Suppose that a pipe carrying a hot fluid with an external temperature of
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Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)
- 2.2 A small dam, which is idealized by a large slab 1.2 m thick, is to be completely poured in a short Period of time. The hydration of the concrete results in the equivalent of a distributed source of constant strength of 100 W/m3. If both dam surfaces are at 16°C, determine the maximum temperature to which the concrete will be subjected, assuming steady-state conditions. The thermal conductivity of the wet concrete can be taken as 0.84 W/m K.arrow_forwardDetermine the conduction heat transfer INSULATOR rate through the wall. T$2 Tst k H Ts2 M L H INSULATOR W Н %3D 0,6 т L = 0,5 m М 3D 2 ст k = 0,15- mK Ts2 = 10°C Ts1 = 30°C,arrow_forwardProblem 2 Suppose that heat conduction occurs at a constant rate of đQ/dt in a hollow sphere with an inner radius of r, at temperature T, and an inner radius of r, at temperature T,. Show that for constant thermal conductivity K, the temperature difference between the two surfaces is given by dQ I dT ( 1 т, - т, 1 4л Кarrow_forward
- Q2. Steam pumped through a long- insulated pipe at a temperature of T= 500 K and provides a convection coefficient of h, = 100 W/m?K at the inner surface of the pipe. The inner and outer radius of the pipe and insulation material are r1 = 10, r2 = 12 and r3 = 17 cm, respectively. The thermal conductivity of the pipe is 100 W/mK. The insulation material is glass fiber and its outer surface is exposed to ambient air at 300 K. If the ambient air provides a convection coefficient of ho = 20 Internal flow Ambient air W/m?K, determine the followings: a. What are the thermal resistance coefficients for convections and conductions b. What is the heat transfer rate per unit length of the pipe c. If the pipe is 30 m long, what will be total heat transfer rate from the pipe. t00 noints)arrow_forwardA cast iron pipe is used to transfer steam with an inlet temperature of 350 C. Inner radius of the pipe is 5 cm. The thickness of the pipe (k=20 W/(mK)) is 0.5 cm and there is an insulation (k=0.07 W/mK) over the pipe with a thickness of 4 cm. Environmental temperature is -5 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 70 W/(m^2K) and environment convection coefficient is 20 W/(m^2K)? Is insulation thickness enough? steam steam 167 W, yes 187 W, yes 147 W, yes 120 W, no nonearrow_forwardA cylindrical electrical heating element is used to heat up a baking oven. The heating element bears a voltage of 120 V/m, and has an electrical resistance of 1000 Ω/m. A ceramic pipe of inside radius rin = 2 mm, and outside radius rout = 5 mm encases the heating element. Thermal conductivity of the ceramic is k = 0.2 W/m-K. Given that the oven air temperature is T∞ = 180oC and convection coefficient h = 10 W/m2-K, find the temperature on the inside of the ceramic pipe.arrow_forward
- A cast iron pipe is used to transfer steam with an inlet temperature of 300 C. Inner radius of the pipe is 15 cm. The thickness of the pipe (k=25 W/(mK)) is 0.7 cm and there is an insulation (k=0.05 W/mK) over the pipe with a thickness of 5 cm. Environmental temperature is -8 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 80 W/(m^2K) and environment convection coefficient is 25 W/(m^2K)? Is insulation thickness enough?arrow_forwardA cast iron pipe is used to transfer steam with an inlet temperature of 300 C. Inner radius of the pipe is 15 cm. The thickness of the pipe (k=25 W/(mK)) is 0.7 cm and there is an insulation (k=0.05 W/mK) over the pipe with a thickness of 5 cm. Environmental temperature is -8 C. Determine the steady heat loss from the pipe if the steam convection coefficient is 80 W/(m^2K) and environment convection coefficient is 25 W/(m^2K)? Is insulation thickness enough? a)197 W, yesb)207 W, yesc)147 W, yesd)150 W, noe)nonearrow_forwardCalculate the overall heat transfer coefficient of the steel pipe based on the inner surface. The inner diameter of the pipe is 12.7 cm, and the thickness of the pipe is 2.4 cm. The convective heat transfer coefficient in the pipe is 350 W / (m² °C), the convective heat transfer coefficient outside the pipe is 25 W / (m² °C), the thermal conductivity of the steel pipe is 15 W / (m °C) . If a pipe is used to deliver steam at 110 °C and the ambient temperature is 30 °C, determine the rate of heat transfer from the pipe per meter. q = AnswerWatts/marrow_forward
- Q2/ The wall of a refrigerator is constructed of fiberglass insulation (k=0.035 W/ m. C) sandwiched between two layers of 1-mm-thick sheet metal (k-15.1 W/m.°C). The refrigerated space is maintained at 3°C, and the average heat transfer coefficients at the inner and outer surfaces of the wall are 4 W/m2.C and 9 W/m2.°C, respectively. The kitchen temperature averages 25°C. It is observed that condensation occurs on the outer surfaces of the refrigerator when the temperature of the outer surface drops to 20°C. Determine the minimum thickness of fiberglass insulation that needs to be used in the wall in order to avoid condensation on the outer surfaces. Sheet metal Kitchen Refrigerated air space 3°C 25°C Insulation 10°C 1 mm mmarrow_forwardWater vapor at a temperature of 120 ° C flows through a stainless steel pipe (k = 57 W / mK). The inner diameter of the pipe is 47 mm, the outer diameter is 50 mm, and the length is 100 m. The heat transfer coefficient between the water vapor and the pipe wall is 200 W / m²K, and the heat transfer coefficient between the outer surface of the pipe and the ambient air is 25 W / m_K. The outdoor air temperature is 10 ° C. Find the thermal conductivity coefficient of the insulation material, since it is desired to insulate with an insulation material with a layer thickness of 50 mm in order to reduce the loss of heat from the pipe by 60%.arrow_forwardA steel pipe (k = 48 W/m∙K) of a heating system carries wet steam at 125 °C. The inner and outer diameters of the pipe are 15 cm and 17 cm respectively. The pipe is insulated on the outside with rockwool insulation (k = 0.05 W/m∙K) of thickness 8 cm. The ambient air temperature is 30 °C. The outside heat transfer coefficient is 22 W/m2∙K. The thermal resistance between the inner pipe surface and the steam is negligible. Calculate the rate of heat flow (in W) from the steam to the ambient over a 7 m length of pipe. calculate the temperature (in °C) of the outer surface of the insulation. calculate the rate of condensation of steam (in kg/hr) over the 7-m length of pipe if the latent heat of steam is 2189 kJ/kg.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning