Thin-walled aluminum tubes of diameter D = 10 mm are used in the condenser of an air conditioner....
Thin-walled aluminum tubes of diameter D = 10 mm are used in the condenser of an air conditioner. Under normal operating conditions, a convection coefficient of hi = 5000 W/m2 · K is associated with condensation on the inner surface of the tubes, while a coefficient of ho = 100 W/m2 · K is maintained by airflow over the tubes.
a. What is the overall heat transfer coefficient if the tubes are unfinned?
b. What is the overall heat transfer coefficient based on the inner surface, Ui, if aluminum annular rectangular fins of thickness t = 1.5 mm, outer diameter Do = 20 mm, and pitch S = 3.5 mm are added to the outer surface? Base your calculations on a 1-m-long section of tube.
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Thin-walled aluminum tubes of diameter D = 10 mm are used in the condenser of an air conditioner....
Steam in a heating system flows through tubes whose outer diameter is D1 =3 cm and...
Steam in a heating system flows through tubes whose outer
diameter is D1 =3 cm and whose walls are maintained at a
temperature of 120oC. Circular aluminum fins (k = 180
W/m.oC) of outer diameters D2 = 6 cm and
constant thickness t = 2mm are attached to the
tubes. The space between the fins is 3 mm. Heat is
transferred to the surrounding air at
T∞ = 25 oC, with a
convection heat transfer coefficient of h = 60
W/m2.oC.
Determine 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...
6. Problem 3 (20 points): A Steam in a heating system flows through tubes whose outer...
6. Problem 3 (20 points): A Steam in a heating system flows through tubes whose outer diameter is 3 cm and whose walls are maintained at a temperature of 120°C. Circular aluminum alloy fins (k = 180 W/m.) of outer diameter 6 cm and constant thickness t 2 mm are attached to the tube, as shown in the figure below. The space between the fins is 3 mm, and thus there are 200 fins per meter length of the tube....
A concentric tube heat exchanger for cooling lubricating oil is comprised of a thin-walled inner tube...
A concentric tube heat exchanger for cooling lubricating oil is comprised of a thin-walled inner tube of 25 mm diameter carrying water and an outer tube of 45 mm diameter carrying the oil. The mass flow rates of both fluids are 0.1 kg/s. The exchanger operates in counter-flow with an overall heat transfer coefficient of 60 W/m2
a 0.4 m diameter, thin walled steel pipe is used to transport saturated steam Problem 3.049...
a 0.4 m diameter, thin walled steel pipe is used to transport
saturated steam
Problem 3.049 A 0.4-m-diameter, thin-walled steel pipe is used to transport saturated steam at a pressure of 20 bars in a room for which the air temperature is 25°C and the convection heat transfer coefficient at the outer surface of the pipe is 20 W/m2-K. (a) What is the heat loss per unit length from the bare pipe (no insulation)? (b) Estimate the heat loss per...
4. A pure copper pipe with inner diameter Di-10 mm ard outer diameter Do-14 mm is surrounded by s...
4. A pure copper pipe with inner diameter Di-10 mm ard outer diameter Do-14 mm is surrounded by saturated steam with pressure p 172 bar and convection coefficient h 6000 carries water with mean velocity u- (a) Determine the convective heat transfer coefficient inside the pipe for water at mean temperature Tm 37° C (b) At this same location, determine the total thermal resistance (per unit length) between the water and the steam. (c) Determine the heat transfer rate (per...
A simple counter flow heat exchanger consists of two co-axial tubes with hot process water passing...
A simple counter flow heat exchanger consists of two co-axial tubes with hot process water passing through the inner tube and clean water through the annular space between the inner and outer tubes. The clean water enters at 20°C and leaves at 50°C. The process water enters at 90°C and leaves at 40°C. The mass flowrate of the process water is 3 kgs-1. The inner tube diameter is 30 mm and the outer tube diameter is 50 mm. Take the...
A hot fluid passes through a thin-walled tube of 10-mm diameter at 18 kg/h at a...
A hot fluid passes through a thin-walled tube of 10-mm diameter at 18 kg/h at a temperature of 85 C. On the outside, coolant flows across the tube at a velocity of 3 m/s at a temperature of 25 C. Neglecting the thermal resistance of the metal wall, calculate 1. (a) The two heat transfer coefficients, (b) Overall heat transfer coefficient, and (c) Cooling rate (in W/m) achieved in the given configuration Assume hot fluid properties are constant at the...
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used...
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used to route superheated steam from the boller to the turbine in a power plant. Safety and economic concerns make it practical to add a 200-mm layer of Insulation (k =0.1 W/mK) to each tube, which is wrapped in a thin sheet of aluminum with an emissivity e =0.15. The air (with a convective coefficient h =5 W/m2K) and wail temperatures of the plant are...
Steam in a heating system flows through tubes whose outer
diameter is D1 =3 cm and whose walls are maintained at a
temperature of 120oC. Circular aluminum fins (k = 180
W/m.oC) of outer diameters D2 = 6 cm and
constant thickness t = 2mm are attached to the
tubes. The space between the fins is 3 mm. Heat is
transferred to the surrounding air at
T∞ = 25 oC, with a
convection heat transfer coefficient of h = 60
W/m2.oC.
Determine 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...
6. Problem 3 (20 points): A Steam in a heating system flows through tubes whose outer diameter is 3 cm and whose walls are maintained at a temperature of 120°C. Circular aluminum alloy fins (k = 180 W/m.) of outer diameter 6 cm and constant thickness t 2 mm are attached to the tube, as shown in the figure below. The space between the fins is 3 mm, and thus there are 200 fins per meter length of the tube....
a 0.4 m diameter, thin walled steel pipe is used to transport
saturated steam
Problem 3.049 A 0.4-m-diameter, thin-walled steel pipe is used to transport saturated steam at a pressure of 20 bars in a room for which the air temperature is 25°C and the convection heat transfer coefficient at the outer surface of the pipe is 20 W/m2-K. (a) What is the heat loss per unit length from the bare pipe (no insulation)? (b) Estimate the heat loss per...
4. A pure copper pipe with inner diameter Di-10 mm ard outer diameter Do-14 mm is surrounded by saturated steam with pressure p 172 bar and convection coefficient h 6000 carries water with mean velocity u- (a) Determine the convective heat transfer coefficient inside the pipe for water at mean temperature Tm 37° C (b) At this same location, determine the total thermal resistance (per unit length) between the water and the steam. (c) Determine the heat transfer rate (per...
A simple counter flow heat exchanger consists of two co-axial tubes with hot process water passing through the inner tube and clean water through the annular space between the inner and outer tubes. The clean water enters at 20°C and leaves at 50°C. The process water enters at 90°C and leaves at 40°C. The mass flowrate of the process water is 3 kgs-1. The inner tube diameter is 30 mm and the outer tube diameter is 50 mm. Take the...
A hot fluid passes through a thin-walled tube of 10-mm diameter at 18 kg/h at a temperature of 85 C. On the outside, coolant flows across the tube at a velocity of 3 m/s at a temperature of 25 C. Neglecting the thermal resistance of the metal wall, calculate 1. (a) The two heat transfer coefficients, (b) Overall heat transfer coefficient, and (c) Cooling rate (in W/m) achieved in the given configuration Assume hot fluid properties are constant at the...
NE Steel tubes (k =35 W/m2.K) of 400-mm inner diameter and 30-mm wall thickness are used to route superheated steam from the boller to the turbine in a power plant. Safety and economic concerns make it practical to add a 200-mm layer of Insulation (k =0.1 W/mK) to each tube, which is wrapped in a thin sheet of aluminum with an emissivity e =0.15. The air (with a convective coefficient h =5 W/m2K) and wail temperatures of the plant are...
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