A metal plate of thickness 200 mm with thermal diffusivity 5.6 x10-6 m²/s and thermal conductivity 20 W/mK is initially at a uniform temperature of 325°C. Suddenly, the 2 sides of the plate are exposed to a coolant at 15°C for which the convection heat transfer coefficient is 100 W/m²K. Determine temperatures at the surface of the plate after 3 min using (a) Lumped system analysis (b) Analytical one term approximation (c) One dimensional Semi infinite solid Analyze and discuss the results

A metal plate of thickness 200 mm with thermal diffusivity 5.6 x10-6 m²/s and thermal conductivity 20 W/mK is initially at a uniform temperature of 325°C. Suddenly, the 2 sides of the plate are exposed to a coolant at 15°C for which the convection heat transfer coefficient is 100 W/m²K. Determine temperatures at the surface of the plate after 3 min using (a) Lumped system analysis (b) Analytical one term approximation (c) One dimensional Semi infinite solid Analyze and discuss the results

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 2.55P: 2.55 A long, 1-cm-diameter electric copper cable is embedded in the center of a 25-cm-square...

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2.38 The addition of aluminum fins has been suggested to increase the rate of heat dissipation from one side of an electronic device 1 m wide and 1 m tall. The fins are to be rectangular in cross section, 2.5 cm long and 0.25 cm thick, as shown in the figure. There are to be 100 fins per meter. The convection heat transfer coefficient, both for the wall and the fins, is estimated to be K. With this information determine the percent increase in the rate of heat transfer of the finned wall compared to the bare wall.
A horizontal, 3-mm-thick flat-copper plate, 1-m long and 0.5-m wide, is exposed in air at 27C to radiation from the sun. If the total rate of solar radiation absorbed is 300 W and the combined radiation and convection heat transfer coefficients on the upper and lower surfaces are 20 and 15W/m2K, respectively, determine the equilibrium temperature of the plate.
3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.
1.19 A cryogenic fluid is stored in a 0.3-m-diameter spherical container is still air. If the convection heat transfer coefficient between the outer surface of the container and the air is 6.8 , the temperature of the air is 27°C, and the temperature of the surface of the sphere is –183°C, determine the rate of heat transfer by convection.
A long 20 cm diameter shaft made of stainless steel 304 comes out of an oven at a uniform temperature of 600°C. The shaft is then allowed to cool slowly in an environment at 200°C with an average heat transfer coefficient of h = 80 W/m².K. Determine [a] the temperature at the center of the shaft and [b] the temperature of the outer surface of the shaft 45 minutes after the start of the cooling Given: Find: Schematic: Assume: Property Data: k= 14.9 W/m°C p= 7900 kg/m³ Cp = 477 J/kg:K a= 3.95 x 10-6 m²/s
Required Information The upper surface of a 85-cm-thick solid plate (k= 237 W/m-K) is being cooled by water with temperature of 20°C. The upper and lower surfaces ofthe solid plate maintained at constant temperatures of 60°C and 120°C, respectively. Given: The thermal conductivity of the solid plate is given ask= 237 W/m K. f2 (T,1+T) = (60°C + 20°C)/2 = 40°C is kuid = 0.631 The thermal conductivity of water at the film temperature of T; W/m/K. Determine the water convection heat transfer coefficient. The water convection heat transfer coefficient is W/m2 -K.
A slab of aluminium 10 cm thick is originally at a temperature of 500°C. It is suddenly immersed in a liquid at 100°C resulting it a heåt transfer coefficient of 1200. W/m2K. Determine the temperature at the center line and the surface 1 min after the immersion. Also the total thermal energy removal per unit area of slab during this period. The properties of aluminium for the given condition are, a = 8.4 x 10-5 m?/s, k =215 W/mK, p = 2700 kg/m3, C= 0.9.kJ/kgK.
Heat transfer
google.com ube Maps Electrically heated draw batch furnaces are commonly used in the heat treatment industry. Consider a draw batch furnace front made of a 20-mm thick steel plate with a ther- mal conductivity of 25 W/m-K. The furnace is situated in a room with surrounding air temperature of 20°C and an aver- age convection heat transfer coefficient of 10 W/m2-K. If the inside surface of the furnace front is subjected to uniform heat flux of 5 kW/m² and the outer surface has an emissiv- ity of 0.30, determine the inside surface temperature of the furnace front. = 20°C Furnace fron 4, = 5 kW/m Air, 20 C h= 10 W/m K e = 0.30 kn25 W/m-K
The thermal conductivity of a solid material can be determined using asetup similar to the one shown in the accompanying figure. The thermocouples are placed at 2.5 cm intervals in the known material (copper alloy, k - 52 w/m.k) and the unknown sample, as shown. The known material is heated on the top by a heating element, and the bottom surface of the sample is cooled by running water through the heat sink shown. Determine the thermal conductivity of the unknown sample for the set of data given in the accompanying table. Assume no heat loss to the surroundings and perfect thermal contact at the common interface of the sample and the copper.
In a quenching process, a copper plate of 3 mm thick is heated up to 350°C and then suddenly, it is dropped into a water bath at 25°C. (1) Calculate the time required for the plate to reach the temperature of 50°C. The heat transfer coefficient on the surface of the plate is 28 W/m2-K. The plate dimensions may be taken as length 40 cm and width 30 cm. (2) Also calculate the time required for infinite long plate to cool to 50°C. Other parameters remain same. (3) Calculate the heat transfer rate loss of the plate when it is at 50°C. Take the properties of copper as: CP = 380 J/kg-K, ρ = 8800 kg/m3, k = 385 W/m-K
In a quenching process, a copper plate of 3 mm thick is heated up to 350°C and then suddenly, it is dropped into a water bath at 25°C. (a) Calculate the time required for the plate to reach thetemperature of 50°C. The heat transfer coefficient on the surface of the plate is 28 W/m2 -K. The plate dimensions may be taken as length 40 cm and width 30 cm. (b) Also calculate the time required for infinite long plate to cool to 50°C. Other parameters remain same. (c) Calculate the heat transfer rate loss of the plate when it is at 50°C. Take the properties of copper as: CP = 380 J/kg-K, ρ = 8800 kg/m3 , k = 385 W/m-K