The strength and stability of tires may be enhanced by heating both sides of the rubber
(a) If steam flow over the tire surfaces maintains a convection coefficient of
(b) To accelerate the heating process, it is recommended that the steam flow be made sufficiently vigorous to maintain the tire surfaces at 200°C throughout the process. Compute and plot the midplane and surface temperatures for this case, as well as for the conditions of part (a).
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Introduction to Heat Transfer
- Ethylene glycol at 40°C flows over a heated plate very wide, 6 m long, at velocity of 0.04 m/s. For a temperature = 90°C, determine: 1- the thickness of the hydrodynamic boundary layer at the end of the plate2- the thickness of the thermal boundary layer at the end of the plate3- the local and average heat transfer coefficient at the end of the plate4- the total heat flux transferred from the heated surface.arrow_forwardair at a dry ball temperature of 95 degrees Celsius and RH 5% is passed over the cooling coil so that the temperature of the air dry ball becomes 50 degrees Celsius. how much heat is released from the air in the process? = (kj / kg)arrow_forward....A journal bearing is to be used for a centrifugal pump where the shaft diameter is 50 mm and the bearing length is 80 mm. The ambient and bearing surface temperatures are 20°C and 45°C, respectively. Which of the following is the heat dissipated by the bearing if the heat dissipation coefficient is 280 W/m2-°C? Group of answer choices 56 W 14 W 73 W 28 Warrow_forward
- Steam is used to heat a cylindrical open tank of water until it boils, after which a proportion of the water in the tank is vaporised. The tank has an internal diameter of 1 m and is initially filled with water to a depth of 2 m. At the start of the process, this water is at 19°C and has a density of 998 kg/m3 . It may be assumed that ambient atmospheric pressure is 1 bar and that any effects arising from hydrostatic head can be ignored, as can heat losses from the tank to the surrounding environment. The heating medium is saturated steam at 5 bar, which enters a heating coil at the base of the tank at 5 kg/min, loses heat to the water in the tank and condenses to form saturated liquid condensate at this pressure. Using the steam table supplied: a) Find the temperature (°C) and power rating (kW) of the heater coil. b) Find the boiling point of the water in the tank under these conditions, and the time required to bring the water to this temperature. c) Find the proportion of water…arrow_forwardA liquid metal flows at a mass rate of 3 kg/s through a constant heat flux 5-cm-i.d tube in a nuclear reactor. The fluid at 473 K is to be heated with the tube wall 30 K above the fluid temperature. Determine the length of the tube required for a 1-K rise in bulk fluid temperature, using the following properties: p = 7.7 x 10^3 kg/m^3v = 8.0 x 10^-8 m^2/sCp = 130 J/(kg K)k = 12 W/mKPr = 0.011 Kaufman's correlation: Nu = 0,625.(Re.Pr)0,4arrow_forwardCalculate the heat losses per unit length in a horizontal tube with an outside diameter of 15 cm, if its surface is kept at 400 K AND the surrounding air has a temperature of 300 K and a pressure of 1 bar.The properties of air at a pressure of 1 bar and a film temperature of 350 K are: In this case, v = 20.76 x 10-6 m2/s , α = 0.2983 x 10-4 m2/s, k = 0.03003 W/mK, Pr = 0.697, β = 2.86 x 10-3 K-1arrow_forward
- 9. The gas density is 0.75 kg per cubic meters and air density is of 1.15 kg per cubic meter. If thedriving pressure is 0.25 KPA. Determine the height of the chimney. 10. A powerplant situated at an altitude having an ambient air of 96.53 KPa and 23.88 degreeCelsius. Flue gases at a rate of 5.0 kg per second enter the stack at 200 degree Celsius andleaves at 160 degree Celsius. The flue gases gravimetric analysis are 18% CO2, 7% O2 and 75%N2. Calculate the height of the stack necessary for a driving pressure of 0.20 KPaKindly answer all please. Thank youarrow_forwardDetermine the temperature of 0.25kg/s of air after passing through an electrical resistor whose power is 20kW. The initial temperature of the air is 20 degrees Celsius.arrow_forwardIn the summer, when the air motion is increased body heat loss is also increased. True or false ?arrow_forward
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- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning