Experimental Investigation of a Phase Change Material Charged Finned-Tube Heat Exchanger

Conference · Sat Jan 01 04:00:00 EST 2022 · 19th International Refrigeration and Air Conditioning Conference at Purdue

OSTI ID:1876549

Yang, Jangho ^[1]; Muehlbauer, Jan ^[2]; Bacellar, Daniel ^[2]; Ling, Jiazhen ^[2]; Aute, Vikrant ^[2]; Hwang, Yunho ^[2]

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1. Univ. of Maryland, College Park, MD (United States); University of Maryland, College Park
2. Univ. of Maryland, College Park, MD (United States)

Understanding different thermal performance aspects of phase change material heat exchangers (PCM-HX) is critical for designing future energy-efficient thermal energy storage systems. This paper presents an experimental performance analysis of a vertically oriented annular finned-tube PCM-HX in a cylindrical container tested under six different melting and solidification test conditions, varied by heat transfer fluid’s (HTF) inlet temperatures and flow directions. The PCM-HX structure with 20 evenly spaced fins was 3D printed in aluminum, and the PCM-HX container was 285 mm in height. The PCM-HX average porosity was 89.7%, where the PCM mass was 246.4 g. Water served as the HTF, and a PCM with a nominal phase change temperature of 35 °C was selected. Instead of opaque conventional insulation sheets, a combination of air-and-argon-filled see-through insulation cylinders was assembled with the PCM-HX to visualize the phase-change phenomena, while minimizing the uncertainties due to heat loss. In total, there were 78 T-type thermocouples installed in the test section which allows a more precise assessment of thermal mass and heat loss, which are often neglected in similar studies found in the literature. We validated the reliability of the test facility as the repeated test results had negligible deviations under the same test conditions. The energy balances between the estimated theoretical and experimentally calculated PCM storage, considering heat loss and thermal mass, were within ±9% deviation for all test conditions. From the experimental investigations, we made several following observations. It was found that the melting pattern of the finned-tube PCM-HX with small gaps between the container wall and the fins was largely affected by the HTF flow directions, unlike the typical straight annular tube PCM-HX. For effective charging and discharging processes, a combination of upward melting and downward solidification is recommended to shorten the test duration. However, an upward solidification should be considered to minimize the cavity formation between the fins caused by the PCM volume contraction during the solidification process.

• Research Organization: University of Maryland, College Park
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Building Technologies Office
• DOE Contract Number: EE0009158
• OSTI ID: 1876549
• Conference Information: Journal Name: 19th International Refrigeration and Air Conditioning Conference at Purdue
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
Phase change material embedded heat exchanger
energy balance
finned-tube
melting
solidification