Heat pipe-based radiator for low grade geothermal energy conversion in domestic space heating

A severe technical drawback of geothermal heat pumps (GHPs) is the fact that the nominal operating temperature available for domestic space heating is typically in the region of 50°C. This is 25°C to 40°C less than conventional boiler settings used in hydronic central heating applications. As a result, GHPs are not generally ideal for direct replacement of conventional hydronic central heating systems because of the low relative distribution temperatures unless extreme measures are taken to improve the thermal insulation of the buildings. A preferable option for GHPs is underfloor heating. In terms of retrofitting existing buildings neither the reinsulating nor the underfloor heating options are attractive due to the large added cost and disruptive nature of the installation. As such, very high performance low temperature radiators that are pluggable into existing hydronic central heating systems are a major enabling technology for this sustainable energy source. In this investigation a Simulation Driven Design technique was utilized to develop a novel low water content and high thermal throughput heat pipe-based radiator. The radiator was subsequently fabricated and tested and showed an exceptionally high power density and very fast response time compared with conventional wet radiators.