Cold thermal energy storage for milk chilling: A numerical and experimental study

Abstract

One of the main challenges in small holding dairy production systems is the commencement of cold-chain from the point of milk production. Such systems often rely on pooled milk in a supply chain, with the chilling operations being initiated once substantial quantities of milk (>500 L) are collected. Hence, there is a need to develop an energy efficient and passive thermal storage device for chilling of small volumes of milk. The present study explored a novel approach of developing the phase change materials (PCM) encapsulated inside a spherical module as an immersion cooling device to chill a pool of milk (5 L) held in a vessel. The application of TiO 2 nanoparticles at (0.05–1.00% by wt. ) for developing nanoparticle enhanced water based PCM with improved energy storage was also explored. Transient energy exchange and phase-transition of the PCMs during the milk chilling process was numerically simulated using enthalpy-porosity and volume of fluid model of computational fluid dynamics (CFD). The CFD simulated results were validated through the experimental observations and the flow visualization of the temperature distribution and melting fronts clearly affirmed the rapidity of energy exchange due to the addition of nanoparticles into the PCM. • TiO 2 nanoparticle enhanced phase change materials (PCM) were capsuled inside a portable stainless steel spherical module. • Experimental and numerical transient energy storage (charging) and discharge during passive milk chilling inside a milking vessel were studied. • Nanoparticles accelerated the energy storage, discharge and milk chilling rates significantly. • Studies revealed the scope of deploying TiO 2 nanoparticle enhanced PCM in energy-efficient real-time passive milk chillers.