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A polished copper sphere of 10-mm diameter, initially at a prescribed elevated temperature
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Fundamentals of Heat and Mass Transfer
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- 5. For what situations will the lumped capacitance method be valid if a solid is in contact with a fluid? Circle all appropriate answers. (a) The resistance to conduction within the solid is small compared to the resistance to convection due to a fluid. (b) The temperature gradient within the solid is large. (c) The Biot number is small (less than 0.1). (d) All of the above. (e) None of the above.arrow_forwardOnce upon a time, a student from a certain university wants to learn crystallization using a Swenson-Walker crystallizer. The capacity of this crystallizer is 0.6124 Ib/s of FeSO4 slurry leaves at 300 K. The flow mechanism of the cooling is counter current through the jacket and its temperature increases from 61 to 70 F. The overall heat transfer coefficient has been estimated to be 190 Sl units. (). Determine the requirement for cooling water in kg/hr (i) Let supposed that each crystallizer unit is 3.5 yard long and each metre of crystallizer provides26.91 ft? surface, how many crystallizer units will be required?arrow_forward7. A long cylindrical nuclear fuel rod has the following steady-state temperature distribution: T(r) = 5001 so0(1-)- + T,, R2 where R is the fuel-rod radius and T, is the surface temperature. T(r) is expressed in kelvins. For a fuel rod with R = 25 mm, T, = 800 K, and thermal conductivity of 40 W/m K, determine both the heat flux at r = R and the heat-transfer rate per unit length of rod, (i.e., Q/L (=] W/m). Plot the temperature distribution. Ts 工arrow_forward
- Metal spheres, 10 mm in diameter, are to be annealed by heating them to 827°C then allowing them to cool slowly in air at 27°C to the point where they are in thermal equilibrium with the air. 2000 balls are annealed in one hour’s time. What is the total rate of their heat transfer if they are made of steel, lead, or copper? a.Sketch the problem. b.Draw lines identifying the control volume, or control mass. c.Identify the states with numbers, letters, or descriptions such as “in” and “out”. d.Write down the knowns and unknowns. e.Identify what is being asked for. f.State all assumptions.arrow_forward5 (a) (i) State two ways in which evaporation is different from boiling. (ii) Give one example of a change of state which does not invalve boiling orevaporation. (b) The graph in Fig. 5.1 shows the variation of temperature with time for a substance that is initially liquid. temperature Eime Fig. 5.1 O State what is taking place at points A, B and C. You should say what changes of state, if any, are taking place. point A point B point C (0 Suggest why the graph is steeper at point C than at point A.arrow_forwardAnswer correctly and quickly as possible please. Please help me with my last three questions, I do not have any ask an expert left. Please.arrow_forward
- AH of vaporization of water is 439.2 cal/g at the normal boing point. Since virus can survive at 404.39 K by forming spores. Most virus spores die at 851.9 K. Hence, autoclaves used to sterilize medical and laboratory instruments are pressurized to raise the boiling point of water to 851.9 K. Find out at what InP (torr) does water boil at 851.9 K? O a. 8460.435 O b. 940.048 c. 1880.097 O d. 2.474arrow_forwardWhat duty is required to cool 1 t of Melons in 12 h from 20°C to 4°C? (Use Table 21.1 dataarrow_forwardSubject mechanical. Caption: take time but solve handwriting accurate Solutions okarrow_forward
- 4. GoBrownsite is an obscure element with a molar mass of 126.2 grams per mol. Below is the cooling curve for GoBrownsite. How much energy needs to be removed from a 250.0 g sample of GoBrownsite knowing the following. Heat of Condensation AH = -165 kJ/°C • Specific heat of liquid GoBrownsite = 197 kJ/g-°C Heat of Freezing AH = - 231 kJ/°C Cooling Curve 80 e) to (1) 60 40 20 -20 Temperature 40 -60 -80 -100 (1) to (s) -120 Timearrow_forwardA new temperature scale is designed with freezing of water at 50 X and boiling at atmospheric pressure occurring at 300 X. Derive a conversion between degrees Celsius and degrees X and convert the following reading: (a) 80 C to Xarrow_forwardA long insulated tube is doped with an exothermic ma- terial which generates steady and uniform heat at rate of è [W/m³]. The tube has an inner radius r₁ and outer radius r₂. The temperature of the outer insulated sur- face is T₂. This tube is used to heat a liquid flowing through it. (a) Write the governing differential equation and boundary conditions to determine the tempera- ture distribution inside the tube. (b) What is the heat flux supplied to the liquid by the tube? e (√₂²-1₁²) / 21₁ 1 Fluid Figure 2: Schematic Insulation T₂ Narrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning