Geothermal energy is a cost effective, reliable, sustainable and environmentally friendly energy stored in the earth mass. Earth ground surface temperature is function of the ambient temperature. The soil temperature yearly fluctuations decrease as the soil is deeper. The deeper it is the more it converges to the mean yearly ambient temperature. Doha summer climate is considered to be hot and humid. Cooling humid fresh air contributes to around 50% of the building cooling load in that area. The purpose of this study is to investigate the effectiveness of using geothermal energy to pre-cool outside air in Doha Qatar. It evaluates two geothermal heat transfer systems to help reduce the overall building energy demand. The first geothermal system is based on closed loop principle. It consists of installing vertical loops that run perpendicular to the surface deep in the ground. The ground loop acts as a heat exchanger to cool the circulating water that will be used to precool building fresh air through air coils. In this study the optimal bore depth is considered to be 300 ft. (91m) with a heat exchange rate of 0.82 refrigeration tons per bore. The second geothermal system uses groundwater to pre-cool the outside air. This system consist on having a production well, an injection well and cooling air coils. Water extracted from the production well at ground temperature passes through air coils to pre-cool outside air. Heated water shall be injected into a second well called the injection well. In this system the minimum spacing between the production well and the injection well is estimated to be 170 ft. (51m). Maximum ground water temperature increase is limited to 8°C to avoid inducing thermal disturbance in the aquifer. Each refrigeration ton would require 0.108 l/s (0.228 cfm) of ground water. To conclude vertical loops compared to the ground water open loops have a higher initial cost since it involves extensive earth works where large number of drilled holes as well as water loops needs to be installed; however, vertical loops are considered more appropriate for Doha area application since it involves lower running cost as well as it preservation of the Doha deep aquifer.
Citation: International Conference on Efficient Building Design, Materials and HVAC Equipment Technologies; October 2-3, 2014; Beirut, Lebanon
Product Details
- Published:
- 2014
- Number of Pages:
- 9
- File Size:
- 1 file , 4.3 MB
- Product Code(s):
- D-ICEB14-15
