Formation Thermal Conductivity | Overview
Thermal conductivity is the physical property of a material that determines how easily heat can pass through it. The average thermal conductivity of a formation that a geothermal ground-loop heat exchanger is installed into is important in order to develop a properly sized heat exchanger for a particular application. The information that is obtained from a formation thermal conductivity (FTC) test can be input directly into most of the popular design software programs.
Importance
The thermal conductivity of a formation is a prerequisite for a properly designed geothermal ground-loop heat exchanger. The thermal conductivity of the formation determines how easily heat can be conducted to and from the circulating fluid in the heat exchanger piping. For example, in a formation with high thermal conductivity, the loop temperature required to reject a given amount of heat to the ground would be less than the loop temperature for a formation with a lower thermal conductivity. Higher loop temperatures for cooling translate into reduced heat pump performance and higher operating costs.
Why Consider FTC Testing?
- Proper testing enables ground loops to be sized to match the existing formation conditions.
- The obtained information provides for a better estimate of installation cost.
- Precision designs save money on drilling, grouting and pipe costs.
- Proper designs allow the system to run more economically.
- Multiple tests can be conducted which would allow the comparison of different grouts.
- Test parameters can be set up to simulate loop response under cooling design conditions.
Why GRTI?
- Un-surpassed Experience
- Over 12 years of experience in measuring and calculating thermal conductivity or various formations and soils.
- Over 25,000 hours of accumulated data has been analyzed from more than 550 separate tests.
- Data analysis performed by Mechanical Engineers with research backgrounds.
- Long test times provide a reliable value for average formation thermal conductivity.
- Dedicated to quality testing and data analysis.
- Follows ASHRAE recommended procedures as found in the 2003 ASHRAE Handbook, HVAC Applications, page 32.14.
- GRTI offers a variety of approaches to obtain an analysis (see various FTC options).