Experiments have been conducted to determine local heat transfer coefficients for flow perpendicular to a long, isothermal bar of rectangular cross section. The bar is of width c parallel to the flow, and height d normal to the flow. For Reynolds numbers in the range
The values of C and m for the front face, side faces, and back face of the rectangular rod are found to be the following:
Determine the value of the average heat transfer coefficient for the entire exposed surface (that is, averaged over all four faces) of a
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Fundamentals of Heat and Mass Transfer
- What is the value of the heat transfer coefficient for air at 37 ° C flowing at 5 m / s perpendicular to a 10 cm x 10 cm square pipe at 93 ° C? h = 23kcal / hm ^ 2 ° C around this valuearrow_forwardWe would like to develop an empirical correlation to determine the heat trans- fer coefficient, h, for turbulent flow in a circular conduit. Please use the order provided for the lists of physical variables and fundamental units in working this problem. The following physical variables are to be included: h, average fluid velocity v, density ρ, viscosity μ, thermal conductivity k, specific heat capacity c, diameter D, and length L. (a) Express each physical variable in terms of fundamental units mass (m), length (l), time (t), and temperature (θ).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_forward
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- (heat transfer ) thanks The velocity of the fluid flowing in parallel over a 500mmx500mm flat heater surface is U= 19 m/s and the inlet velocity temperature is T_∞15 C. The surface temperature of this plate is T_s140 C, the friction force is F_D=0.4 N and the surface area of the plate is A=0.32 m2. According to this;(F_D= 0.4N A=32 m2)a) Surface shear stressb) Find the coefficient of frictionc) Heat transfer coefficientd) What is the amount of heat transfer (electric power) that must be given to maintain a constant surface temperature?arrow_forwardA 6 kg/s of hot liquid flow continuously without leaking in a 40 mm inside diameter with thickness of 7 mm pipe with temperature of 50℃. Thermal conductivity of pipe is 10W/(m℃) and surface conductance of liquid is 9W/(m^2℃). The outer fluid has temperature of 25℃ and surface conductance of 6W/(m^2℃). Cp of hot liquid = 4.2KJ/(Kg℃). Find the minimum length of pipe in meters just to cool down the hot liquid as much as possible if the maximum heat transfer is the constant heat transfer throughout the pipe.arrow_forward8. A lead pipe has 2 cm inside diameter, 3 cm outer diameter, length of 130 cm. Liquid water at 4°C flows through the pipe with a bulk velocity of 0.03 km/hr. Air is blown around the outside of the pipe at 20 deg C. The inside wall of the said pipe has a temperature of 8 deg Celsius. Density of liquid water= 1000 kg/m³ Cp water=4.210 J/kgK Viscosity of liquid water= 1.5674 x10° Pa.s thermal conductivity of lead = 35 W/mK thermal conductivity of water = 0.575 W/mK Find: Overall heat coefficient (U) based on outside surface area b. System's heat transfer rate Prandtl (Pr), Reynolds (Re) numbers and type of flow а. с.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning