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A pipe is used for transporting boiling water in which the inner surface is at 100°C. The pipe is situated where the ambient temperature is 20°C and the convection heat transfer coefficient is 50 W/m2 K. The pipe has a wall thicess of 3 mm and an inner diameter of 25 mm, and it has a variable thermal conductivity given as
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HEAT+MASS TRANSFER:FUND.+APPL.
- 3- Pipes with inner and outer diameter of 50mm and 60mm, respectively, are used for transporting superheated vapor in a manufacturing plant. The pipes with thermal conductivity of 16 W/m.K are connected together by flanges with combined thickness of 20mm and outer diameter of 90mm. Air condition surrounding the pipes has a temperature of 25C and a convection heat transfer coefficient of 10 W/m².K. If the inner surface temperature of the pipe is maintained at a constant temperature of 150C, determine the temperature at the base of the flange and the rate if heat loss through the flange. Air, 25 °C h= 10 W/m².ºC D;= 90 mm D;, = 50 mm T; = 150 °C Pipe, k = 16 W/m•°C D,= 60 mm t= 20 mmarrow_forwardA steam pipe 50 mm diameter and 2.5 m long has been placed horizontally and exposed to still air at 25 degree Celsius. If the pipe wall temperature is 295 degree Celsius, determine the rate of heat loss. At the mean temperature difference of 160 degree Celsius, the thermo-physical properties of air are k =3.64 * 10 -2 W/m v =30.09 * 10 -6 m2/ P r =0.68 Β =1/160 + 273 = 2.31 * 10^-3/Karrow_forwardFluid is flowing through a 20 mm inside diameter and 25 mm outside diameter brass tube at no leaking with temperature at 149oF and length of 10 m. Surface conduction of hot fluid is 5.2 W/m2-K and thermal conductivity of brass is 12.84 W/m2-K. Brass tube is covered by silica of 6 mm thickness with thermal conductivity of 13.84 W/m-K. Outside of it, is a fluid with 45oC with surface conductance of 3.2 W/m2-K. Find the heat transfer from the hot fluid with temperature of 149oF to fluid with temperature of 45oC.arrow_forward
- There are 2 different types of fins: circular section and square section. Both fins are 30 cm length and they are made of copper with 380W/mK_conductivity. The circular section fin diameter is D = 3mm and the lateral width of the square section fin is W = 50 mm. The fin base temperature is -10°C. The fins are immersed in an oil bath at 50°C and perpendicular velocity to the axis of the fins. Obtain the maximum heat rate absorbed in each types of fin for an oil velocity of 60 m/s. Justify every calculation and assumption. Answer: 27.42W (circular section); 987.53W (square section parallel oriented); 1018.6W (square section oblique oriented)arrow_forwardTo maximize production and minimize pumping costs, crude oil is heated to reduce its viscosity during transportation from a production field. (1) Consider a pipe-in-pipe configuration consisting of concentric steel tubes with an intervening insulating material. The inner tube is used to transport warm crude oil through cold ocean water. The inner steel pipe (k, = 40 W/m-K) has an inside diameter of D₁.I 150 mm and wall thickness t, = 20 mm while the outer steel pipe has an inside diameter of D₁,2 = 250 mm and wall thickness to = 1₁. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (k, = 0.0675 W/m.K) between the two pipes does not exceed its maximum service temperature of Tp. max = 70°C. The ocean water is at T = -5°C and provides an external convection heat transfer coefficient of h, = 500 W/m².K. The convection coefficient associated with the flowing crude oil is h; = 450 W/m².K. (2) It is proposed to enhance the performance of the…arrow_forwardConsider a heat treatment furnace situated in a 30oC room with an average convection heat transfer coefficient of 12W/m2K. The door of the furnace is made of 20 mm-thick steel plate with thermal conductivity, k=25W/mK. A constant heat flux of 8kW/m2 is applied to the inner surface of the door, and the outer surface has an emissivity of 0.23. What is the outer surface temperature of the furnace door? Is this safe? What can you do to make it safe?arrow_forward
- Consider a large plane wall of thickness 2L=20mm. Both surfaces of the wall are convectively cooled by the surrounding coolant at To = 250°C with a heat transfer coefficient of h= 1100 W/m².K. A fuel element of a nuclear reactor is considered in the shape of this large plane wall with given constant thermal properties as thermal conductivity k = 30 W/m.K and a = 5 x 10-6m²/s. It is known that heat is generated uniformly within the element at a volumetric rate of q = 1x 107W /m³. A departure from the steady-state conditions associated with normal operation will occur if there is a change in the generation rate. Consider a sudden change to q2 = 2 x 107W/m³. Assuming steady one-dimensional heat transfer along the wall, use the explicit finite- difference method to show how to calculate temperature To at 1.2 sec and temperature Ts at 1.5 sec. (show which equation to use and the calculations in details)arrow_forwardRequired Information The upper surface of a 85-cm-thick solid plate (k= 237 W/m-K) is being cooled by water with temperature of 20°C. The upper and lower surfaces ofthe solid plate maintained at constant temperatures of 60°C and 120°C, respectively. Given: The thermal conductivity of the solid plate is given ask= 237 W/m K. f2 (T,1+T) = (60°C + 20°C)/2 = 40°C is kuid = 0.631 The thermal conductivity of water at the film temperature of T; W/m/K. Determine the water convection heat transfer coefficient. The water convection heat transfer coefficient is W/m2 -K.arrow_forwardOil is flowing through a 45 mm inside diameter iron pipe (k=16 W/mK) at 1.2 m/s. The thickness of pipe is 8 mm. It is being heated by steam outside the pipe, and the steam-film coefficient may be taken as 12 kW/m2 oC. At a particular point along the pipe the oil is at 40 oC, its density is 880 kg/m3, its viscosity is 2.1 cP, its thermal conductivity is 0.135 W/moC and its specific heat is 2.17 J/g oC. a) What is the overall heat transfer coefficient at this point, based on the inside area of the pipe? b) If the steam temperature is 120oC, what is the heat transfer rate at this point, based on the outside area of the pipe? c) Calculate the inside and outside wall temperatures of pipe when the steam temperature is 120oC and bulk temperature of oil is 40oarrow_forward
- Solve for this : An engine cover is made from 1 cm thick stainless steel plate (k = 14 W/m K). Air on the inside of the engine cover is heated to 340°C with a heat transfer coefficient of 7 W/m2K. Outside of the engine coverthe ambient air has a temperature of 70°C. If oil was spilled on the outside of the engine cover (ambient side), it could ignite if the surface temperature were to exceed 200°C. In this configuration, would spilled oil ignite? Use calculations to justify your answer. If a 4 mm thermal coating (k = 1.1 W/m K) was applied tothe outside of the engine, what would the outside temperature of the engine cover be reduced to?arrow_forwardConvection 2. For a boiling process such as shown in Figure below, the ambient temperature Tin Newton's law of cooling is replaced by the saturation temperature of the fluid Tsat. Consider a situation where the heat flux from the hot plate is q=20 x 105 W/m². If the fluid is water at atmospheric pressure and the convection heat transfer coefficient is hw=20 x 103 W/m2 K, determine the upper surface temperature of the plate, Ts, w. In an effort to minimize the surface temperature, a technician proposes replacing the water with a dielectric fluid whose saturation temperature is Teat, d=52 °C. If the heat transfer coefficient associated with the dielectric fluid is h = 3 x 103 W/m2 K, will the technician's plan work?arrow_forwardWater flows in a pipe of 0.0475 m inside diameter at a velocity of 1.5 m/s. Calculate the heat transfer coefficient if the temperature of the water is 60OC and 40OC at the inlet and the outlet of the pipe respectively, and the inside wall temperature of the pipe is 35OC. The physical properties must be calculated at the average water temperature. The thermal conductivity of the pipe at average temperature is 0.639 W/mOC.arrow_forward
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