Problem 3:Refer to the rectangular region in the figure below, the inner boundary surfaces are insulated and heat genrated withinthe cast iron solid ġ" (kw/m'). Determine the temperature distribution within the salid where the boundary surfacesare kept at 20 C. where is the location of the maximum temperature? how much it will be if a =2b = 20 cm and c = 2d =10 cm and heat gencration is 1 kW/m??2b2dZInsulation20ġ" (kW/m)2a

Conduction heat transfer is the transfer of heat by virtue of direct contact or molecular…

Answered: Refer to the rectangular region in the…

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter2: Steady Heat Conduction

Section: Chapter Questions

Problem 2.63P

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As a designer working for a major electric appliance manufacturer, you are required to estimate the amount of fiberglass insulation packing (k = 0.035 W/m K) that is needed for a kitchen oven shown in the figure below. The fiberglass layer is to be sandwiched between a 2-mm-thick aluminum cladding plate on the outside and a 5-mm-thick stainless steel plate on the inside that forms the core of the oven. The insulation thickness is such that the outside cladding temperature does not exceed 40C when the temperature at the inside surface of the oven is 300C. Also, the air temperature in the kitchen varies from 15Cto33C, and the average heat transfer coefficient between the outer surface of the oven and air is estimated to be 12.0W/m2K. Determine the thickness of the fiberglass insulation that is required for these conditions. What would be the outer surface temperature when the inside surface of the oven is at 475C?
P3. After a particularly cold night, Alice leaves a tub of water outside. You may consider the ground and air to have temperatures of Te = -10°C and Th = 10°C respectively. How thick is the layer of ice that forms at the bottom of the tub of water, after the tub has been left outside for a long time? The tub of water initially has a layer of water of thickness ho 10 cm. You may assume that the ground and air remain at a constant temperature throughout, and that the side lengths of the tub a, b » ho, i.e. the heat conduction is one- dimensional. Density of ice and water are pice = 920 kg/m³ and pw = 1000 kg/m³. Ice and water have thermal conductivities of kice = 2.22 W K-1 m' -1 and kw 0.556 W K-1 m' -1.
Q4/ A room on the second floor of a house with a balcony has a door. The door made of teak (wood) and it contains a large sheet of glass (outside winter type) in the middle and constitutes 80% of the area of the door. Door thickness is 40 mm and the temperature in the room 25. °C when the temperature is in the balcony 8 °C. Calculate the rate of heat loss from the room to the balcony through the door. The door dimensions 2m x 1m. Assume Inside and outside still air thermal resistance f= 8.29 W/m2 °C and f. 34.1 W/m2 °C respectively
1. ( 3-units. If the surrounding is held T = 0 and the base is held at T = 100r² sin30. Find the temperature distribution inside the cylinder. A smi-infinite cylinder in a steady state with the environment of radius
3- A large plane wall has a thickness L=50 cm and thermal conductivity k=25 W/m.K. On the left surface (x=0), it is subjected to a uniform heat flux go, while the surface temperature To is constant. On the right surface, it experiences convection and radiation heat transfer while the surface temperature is TL = 225°C and surrounding temperature is 25°C. The emissivity and the convection heat transfer coefficient on the right surface are 0.7 and 15 W/m²K, respectively. (a) Derive the temperature distribution equation for the wall parametrically (based on x, T₁, qo, L, and k). Plane wall Tsurr = 25°C T% = 25°C k = 25 W/m.K h = 15 W/m²K 90 ε = 0.7 T₁ = 225°C (b) Determine the temperature of the left surface of the wall at x=0? L x
4-A spherical interplanetary probe of 0.5 m diameter contains electronics thatdissipate 150 W. If the probe surface has an emissivity of 0.8 and the probe does not receive radiation from other surfaces, as, for example from the sun, what is the probe surface temperature?
Q2: Write down the one-dimensional transient heat conduction equation for a plane wall with constant thermal conductivity and heat generation in its simplest form, and indicate what each term represents. Also, what is the units of every term?
1. A beverage cooler is in the shape of a cube, 42 cm on each inside edge. Its 3.0-cm thick wall are made up of plastic (kr = 0.050 W/mK). When the outside temperature is 20°C, how much ice will melt each hour? Tice is 0°C. 2. One of the possible mechanisms of heat transfer in human body is conduction through body fat. Suppose that heat travels through 0.03 m of fat in reaching the skin, which has a total surface area of 1.7 m² and a temperature of 34°C. Find the amount of heat that reaches the skin in half an hour, if the temperature at the body, interior is maintained at the normal value 37°C ? Thermal conductivity of body fat is k = 0.2 J/sm°C. 3. The air in a room is at 25°C and outside temperature is 0°C. The window of the room has an area of 2m² and thickness 2mm. Calculate the rate of loss of heat by conduction through window ? Thermal conductivity for glass is 1 Wm¯'degree!.
6. a. The heat flux applied to the walls of the biomass combustion furnace is 20 W/m2. The furnace walls have a thickness of 10 mm and a thermal conductivity of 12 W/m.K. If the wall surface temperature is measured to be 50oC on the left and 30oC on the right, prove that conduction heat transfer occurs at a steady state!b. Heating the iron cylinder on the bottom side is done by placing the iron on the hotplate. This iron has a length of 20 cm. The surface temperature of the hotplate is set at 300oC while the top side of the iron is in contact with the still outside air. To reach the desired hotplate temperature, it takes 5 minutes. Then it takes 15 minutes to measure the temperature of the upper side of the iron cylinder at 300oC. Show 3 proofs that heat transfer occurs transiently
under steady-state conditions. If you are given T1 = 200 °C and T2 = 164 °C, determine: a) the conduction heat flux, q,.cond, in m2 W from x = 0 to x = L b) if the dimensions of the triangle ares 15 mm and h 13 mm, calculate the heat transfer due to convection, q,y, in W at x = L Finsulation T2 T T = 20°C h = 500 W/m2.K Triangular Prism x L x 0 L= 50 mm k = 100 W/m-K
3.4 Estimate the rate of heat loss due to radiation from a covered pot of water at 95 ° C. How does this compare with the 60 W that is lost due only to convection and conduction losses? What amount of energy input would be needed to maintain the water at its boiling point for 30 minutes? The polished stainless steel pot is cylindrical, 20 cm in diameter and 14 cm high, with a tight-fitting flat cover. The air temperature in the kitchen is about 25 ° C. State any assumptions you make in deriving your estimates
2. In determining the thermal conductivity of a plateflat insulator, the temperature was measured on both sides of the 25 mm thick plate and gave the results of 318.4 K and 303.2 K. FluxThe measured heat is 35.1 W.m-2. Illustrate the problem in a simple schematic/drawing, then calculate the thermal conductivity inbtu/h.ft.oF and in W/m.K! (0.033 ; 0.058) 3. A coil-shaped cooling pipe is made of SS-304 material. This pipe is 1 ft long, 0.4 inch outside diameter, and inch inside diameter. This coil cooling pipe is used to cool the water in the bath. The temperature of the inner coil pipe is 40oF while the outer coil in contact with water is 80oF. The thermal conductivity of SS-304 is a function of temperature where k(T) = 7.75 + (7.78 x 10-3).T where k is in Btu/h.ft.oF and T is in oF. Calculate the rate of heat dissipation in watts! (1287.7)

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