Customer Reviews

Ground-Source Heat Pumps - Design of Geothermal Systems for Commercial and Institutional Buildings

5 star:		(1)
4 star:		(0)
3 star:		(1)
2 star:		(0)
1 star:		(0)

 

 

I am a professional engineer, located in northern Michigan. For the design of geothermal-heating systems, I discovered that the GHX (Ground Heat Exchanger) is not only one of most expensive elements of the system, its design effects not only the performance of the heat pump, but also the temperature of the ground with which you are exchanging heat. There are three elements to a typical system: the building that you wish to heat or cool, the heat pump, and the GHX. For the systems that I design, near the 45th parallel, in the Great Lakes region, the buildings require far more heating than cooling over the course of a year. This usually results in a long-term lowering of the ground temperature, near the GHX.

This reference book discusses these effects for several kinds of GSHPs (Ground-Source Heat Pumps). Those that exchange heat with the ground, which was my primary interest, but also those that draw heat from surface water such as lakes and ponds. The principles described in the book are summarized in the ASHRAE 2007 handbook (American Society of Heating, Refrigerating and Air-conditioning Engineers), chapter 32. But this reference provides a lot more discussion about the history and sources of the design principles, than what can be found in the ASHRAE summary. I consider the ASHRAE summary to be extremely terse. The additional discussion, provided by this reference, helps resolve some design ambiguities, which derive from other publications, that date back several decades.

One item that I found of particular interest was a brief discussion describing field tests to determine local soil thermal properties. An accurate assessment of the soil thermal properties allows design of a GHX that is sized correctly for the building and the climate. An undersized GHX results in poor performance, usually in a requirement for the hidden cost of supplemental heat. An oversixed GHX, results in additional installation cost, but may be mitgated by a lower operating cost. I think that I may end up prescribing field tests for systems that are already installed, but are not performing as desired. These would be systems where the importance of proper GHX design was not fully appreciated. For the analysis of the data collected, I would use numerical methods and software that I originally wrote during my graduate study at the University of Michigan. I have used these numerical techniques for several years, to analyze test data, for other applications. And, I see another opportunity for their use to improve GHX design.

This is possibly the best book on the market for Ground Source Heat Pumps (GSHP). The book takes the reader/student from beginning heat pump applications (chapter 1) through economics of GSHP systems (chapter 8). My only suggestion would be to update this publication with a chapter on commissioning of these systems.

I have had the privilege of meeting and attending a seminar with one of the authors, Stephen Kavanaugh (an authority on GSHP's) and found him to be a wealth of knowledge (both theory and practical). For a college professor and a PHD I found him refreshing in his practical approach and real world application of the design, construction and operation of GSHP's. I wholeheartedly recommend this publication and attending of one of his seminars. Enjoy!