Active latent heat storage using biowax in a central heating system of a ZEB living lab

Abstract

The Zero Emission Building (ZEB) lab in Trondheim (Norway), owned by SINTEF and NTNU, provides a structure to develop and test innovative solutions in a living laboratory. An innovative latent heat storage (LHS) unit using biowax as phase change material (PCM) has been integrated in the central water-based heating system. The LHS unit stores excess heat from the main heat pump and the district heating network. One challenge is to make use of the full potential of the PCM latent heat to have a compact and effective unit, while the unit itself should have a low associated CO2-footprint. The heat storage capacity is 194 kWh, corresponding to the heat needed on top of the heat pump to cover for 2-3 consecutive days in the coldest days, with a maximum combined heat output of 26 kW. Bio-based wax is used as PCM with melting temperature 37 °C and latent heat 198 kJ/kg. Keywords: Phase Change Materials, PCM, Thermal Energy Storage, Heat Battery, Biowax, Central Heating System