Short-period thermal cyclic test device for large volumes of microencapsulated phase change materials using a Venturi injector

Abstract

Microencapsulated phase change material (MPCM), which has a large amount of heat capacity during phase change, has been used as a thermal storage medium as a building composite material. MPCM is broken by heat-induced volume changes, and hence, thermal cyclic tests must be performed to estimate their durability. Existing methods for thermal cyclic testing have limitations such as few samples that can be tested or long duration of test. This paper proposes a thermal cyclic test device with a Venturi injector designed to test a large number of samples rapidly. Results of the detailed tests on the pressure and flow rate change of the Venturi tube and the reliability assessment of the developed equipment are presented. MPCM slurry can be transported with up to 25% mass concentration of MPCM at a flow rate of 5 LPM. At 25wt%, MPCM slurry could change 100% of its phase within a straight line of a heat exchange pipe length of 0.61 m from 28 to 35 °C. One thermal cycle for 1 kg of MPCM capsules has a duration of 47 s. Finally, a 5000–thermal cycle test of MPCM was carried out, and it showed that using this equipment caused no broken capsules.