Pulsating nanofluid-jet impingement cooling and its hydrodynamic effects on heat transfer

Abstract

Unlocking optimum heat transfer is essential for enhancing solar thermal collector efficiency and advancing sustainable energy solutions. This experimental study investigates a simulated solar thermal collector's heat transfer behavior using jet impingement cooling, emphasizing hydrodynamic effects in pulsating nanofluid-jet impingement. Al2O3-MWCNT/water hybrid nanofluid is utilized, varying pulsating frequency (0.2 Hz ≤ F ≤ 20 Hz), amplitude (4 Vp ≤ A ≤ 20 Vp), waveform (sine, squared, triangular), wave offset (0 ≤ Ⴋ ≤ 4), and nanofluid volume fraction (0.05 vol% ≤ φ ≤ 0.3 vol%) to optimize heat transfer. Results show a significant influence on heat transfer performance for all parameters except waveform. A peak heat transfer enhancement of 24 % is observed for 0.3 vol% Al2O3-MWCNT/water compared to de-ionized water under continuous jet impingement. Additionally, a 20 % enhancement is achieved with a sine waveform at φ = 0.3 vol%, F = 0.2, A = 8, and Ⴋ = 2. Pulsating jet impingement generally yields higher cooling rates, as the cooling curves indicate. These findings provide crucial insights for optimizing heat transfer in solar thermal collectors through pulsating hybrid nanofluid jet impingement cooling.