Concept explainers
A long conducting rod of rectangular cross section
- Using a finite-difference method with a grid spacing of 5 mm, determine the temperature distribution in the rod.
- With the boundary conditions unchanged, what heat generation rate will cause the midpoint temperature to reach 600 K?
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Fundamentals of Heat and Mass Transfer
- A square silicon chip 7mm7mm in size and 0.5-mm thick is mounted on a plastic substrate as shown in the sketch below. The top surface of the chip is cooled by a synthetic liquid flowing over it. Electronic circuits on the bottom of the chip generate heat at a rate of 5 W that must be transferred through the chip. Estimate the steady-state temperature difference between the front and back surfaces of the chip. The thermal conductivity of silicon is 150 W/m K. Problem 1.6arrow_forward2.15 Suppose that a pipe carrying a hot fluid with an external temperature of and outer radius is to be insulated with an insulation material of thermal conductivity k and outer radius . Show that if the convection heat transfer coefficient on the outside of the insulation is and the environmental temperature is , the addition of insulation actually increases the rate of heat loss if , and the maximum heat loss occurs when . This radius, is often called the critical radius.arrow_forward1.4 To measure thermal conductivity, two similar 1-cm-thick specimens are placed in the apparatus shown in the accompanying sketch. Electric current is supplied to the guard heater, and a wattmeter shows that the power dissipation is 10 W. Thermocouples attached to the warmer and to the cooler surfaces show temperatures of 322 and 300 K, respectively. Calculate the thermal conductivity of the material at the mean temperature in W/m K. Problem 1.4arrow_forward
- 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 .arrow_forward1.37 Mild steel nails were driven through a solid wood wall consisting of two layers, each 2.5-cm thick, for reinforcement. If the total cross-sectional area of the nails is 0.5% of the wall area, determine the unit thermal conductance of the composite wall and the percent of the total heat flow that passes through the nails when the temperature difference across the wall is 25°C. Neglect contact resistance between the wood layers.arrow_forwardA section of a composite wall with the dimensions shown below has uniform temperatures of 200C and 50C over the left and right surfaces, respectively. If the thermal conductivities of the wall materials are: kA=70W/mK,kB=60W/mK, kC=40W/mK, and kP=20W/mK, determine the rate of heat transfer through this section of the wall and the temperatures at the interfaces. Repeat Problem 1.34, including a contact resistance of 0.1 K/W at each of the interfaces.arrow_forward
- Problem 4 A cork board (k = 0.039W/m K) 3 cm thick is exposed to air with an average temperature T.. = 30°C with a convection heat transfer coefficient, h = 25 W/m².K. The other surface of the board is held at a constant temperature of 15°C. A volumetric heat generation of 5 W/m³ is occurring inside the wall. Assuming one dimensional conduction, write the governing equation and express the boundary conditions for the wall. (solve the equation is not required) Problomarrow_forwardAn annulus (e.g., a tube) has a temperature of Ti at the inner surface (at ri) and a temperature of To at the outer surface (at ro). Steady-state conditions prevail and there is not any heat generation in the annulus. However, the thermal conductivity k of the annulus is a strong function of temperature and can be described mathematically by the following function k(T) = a + bT + cT2. Calculate the total rate of heat flow (not heat flux) through the annulus if it is L long. Show steps to get to the answer attached.arrow_forwardDo fast i will give you good ratearrow_forward
- Find the steady temperature distribution in the semi infinite plate shown below. The 2D steady heat conduction equation is: use the method of separation of variables.arrow_forwardIt is observed that the temperature distribution, in steady-state, inside a one-dimensional wall with thermal conductivity equal to 50 W/mK and thickness of 50 mm has the form T(°C) = a + bx², where a = 200 °C and b = -2000 °C/m², and x is in meters. (a) What is the heat generation rate (q’’’) in the wall? (b) Determine the heat fluxes on both faces of the wall.arrow_forwardH.W.: Q1: Consider steady two-dimensional heat transfer in a long solid body whose cross section is given in the figure. The temperatures at the selected nodes and the thermal conditions at the boundaries are as shown. The thermal conductivity of the body is k = 45 W/m. °C, and heat is generated in the body uniformly at a rate of g = 6 x 106 W/m3. Using the finite difference method with a mesh size of Ax = Ay = 5.0 cm, determine (a) the temperatures at nodes 1, 2, and 3 and (b) the rate of heat loss from the bottom surface through a 1-m-long section of the body. . 200°C 5 cm 5 cm g=6x 10 W/m² 260 3 240 305 290 Insulation 1 Convection T₂= 20°C, h= 50 W/m² °C 350°C 325arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning