2020/11/24 by Darin J. Sharar, Asher C. Leff, Sharar, Darin J. +5
Engineering · #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Phase Change Materials Research
paper · pdf · doi:10.48550/arxiv.2011.12339
openalex publication_date 2020/11/24 · openalex created_date 2022/07/25 · openalex updated_date 2026/07/28
Adding thermal conductivity enhancements to increase thermal power in\nsolid-liquid phase-change thermal energy storage modules compromises volumetric\nenergy density and often times reduces the mass and volume of active phase\nchange material (PCM) by well over half. In this study, a new concept of\nbuilding thermal energy storage modules using high-conductivity, solid-solid,\nshape memory alloys is demonstrated to eliminate this trade-off and enable\ndevices that have both high heat transfer rate and high thermal capacity.\nNickel titanium, Ni50.28Ti49.36, was solution heat treated and characterized\nusing differential scanning calorimetry and Xenon Flash to determine\ntransformation temperature (78deg-C), latent heat (183 kJm-3), and thermal\nconductivity in the Austenite and Martensite phases (12.92/12.64 Wm-1K-1). Four\nparallel-plate thermal energy storage demonstrators were designed, fabricated,\nand tested in a thermofluidic test setup. These included a baseline sensible\nheating module (aluminum), a conventional solid-liquid PCM module\n(aluminum/1-octadecanol), an all-solid-solid PCM module (Ni50.28Ti49.36), and a\ncomposite solid-solid/solid-liquid PCM module (Ni50.28Ti49.36/1-octadecanol).\nBy using high-conductivity solid-solid PCMs, and eliminating the need for\nencapsulants and conductivity enhancements, we are able to demonstrate a\n1.73-3.38 times improvement in volumetric thermal capacity and a 2.03-3.21\ntimes improvement in power density as compared to the conventional approaches.\nThese experimental results are bolstered by analytical models to explain the\nobserved heat transfer physics and reveal a 5.86 times improvement in thermal\ntime constant. This work demonstrates the ability to build high-capacity and\nhigh-power thermal energy storage modules using multifunctional shape memory\nalloys and opens the door for leap ahead improvement in thermal energy storage\nperformance.\n