Backfill to buried pipe heat exchanger through hole

Abstract

The present invention belongs to the field of building material technology, and is especially backfill material for buried pipe in earth source heat pump air conditioning system. The backfill material for buried pipe in earth source heat pump air conditioning system consists of cement 100 weight portions, quartzite 200-250 weight portions, defoaming agent 0.05-0.1 weight portion, bentonite 1-2 weight portions and water reducing agent 0.2-2 weight portions. When used, the said components are mixed while adding water in the construction site, and the mixture is injected into the drilled hole. The backfill material has high heat conducting coefficient, high operation performance, high impermeability, high strength and no environmental pollution.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a buried pipe backfill material used in a ground source heat pump air conditioning system. Background technique [0002] Buried pipe ground source heat pump heating and air conditioning technology is receiving more and more attention because of its energy saving and environmental protection characteristics. Backfilling is an important link in the construction process of the buried tube heat exchanger, that is, after the drilling is completed and the U-shaped tube is lowered, the backfilling material is injected into the borehole. It is between the buried pipe of the buried pipe heat exchanger and the wall of the borehole, and is used to enhance the heat exchange between the buried pipe and the surrounding rock and soil, prevent the surface water from penetrating into the ground through the borehole, and protect the groundwater from surface pollutants pollu...

AI Technical Summary

Problems solved by technology

At present, the commonly used grouting backfilling materials are mostly mixed slurry of bentonite and fine sand (or cement). The thermal conductivity of this kind of backfilling is only 0.65-0.9W / m.K, and this kind of bentonite backfilling material is easy to dry, shrink and crack. Therefore, in dry areas, the thermal conductivity of this backfill material will drop very little, and the increase in contact thermal resistance due to dehydration will have a serious negative impact on heat transfer.

The use of backfill materials with poor thermal conductivity will significantly increase the thermal resistance in the borehole, resulting in an increase in the total length of the borehole required under the same conditions, which also means an increase in the initial investment and operating costs of the system