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Oklahoma State University

Ground Loop Heat Exchanger Design Software

GLHEPRO for Windows

GLHEPRO is used for designing ground loop heat exchangers for use with ground source heat pump systems.

Version 5.0 now available!

A description of the new features in GLHEPRO V5.0 is available here.

You can download the GLHEPRO V5.0 User Manual here.

GLHEPRO was developed as an aid in the design of vertical borehole-type ground loop heat exchangers used in geothermal heat pump systems. While GLHEPRO may be used for residential system design, it is aimed at commercial systems. The heat exchanger may be composed of any number of boreholes arranged in various configurations.

GLHEPRO performs three different tasks:

  • Simulation (for up to 100 years) of ground loop heat exchangers to determine monthly average and peak heat pump entering and exiting fluid temperatures, as well as power consumption of the heat pump.
  • Determination of the required borehole depth to meet user-specified minimum and maximum heat pump entering fluid temperatures.
  • Sizing of hybrid ground source heat pump (HGSHP) systems by determination of the required borehole depth and necessary supplemental heat rejecter (cooling tower, fluid cooler) or heat extractor (boiler) size.

GLHEPRO is based on the methodology developed by Eskilson at the University of Lund in Sweden, considered by Dr. Spitler to be the best currently available methodology.

A technical paper describing GLHEPRO v3.0 (pdf):  most of the discussion still applies to GLHEPRO v4.1.

Xu and Spitler (2006) (pdf):  discussion of the new GLHE model, which includes improved borehole thermal resistance calculations and consideration of thermal mass.

A paper was published in 2015 by Cullin et al. on the validation of GLHEPro’s results as compared to an actual system and the ASHRAE Handbook Design Method.  Summary of the validation.

Manual for GLHEPRO v4.1 (pdf)

GLHEPRO requires four basic sets of input data:

  • Monthly and monthly peak heating and cooling loads on the heat pumps. These are obtainable from programs such as HVAC Load Calculations for Windows, Trane Systems Analyzer, and other similar programs. GLHEPRO has an interface to the above-named programs which automates the data transfer. For other programs, the loads must be typed in manually.
  • Ground thermal properties. GLHEPRO has a small database of ground thermal properties for a few different ground types. For larger jobs, an in situ test is recommended, using the in situ methodology developed at Oklahoma State University.
  • Ground loop heat exchanger information. The user must select a borehole configuration and specify some related additional information - borehole diameter, borehole spacing, grout and piping properties, and fluid type and flow rate. Open and closed rectangle, line, U-shaped, L-shaped, and stacked L-shaped configurations are available; additionally, the Large Rectangle option can be purchased, which provides additional borehole configurations up to 900 boreholes.
  • Heat pump information. GLHEPRO has a database of heat pump types from most manufacturers. Any models not available in the database may be added by the user using commonly available catalog data.

GLHEPRO offers an easy-to-use Windows interface. The borehole configurations are chosen from one of the following screens, depending on your version:

Regular borehole field selection

Large rectangular field selection

Heat pumps are selected from a database of heat pumps using this screen: