Thermal conductivity pipe for geothermal applications

Abstract

An improved geothermal system for heating and cooling a building includes a fluid loop installed in the ground with opposite ends connected to a heat pump or other heat exchanger. The fluid loop comprises a plastic pipe embedded with heat transfer particles. The pipe is a thermoplastic or thermoset elastomer modified polymer having a modulus of elasticity less than 200,000 psi.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority under 35 U.S.C. §119 to provisional application Ser. No. 61 / 225,815 filed Jul. 15, 2009, herein incorporated by reference in its entirety.BACKGROUND OF THE INVENTION[0002]Geothermal heating and cooling have been well-known for many years. Geothermal heating and cooling takes advantage of the relatively moderate ground temperatures about 4 to 8 feet below the earth surface. A conventional closed loop geothermal system circulates a water-based solution through pipes buried in the ground.[0003]The most common closed loop geothermal systems utilize vertical or horizontal closed loops. A vertical loop system is used mainly when land area is limited, with vertical bores drilled into the ground to a depth of 150-300 feet, with the pipe loops residing in the vertical bores. A horizontal loop system is commonly used when there is more open land, wherein trenches are dug 6 to 8 feet deep, and coils of pipe laid in t...

AI Technical Summary

Benefits of technology

[0027]The present invention is directed towards an improved plastic pipe for geothermal heating and cooling. The pipe is an elastomer modified polymer having thermally conductive particles embedded therein. The particles constitute 30-70% of the pipe, by volume, or 40-90%, by weight. This improved geothermal pipe has a modulus of elasticity less than 200,000 psi. The enhanced thermal conductivity of the pipe allows a shorter length of pipe to be used, with enhanced heat transfer between the fluid in the pipe and ground, as compared to conventional geothermic pipes. The improved heat transfer minimizes the field for the geothermal system. The pipe can be used in both horizontal and vertical systems. The reduced pipe length reduces installation costs and increases installation versatility.

Problems solved by technology

Drilling of vertical bores is generally more expensive than trenching for horizontal loops.

However, the horizontal loops require longer length of pipe due to the seasonal variations in the soil temperature and moisture content.

While geothermal systems are more energy efficient than conventional fossil fuel heating systems, the initial installation of geothermal systems is more expensive than conventional systems due to the cost of the pipe and the cost of equipment and labor for installing the pipe.

Vertical geothermal systems are more expensive than horizontal systems, since drilling is costlier than trenching.

However, horizontal geothermal systems require substantial open areas to lay the pipe coils.

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