An electrically heated plate 15cm high and 10cm wide is maintained at 140°C. Estimate the rate of heat dissipation from both sides of the plate in an atmospheric at 20° C, if the radiation heat transfer co-efficient is 8.72W /m² -K. For air at the mean temperature of 80°C; Take kinematic viscosity= 21.09x10 m² /s, Pr 0.692, and k = 0.0305 W/m-K.

An electrically heated plate 15cm high and 10cm wide is maintained at 140°C. Estimate the rate of heat dissipation from both sides of the plate in an atmospheric at 20° C, if the radiation heat transfer co-efficient is 8.72W /m² -K. For air at the mean temperature of 80°C; Take kinematic viscosity= 21.09x10 m² /s, Pr 0.692, and k = 0.0305 W/m-K.

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.

Chapter3: Transient Heat Conduction

Section: Chapter Questions

Problem 3.10P: 3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the...

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3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?
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Partially-frozen ice cream is being placed in a package before completion of the freezing process. The package has dimensions of 8 cm by 10 cm by 20 cm and is placed in air- blast freezing with convective heat coefficient of 50 W/(m2 K) for freezing. The product temperature is -5°C when placed in the package, and the air temperature is -25°C. The product density is 700 kg/m3, the thermal conductivity (frozen) is 1.2 W/(m K), and the specific heat of the frozen product is 1.9 kJ/(kg K). If the latent heat to be removed during blast freezing is 100 kJ/kg, estimate the freezing time.
A stainless steel ball (ρ = 8055 kg/m3, cp = 480 J/kg·K) of diameter D = 0.15 m is removed from the oven at a uniform temperature of 350°C. The ball is then subjected to the flow of air at 1 atm pressure and 30°C with a velocity of 6 m/s. The surface temperature of the ball eventually drops to 250°C. Determine the average convection heat transfer coefficient during this cooling process and estimate how long this process has taken. The average surface temperature is 300°C, and the properties of air at 1 atm pressure and the free stream temperature of 30°C are Pr = 0.7282, μs at 300°C = 2.934 × 10–5 kg/m·s, μ∞ = 1.872 × 10–5 kg/m·s, v = 1.608 × 10–5 m2/s, and k = 0.02588 W/m·°C. The average convection heat transfer coefficient during this cooling process is ____ W/m2·°C and time taken is ____ minutes.
Air at 1 atmosphere pressure enters a pipe with a 20 mm inner diameter, 1 m length and a constant surface temperature of 93.3 oC at 15.1 oC and leaves the pipe at 60.5 oC. Since the speed of the air is 2.5 m/s, calculate the convective heat transfer coefficient on the inside of the pipe. Test the accuracy by calculating the heat to be transferred.
A long aluminum wire of diameter 3 mm is extruded at a temperature of 280°C. The wire is subjected to cross air flow at 20°C at a velocity of 5.00 m/s. Determine the rate of heat transfer from the wire to the air per meter length when it is first exposed to the air. The properties of air at 1 atm and the film temperature of (Ts + T∞)/2 = (280 + 20)/2 = 150°C are k = 0.03443 W/m·°C, ν = 2.860 × 10−5 m2/s, and Pr = 0.70275. The rate of heat transfer from the wire to the air per meter length when it is first exposed to the air is ___ W.
A 3 m internal diameter spherical tank made of 1 cm thick stainless steel (k =15 W/mK) is used to store water at 4℃, as shown in Figure 2.2. Inner surfaceof the tank is 4℃, while the outer surface of the tank is painted with blackcolour paints with emissivity, ? = 0.88 measured at temperature 5℃. It islocated outdoor at 40℃ and is subjected to wind at 25 km/h. Determine the total heat transfer rate to the ice water.
The air at 1 ATM and 35⁰c flow through a cylinder 5 cm in diameter,at Velocity 50 cm/s. The surface temperature of the cylinder is guarded at 150⁰c *)Calculating heat loss per cylinder unit
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A 15 mm 3 15 mm silicon chip is mounted such that the edges are flush in a substrate. The chip dissipates 1.4 W of power uniformly, while air at 20°C (1 atm) with a velocity of 25 m/s is used to cool the upper surface of the chip. If the substrate provides an unheated starting length of 15 mm, determine the surface temperature at the trailing edge of the chip. Evaluate the air properties at 50°C
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