Water is to be heated from 20°C to 64°C by flowing through a 5 cm diameter circular pipe as shown in the figure (not scaled) with a mass flow rate of 0.01 kg/s. i- Determine the pipe length if the pipe is heated with a constant surface heat flux of 300 W/m? Calculate the surface temperature of the pipe at the outlet (x=L) and at the half length (x=L/2). hint: assume fully developed flow, then check your assumption If the pipe surface has a constant surface temperature 90°C (instead of a constant surface heat flux constant surface heat flux (i&ii) or temperature ii- (iii) water D= 5cm i11- 20°C 0.01kg/s 64°C boundary condition), determine the pipe length

Water is to be heated from 20°C to 64°C by flowing through a 5 cm diameter circular pipe as shown in the figure (not scaled) with a mass flow rate of 0.01 kg/s. i- Determine the pipe length if the pipe is heated with a constant surface heat flux of 300 W/m? Calculate the surface temperature of the pipe at the outlet (x=L) and at the half length (x=L/2). hint: assume fully developed flow, then check your assumption If the pipe surface has a constant surface temperature 90°C (instead of a constant surface heat flux constant surface heat flux (i&ii) or temperature ii- (iii) water D= 5cm i11- 20°C 0.01kg/s 64°C boundary condition), determine the pipe length

Principles of Heat Transfer (Activate Learning with these NEW titles from Engineering!)

8th Edition

ISBN:9781305387102

Author:Kreith, Frank; Manglik, Raj M.

Publisher:Kreith, Frank; Manglik, Raj M.

Chapter7: Forced Convection Inside Tubes And Ducts

Section: Chapter Questions

Problem 7.4P

See similar textbooks

Similar questions

Consider an air solar collector that is 1 m wide and 5 m longand has a constant spacing of 3 cm between the glass cover andthe collector plate. Air enters the collector at 30°C at a rate of0.15 m3/s through the 1-m-wide edge and flows along the 5-mlong passage way. If the average temperatures of the glasscover and the collector plate are 20°C and 60°C, respectively,determine (a) the net rate of heat transfer to the air in thecollector and (b) the temperature rise of air as it flows throughthe collector.
Combustion gases passing through a 5-cm-internal-diameter circular tube are used to vaporize waste water at atmospheric pressure. Hot gases enter the tube at 225 kPa and 250oC at a mean velocity of 2.5 m/s, and leave at 150o If the average heat transfer coefficient is 150 W/m2K and the inner surface temperature of the tube is 110oC, determine (a) the tube length and (b) the rate of evaporation of water.
Water is to be heated from 15°C to 65°C as it flows through a 3-cm-internaldiameter 5-m-long tube . The tube is equipped with an electric resistance heater that provides uniform heating throughout the surface of the tube. The outer surface of the heater is well insulated, so that in steady operation all the heat generated in the heater is transferred to the water in the tube. If the system is to provide hot water at a rate of 10 L/min, determine the power rating of the resistance heater. Also, estimate the inner surface temperature of the tube at the exit.
The blades of a wind turbine turn a large shaft at a relatively slow speed. The rotational speed is increased by a gearbox that has an efficiency of 0.93. In turn, the gearbox output shaft drives an electric generator with an efficiency of 0.95. The cylindrical nacelle, which houses the gearbox, generator, and associated equipment, is of length L = 6 m and diameter D = 3 m. If the turbine produces P = 2.5 MW of electrical power, and the air and surroundings temperatures are T = 25 oC and Tsur = 20 oC, respectively, determine the minimum possible operating temperature inside the nacelle. The emissivity of the nacelle is 0.83, and the convective heat transfer coefficient is h = 35 W/m2 .K. The surface of the nacelle that is adjacent to the blade hub can be considered to be adiabatic, and solar irradiation may be neglected. Use Fin or N number of fins to reduce the Ts of the nacelle less than 143 oC
Water enters a 5-mm-diameter and 13-m-long tube at 15ºC with a velocity of 0.3 m/s, and leaves at 45ºC. The tube is subjected to a uniform heat flux of 2000 W/m2 on its surface. The temperature of the tube surface at the exit is(a) 48.7ºC (b) 49.4ºC (c) 51.1ºC (d) 53.7ºC (e) 55.2ºC(For water, use k = 0.615 W/m⋅°C, Pr = 5.42, ν =0.801×10-6 m2/s)
Air enters a 20-cm-diameter 12-m-long underwater duct at 50°C and 1 atm at a mean velocity of 7 m/s, and is cooled by the water outside. If the average heat transfer coefficient is 85 W/m2 °C and the tube temperature is nearly equal to the water temperature of 5°C, determine the exit temperature of air and the rate of heat transfer
The chilling room of a meat plant is 15 m × 18 m × 5.5 m in size and has a capacity of 350 beef carcasses. The power consumed by the fans and the lights in the chilling room are 22 and 2 kW, respectively, and the room gains heat through its envelope at a rate of 14 kW. The average mass of beef carcasses is 220 kg. The carcasses enter the chilling room at 35C, after they are washed to facilitate evaporative cooling, and are cooled to 16°C in 12 h. The air enters the chilling room at 2.2°C and leaves at 0.5°C. Determine (a) the refrigeration load of the chilling room and (b) the volume flow rate of air. The average specific heats of beef carcasses and air are 3.14 and 1.0 kJ/kg · °C, respectively, and the density of air can be taken to be 1.28 kg/m3 .
The net radiant-heat exchange between a 20-by-20 ft rough plaster panel-heated ceiling and a 20-by-10-ft side wall, which has an emissivity of 0.80, is 2400 Btu/hr. If the surface temperature of the ceiling is 120 deg. F, determine the average surface temperature of the side wall.
The velocity profile in fully developed laminar flow in a circular pipe, in m/s, is given by u(r) = 6(1 - 100r2), where r is the radial distance from the centerline of the pipe in m. Determine (a) the radius of the pipe, (b) the average velocity through the pipe, and (c) the maximum velocity in the pipe.
Consider turbulent forced convection in a circular tube. Will the heat flux be higher near the inlet of the tube or near the exit? Why?
Air at 10oC enters a 10-cm-diameter and 4-m-long pipe at a rate of 0.035 kg/s. The inner surface of the pipe has a roughness of 0.22 mm, and the pipe is nearly isothermal at 60o Determine the rate of heat transfer to air using the Nusselt number relation given by (a) Eq. 8–66 and (b) Eq. 8–71. Evaluate air properties at a bulk mean temperature of 20oC. Is this a good assumption?
An 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/s