Geothermal system utilizing supplemental ground heat from drainage fields

Abstract

Geothermal ground coils are installed and embedded in fill at the bottom of excavations, made for drainage fields associated with septic and other effluent systems, prior to the addition of the drainage field sanitary fill. This configuration eliminates the need for expensive bore holes and provides a ground heat source that is at a higher temperature than natural ground formations due to the supplemental heat imparted to the ground by the drain field effluent Fouling of the outside heat transfer surfaces of the ground coils is also avoided because of the clarifying and filtering action of the drain field fill. This provides an improved ground source heat pump system wherein the installation costs are reduced arid the capacity and efficiency of the system are improved.

Description

REFERENCES CITED [REFERENCES BY][0001]U.S. Patent Documents2,563,262August, 1951Moore 126 / 3444,448,347May, 1984Dunstan 165 / 9095,477,914December, 1995Rawlings165 / 455,533,355July, 1996Rawlings165 / 455,730,208March, 1998Barban165 / 455,738,164April, 1998Hilderbrand165 / 455,758,717June, 1998Grossman165 / 47FIELD OF INVENTION [0002] The present invention relates to heat recovery systems and methods, and more particularly pertains to a system and method for recovery of heat from the ground affected by drainage fields. BACKGROUND OF THE INVENTION [0003] Several prior art patents have utilized the earth as a source of heat and as a heat sink. Commercial geothermal energy systems are available and have been in use for several years. These systems normally utilize a water feed heat pump for both heating and cooling. The circulating fluid that feeds the heat pump flows through tubes that are buried deep in the ground and the circulating fluid uses the ground surrounding the tubes as both a heat sour...

AI Technical Summary

Benefits of technology

[0011] The liquid discharged from septic tanks is typically 5-10 degrees Fahrenheit higher than normal ground temperatures. Since the liquid distributed by the septic systems perforated pipes is subject to further exothermal bacterial digestion in the drain field, the ground temperatures under the drain fields will be effected not only by natural geothermal heat flux, but additional heating is achieved from the sensible heat from the waste liquids from the building and from the heat produced by the bacterial digestion in the septic tank and the drainage fields. Since higher moisture...

Problems solved by technology

In practice, the heat transfer efficiency of these systems rapidly decreases because wastewater is inherently dirty and causes a buildup of material on the heat exchange surfaces.

This fouling of the heat exchange surfaces reduces the heat transfer coefficient between the wastewater and the circulating fluid inside the coils and the amount of heat recovered by these systems drops off very quickly and renders them as being impractical.

However in actual practice, during the coldest periods of the year, the heat load obviously increases and the heat removal requirement from the ground in contact with ...

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