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4. Air at 200 °C is flowing inside rectangular tube (2cm x 6cm cross section) with...
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct...
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct of inner cross section of 25x25cm at a mass flow rate of 1.0 kg/s. The duct is exposed to air at 35°C with a combined convection-radiation heat transfer coefficient of 15 W/m2K. The convection heat transfer coefficient at the inner surface is 75 W/.m2.K. If the air temperature in the duct should not increase by more than 1°C determine the maximum...
A long rectangular copper bar of a cross section of 2cm by 3cm and a long...
A long rectangular copper bar of a cross section of 2cm by 3cm and a long cylindrical copper rod of 2.2 cm in diameter are initially at a uniform temperature of 120 °C. They are then exposed to a cooling air stream at 22 °C with a heat transfer coefficient of 180 W/m-K. Taking the properties of the copper to be k = 400 W/m-K and p-8930 kg/m', and C -0.385 kJ/kg-K, determine: a How long would it take for...
4. (25 pts) Water is flowing inside a thin wall, smooth pipe of diameter 0.05 m...
4. (25 pts) Water is flowing inside a thin wall, smooth pipe of diameter 0.05 m at a mass flowrate of 0.3 kg/s. The water enters the pipe at a mean temperature Tm,i= 80 °C and exits at Tm,o= 80 °C while the pipe surface temperature is maintained at Ts= 20 °C along its entire length. a. Is the flow turbulent or laminar? b. Calculate the average convection heat transfer coefficient inside the tube. c. Calculate the length of the...
Q2 A main trunk duct of air-conditioning system shown in Figure 2 is rectangular in cross-section...
Q2 A main trunk duct of air-conditioning system shown in Figure 2 is rectangular in cross-section (40 cm x 80 cm). Air at atmospheric pressure and temperature of 20c flows inside the duct with velocity of 7 m/s. The cross sectional srea snd definition of characteristic length for the duct are given in Figure 2. The duct is assumed to be m long. The flow inside the duct is assumed fully developed. (a)Find properties of air using suitable value of...
4 Air (with density 6.08 k3 and viscosity coefficient 2.95 x 10 Pa.s) at an average pressure of 10 bar and a bulk temperature of 600 K flows through a 0.5 m long, 20 mm internal diameter circular tub...
4 Air (with density 6.08 k3 and viscosity coefficient 2.95 x 10 Pa.s) at an average pressure of 10 bar and a bulk temperature of 600 K flows through a 0.5 m long, 20 mm internal diameter circular tube at 3.0 m3 hr1. The heat flux from the tube wall is 10 kW m2. Calculate the heat transfer coefficient and the inside wall temperature of the tube. [Nu0.023 Re08 Pr04; Pr 0.69] [20 marks]
4 Air (with density 6.08 k3...
8. An circular in of rectangular profile is attached to a circular tube having an outside...
8. An circular in of rectangular profile is attached to a circular tube having an outside diameter mm and a surface temperature of 250 °C. The finis 1 mm thick and 10 mm long and the temperature and the convection coefficient associated with the adioining fluid are 25 and 2 W/m .K, respectively. The thermal conductivity of the fin material may be assumed to W/m.ºc. ir fins are spaced at 5-mm increments: Determine the increase in heat transfer from the...
Annular aluminum fins of rectangular profile are attached to a circular tube having an outside diameter...
Annular aluminum fins of rectangular profile are attached to a circular tube having an outside diameter of 50 mm and an outer surface temperature of 400°C. The fins are mm thick and 20 mm long. The system is in ambient air at a temperature of 20°C, and the surface convection coefficient is 40 W/ mK. (a) What are the fin efficiency and effectiveness? (b) If there are 125 such fins per meter of tube length, what is the rate of...
G4 Problem Statement: Circular fins of uniform cross section, with diameter of 14 mm and length 7...
G4 Problem Statement: Circular fins of uniform cross section, with diameter of 14 mm and length 70 mm are attached to the wall with surface temperature o C. The fin is made of material with thermal conductivity of 210 W/mk, and exposed to an ambient air condition of 24 °C and the convection heat transfer coefficient of 190 W/m2k. f 300 1- Plot the temperature variation for the following boundary conditions a- Infinitely long fin b- Adiabatic fin tip c-...
“A pipe is carrying hot water through a cold storage facility. The ambient air in the...
“A pipe is carrying hot water through a cold storage facility. The ambient air in the cold storage has temperature of ?5?C. To maintain uniform temperature in the cold storage, blowers installed in the facility induce a 3 m/s velocity to the cold air (which can be assumed to be flowing across the water pipe). Hot water inside the pipe has a mean velocity of 0.5 m/s. The internal and exter- nal diameter of the pipe are 8.4 cm and...
Problem 2 A brass tube of inner and outer diameters D,-2 cm and Do-3 cm, respectively, is used to...
Problem 2 A brass tube of inner and outer diameters D,-2 cm and Do-3 cm, respectively, is used to transfer heat from ambient air flowing across the tube to cold refrigerant (R-22) flowing inside the tube. The ambient air is flowing at un-0.1 m/s, and To 30°C. The cold refrigerant flow rate is m 1 gs, and its mean temperature is Tm-20°C. (a) Find the overall heat transfer coefficient, UA (b) To enhance the heat transfer, 16 straight fins of...
Cold conditioned air at 10°C is flowing inside a 1.5 cm thick square aluminum (k = 240 w/mK) duct of inner cross section of 25x25cm at a mass flow rate of 1.0 kg/s. The duct is exposed to air at 35°C with a combined convection-radiation heat transfer coefficient of 15 W/m2K. The convection heat transfer coefficient at the inner surface is 75 W/.m2.K. If the air temperature in the duct should not increase by more than 1°C determine the maximum...
A long rectangular copper bar of a cross section of 2cm by 3cm and a long cylindrical copper rod of 2.2 cm in diameter are initially at a uniform temperature of 120 °C. They are then exposed to a cooling air stream at 22 °C with a heat transfer coefficient of 180 W/m-K. Taking the properties of the copper to be k = 400 W/m-K and p-8930 kg/m', and C -0.385 kJ/kg-K, determine: a How long would it take for...
4. (25 pts) Water is flowing inside a thin wall, smooth pipe of diameter 0.05 m at a mass flowrate of 0.3 kg/s. The water enters the pipe at a mean temperature Tm,i= 80 °C and exits at Tm,o= 80 °C while the pipe surface temperature is maintained at Ts= 20 °C along its entire length. a. Is the flow turbulent or laminar? b. Calculate the average convection heat transfer coefficient inside the tube. c. Calculate the length of the...
Q2 A main trunk duct of air-conditioning system shown in Figure 2 is rectangular in cross-section (40 cm x 80 cm). Air at atmospheric pressure and temperature of 20c flows inside the duct with velocity of 7 m/s. The cross sectional srea snd definition of characteristic length for the duct are given in Figure 2. The duct is assumed to be m long. The flow inside the duct is assumed fully developed. (a)Find properties of air using suitable value of...
4 Air (with density 6.08 k3 and viscosity coefficient 2.95 x 10 Pa.s) at an average pressure of 10 bar and a bulk temperature of 600 K flows through a 0.5 m long, 20 mm internal diameter circular tube at 3.0 m3 hr1. The heat flux from the tube wall is 10 kW m2. Calculate the heat transfer coefficient and the inside wall temperature of the tube. [Nu0.023 Re08 Pr04; Pr 0.69] [20 marks]
4 Air (with density 6.08 k3...
8. An circular in of rectangular profile is attached to a circular tube having an outside diameter mm and a surface temperature of 250 °C. The finis 1 mm thick and 10 mm long and the temperature and the convection coefficient associated with the adioining fluid are 25 and 2 W/m .K, respectively. The thermal conductivity of the fin material may be assumed to W/m.ºc. ir fins are spaced at 5-mm increments: Determine the increase in heat transfer from the...
Annular aluminum fins of rectangular profile are attached to a circular tube having an outside diameter of 50 mm and an outer surface temperature of 400°C. The fins are mm thick and 20 mm long. The system is in ambient air at a temperature of 20°C, and the surface convection coefficient is 40 W/ mK. (a) What are the fin efficiency and effectiveness? (b) If there are 125 such fins per meter of tube length, what is the rate of...
G4 Problem Statement: Circular fins of uniform cross section, with diameter of 14 mm and length 70 mm are attached to the wall with surface temperature o C. The fin is made of material with thermal conductivity of 210 W/mk, and exposed to an ambient air condition of 24 °C and the convection heat transfer coefficient of 190 W/m2k. f 300 1- Plot the temperature variation for the following boundary conditions a- Infinitely long fin b- Adiabatic fin tip c-...
Problem 2 A brass tube of inner and outer diameters D,-2 cm and Do-3 cm, respectively, is used to transfer heat from ambient air flowing across the tube to cold refrigerant (R-22) flowing inside the tube. The ambient air is flowing at un-0.1 m/s, and To 30°C. The cold refrigerant flow rate is m 1 gs, and its mean temperature is Tm-20°C. (a) Find the overall heat transfer coefficient, UA (b) To enhance the heat transfer, 16 straight fins of...
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