Numeral analysis and experimental verification of pressure pre-cooling of golden pears

In order to provide theoretical reference for air flow rate choice and carton design in pressure pre-cooling of vegetables and fruits, a mathematical model of pressure pre-cooling of golden pears was developed according to the flow and heat transfer principles in pressure pre-cooling process. The commercial computational fluid dynamics software was utilized to simulate the cooling process of golden pears with straight and staggered stacking patterns in cartons respectively. The key parameters that affected cooling process such as different air flow rates, type and size of vent hole, were analyzed by simulation and test. Results show that the numerical simulations give the good prediction with the experimental data and mathematical model is reasonable. Cooling time decreases by 15%～20% when air flow rate increases from 1m/s to 2 m/s. The effect on cooling rate of different vent hole types is about 5%. The cooling time of golden pears with vent hole size 45 mm is about 10% shorter than that with vent hole size 40 mm. The effect on cooling time of different stacking patterns is within 10%～12%. Therefore, it is suggested that air flow rate is between 1.5 m/s and 2 m/s, vent hole type is circle with diameter about 45mm, stacking pattern is staggered stacking.