The goal of the investigation is to determine the heat transfer between heat pipes and sand-gravel storage media by carrying out in a small size experiment. The experiment consists of a highly insulated box filled with two kinds of sand material crossed by a plastic heat pipe.
Heat transfer is measured under dry and water satured conditions in a cross-section.
The conclusions are clear. To obtain necessary heat conduction in sand-gravel material, the storage media is to be water satured. In this case, handling of such material on site is rather complex. The conduction is highly dependent on the thermal properties of the storage media and so is the overall thermal performance of a storage applying such media. For sandy media no convectional heat transport is found.