4. An electrical heater in the form of a horizontal disk of 400-mm diameter is used to heat the bottomof a tank filled with engine oil at a temperature of 5°C. Calculate the power required to maintainthe heater surface temperature at 70°C.tal uninsulated steam pipe passes throupipe of

Power required to maintain the heater surface temperature at 70°C is 468 W. Explanation is given…

Answered: 4. An electrical heater in the form of…

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter9: Heat Transfer With Phase Change

Section: Chapter Questions

Problem 9.23P

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In the final stages of production, a pharmaceuticalis sterilized by heating it from 30°C to 75°C as it moves at0.2 m/s through a straight thin-walled stainless steeltube of 12.7-mm diameter. A uniform heat flux is maintained by an electric resistance heater wrappedaround the outer surface of the tube. If the tube is 10 m long, what is the required heat flux? If fluidenters the tube with a fully developed velocity profile and a uniform temperature profile, what is thesurface temperature at the tube exit? Fluid properties may be approximated as ? = 1000 kg/m3, cp =4000 J/kg K, ? = 2 x 10-3 kg/s m, k = 0.8 W/m K, and Pr = 10.
Can someone please help me with creating an excel spreadsheet to calculate heat transfer phenomenon from a cylindrical fuel rod to the coolant? The excel sheet needs to be able to calculate these 3 things: Heat generated in a fuel rod at a distance ‘r’ from the center; Total Heat generated in the Reactor; the maximum temperature in the fuel and the cladding surface temperature, for a fuel rod at a distance ‘r’ from the center. The fuel used in this will be UO2 and there is a thin layer of helium that will separate the fuel from the cladding material. The user input parameters will be: the thermal neutron flux at the core, thermal conductivity of fuel, thermal conductivity of helium, thermal conductivity of the cladding, thickness of the helium layer, thickness of the cladding, diameter of the fuel pellet, fuel rod location (r), Cylindrical Reactor Size, and the fuel enrichment. For the fluid the user input will be coolant temperature and the heat transfer coefficient.
Task 3Superheated steam at 575ºC is routed from a boiler to the turbine of an electric power plant through steel tubes (k = 35 W/m K) of 300 mm inner diameter and 30 mm wall thickness. To reduce heat loss to the surroundings and to maintain a safe-to-touch outer surface temperature, a layer of calcium silicate insulation (k = 0.10 W/m K) is applied to the tubes, while degradation of the insulation is reduced by degradation of the insulation is reduced by wrapping it in a thin sheet of aluminium having an emissivity of ε= 0.20. The air and wall temperatures of the power plant are 27ºC. Assume that the inner surface temperature of a steel tube corresponds to that of the steam and the convection coefficient outside the aluminium sheet is 6 W/m2 K, (a) What is the minimum insulation thickness needed to ensure that the temperature of the aluminium does not exceed 50ºC? (b) What is the corresponding heat loss per unit meter?(c) What is the difference between lagged and unlagged pipes in…
You are asked to design a metal hot dog holder for roasting hot dogs over an opencampfire. The holder is to be designed such that while the end holding the hot dogbecomes cherry red (1400oF), the other end can still be held without using aninsulated handle or glove (~95oF). Design it such that it can be used even on awarm, still day, Tf = 90oF (Assume the convective heat transfer coefficient, h, fora horizontal cylinder is uniform over the whole cylinder and equal to 4.0Btu/hrft2oF)
Problem-1: Superheated steam at an average temperature 200°C is transported through a steel pipe (k = 50 W/m-K, D₁ = 8.0 cm, D₁ = 6.0 cm, and L=20.0 m). The pipe is insulated with a 4-cm thick layer of gypsum plaster (k = 0.5 W/m K). The insulated pipe is placed horizontally inside a warehouse where the average air temperature is 10°C. The steam and the air heat transfer coefficients are estimated to be 800 and 200 W/m2.K, respectively. Calculate (a) the daily rate of heat transfer from the superheated steam and (b) the temperature on the outside surface of the gypsum plaster insulation.
3. Compute for the Nusselt value of a natural convection in a small holding tank with a heating element at the bottom. The calculated Ra number is 2.37 x 10º.
1. A composite furnace wall is made up of a 12-in. lining of magnesite refractory brick, a 5-in.thickness of 85% magnesia, and a steel casing 0.10-in. thick. Flue gas temperature is 2200 F andthe boiler room is at 80 F. Gas side film coefficient is 15 Btu/hr-sq.ft-F and air side is 4.0.Determine:a. The thermal current Q/Ab. Interface temperaturesc. Effect on thermal current and inside refractory wall temperature if the magnesia insulation weredoubled.
Design a hydrocooling unit that can cool fruits andvegetables from 30 to 5°C at a rate of 20,000 kg/h under thefollowing conditions:The unit will be of flood type, which will cool the productsas they are conveyed into the channel filled with water. Theproducts will be dropped into the channel filled with water atone end and be picked up at the other end. The channel canbe as wide as 3 m and as high as 90 cm. The water is to becirculated and cooled by the evaporator section of a refrigerationsystem. The refrigerant temperature inside the coils is tobe 22°C, and the water temperature is not to drop below 1°Cand not to exceed 6°C.Assuming reasonable values for the average product density,specific heat, and porosity (the fraction of air volume ina box), recommend reasonable values for (a) the water velocitythrough the channel and (b) the refrigeration capacity ofthe refrigeration system.
2.7 A very thin silicon chip is bonded to a 6-mm thick aluminum substrate by a 0.02-mm thick epoxy glue. Both surfaces of this chip-aluminum system are cooled by air at , where the convective heat transfer coefficient of air flow is . If the heat dissipation per unit area from the chip is under steady-state conditions, draw the thermal circuit for the system and determine the operating temperature of the chip.
3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
A fuel rod of a PWR consists of about 320 solid fuel pellets inside a zircaloy cladding. Use the specified data to plot the distribution of temperature in the fuel rod. The temperature distribution should include the fuel region, the gap region, the cladding region, and end at the bulk coolant for two cases of low and high lin- ear heat generation rates. Data: Druel = 0.96 cm, Dinside Clad = 0.985 cm, Doutside Clad = 1.12 cm, kfuel = 1.73 W/m C, kclad = 5.2 W/m C, Twater = 300 C, Low = 5 kW/ft (164 W/cm), and d'High = 15 kW/ft (492 W/cm). The heat transfer coefficient from the fuel rod to bulk coolant is 34 kW/m².C. The heat transfer coefficient in the gap region is 5.7 kW/m2.C for the low and is 11.4 kW/m.C for the high linear heat generation rate.
A fuel rod of a PWR consists of about 320 solid fuel pellets inside a zircaloy cladding. Use the specified data to plot the distribution of temperature in the fuel rod. The temperature distribution should include the fuel region, the gap region, the cladding region, and end at the bulk coolant for two cases of low and high lin- ear heat generation rates. Data: Druel = 0.96 cm, Dinside Clad = 0.985 cm, Doutside Clad = 1.12 cm, kfnel = 1.73 W/m C, kclad = 5.2 W/m C, Twater = 300 C, 41ow = 5 kW/ft (164 W/cm), and d'High = 15 kW/ft (492 W/cm). The heat transfer coefficient %3D from the fuel rod to bulk coolant is 34 kW/m.C. The heat transfer coefficient in the gap region is 5.7 kW/m.C for the low and is 11.4 kW/mC for the high linear heat generation rate.

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