Experimental results for heat transfer over a flat plate with an extremely rough surface were found to be correlated by an expression of the form
where
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Fundamentals of Heat and Mass Transfer
- Determine 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_forwardCalculate the heat losses per unit length in a horizontal tube with an outside diameter of 15 cm, if its surface is kept at 400 K AND the surrounding air has a temperature of 300 K and a pressure of 1 bar.The properties of air at a pressure of 1 bar and a film temperature of 350 K are: In this case, v = 20.76 x 10-6 m2/s , α = 0.2983 x 10-4 m2/s, k = 0.03003 W/mK, Pr = 0.697, β = 2.86 x 10-3 K-1arrow_forwardA long 8-cm diameter vertical steam pipe whose external surface temperature is 90 degrees C passes through some open area that is not protected against the wind blows. Determine the rate of heat loss from the pipe per unit length when the air is at 1 atm, 7 degrees Celsius and the wind is blowing across the pipe at a velocity of 50 km/h. From Table A-1:Thermal conductivity, k = 0.0275 W/m degrees Celsius ,viscosity, v = 1.77 x 10^-5 m^2/sPrandtl no. Pr = 0.71arrow_forward
- Hot engine oil at 150°C is flowing in parallel over a flat plate at a velocity of 3.30 m/s. Surface temperature of the 1.800-m long flat plate is constant at 50°C. The properties of engine oil at Tf = (150°C + 50°C)/2 = 100°C are k = 0.1367 W/m∙K, v = 2.046 × 10−5 m2/s, Pr = 279.1. Determine the local convection heat transfer coefficient at 0.200 m from the leading edge and the average convection heat transfer coefficient. The local convection heat transfer coefficient at 0.200 m from the leading edge is ___ W/m2·K. The average convection heat transfer coefficient is ___ W/m2·K.arrow_forwardA long 8-cm diameter vertical steam pipe whose external surface temperature is 90oC passes through some open area that is not protected against the wind blows. Determine the rate of heat loss from the pipe per unit length when the air is at 1 atm, 7oC and the wind is blowing across the pipe at a velocity of 50 km/h. From Table A-1: Thermal conductivity, k = 0.0275 W/m oC , viscosity, v = 1.77 x 10-5 m2/s Prandtl no. Pr = 0.71arrow_forwardAn average man has abody surface area of 1.8m2 and a skin temperature of 33degrees celcius .The convection heat transfer coefficient for a clothed person walking in still air is expressed as {h,8.6V^0.53}FOR 0.5<v<2m/s,where V is the walking velocityin m/s.Assuming the average surface temperature of the clothed person to be 30degrees celcius, determine the rate of heat loss from an average man walking in still air at 10degrees celcius by convectionat a walking velocity of (a)0.5m/s (b)1.0m/s (c)1.5m/s (d)2.0m/sarrow_forward
- During a cold winter day, wind at 55 km/h is blowing parallel to a 4m high and 10m long wall of a house. If the air outside is at 5 degrees Celsius and the surface temperature of the wall is 12 degrees Celsius , determine the rate of heat loss from the wall by convection. What would your answer be if the wind velocity has doubled? From Table A-1:thermal conductivity, k = 0.0246 W/m degrees Celsiusviscosity, v = 1.4 x 10^-5 m^2/sPrandtl no. Pr = 0.717arrow_forwardHot water, k=48 W/m. It flows at a speed of 1.4 m/s along the cast iron pipe at oC. The inner and outer diameters of the pipe are 3.0 and 3.5 cm, respectively. The pipe is located within 15 m of a basement with a temperature of 15 °C. If the temperature of the water drops from 70 oC to 67 oC while passing through the basement and the film heat transfer coefficient on the inner surface of the pipe is 400 W/m2. Calculate the convective heat transfer coefficient on the outer surface of the pipe and the heat to be transferred.arrow_forward
- Principles of Heat Transfer (Activate Learning wi...Mechanical EngineeringISBN:9781305387102Author:Kreith, Frank; Manglik, Raj M.Publisher:Cengage Learning