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The performance of gas turbine engines may beimproved by increasing the tolerance of the turbineblades to hot gases emerging from the combustor. Oneapproach to achieving high operating temperaturesinvolves application of a thermal barrier coating (TBC) to the exterior surface of a blade, while passingcooling air through the blade. Typically, the blade ismade from a high-temperature superalloy, such asInconel
Consider conditions for which hot gases at
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Chapter 3 Solutions
Introduction to Heat Transfer
- 7.43 Liquid sodium is to be heated from 500 K to 600 K by passing it at a flow rate of 5.0 kg/s through a 5-cmID tube whose surface is maintained at 620 K. What length of tube is required?arrow_forwardDetermine the rate of heat transfer per meter length to a light oil flowing through a 2.5-cm-ID, 60-cm-long copper tube at a velocity of 0.03 m/s. The oil enters the tube at 16C, and the tube is heated by steam condensing on its outer surface at atmospheric pressure with a heat transfer coefficient of 11.3 kW/m K. The properties of the oil at various temperatures are listed in the following table: Temperature, T(C) 15 30 40 65 100 (kg/m3) 912 912 896 880 864 c(kJ/kgK) 1.80 1.84 1.925 2.0 2.135 k(W/mK) 0.133 0.133 0.131 0.129 0.128 (kg/ms) 0.089 0.0414 0.023 0.00786 0.0033 Pr 1204 573 338 122 55arrow_forwardSteel balls (diameter = 21 mm, p = 7833 kg/m , k = 54 W/m•°C, Cp = 0.465 kJ/kg.°C, and a = 1.474x10 m /s) are annealed by heating them first to 870°C in a furnace and then allowing them to cool slowly to 85°C in ambient air at 27°C. What is the total rate of heat %3D transfer from the balls to the ambient air, when 2367 balls are to be annealed per hour (kW)? Select one: A. 11.15 B. 9.12 C. 9.85 D. 8.38 E. 10.50arrow_forward
- 1. Water (C, = 4180 J/kg-K) enters a 4-cm-diameter tube at 15°C at a rate of 0.06 kg/s. The tube is subjected to a uniform heat flux of 2500 W/m: on the surfaces. Compute for the length of the tube required in order to heat the water to 45°C.arrow_forwardConduction 1. A thermodynamic analysis of a proposed Brayton cycle gas turbine yields P= 5 MW of net power production. The compressor, at an average temperature of T. = 400°C, is driven by the turbine at an average temperature of T₁ = 1000°C by way of an L = 1m-long, d= 70mm - diameter shaft of thermal conductivity k = 40 W/m K. Compressor min T Combustion chamber Shaft L Turbine Th out (a) Compare the steady-state conduction rate through the shaft connecting the hot turbine to the warm compressor to the net power predicted by the thermodynamics- based analysis. (b) A research team proposes to scale down the gas turbine of part (a), keeping all dimensions in the same proportions. The team assumes that the same hot and cold temperatures exist as in part (a) and that the net power output of the gas turbine is proportional to the overall volume of the device. Plot the ratio of the conduction through the shaft to the net power output of the turbine over the range 0.005 m s Ls 1 m. Is a…arrow_forwardplease show full and detailed solution.arrow_forward
- It has been suggested that a heat engine could be developedthat made use of the temperature difference between waterat the surface of the ocean and water several hundredmeters deep. In the tropics, the temperatures may be 27°Cand 4°C, respectively. (a) What is the maximum efficiencysuch an engine could have? (b) Why might such an enginebe feasible in spite of the low efficiency? (c) Can you imagineany adverse environmental effects that might occur?arrow_forwardQuestion #7 Steam at 320°C flows in a stainless steel pipe (k-15W/m K) whose inner and outer diameter are 5cm and 5.5cm respectively. The pipe is covered with 3cm thick glass wool insulation (-0.038W/mK). Heat is lost to the surroundings at 5°C by natural convection and radiation, with a combined natural convection and radiation heat transfer coefficient of h 15W/m² K. Taking the heat transfer coefficient inside the pipe to be happe = outside pipe = 80 W/m²K. (A) Draw the schematic diagram of this problem and label all quantities. (B) Draw the thermal network diagram of this problem and label all thermal resistors and the direction of heat flow. (C) Determine the (i) inner surface area (ii) outer surface area (iii) inner thermal resis- tance (iv) outer thermal resistance (v) thermal resistance across pipe and (vi) thermal resistance across insulation. (D) Determine the total thermal resistance for the unit length of pipe. (E) Determine the rate of heat loss from the steam per unit…arrow_forwardi need the answer quicklyarrow_forward
- Fast..arrow_forwardAn electric motor is to be connected by a horizontal steel shaft (k 42.56 W/m.K), 25 mm in diameter to an impeller of a pump, circulating liquid metal at a temperature of 540°C. If the temperature of electric motor is limited to a maximum value of 52°C with the ambient air at 27°C and heat transfer coefficient of 40.7 W/m2.K, what length of shaft should be specified between the motor and pump? Steel shaftarrow_forward2-D: A fin may be manufactured as an integral part of a surface by using a casting or extrusion process, or it may be separately brazed or adhered to the surface. From thermal considerations, which option is preferred? 2-E: What is the difference between steady-state and transient heat transfer processes? Give an example for each of them. 2-F: What is the physical interpretation of the Biot number? 2-G: For flow over a flat plate, sketch variation of local convective heat transfer coefficient, h(x), versus the distance along the plate x for laminar, transition, and turbulent flow regimes.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning
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