Freshly harvested berries measuring 2 cm in diameter are chilled from 18°C to 7°C in a chiller at 2°C, with a surface heat transfer coefficient of 25 W/m2 K. They are then loaded in 250 kg batches into containers and held for 12 h in a cold store operating at 2°C prior to further processing. Each container weighs 50 kg. The cold store holds an average of 2.5 t of berries and measures 3 m high by 10 m  10 m. The walls and roof are insulated with 300 mm of polyurethane foam and the floor is constructed from 450 mm of concrete. The ambient air temperature in the factory averages 12°C and the soil temperature 9°C. An operator spends an average of 45 min per day moving the containers within the store and switches on four 100W lights when inside the store. Calculate the time required to cool the berries in the chiller and determine whether a 5-kW refrigeration unit using R-717 as refrigerant would be suitable for the cold store. The outside temperature is 20°C. Design the refrigeration system (operating temperatures and refrigerant flow rate). (Additional data: thermal conductivity of the berries 0.127W/(m.K), thermal conductivity of the insulation 0.026 W/(m.K), thermal conductivity of concrete 0.87W/(m.K), specific heat of the berries 3778 J/(kg.K), specific heat of the container 480 J/(kg.K), the density of the berries 1050 kg/m3, the heat produced by the operator 240 W and the average heat of respiration of the berries 0.275 J/kg/s). Assume any information necessary. Provide source for your assumed information

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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K .1 Freshly harvested berries measuring 2 cm in diameter are chilled from 18°C to 7°C in a chiller at 2°C, with a surface heat transfer coefficient of 25 W/m2 K. They are then loaded in 250 kg batches into containers and held for 12 h in a cold store operating at 2°C prior to further processing. Each container weighs 50 kg. The cold store holds an average of 2.5 t of berries and measures 3 m high by 10 m  10 m. The walls and roof are insulated with 300 mm of polyurethane foam and the floor is constructed from 450 mm of concrete. The ambient air temperature in the factory averages 12°C and the soil temperature 9°C. An operator spends an average of 45 min per day moving the containers within the store and switches on four 100W lights when inside the store. Calculate the time required to cool the berries in the chiller and determine whether a 5-kW refrigeration unit using R-717 as refrigerant would be suitable for the cold store. The outside temperature is 20°C. Design the refrigeration system (operating temperatures and refrigerant flow rate). (Additional data: thermal conductivity of the berries 0.127W/(m.K), thermal conductivity of the insulation 0.026 W/(m.K), thermal conductivity of concrete 0.87W/(m.K), specific heat of the berries 3778 J/(kg.K), specific heat of the container 480 J/(kg.K), the density of the berries 1050 kg/m3, the heat produced by the operator 240 W and the average heat of respiration of the berries 0.275 J/kg/s). Assume any information necessary. Provide source for your assumed information

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