Chapter 4, Problem 4.1P

3.16 A large, 2.54-cm.-thick copper plate is placed between two air streams. The heat transfer coefficient on one side is and on the other side is . If the temperature of both streams is suddenly changed from 38°C to 93°C, determine how long it takes for the copper plate to reach a temperature of 82°C.

2.29 In a cylindrical fuel rod of a nuclear reactor, heat is generated internally according to the equation where = local rate of heat generation per unit volume at r = outside radius = rate of heat generation per unit volume at the centerline Calculate the temperature drop from the centerline to the surface for a 2.5-cm-diameter rod having a thermal conductivity of if the rate of heat removal from its surface is 1.6 .

Steam at 150 ° C flows in a pipe having an inner radius of 50 mm and an outer radius of 55 mm. The convective heat transfer coefficient between the steam and the inner pipe wall is 2500 W / (m² ° C). The outer surface of the pipe exposed to ambient air is 25 ° C with a convective heat transfer coefficient of 10 W / (m² ° C). Assuming steady state, calculate the rate of heat transfer per meter of pipe from steam to air. Assume that the thermal conductivity of stainless steel is 15 W / (m ° C.). Steps of work according to example 4.16 Singh. a. Find the overall heat transfer coefficient = Answer W / m² ° C. b. Heat transfer rate per meter of pipe = Answer

A hollow cylinder 6 cm internal diameter and 12 cm outer diameter has a heat generation rateof 5 × 106 W/m3. The inner surface is maintained at 380°C and the outer surface at 360°C. Theconductivity of the material is 30 W/mK. Determine(a) The location and value of the maximum temperature.(b) The fraction heat generated going to the inner surface.

A flat surface is covered with insulation with a thermal conductivity of 0.08 W/m · K. The temperature at the interface between the surface and the insulation is 300 °C. The outside of the insulation is exposed to air at 30 °C, and the heat transfer coefficient for convection between the insulation and the air is 10 W/m2 • K. Ignoring radiation, determine the minimum thickness of insulation, in meter, such that the outside of the insulation is no hotter than 60 °C at steady state.

The thermal conductivities of human tissues vary greatly. “Fat” and “skin” have conductivities of approximately 0.200 W /m 0K and 0.0200 W /m 0K, respectively, while other “tissues” inside the body have conductivities of approximately 0.500 W /m 0 Assume that between the core region of the body and the skin surface lies a “skin” layer of 1.00mm, a “fat” layer of 0.500 cm., and 3.20 cm. layer of other “tissues”.   Find the rate of energy loss when the core temperature is 37.00C and the exterior temperature is 0.000 Assume a body area of 2.00 m2. (Both a protective layer of clothing and an insulating layer of unmoving air are absent).

A heat conducting rod, 0.30 m long, is made of an aluminum section that is 0.10 m long, and a copper section that is 0.20 m long. Both sections have cross-sectional areas of 0.00040 m2. The aluminum end is maintained at a temperature of 10°C and the copper end is at 170°C. The thermal conductivity of aluminum is 205 W/m • K and of copper is 385 W/m • K. Steady state has been reached, and no heat is lost through the well-insulated sides of the rod. The temperature of the aluminum-copper junction in the rod is closest to

What is the temperature, T2, on the right-hand side of layer B, in Celsius and the  uniform volumetric heat generation, q̇B [W/m3], within layer B?

Question No. 11: a) Derive the general heat conduction equation in Cartesian coordinates. b) Electric heater wires are installed in a solid wall having a thickness of 8 cm and k =2.5W/m ◦C.The right face is exposed to an environment with h=50W/m2◦C and T∞ = 30°C, while the left face is exposed to h=75W/m2◦C and T∞ =50◦C. What is the maximum allowable heat-generation rate such that the maximum temperature in the solid does not exceed 300◦C?