Preparation and performance of modified sodium acetate trihydrate composite phase change material for thermal energy storage

WU Dongling1 LI Tingxian1 HE Feng1 WANG Ruzhu1

(1.Institute of Refrigeration and Cryogenics, Shanghai Jiao Tong University, Shanghai, China 200240)

【Abstract】Phase separation and supercooling are common phenomenon of salt hydrates, which is a key problem affecting the thermal stability and thermal performance of phase change material. Sodium acetate trihydrate (SAT), as a low and medium temperature salt hydrate, is the main study object. Carboxyl methyl cellulose (CMC) and disodium hydrogen phosphate dodecahydrate (DHPD) were firstly used to modify SAT by melt blending method. A high-performance composite phase change material (PCM) was prepared by optimizing the ratio of the additives. The thermophysical properties and stability of different samples were tested by using differential scanning calorimetry (DSC) and a melting-freezing setup. The effects of the additives on phase change enthalpy, phase change temperature, supercooling and phase separation were analyzed. Finally, a high-density heat reservoir was built by using the modified PCM and a phase change thermal storage water system was set up. The thermal storage and release performances of the system under different working conditions were analyzed. The results showed that adding 0.5% CMC as the thickening agent and 2% DHPD as the nuclear agent could avoid phase separation and decrease supercooling degree. The phase change enthalpy and temperature range of modified SAT were 258 k J·kg−1 and 57 °C, respectively. The modified PCM had good cycling stability and its supercooling degree was smaller than 2 °C. In addition, the output water temperatures of the phase change thermal storage water system under different cooling conditions can be heated up to over 50 °C. The efficiency was higher than 90% and the exothermic power was as high as 10 kW. The exothermic power, released heat and thermal storage/release efficiency increased with the decrease in the inlet water temperature. The system had good storage and release performance and its energy storage density was 2.6 times as higher as traditional water tank.

【Keywords】 salt hydrate; sodium acetate trihydrate; composite phase change material for thermal energy storage; supercooling; thermal stability; thermal storage and release;

【DOI】

【Funds】 National Natural Science Foundation of China for Excellent Young Scholars (51522604) Science Fund for Innovation Research Groups of the National Natural Science Foundation of China (51521004)

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(Translated by WANG YX)

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This Article

ISSN:0438-1157

CN: 11-1946/TQ

Vol 69, No. 07, Pages 2860-2868

July 2018

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Article Outline

Abstract

  • Introduction
  • 1 Experimental materials and methods
  • 2 Results and discussion
  • 3 Conclusions
  • References