It has been suggested that heat transfer from a surface can be augmented by wetting it with water. As a specific example, consider a horizontal tube that is exposed to a transverse stream of dry air. You may assume that the tube, which is maintained at a temperature
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Fundamentals of Heat and Mass 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_forwardWater flows in a 3.5-cm-diameter pipe so that the Reynolds number based on diameter is 2000 (laminar flow is assumed). The average bulk temperature is 10°C. What would the heat transfer coefficient be in W/m2.°C for such a system if the tube wall was subjected to a constant heat flux and the velocity and temperature profiles were completely developed? Evaluate properties at bulk temperature.arrow_forwardProblem: Convection related Water enters a tube at 27°C with a flow rate of 450 kg/h. The rate of heat transfer from the tube wall to the fluid is given as qs′(W/m)=ax, where the coefficient a is 20 W/m^2 and x(m) is the axial distance from the tube entrance. (a) Beginning with a properly defined differential control volume in the tube, derive an expression for the temperature distribution Tm(x) of the water. (b) What is the outlet temperature of the water for a heated section 30 m long? (c) Sketch the mean fluid temperature, Tm(x), and the tube wall temperature, Ts(x), as a function of distance along the tube for fully developed and developing flow conditions.arrow_forward
- t = 30 + 0.9563 (62.2- 30) = 60.79°C (Ans.) Example 4.14. A very thin glass walled 3 mm diameter mercury thermometer is placed in a stream of air, where heat transfer coefficient is 55 W/m2°C, for measuring the unsteady temperature of air. Consider cylindrical thermometer bulb to consist of mercury only for which k and a = 0.0166 m2/h. Calculate the time required for the temperature change to reach half its final or, %3D 8.8 W/m C %3D value.arrow_forwardFor a water flow over a steel surface, the temperature of water at a specific location was found to change with the vertical distance from the surface (y) up to a distance of 0.015 m as T(y) = 60 + 20y + tan(y), where temperature is in °C and y is in cm. The surface temperature and ambient temperature was measured as 60°C and 105°C, respectively. The thermal conductivity of steel and water are, respectively, 48 W/m-K and 0.6 W/m-K. What is the local convection coefficient at this location?arrow_forwardHeat Transferarrow_forward
- 350 pipes are fixed as square in a pipe bundle used for condenser. PipeThe outer diameters are 8 mm and the steam at 0.2 bar is desired to be condensed on the pipes. pipe outer The surface temperature is kept constant at 30 °C. If the length of the pipes is 1.5 m, the heat transferred in the systemCalculate the amount of energy and the amount of condensed steamarrow_forwardFluid is flowing through a 20 mm inside diameter and 25 mm outside diameter brass tube at no leaking with temperature at 65℃ and length of 10 m. Surface conduction of hot fluid is 5.2W/(m^2℃) and thermal conductivity of brass is 12.84W/(m℃). Brass tube is covered by silica of 6 mm thickness with thermal conductivity of 13.84W/(m℃) . Outside of it, is a fluid with 45℃ with surface conductance of 3.2W/(m^2℃). Find the heat transfer from the hot fluid with temperature of 65℃ to fluid with temperature of 45℃.arrow_forwardA liquid is heated from 20 to 70 oC as it flows at 0.025 kg/s through a steel tube of 10 mm and 12m long. A uniform heat flux is maintained on the tube surface. Using the following liquid properties ρ = 1000 kg/m3, Cp = 4100 J/kg.K, k = 0.45 W/m.K, Pr = 10, μ = 2x10-3 kg/s.m. Calculate the average heat flux on the tube. Calculate the heat transfer coefficient at end of tube Calculate the surface temperature at exit and the heat transfer coefficient for first 1m of pipe?arrow_forward
- show complete and detailed solution.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_forwardAn incompressible fluid flows through a rectangular cross section duct, with width much larger than height of the cross section. The duct surface is heated at a uniform rate along its length. If the centreline of the flow is along the centre of the duct where y = 0, the distance from the centreline to the surface of the duct is b = 25 mm, and the thermal conductivity of the fluid is 0.6 W/mK, what is the local heat transfer coefficient in the developed region of the flow? Give your answer in W/m2K to 1 decimal place. I AM POSTIING THIS AGAIN. PLEASE STOP ? COPY FROM INTERNET AND SEND RANDOM SOLUTION. HINT THE FINAL ANSWER IS 38.4 But i need step by step solution. if you don't get this value don't send it please, reject and add the creditarrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning