Fabrication of a Thermal Management Device with high thermal energy storage Utilizing the Endothermic Decomposition of Ammonium Carbamate

Authors:
  • TTTing Tao
    Ting Tao
  • JXJiyuan Xu
    Jiyuan Xu
  • LZLu Zhang
    Lu Zhang
  • ZWZhiyong Wei
    Zhiyong Wei
  • HZHong Zhao
    Hong Zhao
  • JQJiyu Qian
    Jiyu Qian
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Abstract
The escalating heat flux in modern electronics has rendered efficient heat dissipation at standard operating temperatures (~80 °C) a critical bottleneck, severely constraining the performance scaling of next-generation devices. Here, we propose an active cooling strategy based on thermochemical energy storage, utilizing the reversible endothermic decomposition of ammonium carbamate (AC) (NH₂COONH₄(s) → 2NH3(g) + CO₂(g), ΔH = 159.32 kJ·mol⁻¹) for low-to-medium temperature applications (50–100 °C). Experimental results demonstrate that chemical cooling system achieves a gravimetric cooling capacity of 2010 kJ·kg⁻¹, surpassing that of paraffin (180 kJ·kg⁻¹) by an order of magnitude and exceeding typical hydrated salts (200–300 kJ·kg⁻¹) by more than sevenfold. Under a constant 100 W thermal load, a 140 g charge of AC maintained the system temperature below 100 °C for 92 minutes, validating its efficacy in high-performance heat removal. Importantly, experiments in a custom reactor revealed that the decomposition kinetics of AC are precisely tunable through temperature and pressure regulation, allowing for responsive, on-demand control of the cooling process. This combination of high energy density and precise controllability facilitates a shift from passive dissipation to active thermal regulation. Combined numerical and experimental investigations reveal that the persistent thermal protection arises from a synergistic mechanism: a spatially uniform reaction front guarantees maximum chemical enthalpy conversion, while advective transport of the gaseous by-products enables substantial sensible heat extraction. To ensure the practical viability of the AC-based cooling system, potential challenges associated with gaseous ammonia (NH₃) by-products were proactively addressed. A metal-salt-based sorption strategy was therefore implemented for effective NH₃ capture. Moreover, comprehensive corrosion assessments confirmed the excellent compatibility of the decomposition environment with aluminum reactor architectures. By rigorously validating by-product sequestration and material compatibility, this work establishes ammonium carbamate as a viable, high-enthalpy thermochemical heat sink that fundamentally transcends the energy density limits of traditional phase-change materials.

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