A large truck is to transport 30,000 Kg of orange pre-cooled to 4oC

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To determine the refrigeration load for transporting 30,000 kg of oranges at 4°C in a truck with an ambient temperature of 27°C, the heat transfer rate through the truck walls is calculated using UA=80W per °C temperature difference. The air entering the cargo space at a rate of 4L/s, combined with the density of air at 1.15 kg/m³, allows for the calculation of the mass flow rate of the incoming air. Additionally, the heat of respiration for the oranges at 4°C is 0.017 W/kg, contributing to the overall refrigeration requirement. Applying the First Law of Thermodynamics and considering steady-state conditions will help in determining the total refrigeration load and the amount of ice needed for a 15-hour trip. This systematic approach ensures accurate calculations for maintaining the desired temperature during transport.
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A large truck is to transport 30,000 Kg of orange pre-cooled to 4oC under average temperature of 27oC. The structure of the walls of the truck is such that the rate of heat transportation is UA=80W per oC temperature difference between the ambient and the oranges. From past experience, ambient air is estimated to enter the cargo space of the truck through the cracks at a rate of 4L/s. Also, the average heat of respiration of the oranges at 4oC is 0.017W/kg for this particular load. Disregarding any condensation and taking the density of air to be 1.15kg/m3, determine the refrigeration load of this truck and the amount of ice needed to meet the entire refrigeration need of the truck for a 15hour trip.

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The 1st Law of Thermodynamics is always a good place to start. Use the volumetric flow rate of the air and its density to figure out the mass flow rate, then look up the necessary properties from the appropriate table. Keep in mind conservation of mass though, if this is a steady state problem then equal amounts of mass will enter and leave the system.
 

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