Abstract: A horizontal ground-coupled heat exchanger for a geothermal system. The underground portion of the system includes; at least one conduit located in the soil below its frost line containing a heat transfer liquid; at least one stratum between the at least one conduit and the soil, totally disposed beneath the surface of the soil at a depth from the surface of the soil of 1.2-3 m and completely separated from the soil by at least two layers of a thin thermo-conductive waterproof material, the at least one stratum containing heat conductive water saturated fill material with the at least one conduit being disposed therein; and a means to compensate for small leaks of water from the at least one stratum. The size of the smallest dimension of the stratum per conduit is determined; the sizing is based on a user selected stratum efficiency parameter employing a relation provided herein.

Abstract: Horizontal ground-coupled heat exchanger for geothermal systems is proposed. The exchanger includes sub-surface formation of not expensive special structure heat conductive stratum around conduit loops. Analytical and finite element modeling allowed estimating the new structure efficiency. The proposed decision permits to increase by 2-3 times the transmitted heat power of the exchanger and correspondently to reduce the required pipe length and land area. The underground loop must be sized to meet the peak thermal power load. The proposed exchanger structure may fill simply this requirement, because at relatively short-term operation the efficiency of the proposed structure is even higher and reaches increasing by 2.5-4 times in dependence on climate zone.

Abstract: An electric heating device based on a ribbon of crystalline metal foil with high specific resistance, which is additionally treated to increase its plasticity and/or additionally coated with a mold release agent to enhance compatibility of the ribbon and insulating envelope. The ribbon combines high electrical resistance, high stability, sufficient mechanical strength and relative cheapness with very important properties including significant plasticity and compatibility with insulating polymers, including rubber and silicone. The above compatibility provides high reliability and life span. Different structures for flexible and rigid heaters on the basis of this ribbon are described, as are different applications.