Investigation of Thermal Performance Enhancement on Soil Heat Storage using Borehole Heat Exchangers
Date Issued
2009
Date
2009
Author(s)
Kuo, Hsuan-Shih
Abstract
The use of vertical U-shaped borehole heat exchangers for air-conditioning purposes has been widely practiced in the developed nations for a long time. The objective of maximizing system performance by an optimized design for borehole heat exchangers is of significant importance, for it’s hardly changeable after initial installation. Current thesis conducted thorough analysis and investigated several design strategies on borehole heat exchangers, First by setting up computer programs for steady mathematical analytic model for borehole heat exchangers for further analysis. After verifying the accuracy of the mathematical model by comparing with foreign experimental studies, the experimental settings is then to be used as a baseline for optimization on dominant design parameters such as optimal borehole depth, grout thermal conductivity and mass flow rate of working fluid.Also, the studies regarding the heat conducting behavior and characteristics inside and outside the borehole heat exchangers is conducted using Fluent, a commercial computational fluid dynamics software. After the simulation results are verified to be correct, further thermal enhancement strategies is then studied using simulation method to observe the effect on transient response of the system, such as oscillating operation, and inlet/outlet pipe spacing adjustment of single U-tube borehole heat exchangers.he results of simulation described in the thesis, the transient response of outlet temperature can be reduced by a maximum if 1degree Celsius, and after the system reaches equilibrium the outlet temperature is still reduced by 0.5degree Celsius. Although there is no significant improvement using other strategies, the full 3D flow & energy field analysis still enable us a whole view of the detailed thermal behavior inside the borehole for future reference of improvement.
Subjects
Borehole Heat Exchangers
CFD
Heat Coupling
Air-Conditioner
Soil
Geothermal Heat Pump
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-98-R96522310-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):ec578b84b6ef2ed671ae3eca12536752