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A long power transmission cable is buried at a depth(ground-to-cable-centerline distance) of 2 m. The cableis encased in a thin-walled pipe of 0.1-m diameter, and,to render the cable superconducting (with essentiallyzero power dissipation), the space between the cableand pipe is filled with liquid nitrogen at 77 K. Ifthe pipe is covered with a superinsulator
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Introduction to Heat Transfer
- 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)arrow_forwardDetermine the thermal conductivity of water vapor at 174°C.arrow_forwardA piece of chromium steel of length 7.4 cm (density = 8780 kg/m^3; k = 50 w/mK and specific heat cp = 440j/kgK with mass 1.27 kg is rolled into a solid cylinder and heated to a temperature of 600 deg C and quenched in oil at 36 deg C. Show that the lumped capacitance system analysis is applicable and find the temperature of the cylinder after 4 min. What is the total heat transfer during the period? You may take the convective heat transfer coefficient between the oil and cylinder at 280 w/m^2 k.arrow_forward
- In addition , the space between the upper cap, the lower cap, and the cylindrical wall is filled with linear insulating material of permeability u.arrow_forward1. A copper rod is 0.50 m long and has a cross-sectional area of 4.0×10-4m². One end of the rod is kept at 30 °C, while the other end is at 75 °C. The sides of the rod are insulated so that heat losses through the sides are negligible. (a) Find how much heat flows through the rod per second. (b) What is the temperature at 0.30m from the higher-temperature end of the rod? The thermal conductivity of copper is 390'lsm °C:arrow_forwardA plane wall is 2m high and 3m wide and is 20cm thick. It is made of a material that has a thermal conductivity of 0.50W/m-K. A temperature difference of 60 degrees Celsius is imposed on the two large faces. Find the heat flux.arrow_forward
- Example: current of 200 A is passed through a stainless-steel wire [k = 19 W/m · ◦C] 3 mm in diameter. he resistivity of the steel may be taken as 70 μ · cm, and the length of the wire is 1 m. The ire is submerged in a liquid at 110 ◦C and experiences a convection heat-transfer coefficient of k W/m2 · ◦C. Calculate the center temperature of the wire.arrow_forward4. A wall of thickness 10cm conducts heat at rate of 30W/m² when the temperature difference across wall is 10K. What is thermal conductivity (W/mK)arrow_forwardA wall in a house contains a single window. The window consists of a single pane of glass whose area is 0.13 m2 and whose thickness is 8 mm. Treat the wall as a slab of the insulating material Styrofoam whose area and thickness are 19 m2 and 0.10 m, respectively. Heat is lost via conduction through the wall and the window. The temperature difference between the inside and outside is the same for the wall and the window. Of the total heat lost by the wall and the window, what is the percentage lost by the window?arrow_forward
- An ideal mono-atomic gas is confined in a cylinder with the help of a piston that can slide inside the cylinder without friction. The cylinder I placed on a horizontal platform in a vacuum chamber. The walls of the cylinder and the piston are made of heat insulating materials. Initially the temperature of the gas is 'T, and the piston stays in equilibrium. The temperature of the gas is quickly increased n times and then the gas is allowed to expand. If the piston rises and again acquires an equilibrium state, find the temperature of the gas in this new equilibrium state.arrow_forwardEx1. A piece of chromium steel of length 7.4cm (density=8780kg/m³ ; k = 50w/mK and specific heat cp = 440j/kgK) with mass 1.27kg is rolled into a solid cylinder and heated to a temperature of 600°C and quenched in oil at 36°c. Show that the lumped capacitance system analysis is applicable and find the temperature of the cylinder after 4min. What is the total heat transfer during this period? You may take the convective heat transfer coefficient between the oil and cylinder at 280w/m2k.arrow_forwardDetermine the total length and mean length per turn of a circular coil of diameter 4.3 mm is made up of Copper consists of 1049 turns. Take the electrical conductivity value and resistance of the copper coil as 63 MS/m and 14 2 respectively. Solution: Cross-sectional Area of the wire (in m²) = Total Length of the Coil (in m) = Mean Length per turn of the Coil (in m)=arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning