| dc.description.abstract | Air pollution is one of the main environmental problems mankind faces in the 21^(st)
century caused by to the extensive use of fossil fuels. One of the opportunities to
overcome this problem is to develop new technologies and methods to profit from the
energy stored in the ground. A promising high-efficiency technology for the thermal
control of buildings is the shallow geothermal energy. This technology is growing
rapidly because it consumes less conventional energy for operation, which in turn results
in fewer CO_(2) emissions. This technology harnesses constant and moderate ground
temperature for thermal control of a building using foundation piles. Outside air
temperature changes with the season, while ground temperature remains moderate and
constant. In summer, ground temperature is lower than air temperature, and so the
ground may be used as a heat sink. The opposite is true in winter; the ground becomes a
heat source. This technology is used efficiently in cold, heating dominated climates.
Could this be true in hot, cooling dominated climates?
To achieve the ultimate goal and answer the above question, this study
considered the different elements of a full SGES, namely: soil, climate, energy pile, and
ground source heat pump. First, The need for a new, easy, and quick in-situ method to
thermally characterize soils lead to the development of the Thermal Cone Test. Second,
the soil-climate interaction and its effect on the thermodynamic efficiency of energy
piles was an important factor to consider, where the decrease in soil saturation leads to a
decrease in the heat exchange rate of energy piles. Third, the thermal use of foundation pile changes the pile and surrounding soil temperature where both materials are
temperature dependent. This change in temperature leads to a change in the mechanical
behavior of energy piles. Fourth, a full-scale test on installed and instrumented energy
piles group was needed to understand the thermodynamics of a full system and to
provide experimental data for a full economic study. Finally, this study was capped by
an economic analysis to evaluate the cost, benefits, payback period, and feasibility of
SGES in cooling dominated climates.
The study presented in this dissertation found that integrating energy piles in
heating and cooling systems in hot, cooling dominated climates could be economical and
environmentally friendly solution, but attention should be paid to the thermodynamic
efficiency of the system when unsaturated soil layer is encountered, and to the long term
mechanical behavior of foundation piles in high plasticity clay where additional
settlement could take place resulting from the increased creep rate caused by soil
heating. | en |
