Development of Next Generation Phase-Change Materials for Heat-Storage Applications

  • Supervisors: Prof. Colin Pulham, University of Edinburgh & Prof. Russell Morris, University of St Andrews
  • Sponsor Company: Sunamp Ltd.
  • PhD Student: Rowan Clark

42% of UK energy consumption is in the form of heat – associated with domestic and commercial heating of buildings, and the heating requirements for a wide range of industrial processes.  Hence there is a very strong driver towards the exploitation of renewable heat, and a key challenge for renewable heat must be effective heat storage.  Sunamp has developed a compact heat store (termed a heat battery), which can replace domestic boilers, hot water tanks and air conditioning units, and will connect to solar panels and other forms of renewable energy heating and cooling equipment.  Key to the development of high-performance heat batteries is the intelligent selection and extensive characterisation of appropriate heat-storage materials that perform reproducibly over many (thousands) heating and cooling cycles.  Hence this project is focussing on the two strands of research outlined below.

(1)        Development and exploitation of new phase-change materials (PCMs) based on salt hydrates to cover specific temperature ranges for which there are currently no suitable candidate materials with the required properties.  In particular we wish to develop PCMs that have better reproducibility over many heating and cooling cycles, and which have higher energy densities.

(2)        Development and exploitation of thermochemical heat-storage materials (TCMs). These are compounds that on heating undergo a reversible chemical reaction with an enthalpy change.  Examples include dehydration of a metal salt, thermal decomposition of a metal hydroxide, or dehydration of a framework material such as a zeolite.  Potential advantages of TCMs include significantly higher energy densities; higher operating temperatures; and facile long-term storage in the “charged” state without the requirement for thermal insulation.  We are investigating several interesting candidate materials that span the temperature range 80-600 °C and which offer very high energy densities.