Experimental determination of thermal conductivity and thermal diffusivity of whole green (unripe) and yellow (ripe) Cavendish bananas under cooling conditions

摘要

Bananas are cooled to 13 ℃ after their harvest to extend their shelf life and prevent post-harvest losses. Since they are subjected to chilling injuries at temperatures below 11 ℃, thermal properties should be known to design a cooling process. For this purpose, thermal diffusivity and thermal conductivity of green and yellow Cavendish bananas were determined experimentally using analytical solution of heat transfer for an infinite cylinder. Experiments were carried out in cooling chambers, and temperature change of bananas were recorded using thermistors. Thermal conductivity-diffusivity values of the green and yellow bananas changed from 0.302 to 0.338 W/m-K and 1.442 × 10~(-7) to 1.500 × 10~(-7) m~2/s, respectively. These values were validated by literature data and additional experiments where simulated and experimental data were compared while the effect of banana peel on the cooling rates was also explained. These comparisons demonstrated the significance of knowing thermal conductivity-diffusivity values separately for designing and optimizing a cooling process.