Concept explainers
An experimental procedure for validating results of Problem 6.14 involves preheating a copper disk to an initial elevated temperature
Consider experimental conditions for which a disk of diameter
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Fundamentals of Heat and Mass Transfer
- What duty is required to cool 1 t of Melons in 12 h from 20°C to 4°C? (Use Table 21.1 dataarrow_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 ( ks = 40 W/m-K) has an inside diameter of Di, 1 = 150 mm and wall thickness t; = 20 mm while the outer steel pipe has an inside diameter of D2 = 250 mm and wall thickness, = 1,. Determine the maximum allowable crude oil temperature to ensure the polyurethane foam insulation (k, = 0.0425 W/m.K) between the two pipes does not exceed its maximum service temperature of Tp, max = 70°C. The ocean water is at Too, o ho T = -5°C and provides an external convection heat transfer coefficient of h = 500 W/m²K. The convection coefficient associated with the flowing crude oil is h₁ = 450 W/m²K. (2) It is proposed to enhance the performance of…arrow_forwardState the objective of the experiment and explain briefly what was done to achieve this objectivearrow_forward
- Note:- • Do not provide handwritten solution. Maintain accuracy and quality in your answer. Take care of plagiarism. • Answer completely. • You will get up vote for sure.arrow_forwardA chromel–constantan thermocouple measuring the temperature of a fluid is connected by mistake with copper–constantan extension leads (such that the two constantan wires are connected together and the copper extension lead wire is connected to the chromel thermocouple wire). If the fluid temperature was actually 250 C and the junction between the thermocouple and extension leads was at 90 C, what e.m.f. would be measured at the open ends of the extension leads if the reference junction is maintained at 0 C? What fluid temperature would be deduced from this (assuming that the connection error was not known)?arrow_forwardFor Heat transfer through cylinder tube wall, the temperature is to be a linear function of r (radius) of the tube. Select one: O True O False The conductivity of H20 in solid form (ice) is higher than that of H20 in liquid form (water). Select one: O True O False F, (Correction factor for temperature in some heat exchangers) should be 1.0 or greater than 1.0 in some cases. Select one: O True Falsearrow_forward
- nnoD :s D betae u 3. Temperature Rise in a Heating Wire. A current of 250 A is passing through stainless-steel wire having a diameter of 5.08 mm. The wire is 2.44 m long and has a resistance of 0.0843 N . The outer surface is held constant at 427.6 K. The thermal conductivity is k 22.5 W/m K. Calculate the center-line temperature at steady state. evard bae 0S 008 i 4R FO Insarrow_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_forwardA plane wall of thickness 20 mm is exposed to surrounding air at 30 °C. A heat source of 500 W/m³ is applied to the wall uniformly. A thermocouple is installed at the center of the wall thickness which denotes the origin x = 0. At steady state, it is desirable that the thermocouple reading is 48 °C. Considering four different materials as given in Table 1, choose any two of the materials for your analysis. Analyze the effects of choosing these materials on the convective coefficient and explain why. Table 1 Material No Thermal conductivity (W/mK) 1 0.027 2 0.036 3 0.058 4 0.087arrow_forward
- I- A mesurement system is to be used to mesure a presure of 250 Hz. For accurate readings, the time constant of the system sholud be (e) 0.01, (f) 1E-4, (g) 0.025. II- The bi-metallic thermometer is used to measure temperatures of --- variation. (a) very high, (b) very low, (c) above 1 Hz, (d) above 10 Hz, (e) above 100 Hz, (f) none of these. III- The static Pitot tube is suitable for measuring dynamic, (b) variable, (c) controlled, (d) directly constant, (e) dynamic, (f) constant. IV- The Borden-type gauge is a good choice to measure dynamic, (b) variable, (c) controlled, (d) directly constant, (e) dynamic, (f) static --------- sec. (a) 250, (b) 2.5, (c) 25, (d) 0.25, ---frequency fluid velocities. (a) directly pressures. (a) directly -------arrow_forwardDefine and briefly elaborate the terms listed below, support your elaboration with mathematical equations and illustrations where necessay 4. Prandtl, Schmidt, Lewis, Nusselt, and Sherwood number 5. Mole fraction of species and mass fraction of species. 6. Critical radius of insulation related to heat transfer in pipes.arrow_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