Heat and mass transfer coefficients for natural convection in fruit packages Original Research Article

The table grape exporting industry faces two major problems associated with long distance refrigerated transportation: damage due to mold growth and unexpected temperature rise, that accelerate mold proliferation and causes water loss in the fruit. To overcome mold growth, a usual practice points toward the use of gas generators. Thermal damage due to refrigeration brake down could be predicted with the help of heat transfer correlations that apply to this specific situation. These correlations, extended to mass transfer prediction by using Nusselt and Sherwood number analogy for heat and mass transfer, allows the evaluation of the behavior of gas generators. In our work, a new heat transfer correlation [Nu = 1.5(GrPr)1/4] was proposed to predict the heat transfer coefficient inside the carton used in grape transport to allow estimation of internal temperature change during transportation. Making use of the heat and mass transfer analogy, the correlation was extended in order to estimate the mass lost in a vapor generator loaded with methyl jasmonate [Sh = 1.5(GrmSc)1/4]. The lost of this volatile compound was measurement with GC/MS. The proposed correlation was experimentally validated for different carton sizes across the temperature range 0–25 °C.