Influence of use conditions on heat transfer in an insulated box equipped with a phase change material

Abstract

An insulated box with Phase Change Material (PCM – ice, melting point ∼ 0 °C) and loaded by test product (Tylose) was investigated experimentally to study the effect of the PCM position, Aspect Ratio (AR = height/width) of box, ambient temperature, initial test product temperature and spacing beneath the test product. The temperature and the air velocity measured by thermocouples and Particle Image Velocimetry (PIV), respectively, were analyzed under stable conditions. The maximum product temperature was lower for PCM at the top (6.6 °C, AR ≈ 1) than for PCM on a sidewall (7.7 °C, AR ≈ 1) and increased with AR (9.9 °C, AR ≈ 1.7). A non-linear relation between ambient temperature and product temperature was observed with the maximum product temperature from 5.2 °C (10 °C ambient) to 9.1 °C (30 °C ambient). The influence of spacing beneath the product was negligible despite different airflow patterns. Simple equations were proposed to predict the maximum storage time and mean temperature in the box enabling us to study the influence of PCM and product mass, melting point, box insulation and ambient temperature.