Energy storage and milk chilling performance of metal oxide nanofluids

• Published in: Food and bioproducts processing 2023-08, Vol.140, p.46-59
• Main Authors: Prakash, Ravi, Mutharayappa, Manjunatha, Guruvanna, Mahesh Kumar, Pushpadass, Heartwin Amaladhas, Ravindra, Menon Rekha, Battula, Surendra Nath
• Format: Article
• Language: English
• Subjects: Buoyancy driven phase transition; Melting; Metal-oxides; Microbes; Milk chilling; Milk quality; Nanoparticles; Phase change materials; Solidifications; Transient energy storage
• ISSN: 0960-3085; 1744-3571
• DOI: 10.1016/j.fbp.2023.04.004

The commencement of the cold-chain from the milk production points in smallholder and unorganized dairying in developing nations is still an unmet need. In the present study, an attempt was made to develop nanofluid based phase change materials (n-PCMs), using Al2O3, CuO and TiO2 nanoparticles (at 0.00%, 0.50% and 1.00%) for efficient storage of thermal energy and its subsequent utilization in rapid chilling of milk. Thermal conductivity of the n-PCMs was enhanced up to 29.49% as compared to the base fluid (water) and exhibited the supercooling reduction by 53.74%. Slight reductions in the specific and latent heats were observed (maximum at 1.00% level of nanoparticles) in the range of 0.10–0.25 and 0.4–0.8 kJ/kg, respectively. The n-PCMs capsuled inside a spherical module exhibited energy storage and milk chilling rate augmentations up to 31.97% and 39.11%, respectively. Temperature mapping of n-PCMs along the central vertical points (viz., upper, middle and lower) inside the spherical capsule exhibited the distinct trends during the pre and post phase-transition regimes, which were primarily driven by the buoyancy and natural convections. The study demonstrated the feasibility of developing the energy efficient passive chillers for rapid chilling of milk under the field conditions. •Energy storage and milk chilling performance augmented by metal oxide nanoparticles.•Nanoparticles reduced the supercooling and enhanced thermal conductivity of n-PCM.•The phase-transition rates varied with location of n-PCMs inside the capsule.•Buoyancy driven unconstrained melting was influenced by gravity.