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A pipe carrying superheated steam in a basement at 10°C has a surface temperature of 150°C. Heat loss from the pipe occurs by radiation
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Chapter 1 Solutions
Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
- An ice chest whose outer dimensions are 30 cm*40 cm*40 cm is made of 3 cm thick Styrofoam (k = 0.033 W/m°C). Initially, the chest is filled with 30 kg of ice at 0 °C, and the inner surface temperature of the ice chest can be taken to be 0 °C at all times. The heat of fusion of water at 0 °C is 333.7 kJ/kg, and the surrounding ambient air is at 20 °C. Disregarding any heat transfer from the 40 cm*40 cm base of the ice chest, determine how long it will take for the ice in the chest to melt completely if the ice chest is subjected to (a) calm air and (b) winds at 30 km/h (assume the heat transfer coefficient on the front, back and top surfaces to be the same as that on the side surfaces). Use the thermophysical properties of air as follows: k = 25.5×10-3 W/mK, ν = 15×10-6 m2/s, α = 21.1×10-6 m2/s, and β = 3.43×10-3 K-1.arrow_forwardA ball with diameter of 4 inches, is suspended in the middle of a room at 530°R. The ball's surface is maintained at a temperature of 700°R If the convection heat transfer coefficient is 0.04 kW/m2-°C and the emissivity of the surface is 0.7, determine the total rate of heat transfer from the ball.arrow_forwardQuestion 1: Consider a 0.8-m-high and 1.5-m-wide double-pane window consisting of two 4-mm-thick layers of glass (k 0.78 W/m · °C) separated by a 10-mm-wide stagnant air space (k 0.026 W/m · °C). Determine the steady rate of heat transfer through this double-pane window and the temperature of its inner surface for a day during which the room is maintained at 20°C while the temperature of the outdoors is 10°C. Take the convection heat transfer coefficients on the inner and outer surfaces of the window to be h1 10 W/m2 · °C and h2 40 W/m2 · °C, which includes the effects of radiation.arrow_forward
- Brass plate of 6 cm thickness that are initially at 25 °C are heated by passing it through an oven that is maintained at 700 •C. The plate remains in the oven for a period of 10 minutes. Taking the heat transfer coefficient (h= 130 W/m2. °C). Determine the center temperature of the plate and the temperature at the distance of 2 cm from the center of the plate. Taking p=8530 kg/m3, Cp=380 J/kg. • * .C, a= 33.9*10-6 m2/sarrow_forwardQ2/ A 4-m-internal-diameter spherical tank made of 1.75-cm-thick stainless steel (k 15 W/m °C) is used to store iced water at 0°C. The tank is located in a room whose temperature is 35°C. The walls of the room are also at 35°C. The outer surface of the tank is black, and heat transfer between the outer surface of the tank and the surroundings is by natural convection and radiation. The convection heat transfer coefficients at the inner and the outer surfaces of the tank are 80 W/m2 °C and 10 W/m2· °C, respectively. 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 l-h period. The heat of fusion of water at atmospheric pressure is hif 334 kJ/kg.arrow_forwardThere is a cylindical piece of nickel, that is 5 cm in diameter and 10 cm in length, that is initially at 20 degrees Celcius before being dropped into a hot fluid that is at 190 degrees Celcius. Determine the amount of heat gained by the cylinder until its temperature rises to 80 degrees Celcius. Show details in calculations and specify values retrieved from property tables.arrow_forward
- A student living in a 4 - m 5 - m 3 - m dormitory room turns on her 100 - W fan before she leaves the room on a summer day, hoping that the room will be cooler when she comes back in the evening. Assuming all the windows are tightly closed and disregarding any heat transfer through the walls and the windows, determine the temperature in the room when she comes back 8 h later. Use specific heat values at room temperature, and assume the room to be at 100 kPa and 20 ° C in the morning when she leaves.arrow_forwardA pipe in a manufacturing plant is transporting superheated vapor at a mass flow rate of 0.3 kg/s. The pipe is 10 m long and has an inner diameter of 5 cm and a wall thickness of 6 mm. The pipe has a thermal conductivity of 17 W/m·K, and the inner pipe surface is at a uniform temperature of 120°C. The temperature drop between the inlet and exit of the pipe is 7°C, and the constant pressure specific heat of vapor is 2190 J/kg·°C. If the air temperature in the manufacturing plant is 25°C, determine the heat transfer coefficient as a result of convection between the outer pipe surface and the surrounding air.arrow_forwardAn aluminium pan whose thermal conductivity is 237 W/m/°C has a flat bottom whose diameter is 20 cm and thickness 0.4 cm. Heat is transferred steadily to boiling water in the pan through its bottom at a rate of 500 W. If the inner surface of the bottom of the pan is 105°C, determine the temperature of the outer surface of the bottom of the pan. Note: All the derivation steps must be shown.arrow_forward
- A 1000-W iron is left on the ironing board with its base exposed to the air at 20°C. The convection heat transfer coefficient between the base surface and the surrounding air is 35 W/m2 °C. If the base has an emissivity of 0.6 and a surface area of 0.02 m2, determine the temperature of the base of the iron.arrow_forwardHow does the science of heat transfer differ from the science of thermodynamics? Give your answers with real-life practical examples.arrow_forwardConsider hotdog being cooked in boiling water in a pan. Would the heat transfer be modeled as one-dimensional or two-dimensional? Would the heat transfer be steady or transient? Explain.arrow_forward
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