"This thesis develops a theoretical framework, termed [Effectiveness] - BLU, to characterize the relation between temperatures, thermal contact and borehole length as it relates to the heat transfer processes in ground coupled heat exchangers used for ground source heat pump systems.
Borehole outflow temperature depends on the inflow temperature, the heat imposed on the borehole and the temperature history of the ground. In addition, variation of outflow temperature influences inflow temperature, even for the case of constant heat pump load. Because of this kind of feedback, the borehole inflow temperature may not be constant even with a fixed building load. Considering the complexity, the research is divided into two sections: "open loop" problems and "closed loop"problems. For "open loop" problems, the inflow temperature is specified and taken to be independent of the outflow temperature. The development of the [Effectiveness] - BLU analysis begins with the "open loop" problems. The analysis is then extended to "closed loop" problems for which the inflow temperature is dictated by outflow temperature and specified heat pump load. The impact of both steady and periodic loads on the conductance and fluid temperatures are quantified.
In the [Effectiveness] - BLU analysis, the dimensionless conductance quantifies time-dependent thermal contact between the circulating fluid and the ground surrounding the borehole. The dimensionless conductance quantifies the quasi-steady heat transfer with only three dimensionless parameters: the Fourier Number, the Biot Number, and the Number of Borehole Length Units. The resulting graphs enable determination of optimal borehole length, a result not previously recognized. Seasonal equivalent conductance and peak borehole outflow temperature are used to evaluate the effect of building loads on heat transfer through the borehole. A multi-year simulation has also been conducted to reveal the behavior of ground heat exchangers under periodic load."--Abstract, page iii.
Crosbie, A. L. (Alfred L.)
Baur, Stuart Werner, 1965-
Mechanical and Aerospace Engineering
M.S. in Mechanical Engineering
Missouri University of Science and Technology
xi, 59 pages
© 2014 Chou Shen, All rights reserved.
Thesis - Open Access
Library of Congress Subject Headings
Ground source heat pump systems
Heat exchangers -- Thermodynamics
Heat -- Transmission -- Mathematical models
Heat exchangers -- Design and construction
Heat pumps -- Design
Electronic OCLC #
Shen, Chou, "An effectiveness - based analysis of ground coupled heat exchangers" (2014). Masters Theses. 7274.