Field demonstrated extended Graetzian viscous dissipative thermo-photonic energy conversion with a blended MgO/PVDF/PMMA coated glass-PDMS micro-pillar heat exchanger

Ross Y.M. Wong, C. Y. Tso, S. C. Fu, Christopher Y.H. Chao

Research output: Journal article publicationJournal articleAcademic researchpeer-review

1 Citation (Scopus)

Abstract

Chilled water harvesting is a fundamental application of passive radiative cooling and promotes energy conservation for space cooling in buildings potentially, which relies on well-designed radiative cooling materials and heat transfer interface. This paper reports a scenario leading to viscous dissipative thermo-photonic energy conversion, which takes place in low Peclet number regime of an order of magnitude of 100, where heat transfer is non-Graetzian. Compared to benchmarked glass-polydimethylsiloxane radiative cooler and barium sulphate coating, a newly developed trinary micro-porous 32/4/4 magnesium-oxide/poly(vinylidene-fluoride)/poly(methyl-methacrylate) radiative cooling blend, featuring high atmospheric window emissivity and solar reflectivity, both exceeding 97%, demonstrated a superior cooling performance with additional temperature reduction of 1.6 °C at daytime. Meanwhile, it chilled water at a flow rate of 6.3 µL/s by 1.3 °C upon coating on a glass-polydimethylsiloxane micro-pillar heat exchanger. Quantitative evaluation on the chilled water capacity was carried out at nighttime when the system ran pseudo-steadily. Cooling power measurement on a radiative cooler of same materials recorded a cooling power of 134 W/m2 which is close to the ideal limit. And measured water temperature reduction and cooling efficiency were 2.5 °C and 6.3% respectively. They were significantly lower than the saturation limit. Degraded thermal and energy conversion performances, attributive to extended Graetzian viscous dissipation, were discussed theoretically.

Original languageEnglish
Article number124520
JournalInternational Journal of Heat and Mass Transfer
Volume215
DOIs
Publication statusPublished - 15 Nov 2023

Keywords

  • Energy conversion
  • Extended Graetzian heat transfer
  • Low Peclet number flow
  • Micro-fabrication
  • Radiative cooling

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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