A THERMAL STABILITY STUDY OF THE UREA-SODIUM NITRATE EUTECTIC MIXTURE AS A PCM

The eutectic mixture formed by urea and sodium nitrate has been previously identified as a PCM candidate by the authors for heating and domestic hot water storage applications. It presents a melting point of 86 degrees C, a melting enthalpy of 172 J/g and a price around 0.9 (sic)/kg. In a previous work of some of the authors, the thermal stability of the eutectic mixture was preliminarily evaluated using an accelerated thermal cycling test that comprised 210 thermal cycles. Under the experimental conditions applied, the PCMs showed a stable behaviour. The main objective of the present work is to evaluate the stability of the mixture for longer periods of use under conditions representative of actual applications. Thermal degradation segregation will be assessed experimentally close to operation conditions.