Reactive cooling simulation of electronic components

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Applied Thermal Engineering, Volume 228
Low-grade heat recovery is an indispensable solution towards high energy efficiency of power electronics. The fast pace of sustainable digitalisation calls for developing alternative solutions to create a sustainable loop for decreasing the energy footprint. However, heat transfer under low-temperature differences challenges effective heat recovery processes. Therefore, in this paper, reactive fluid performance in a practical heat exchanger is investigated using high-fidelity finite rate chemistry method, which is a key step to deploy the attractive Ericsson cycle for low-temperature heat-to-electricity conversion. Under fixed thermal efficiency, it is found that replacing non-reactive fluid by N2O4 reactive fluid can immediately boost electrical efficiency of an Ericsson cycle by at least 260%. The needed primary heat exchanger component in an integrated cooling and power electronic system can be 54.8% smaller in volume whilst enabling a 26% higher thermal performance, provided that the hot source temperature is low (<403 K). For thermal processes involving high temperature hot source, substantial limitation of chemical reaction rate on the effectiveness of an Ericsson cycle is identified. Remarkably, low temperature difference is not a limitation for reactive heat transfer that continuous endo-/exothermic reaction happening throughout a heat exchanger improves Nusselt number Nu = 7.5 by a factor of ∼ 1.3 than the corresponding value (Nu = 5.9) for non-reactive fluid. Turbulence is found beneficial for reactive heat transfer, suggesting the use of corrugated-type heat exchangers for better thermal exchange rates.
Funding Information: The financial support from The Swedish Energy Agency (Project No.: 48497-1, Dissociating gas for efficient harvesting of low temperature waste heat) is greatly acknowledged. The simulations were performed on resources provided by the Swedish National Infrastructure for Computing (SNIC) at Tetralith and PDC centre. Publisher Copyright: © 2023 The Author(s)
Ericsson cycle, Finite-rate chemistry, Heat exchanger, Low-grade heat, Reactive heat transfer, Waste Energy
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Zhang, K, Laitinen, A, Shen, Y, Vuorinen, V & Duwig, C 2023, ' Reactive cooling simulation of electronic components ', Applied Thermal Engineering, vol. 228, 120519 .