Unique characteristics of biologically active materials such as fruits, vegetables, andother products require special care in handling. Following harvest and separationfrom producing plants, glucose is catabolized to produce carbon dioxide, watervapor, and heat, with attendant internal energy generation. Consider a single apple,spherical in shape, diameter 80 mm, which is ventilated with air at 5°C and h= 7.5W/m2.K. Within the apple thermal energy is uniformly generated at 4000.0J/kg.day.The density and thermal conductivity of the appleare 840 kg/m3 and 0.5 W/m.K.a. Derive anequation for temperature distribution inside the apple. Use theboundary conditions @r R, T = Ts, and @r=0, dT/dr 0. Ts is the surfacetemperature of sphere to be determined using convection equation.b. Determine the apple center and surface temperatures.

Calculate the surface temperature using the energy balance.

Answered: Unique characteristics of biologically…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

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C heat and mass transfer problem
Plate glass 5 mm thick at 200°C is to be cooled from both sides using air at 40°C. If surface cracks are to be avoided, determine the maximum value of convective heat transfer coefficient. Material properties are density = 2500 kg/m3, = specific heat 670 J/kgK. Thermal conductivity 0.744 W/mk. Also determine the time required in this to cool the plate to 80°C. o 12:03
14- A south wall group D at (32 oN, Kw = 0.65). The room temperature is (24 oC). The maximum outside temperature is (42 oC). The daily range is (12 oC). Its heat transfer coefficient is (1.2 W/m2.oC) and dimensions are (5 x 3 m) with door of dimensions of (1.5 x 2 m). At (17 PM) in August, its Cooling load is Select one: a. 361.7 W b. None of these c. 261.7 W d. 303 W
A food product with 80% moisture content in a 10 cm diameter can wants to be frozen. The density of the product is 1000 kg / m³, the thermal conductivity is 1.0 W / (m K), and the initial freezing temperature is -2 ° C. After 14 hours in the freezing medium -30 ° C, the product temperature becomes -10 ° C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder.
14- A south wall group D at (32 oN, Kw = 0.65). The room temperature is (24 oC). The maximum outside temperature is (42 oC). The daily range is (12 oC). Its heat transfer coefficient is (1.2 W/m2.0C) and dimensions are (5 x 3 m) with door of dimensions of (1.5 x 2 m). At (17 PM) in August, its Cooling load is Select one: Q2 a. 361.7 W b. None of these c. 261.7 W d. 303 W
Homework problem for unsteady-state heat transfer Consider a product to be sterilized if its coldest location during heating reaches 115°C. Consider sterilization of potatoes where potatoes (4 cm diameter) is heated in steam at 121°C. Assume symmetrical heating of potatoes and the heat transfer coefficient between the steam and the potatoes is 20 W/m² K. The thermal diffusivity for potatoes is 1.5 × 107m²/s and the thermal conductivity is 0.4 W/m K. The potatoes are initially at 30°C. 1) Calculate the heating time needed for sterilization. 2) Calculate the temperature at the center of the potato after heating 1000 s and 2000 s. Plot how the temperature at the center changes with time t. 3) Calculate the temperature at the surface of the potato at 2000 s. Qualitatively plot how the temperature changes across the apple at t = 2000 s.
Plate glass 5 mm thick at 200°C is to be cooled from both sides using air at 40°C. If surface cracks are to be avoided, determine the maximum value of convective heat transfer coefficient. Material properties are density = 2500 kg/m3, specific heat 670 J/kgK. Thermal conductivity 0.744 W/mk. Also determine the time required in this to cool the plate to 80°C.
A 10 cm-thick beef steak is being frozen in a -40°C room. The product has 73% moisture content, density of 970 kg/m³, and thermal conductivity (frozen) of 1.1 W/(m K). Estimate the freezing time using Plank’s equation. The product has an initial freezing temperature of -1.75°C, and the movement of air in the freezing room provides a convective heat-transfer coefficient of 10 W/(m² K). a. tf =... h
The main body of plenum is a steel vessel of diameter 0.1meters has two semicircle domed ends. During operation is will contain mix of fuel and air at approximately 250OC. The wall of the vessel is 0.03meters thick and the plenum is 0.45meters long. Estimate the rate of heat loss from the vessel when the outside air temperature is 45OC. The thermal conductivity of steel is 45 W/m K and the surface heat transfer coefficient on the air side is 8 W/m2 . On the inside it is 65W/m2 . If it was possible to clad the plenum calculate the reduction in the rate of heat loss. Assume the lagging would be 5mm thick and has a thermal conductivity of 0.05 W/m.
(B) Cylindrical Water cans (diameter 6.5cm and length 15cm) are to be cooled from initial temperature of 20°C by placing theme in a cooler with ambient temperature of 1°C. Compare the initial cooling rates when the cans are laid horizontally to when the cans are laid vertically. Take v = 15.55x10° m²/s, k=0.024 W/mK and Pr=0.7. Nu = 0.53RA' a4 for horizontal orientation Nu = 0.59 Ra"4 for vertical orientation
Can you help me answer my sample problem for my review?
Steel cubes 10 mm in width are annealed by heating to 1,377 K and then slowly cooling to 469 K in an air environment for which T∞ = 301 K and h = 24 W/m2-K. Assuming the properties of the steel to be k = 24 W/m · K, ρ = 7,047 kg/m3, and c = 916 J/kg · K, estimate the time required for the cooling process.

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