAHX are studied, by varying the diameter (in the range 0.2–0.5 m) and length (between 20 and 140 m) of the buried pipes. The results indicate that: smaller tube diameters enhance the heat transfer; a tube length between 80 and 100 m is recommended. Using the EAHX, the reduction of the thermal power of the coils in the air-handling unit is greater than 40% in most cases. Finally, the efficiency of the EAHX is assessed as a function of the tube length and diameter, reaching values up to 0.9.
Highlights
Using the EAHX, the reduction of the thermal power of the coils in the air-handling unit is greater than 40% in most cases
Once the latter condition was reached, the outlet air temperature, efficiency of the EAHX, reduction of the power of the heating and cooling coils in the air-handling unit (AHU) due to the pre-treatment of the air operated by the EAHX were evaluated both in winter and summer season
In this paper it is shown how the earth-to-air heat exchanger (EAHX) used upstream of an air-handling unit (AHU) inserted in an air-conditioning system can lead to considerable reductions
Summary
The most common are solar, wind, biomass, rain, tides, waves, and geothermal heat-based energies. The systems exploiting geothermal energy take advantage of the temperature property of the ground to be constant after a certain depth. They have the common denominator of use the ground to lessen the building cooling load in summer and heating load in winter. The soil becomes a heat source-sink for the heating and cooling of the built environment as well as for providing domestic hot water, with the result of preserving a certain amount of primary energy, lowering the environmental impact connected to polluting emissions, as summarized by Soni et al [1] and
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