In a meat processing plant, 2-cm-thick steaks
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HEAT+MASS TRANSFER:FUND.+APPL.
- Heat is transferred at a rate of 0.1 kW through glass wool insulation (density=100kg/m3) with a 5-cm thickness and 2-m2 area. If the hot surface is at 70C, determine the temperature of the cooler surface.arrow_forward3- Stainless steel ball bearings have a diameter of 1.2 cm are to be quenched in water. The balls leave the oven at a uniform temperature of 900°C and are exposed to air at 30°C for a while before they are dropped into the water. If the temperature of the balls is not to fall below 850°C prior to quenching and the heat transfer coefficient in the air is 125 W/m² - °C, determine how long they can stand in the air before being dropped into the water. Given: Stainless steel [ k= 15.1 W/m.°C, p= 8085 kg/m3, and Cp= 0.480 kJ/kg.°C. and a=3.95 × 106 m³/s]arrow_forwardA pipe in a manufacturing plant is transporting superheated vapor at a mass flow rate of 0.3 kg/s. The pipe is 10 m long and has an inner diameter of 5 cm and a wall thickness of 6 mm. The pipe has a thermal conductivity of 17 W/m·K, and the inner pipe surface is at a uniform temperature of 120°C. The temperature drop between the inlet and exit of the pipe is 7°C, and the constant pressure specific heat of vapor is 2190 J/kg·°C. If the air temperature in the manufacturing plant is 25°C, determine the heat transfer coefficient as a result of convection between the outer pipe surface and the surrounding air.arrow_forward
- A house is to be maintained at 21°C DBT and 50% RH, while the outdoor conditions are -30°C DBT and 100% RH. The inner and outer surface heat transfer coefficients are 8.3 W/m2.K and 34.4 W/m?.K, respectively. The exterior walls of the houses are chosen such that they have a thermal resistance of 0.45 m2.°C/W. Determine whether the walls are insulated sufficiently to prevent moisture condensation on the inner surfaces or not. If the selected wall construction may lead to condensation, what is the minimum thickness of insulation (kjns=0.036 W/m2 K) ?to be added to prevent condensationarrow_forwardA pipe in a manufacturing plant is transporting superheated vapor at a mass flow rate of 0.3 kg/s. The pipe is 10 m long, has an inner diameter of 5 cm and pipe wall thickness of 6 mm. The pipe has a thermal conductivity of 17 W/m.K, and the inner pipe surface is at a uniform temperature of 120 °C. The temperature drop between the inlet and the exit of the pipe is 7 °C, and the constant pressure specific heat of vapor is 2190 J/kg.°C. If the air temperature in the manufacturing plant is 25°C, determine the heat transfer coefficient as a result if convection between the outer pipe surface and the surrounding air. T(r) = 120°C Superheated Air, 25°C r2 vapor r1 0.3 kg/s L = 10 m Tin-Tout = 7°Carrow_forwardSteel rods (p = 7832 kg/m2, cn= 434 J/kg.K, and k = 63.9 W/m-K) are heated in a furnace to 850°C and then quenched in a water bath at 50°C for a period of 55 seconds as part of a hardening process. The convection heat transfer coefficient is 650 W/m2.K. If the steel rods have diameter of 40 mm and length of 2 m, determine their average temperature when they are taken out of the water bath. (Round off the answer to 1 decimal point.) °Carrow_forward
- 4-48 In a meat processing plant, 2-cm-thick steaks (k 0.45 W/m-K and a 0.91 × 10-7 m2/s) that are initially at 25°C are to be cooled by passing them through a refrigeration room at-11°C. The heat transfer coefficient on both sides of the steaks is 9 W/m2-K. If both surfaces of the steaks are to be cooled to 2°C, determine how long the steaks should be kept in the refrigeration room. Solve this problem using analytical one-term approximation method (not the Heisler charts).arrow_forwardBrass plate of 6 cm thickness that are initially at 25 °C are heated by passing it through an oven that is maintained at 700 •C. The plate remains in the oven for a period of 10 minutes. Taking the heat transfer coefficient (h= 130 W/m2. °C). Determine the center temperature of the plate and the temperature at the distance of 2 cm from the center of the plate. Taking p=8530 kg/m3, Cp=380 J/kg. • * .C, a= 33.9*10-6 m2/sarrow_forwardA cylindrical rod with a diameter of 20 mm and a length of 300 mm is heated to a temperature of 200°C. The rod is then placed in a tank of water maintained at a constant temperature of 25°C. The convection heat transfer coefficient for the water is 2000 W/m²K. Determine the time taken for the temperature of the rod to reach 50°C.arrow_forward
- 1. For heat transfer purposes, an egg can be considered to be a 4-cm diameter sphere having the properties of water. An egg that is initially at 8°C is dropped into boiling water at 100°C. The heat transfer coefficient at the surface of the egg is estimated to be 400 W/m2°C. If the egg is considered cooked when its center temperature reaches 60°C, determine how long the egg should be kept in the boiling water? Assume negligible internal resistance íarrow_forwardA 30-cm-diameter, 4-m-high cylindrical column of a house made of concrete (k = 0.79 W/m·K, a 5 5.94 * 1027 m2/s, r = 1600 kg/m3, and cp = 0.84 kJ/kg·K) cooled to 14°C during a cold night is heated again during the day by being exposed to ambient air at an average temperature of 28°C with an average heat transfer coefficient of 14 W/m2?K. Using analytical one-term approximation method (not the Heisler charts), determine (a) how long it will take for the column surface temperature to rise to 27°C, (b) the amount of heat transfer until the center temperature reaches to 28°C, and (c) the amount of heat transfer until the surface temperature reaches to 27°C.arrow_forwardIn a production facility, 3-cm-thick large brass plates(k = 110 W/m·K, r = 8530 kg/m3, cp = 380 J/kg·K, and a =33.9 * 1026 m2/s) that are initially at a uniform temperatureof 25°C are heated by passing them through an oven maintainedat 700°C. The plates remain in the oven for a period of10 min. Taking the convection heat transfer coefficient to beh 5 80 W/m2·K, determine the surface temperature of theplates when they come out of the oven. Solve this problemusing analytical one-term approximation method (not theHeisler charts). Can this problem be solved using lumpedsystem analysis? Justify your answer.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning