How does pile size affect solar energy storage?

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Can energy piles store solar thermal energy underground?

Ma and Wang proposed using energy piles to store solar thermal energy underground in summer, which can be retrieved later to meet the heat demands in winter, as schematically illustrated in Fig. 1. A mathematical model of the coupled energy pile-solar collector system was developed, and a parametric study was carried out.

How much solar energy can a 10 m-long energy pile store?

Under the specific thermal boundary conditions adopted, the maximum daily average rate of solar energy storage reached 150 W/m for the 10 m-long energy pile. It decreased to about 35 W/m as the pile length increased to 50 m.

How does pile size affect solar energy storage?

As the pile diameter increases, there has a relatively larger volume of concrete for solar energy storage, leading to a lower pile temperature. As a result of its lower temperature, a higher rate of solar energy storage is observed for cases with larger pile diameters.

What is a coupled energy pile-solar collector system?

For a coupled energy pile-solar collector system in practical engineering, the solar collectors will be mounted on the exterior walls and roofs of buildings to minimise additional land use. To avoid oversizing the solar collector area, it is important to maximise the efficiency of the solar collector through optimal design.

How does a solar energy pile-soil system work?

The heat-carrying fluid particle transports heat from the solar collector to the energy pile-soil system continuously. The rate of charging and discharging depends on the flowrate, the intensity of radiation, and the condition of the energy pile-soil system.

Can energy piles be used for underground energy exchange?

Energy piles, which are combinations of BHEs with pile foundations, could be used for underground energy exchange without the need for drilling holes [ , , ]. Energy piles have been combined with ground source heat pump (GSHP) systems for building heating or cooling for years [ 33 ].