Research Papers

A Simulink®-Based Building Load-Ground Source Heat Pump Model Used to Assess Short-and Long-Term Heat Pump and Ground Loop Performance

[+] Author and Article Information
Jonathan L. Gaspredes, Tess. J. Moon

Department of Mechanical Engineering,
University of Texas at Austin,
Austin, TX 78712

Glenn. Y. Masada

Department of Mechanical Engineering,
University of Texas at Austin,
Austin, TX 78712
e-mail: masada@mail.utexas.edu

1Corresponding author.

Manuscript received February 13, 2013; final manuscript received November 19, 2013; published online January 24, 2014. Assoc. Editor: S. A. Sherif.

J. Thermal Sci. Eng. Appl 6(2), 021013 (Jan 24, 2014) (10 pages) Paper No: TSEA-13-1032; doi: 10.1115/1.4026081 History: Received February 13, 2013; Revised November 19, 2013

An integrated building load-ground source heat pump model is developed to capture short-term (30 s) and long-term (10–20 yr) performance of ground source heat pumps with vertical boreholes. The model takes advantage of the built-in computation and organization functions of the simulink®/matlab environment to couple the component building load, heat pump, and ground loop models at every time step. The building load model uses the HAMBASE thermal program and is applicable to residential and commercial buildings. The heat pump model uses manufacturer data and sensible heat corrections to accurately model heat pump operation across a wide range of input conditions. The ground loop model is a combination of Hellstrom's borehole tube model, Eskillson's long-term (>10 yr) g-function ground model and the one-dimensional, short-term (<5 min) numerical ground model by Xu. Fifteen year simulation results for a base case residential house are presented to illustrate the integrated model's ability to predict a wide range of time responses and to illustrate a limiting ground loop sizing criterion that reveals the slow degradation in system performance due ground heating effects. Simulations with varying borehole lengths also illustrate the sensitivity of ground loop sizing on the system's thermal and economic performances. The work emphasizes the importance of proper borehole sizing, design, and placement especially in cooling-dominated climates, where the unbalance of heat loads to the ground cause slowly rising ground temperatures.

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U.S. Department of Energy, 2011, “2010 U.S. Buildings Energy End-Use Splits, by Fuel Type (Quadrillion Btu),” accessed: 20-Nov-2011, http://buildingsdatabook.eren.doe.gov/TableView.aspx?table=1.1.5
U.S. Department of Energy, 2011, “Buildings Share of U.S. Primary Energy Consumption (Percent),” accessed: 20-Nov-2011, http://buildingsdatabook.eren.doe.gov/TableView.aspx?table=1.1.3
Fisher, D. E., and Rees, S. J., 2005, “Modeling Ground Source Heat Pump Systems in a Building Energy Simulation Program (EnergyPlus),” 9th International IBPSA Conference, Montreal, Canada, pp. 311–318.
Hughes, P. J., 2008, “Geothermal (Ground-Source) Heat Pumps: Market Status, Barriers to Adoption, and Actions to Overcome Barriers,” Oak Ridge National Laboratory.
U.S. Department of Energy, 2008, “Energy Consumption in Texas Homes,” accessed: 20-Nov-2011, http://apps1.eere.energy.gov/states/state_home.cfm/state=TX
Navigant Consulting, 2009, “Ground-Source Heat Pumps: Overview of Market Status, Barriers to Adoption, and Options for Overcoming Barriers.”
Hammond, M., 2012, ClimateMaster, http://www.climatemaster.com/index
Spitler, J. D., and Cullin, J., 2008, “Misconceptions Regarding Design of Ground-Source Heat Pump Systems,” Proceedings of the World Renewable Energy Congress, Glasgow, UK.
Spitler, J. D., 2000, “GLHEPRO—A Design Tool for Commercial Building Ground Loop Heat Exchangers,” Proceedings of the Fourth International Heat Pumps in Cold Climates Conference, Aylmer, Québec, Canada.
Duffy, M. J., Hiller, M., Bradley, D. E., Keilholz, W., and Thornton, J. W., 2009, “ TRNSYS—Feature and Functionality for Building Simulation 2009 Conference,” Building Simulation, Glasgow, Scotland, pp. 1950–1954.
Hackel, S., Nellis, G., and Klein, S., 2008, “Optimization of Cooling-Dominated Hybrid Ground Coupled Heat Pump Systems,” Proceedings of 9th International IEA Heat Pump Conference, Zurich, Switzerland.
Clark, D. R., and May, W. B., 1985, “Hvacsim + Building Systems and Equipment Simulation Program–User's Guide,” U.S. Department of Commerce, National Bureau of Standards, Gaithersburg, MD.
Crawley, D. B., Lawrie, L. K., Winkelmann, F. C., Buhl, W. F., Huang, Y. J., Pedersen, C. O., Strand, R. K., Liesen, R. J., Fisher, D. E., Witte, M. J., and Glazer, J., 2001, “EnergyPlus: Creating a New-Generation Building Energy Simulation Program,” Energy Build., 33, pp. 319–331. [CrossRef]
Kavanaugh, S. P., 1985, “Simulation and Experimental Verification of Vertical Ground-Coupled Heat Pump Systems,” Ph.D. thesis, Oklahoma State University, Stillwater, OK.
Hirsch, J. J., 2009, “eQuest v3—Overview, Energy Design Resources.”
De Wit, M., 2006, “Heat Air and Moisture Model for Building and Systems Evaluation,” Technische Universiteit, Eindhoven, The Netherlands.
Mathworks, 2011, “Simulink-Simulation and Model-Based Design,” accessed: 01-Nov-2011, http://www.mathworks.com/products/simulink/
ANSI/ASHRAE 140-2007, 2007, “Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs,” ANSI/ASHRAE.
Gaspredes, J. L., 2011, “Development of an Integrated Building Load-Ground Source Heat Pump Model as a Test Bed to Assess Short- and Long-Term Heat Pump and Ground Loop Performance,” M.S. thesis, The University of Texas at Austin, Austin, TX.
ClimateMaster, 2010, “Tranquility 20 Single Stage Series Submittal Data,” ClimateMaster, Oklahoma City, OK.
Hellström, G., 1991, “Ground Heat Storage: Thermal Analyses of Duct Storage Systems,” Department of Mathematical Physics, Lund University Lund, Sweden.
Xu, X., 2007, “Simulation and Optimal Control of Hybrid Ground Source Heat Pump Systems,” Ph.D. thesis, Oklahoma State University, Stillwater, OK.
Eskilson, P., 1987, “Thermal Analysis of Heat Extraction Boreholes,” Ph.D. thesis, University of Lund, Lund, Sweden.
Yavuzturk, C., 1999, “Modeling of Vertical Ground Loop Heat Exchangers for Ground Source Heat Pump Systems,” Ph.D. thesis, Oklahoma State University, Stillwater, OK.
American Society of Petroleum Geologists, 1974, Geological Maps of Texas, Austin, TX.
O'Neal, D. L., Gonzalez, J., and Aldred, W., 1994, “A Simplified Procedure for Sizing Vertical Ground Coupled Heat Pump Heat Exchangers for Residences in Texas,” Energy Systems Laboratory, Texas A&M University.
ClimateMaster, “GeoDesigner,” www.climatemaster.com/downloads/RP419.pdf
U.S. Department of Energy, 2011, Residential Electricity Prices (cents/kWh).


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Fig. 1

Building, heat pump, and ground loop components of a GSHP system

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Fig. 2

g-functions for typical borehole configurations—data from GLHEPRO 4.0 [9]

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Fig. 3

(Left) q(t) and its piecewise approximation, (right) resulting temporal superposition of q(t)

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Fig. 4

Monthly average water temperature entering ground loop (-GL) and heat pump (-HP), GLHEPRO and IBL-GSHP ground loop models, Jan.–Dec. with full internal loads

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Fig. 5

Base case—building zone 1 and zone 2 air and wall temperatures, June 30, 12:00–15:00

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Fig. 6

Base case—average hourly heat rate rejected to ground loop water by heat pump (positive—cooling. negative—heating), Year 1, Jan–Dec

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Fig. 7

Base case—monthly mean, max and min heat pump EWT, 15 yr, based on hourly averages

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Fig. 8

Base case—annual and peak monthly heat pump electricity used over 15 yr

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Fig. 9

Maximum yearly heat pump EWT for different borehole lengths, based on hourly averages

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Fig. 10

Total annual cooling for different borehole lengths



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