ESCUELA SUPERIOR POLITÉCNICA DEL LITORAL FACULTAD DE INGENIERÍA MECÁNICA Y CIENCIAS DE LA PRODUCCIÓN
Taller IHT Objetivo:
Aplicar el Software Interactive Heat Transfer para el desarrollo de ejercicios ejercicios de Transferencia T ransferencia de Calor. Una vez realizada la explicación por parte del docente sobre el Software en cuanto a las aplicaciones del mismo y el uso de sus herramientas. Desarrollar los siguientes ejercicios, escoja 2 para desarrollarlos (obligatoriamente deberá realizar el ejercicio 1), utilizando dicho Software. Ejercicios a Desarrollar:
1. Consider the solid solid tube (Solid (Solid tube with uniform uniform heat generation generation is insulated insulated at the outer outer surface and cooled at the inner surface.) Using Equation (1) with Equation (2) in the IHT workspace, calculate and plot the temperature distributions for a tube of inner and outer radii, 50 mm and 100 mm, mm, and a thermal conductivity conductivity of 5 W/m K for volumetric generation generation rates of 1x10^5, 5x10^5, and 1x10^6 W/m3. The inner surface is cooled by a fluid at 30°C with a convection coef ficient of 1000 W/m2-K.
̇ ̇ − − 4 4 ̇ − = ℎ2 (, − ∞ )
= , +
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2. A long bar of rectangular cross section, 0.4m x 0.6m on a side and having a thermal conductivity of 1.5 W/m-K, is subjected to the boundary conditions shown below. Two of the sides are maintained at a uniform temperature of 200°C. One of the sides is adiabatic, and the remaining side is subjected to a convection process with T = 30°C and h = 50W/m2-K. Using an appropriate numerical technique with a grid spacing of 0.1m, determine the temperature distribution in the bar and the heat transfer rate between the bar and the fluid per unit length of the bar
3. A composite spherical shell of inner radius r 1 = 0.25 m is constructed from lead of outer radius r 2 = 0.30 m and AISI 302 stainless steel of outer radius r 3 = 0.31 m. The cavity is filled with radioactive wastes that generate heat at a rate of ̇ = 5x10 5 W/m3. It is proposed
to submerge the container in oceanic waters that are at a temperature of ∞ = 10°C and provide a uniform convection coefficient of h = 500 W/m 2-K at the outer surface of the container. Are there any problems associated with this proposal?
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4. As an alternative to storing radioactive materials in oceanic waters, it is proposed that the system of Problem 3 be placed in a large tank for which the flow of water, and hence the convection coefficient h, can be controlled. Compute and plot t he maxim um temperature
of the lead, T(r 1), as a function of h for 100 ≤ h ≤ 1000 W/m2-K. If the temperature of the lead is not to exceed 500 K, what is the minimum allowable value of h? To improve system reliability, it is desirable to increase the thickness of the stainless steel shell. For h = 300, 500, and 1000 W/m 2-K, compute and plot the maximum lead temperature as a function of shell thickness for r 3 ≥ 0.30 m. What are the corresponding values of the maximum allowable thickness?
5. A steam pipe of 0.12-m outside diameter is insulated with a layer of calcium silicate. If the insulation is 20 mm thick and its inner and outer surfaces are maintained at , =
800 and , = 490 , respectively, what is the heat loss per unit length ( ´) of the pipe? We wish to explore the effect of insulation thickness on the heat loss ´ and outer surface
,, with thw inner surface temperature fixed at , = 800 . The aouter surface is exposed to an airflow ( ∞ = 25 ) that maintains a convection coefficient of ℎ = 2 5
and to large surroundings for which = ∞ = 25 . The surface emissivity of calcium silicate is approximately 0.8. Compue and plot the temperature distribution in the insulation as a function of the dimensionless radial coordinate, ( − / ( − , where = 0.06 and is a variable 0.06 < ≤ 0.20 . Compute and plot the heat loss as a function of the insulation thickness for 0 ≤ − ≤ 0.14 m
Referencia Bibliográfica:
Incropera, F. (2007).
Fundamentals of heat and mass transfer .
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