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3. Consider a cylinder of 20 mm in diameter (D) and 100 mm in length (L)...
A long horizontal cylinder with diameter of d-60 mm and length of L-1 m is at 27°C and is placed ...
A long horizontal cylinder with diameter of d-60 mm and length of L-1 m is at 27°C and is placed in a quiescent environment at 4°C. Find the cooling rate (q). End effects (heat transfer from the two ends of the cylinder) are negligible. The following relation (Churchill and Chu) for Nusselt number can be used. Air (T-288.5K): v=14.87x10° m2/s, k=0.0254 w/m-K, α=21.0x10-6 m2/s, Pr-0.71, B-3.47x1031/K. 1. Quiescent air 7,-4°C 0.06 m diameter T 27 C L=1m MUD 10.60 +...
7.34 Consider the following fluids, each with a velocity of V- 3 m/s and a temperature of T 20°C,...
7.34 Consider the following fluids, each with a velocity of V- 3 m/s and a temperature of T 20°C, in cross flow over a 10-mm-diameter cylinder maintained at 50°C: atmospheric air, saturated water, and engine oil. (a) Calculate the rate of heat transfer per unit length, q, using the Churchill-Bernstein correlation. (b) Generate a plot ofq as a function of fluid velocity for o.5 s Vs 10 m/s.
7.34 Consider the following fluids, each with a velocity of V- 3...
A cylinder with diameter D=6mm has a volumetric heat generation of 176.8×105 W/m3. The surface is...
A cylinder with diameter D=6mm has a volumetric heat generation of 176.8×105 W/m3. The surface is exposed to air convection with a velocity of V∞ =11.11m/s and temperature at T∞=10 °C. You can initially evaluate air thermal properties at T∞ using Table A.4 or any other available data. (a)Determine the surface temperature Ts of the cylinder (12 points). (b)Is it reasonable to use T∞ rather than the film temperature to evaluate the air properties in this case (3 points)?
Problem 7.036 A long, cylindrical, electrical heating element of diameter D = 10 mm, termal conductivity...
Problem 7.036 A long, cylindrical, electrical heating element of diameter D = 10 mm, termal conductivity k = 240 w/m·K, density ρ = 2700 kg/m3, and specific heat cp-900 נ/kg-K is installed in a duct for which air moves in cross flow over the heater at a temperature and velocity of 27°C and 20 m/s, respectively (a) Neglecting radiation, estimate the steady-state surface temperature when, per unit length of the heater, electrical energy is being dissipated at a rate of...
A can of engine oil with a length of 155 mm and a diameter of 100...
A can of engine oil with a length of 155 mm and a diameter of 100 mm is placed vertically in the trunk of a car. In a hot summer day, the temperature in the trunk is 43°C. If the surface temperature of the can is 17°C, determine heat transfer rate from the can surface. Neglect the heat transfer from the ends of the can and radiation heat transfer. Given: The properties of air at film temperature of 30°C. k...
A circular pipe, with an outside diameter of 30 mm and a wall thickness of 4 mm, is held stationary in a stream of air...
A circular pipe, with an outside diameter of 30 mm and a wall thickness of 4 mm, is held stationary in a stream of air for which T-30°C, F-1 atm , and V-25 m/s . The pipe, which is made of PVC, experiences cross-flow conditions in the moving air 1) The temperature at the inner surface of the pipe is maintained at 90°C. The outer surface of the pipe is smooth. Also, assume that steady-state conditions exist. Since the outer...
3. A cooling system uses 8 copper cylindrical fins of diameter 6 mm and length 100...
3. A cooling system uses 8 copper cylindrical fins of diameter 6 mm and length 100 mm to dissipate heat. The surface around the fins is maintained at 150 °C, and the tips of the fins are insulated. Air at 50 °C is used to cool the fins, flowing at 5 m/s. The flows around the fins do not affect each other. (a) Determine the average convection coefficient around each fin. (b) Calculate the overall heat dissipation rate of the...
T,= 75 °C T= 25°C V = 10 m/s Air 3. (25 pts) Atmospheric air at...
T,= 75 °C T= 25°C V = 10 m/s Air 3. (25 pts) Atmospheric air at 25 °C flows across a long pipe at a uniform velocity of 10 m/s. The pipe has an external diameter of 120 mm and its surface temperature is maintained at 75 °C. Determine the rate of heat transfer per unit length of the pipe and the drag force exerted per unit length of the pipe. Hint: You can use the information on the next...
A circular pipe of 25-mm outside diameter and 500-mm length is placed in an airstream at...
A circular pipe of 25-mm outside diameter and 500-mm length is placed in an airstream at 25°C and 1-atm pressure. The air moves in cross flow over the pipe at 15 m/s, while the outer surface of the pipe is maintained at 100 °C, what is the rate of heat transfer from the pipe? submit you answer in W.
A 25-mm-diameter hot surface at is cooled by an air jet exiting a 5-mm-diameter round nozzle wi...
A 25-mm-diameter hot surface at
is cooled by an air jet exiting a 5-mm-diameter round nozzle with
a velocity of 35 m/s and temperature of 25. The
nozzle exit is 25 mm from the hot surface. Determine the percentage
change in average heat transfer coefficient at the hot surface if
the air is replaced with carbon dioxide or helium. Use material
properties from reputable tables.
We were unable to transcribe this imageWe were unable to transcribe this imageWe were unable...
A long horizontal cylinder with diameter of d-60 mm and length of L-1 m is at 27°C and is placed in a quiescent environment at 4°C. Find the cooling rate (q). End effects (heat transfer from the two ends of the cylinder) are negligible. The following relation (Churchill and Chu) for Nusselt number can be used. Air (T-288.5K): v=14.87x10° m2/s, k=0.0254 w/m-K, α=21.0x10-6 m2/s, Pr-0.71, B-3.47x1031/K. 1. Quiescent air 7,-4°C 0.06 m diameter T 27 C L=1m MUD 10.60 +...
7.34 Consider the following fluids, each with a velocity of V- 3 m/s and a temperature of T 20°C, in cross flow over a 10-mm-diameter cylinder maintained at 50°C: atmospheric air, saturated water, and engine oil. (a) Calculate the rate of heat transfer per unit length, q, using the Churchill-Bernstein correlation. (b) Generate a plot ofq as a function of fluid velocity for o.5 s Vs 10 m/s.
7.34 Consider the following fluids, each with a velocity of V- 3...
Problem 7.036 A long, cylindrical, electrical heating element of diameter D = 10 mm, termal conductivity k = 240 w/m·K, density ρ = 2700 kg/m3, and specific heat cp-900 נ/kg-K is installed in a duct for which air moves in cross flow over the heater at a temperature and velocity of 27°C and 20 m/s, respectively (a) Neglecting radiation, estimate the steady-state surface temperature when, per unit length of the heater, electrical energy is being dissipated at a rate of...
A circular pipe, with an outside diameter of 30 mm and a wall thickness of 4 mm, is held stationary in a stream of air for which T-30°C, F-1 atm , and V-25 m/s . The pipe, which is made of PVC, experiences cross-flow conditions in the moving air 1) The temperature at the inner surface of the pipe is maintained at 90°C. The outer surface of the pipe is smooth. Also, assume that steady-state conditions exist. Since the outer...
3. A cooling system uses 8 copper cylindrical fins of diameter 6 mm and length 100 mm to dissipate heat. The surface around the fins is maintained at 150 °C, and the tips of the fins are insulated. Air at 50 °C is used to cool the fins, flowing at 5 m/s. The flows around the fins do not affect each other. (a) Determine the average convection coefficient around each fin. (b) Calculate the overall heat dissipation rate of the...
T,= 75 °C T= 25°C V = 10 m/s Air 3. (25 pts) Atmospheric air at 25 °C flows across a long pipe at a uniform velocity of 10 m/s. The pipe has an external diameter of 120 mm and its surface temperature is maintained at 75 °C. Determine the rate of heat transfer per unit length of the pipe and the drag force exerted per unit length of the pipe. Hint: You can use the information on the next...
A circular pipe of 25-mm outside diameter and 500-mm length is placed in an airstream at 25°C and 1-atm pressure. The air moves in cross flow over the pipe at 15 m/s, while the outer surface of the pipe is maintained at 100 °C, what is the rate of heat transfer from the pipe? submit you answer in W.
A 25-mm-diameter hot surface at
is cooled by an air jet exiting a 5-mm-diameter round nozzle with
a velocity of 35 m/s and temperature of 25. The
nozzle exit is 25 mm from the hot surface. Determine the percentage
change in average heat transfer coefficient at the hot surface if
the air is replaced with carbon dioxide or helium. Use material
properties from reputable tables.
We were unable to transcribe this imageWe were unable to transcribe this imageWe were unable...
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