Next Article in Journal
Cooling Performance Characteristics of the Stack Thermal Management System for Fuel Cell Electric Vehicles under Actual Driving Conditions
Next Article in Special Issue
Coordination Control Strategy for AC/DC Hybrid Microgrids in Stand-Alone Mode
Previous Article in Journal
Power Production Losses Study by Frequency Regulation in Weak-Grid-Connected Utility-Scale Photovoltaic Plants
Previous Article in Special Issue
Effect of Guide Vane Clearance Gap on Francis Turbine Performance
Article Menu
Issue 5 (May) cover image

Export Article

Open AccessArticle
Energies 2016, 9(5), 318; doi:10.3390/en9050318

Effect of Borehole Material on Analytical Solutions of the Heat Transfer Model of Ground Heat Exchangers Considering Groundwater Flow

School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 136-701, Korea
*
Author to whom correspondence should be addressed.
Academic Editor: Jang-Ho Lee
Received: 31 December 2015 / Revised: 10 March 2016 / Accepted: 18 April 2016 / Published: 25 April 2016
(This article belongs to the Special Issue Selected Papers from 5th Asia-Pacific Forum on Renewable Energy)
View Full-Text   |   Download PDF [8541 KB, uploaded 25 April 2016]   |  

Abstract

Groundwater flow is one of the most important factors for the design of a ground heat exchanger (GHEX) since the thermal environment of the ground around the buried GHEX is significantly affected by heat convection due to the groundwater flow. Several preceding studies have been conducted to develop analytical solutions to the heat transfer model of GHEX with consideration of groundwater flow. One of these solutions is the combined heat transfer model of conduction and convection. However, the developed combined analytical models are inapplicable to all of the configurations of ordinary GHEXs because these solutions assume that the inner part of the borehole is thermally inert or consists of the same material as that of the surrounding ground. In this paper, the applicability of the combined solid cylindrical heat source model, which is the most suitable to energy piles until now, was evaluated by performing a series of numerical analyses. In the numerical analysis, the inner part of the borehole was modeled as two different materials (i.e., permeable ground formation and impermeable fill such as concrete) to evaluate applicability of the analytical solution along with different diameter-length (D/L) ratios of borehole. In a small value of the D/L ratio, the analytical solution to the combined heat transfer model is in good agreement with the result of numerical analysis. On the other hand, when increasing the D/L ratio, the analytical solution significantly overestimates the effect of groundwater flow on the heat transfer of GHEXs because the analytical solution disregards the existence of the impermeable region in the borehole. Consequently, such tendency is more critical in the GHEX with a large D/L ratio such as large-diameter energy piles. View Full-Text
Keywords: analytical solution; combined heat transfer model; ground heat exchanger (GHEX); energy pile; groundwater flow; numerical analysis analytical solution; combined heat transfer model; ground heat exchanger (GHEX); energy pile; groundwater flow; numerical analysis
Figures

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Park, S.; Lee, S.; Lee, H.; Pham, K.; Choi, H. Effect of Borehole Material on Analytical Solutions of the Heat Transfer Model of Ground Heat Exchangers Considering Groundwater Flow. Energies 2016, 9, 318.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Energies EISSN 1996-1073 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top