3. A 2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k = 0.15 W/m · °C. Electrical measurements indicate that a current of 10 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T = 30°C with a heat transfer coefficient of h = 24 W/m2 · °C, determine the temperature at the interface of the wire and the plastic cover in steady operation. Also determine if doubling the thickness of the plastic cover will increase or decrease this interface temperature.

3. A 2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k = 0.15 W/m · °C. Electrical measurements indicate that a current of 10 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T = 30°C with a heat transfer coefficient of h = 24 W/m2 · °C, determine the temperature at the interface of the wire and the plastic cover in steady operation. Also determine if doubling the thickness of the plastic cover will increase or decrease this interface temperature.

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 2.32P

See similar textbooks

Similar questions

0/1 The thermal conductivity of Aluminum material at127°Cand 527 C are 240 and 218 W/m. K, respectively. Determine ko and B, constants for the used material. k=ko (1 + BT) is assumed with T in °C. 0/2 Heat is generated in a slab of 120 mm thickness with a conductivity of 200 W/m K at a rate of 106W/m. Determine the temperature at the mid and quarter planes if the surface of the solid on both sides are exposed to convection at 30°C with a convection coefficient of 500 W/m K. Also find the heat flow rate at these planes and the temperature gradients at these planes. 0/3 1. Determine the heat flow for (i) rectangular fins and (ii) triangular fin of 20 mm length and 3 mm base thickness. Thermal conductivity = 45 W/m K. Conwection coefficient h= 100 W/m K, base temperature = 120°C surrounding fluid temperature = 35°C. Determine also the fin effectiveness. 2. A circumferential fin on a pipe of 50 mm OD is 3 mm thick and 20 mm long. Using the property values and other parameters in 1,…
Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k=2.3 W/m °C, and surface area A= 20 m2. The left side of the wall at x= 0 is subjected of T1 = 80°C. while the right side losses heated by convection to the surrounding air at T∞=15 oC with a heat transfer coefficient of h=24 W/m2 oC . Assuming constant thermal conductivity and no heatgeneration in the wall, (a) express the differential equation and the boundary conditions forsteady one-dimensional heat conduction through the wall, (b) obtain a relation for thevariation of temperature in the wall by solving the differential equation, and (c) evaluate therate of heat transfer through the wall
HEAT TRANSFER (a) Determine the thermal conductivity of an insulating material given the following data: steel pipe with 0.1025 m inner diameter and 0.1150 m outer diameter, insulation thickness 3 cm, heat flow per meter is 150 W/m, steel thermal conductivity 55 W/m-°C, and overall temperature difference of 72.2°C. If the temperature of the steam inside the pipe is 128°C, (b) find the outside temperature of the insulating material.
A wall with a thermal conductivity of 0.4 W/m-°C is maintained at 45°C. The heat transfer through the wall is 220 W. The wall surface area is 2.0m² and its thickness is 1.5 cm. Determine the temperature at the other surface.
A plane wall 15 – cm thick has a thermal conductivity given by the relation k = 2.0 + 0.0005 T, W/m – K where T is in Kelvin. If one surface of this wall is maintained at 150 oC and the other at50 oC, determine the rate of heat transfer per square meter. Sketch the temperaturedistribution through the wall.
Consider a large plane wall of thickness L = 0.4 m, thermal conductivity k=2.3 W/m °C,and surface area A= 20 m2. The left side of the wall at x= 0 is subjected of T1 = 80 C. while the right side losses heated by convection to the surrounding air at Too=15 C with a heat transfer coefficient of h=24 W/m2 .C. Assuming constant thermal conductivity and no heat generation in the wall, (a) express the differential equation and the boundary conditions for steady one-dimensional heat conduction through the wall, (b) obtain a relation for the variation of temperature in the wall by solving the differential equation, and (c) evaluate the rate of heat transfer through the wall
If the rate of heat flow through a furnace wall is 0.94 kW/m². The wall consisting of 0.20 m thick inner layer of chrome brick, a center layer of kaolin brick of 10.0 cm and an outer layer of masonry brick 100 mm thick, having a thermal conductivity of 1.25 W/m°C , 0.74x10ª kW/m°C_and 0.555x10³ kW/m°C respectively. The unit surface conductance at the inner surface is 74 W/m2 °C and the outer surface temperature is 70 °C . The temperature of the gases inside the furnace is 1670 °C , assume steady heat flow, Calculate the following: 1- The temperatures of the gases inside the furnace. 2- The interior surface temperature of the inner and outer layers.
Heat is lost through the glass pane of a window. The thickness of the glass is 3 mm, and the window is 0.9 m by 1.8 m. The thermal conductivity of glass is 0.8 W/mK. If the temperature difference across the glass is 17 K, what is the total heat transfer through the pane of glass? Give your answer in Watts to the nearest integer.
The temperature on the left surface of the wall is measured as T1 = 60 C under continuous conditions where there is no heat generation in a planar wall with a thickness of 40 cm and a heat conduction coefficient of k = 2.5W / mC. After finding the temperature distribution inside the wall, find the wall temperature (C) at x = 0.10 m.
Under steady-state conditions, the wall of a brick house is measured to have an inside temperature of T = 29O K and an outside temperature of To = 320 K . Assume %3D this wall has constant thermal conductivity k = 1.5 W/(m²-K) and the temperature profile through the wall is linear. If the brick wall is 0.11 m thick, determine the total heat transfer through the wall (in Watts) if the wall has an area of 25 m².
A stainless steel alloy has cylindrical shape (k = 25 W/m.oC), diameter is 10 cm and 25 cm long, taken to furnace. The initial temperature is 90 oC, the furnace temperature is 1260 oC and the heat transfer coefficient is h = 100 W/m2.oC. Determine the time required for a stainless steel alloy to reach 830 oC. Take thermal diffusivity (k⁄ρ c = 0.45 × 10−5 m2/s).
The average rate at which energy is conducted outward through the ground surface in North America is 54.0 mW/m2, and the average thermal conductivity of the near surface rocks is 2.50 W/m K. Assuming a surface temperature of 10.0oC, find the temperature at a depth of 10.0 km. Ignore the heat generated by the presence of radioactive elements.