(a) What is the physical interpretation of the Grashof number?(b) A glass-door firescreen, used to reduce exfiltration of room airthrough a chimney, has a height of 0.71 m and a width of 1.02 m andreaches a temperature of 232°C. If the room temperature is 23°C,estimate the convection heat rate from the fireplace to the room.(Assume air properties: k= 33.8 x10³ W/mK, v = 26.4x10“ m²/s, a =38.3x10-6 m²/s, Pr= 0.69)

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Answered: (a) What is the physical interpretation…

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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A food product with 73% moisture content in a 7 cm diameter can wants to be frozen. The density of the product is 970 kg / m³, the thermal conductivity is 1.2 W / (m K), and the initial freezing temperature is -2 ° C. After 11 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. h = W / (m² K).
(Heat Transfer) A furnace wall is composed of 20.32cm of fireclay brick (k=1.32 W/m^2.k), 10.16cm mineral wool (k=0.039 W/m^2.k), and 10.16cm of common brick (k=0.69 W/m^2.k). The surface temperature of the common brick is 60°C and the interface temperature between the common brick and the mineral wool is 30°C. The temperature of the gases is 1000°C and the temperature of the outside air is 30°C. Determine the outside air coefficient hc=W/m^2.k
Number 3 A food product with 80% moisture content in a 7 cm diameter can wants to be frozen. The density of the product is 1000 kg/m³, the thermal conductivity is 1.0 W/(m²K), and the initial freezing temperature is -1.75°C. After 8 hours in the freezing medium -25°C, the product temperature becomes -10°C. Estimate the convection heat transfer coefficient of the freezing medium. Assume the can as an infinite cylinder. h= answer in W/(m²K)
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
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.
In the arctic sea, the ice sheets are melting. Let's calculate the temperautre distribution in one such ice sheet. The sheet is 2 m thick. Under the sheet there is ice-water mixture and it can be assumed that the temperature of the bottom surface of the ice sheet is approximately 0°C. Air at -20°C is blowing above the sheet. The convection coefficient of air is 15 W/m².K. The thermal conductivity of ice is 2.2 W/m.K. What is the temperautre of icesheet at its center (i.e., at 1 m from the surface)?
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
(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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