20°C of a horizontal plate 16 cm long and 20 cm wide. Note that it hangs suspended in the air environment in . The plate is wrapped with 20W electrical heating elements. The heater is operating and the plate temperature is rising. Continuous Find the temperature of the plate when the operating conditions are reached. The Spreading of the plate is 0.90 and the temperature of the surrounding surfaces is 17°C. is. AİR T=20°C L=16 cm RESİSTANCE WIRE

20°C of a horizontal plate 16 cm long and 20 cm wide. Note that it hangs suspended in the air environment in . The plate is wrapped with 20W electrical heating elements. The heater is operating and the plate temperature is rising. Continuous Find the temperature of the plate when the operating conditions are reached. The Spreading of the plate is 0.90 and the temperature of the surrounding surfaces is 17°C. is. AİR T=20°C L=16 cm RESİSTANCE WIRE

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.

Chapter1: Basic Modes Of Heat Transfer

Section: Chapter Questions

Problem 1.48P: A horizontal, 3-mm-thick flat-copper plate, 1-m long and 0.5-m wide, is exposed in air at 27C to...

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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.
An electrical transmission line of 1.2-cm diameter carries a current of 200 amps and has a resistance of 310-4 ohm per meter of length. If the air around this line is at v, determine the surface temperature on a windy day, assuming a wind blows across the line at 33 km/h.
The air-conditioning system in a Chevrolet van for use in desert climates is to be sized. The system is to maintain an interior temperature of 20C when the van travels at 100 km/h through dry air at 30C at night. If the top of the van is idealized as a flat plate 6 m long and 2 m wide and the sides as flat plates 3 m tall and 6 m long, estimate the rate at which heat must be removed from the interior to maintain the specified
Consider a hot automotive engine, which can be approximated as a 0.5-m-high, 0.40-m-wide, and 0.8-m-long rectangular block. The bottom surface of the block is at a temperature of 100°C and has an emissivity of 0.95. The ambient air is at 20°C, and the road surface is at 25°C. Determine the rate of heat transfer from the bottom surface of the engine block by convection and radiation as the car travels at a velocity of 80 km/h. Assume the flow to be turbulent over the entire surface because of the constant agitation of the engine block.
Consider a 1.2-m-high and 2-m-wide glass windowwith a thickness of 6 mm, thermal conductivity k = 0.78W/m·K, and emissivity « = 0.9. The room and the wallsthat face the window are maintained at 25°C, and the averagetemperature of the inner surface of the window is measuredto be 5°C. If the temperature of the outdoors is 25°C,determine (a) the convection heat transfer coefficient on theinner surface of the window, (b) the rate of total heat transferthrough the window, and (c) the combined natural convectionand radiation heat transfer coefficient on the outer surface ofthe window. Is it reasonable to neglect the thermal resistanceof the glass in this case?
A heating system is to be designed to keep the wings of an aircraft cruising at a veloeity of 900 km/h above freezing temperatures during flight at 12.200-m altitude where the standard atmospheric conditions are -55.4°C and 188 kPa. Approximating the wing as a cylinder of elliptical cross section whose minor axis is 30 cm and disregarding radiation, determine the average convection heat transfer coefficient on the wing surface and the average rate of heat transfer per unit surface area.
A 6 cm diameter sphere is initially at a temperature of 100C. Later, this sphere was thrown into water at 800C. Calculate how long it will take for the center temperature of the sphere to reach 500C by taking the convection heat transfer coefficient as 80W / m2K. Thermal properties of sphere material: k=0,627 W/moC a=0,151x10-6 m2/s
A 10-cm-wide and 15-cm high vertical hot surface in 5°C air is to be cooled by a heat sink equally spaced fins of rectangular profile (see the figure). The fins are 0.05 cm thick and 15 cm long in the vertical direction and have a height of 2.5 cm from the base. Determine the optimum fin spacing and the rate of heat transfer by natural convection from the heat sink if the base temperature is 35°C. (7.1 mm, 13.54 W)
How can we use the transient temperature charts when the surface temperature of the geometry is specified instead of the temperature of the surrounding medium and the convection heat transfer coefficient?
A 6-m-internal-diameter spherical tank made of 1.5-cm-thick stainless steel (k = 15 W/m·K) is used to store iced water at 0°C in a room at 20°C. The walls of the room are also at 20°C. The outer surface of the tank is black (emissivity « = 1), and heat transfer between the outer surface of the tank and the surroundings is by natural convection and radiation. Assuming the entire steel tank to be at 0°C and thus the thermal resistance of the tank to be negligible, determine (a) the rate of heat transfer to the iced water in the tank and (b) the amount of ice at 0°C that melts during a 24-h period. The heat of fusion of water is 333.7 kJ/kg.
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.
An automotive engine can be approximated asa 0.4-m-high, 0.60-m-wide, and 0.7-m-long rectangularblock. The bottom surface of the block is at a temperatureof 75°C and has an emissivity of 0.92. The ambient airis at 5°C, and the road surface is at 10°C. Determine therate of heat transfer from the bottom surface of the engineblock by convection and radiation as the car travels at avelocity of 60 km/h. Assume the flow to be turbulent over theentire surface because of the constant agitation of the engineblock. How will the heat transfer be affected when a 2-mmthickgunk (k = 3 W/m?K) has formed at the bottom surface asa result of the dirt and oil collected at that surface over time?Assume the metal temperature under the gunk still to be 75°C.