Q. Steam in a heating system flows through tubes whose outer diameter is 5 cm and whose walls are maintained at a temperature of 130 °C. Circular aluminum alloy 2024-T6 fins k = 186 W/m.K of outer diameter 6 cm and constant thickness 1 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 250 fins per length of the tube. Heat is transferred to the surrounding air at 25 C, with a heat transfer coefficient of 40W/m².K. Determine: 1. The increase in heat transfer from the tube per meter of its length as result of adding fins. 2. The efficiency of the fins. 3. Temperature at mid-point of the fins. Note: Equations and any other data required can be taken from textbook/handbook. 130°C 25°C

Q. Steam in a heating system flows through tubes whose outer diameter is 5 cm and whose walls are maintained at a temperature of 130 °C. Circular aluminum alloy 2024-T6 fins k = 186 W/m.K of outer diameter 6 cm and constant thickness 1 mm are attached to the tube. The space between the fins is 3 mm, and thus there are 250 fins per length of the tube. Heat is transferred to the surrounding air at 25 C, with a heat transfer coefficient of 40W/m².K. Determine: 1. The increase in heat transfer from the tube per meter of its length as result of adding fins. 2. The efficiency of the fins. 3. Temperature at mid-point of the fins. Note: Equations and any other data required can be taken from textbook/handbook. 130°C 25°C

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 7.55P

See similar textbooks

Similar questions

3.10 A spherical shell satellite (3-m-OD, 1.25-cm-thick stainless steel walls) re-enters the atmosphere from outer space. If its original temperature is 38°C, the effective average temperature of the atmosphere is 1093°C, and the effective heat transfer coefficient is , estimate the temperature of the shell after reentry, assuming the time of reentry is 10 min and the interior of the shell is evacuated.
3.14 A thin-wall cylindrical vessel (1 m in diameter) is filled to a depth of 1.2 m with water at an initial temperature of 15°C. The water is well stirred by a mechanical agitator. Estimate the time required to heat the water to 50°C if the tank is suddenly immersed in oil at 105°C. The overall heat transfer coefficient between the oil and the water is , and the effective heat transfer surface is .
a] Steam at 280 oC, tube=26 W/m. It flows at a speed of 4.0 m/s along a pipe made of iron-steel material with a temperature of 0°C. The inner diameter of the iron-steel pipe is 6.0 cm and the outer diameter is 6.8 cm. In order to reduce the heat transfer, the iron-steel pipe is first covered with 2.0 cm thick glass wool (k = 0.38 W/m. oC), then with another 3.5 cm thick insulation material (k = 0.01 W/m. oC). The insulated iron-steel pipe is in the atmospheric environment where the temperature is 18 oC. The convective heat transfer coefficient on the outside atmospheric side of this pipe, where the steam flows, is 36 W/m2. oC, the film heat transfer coefficient on the steam side is 80 W/m2. Calculate the heat transferred per unit pipe length (W/m), since it is known to be °C. b] Calculate the thickness of the material when the pipe is sheathed externally with a material with a thermal conductivity of k=0.02 W/m.oC in order to reduce the heat to be transferred by 20% in the unit pipe…
A domestic refrigerator with inner dimensions of 0,7 m by 0,7 m at the base and height 1m was designed to maintain a set temperature of 6 degrees Celsius. The bodies consist of two 10 mm thick layers of Aluminum (k=225 W/mK) separated by a 30 mm polyurethane insulation (k=0,028 W/mK). If the convection heat transfer coefficient at the inner and outer surfaces are 11,6 W/m²K and 14,5 W/m²K respectively, calculate the outer surface temperature of Aluminum in degrees Celsius to 2 decimal places. 2)calculate the resistance (R) for the insulation layer in K/W to 4 decimal places. 3)calculate the steady rate of heat transfer from the interior to maintain the specified temperature in the kitchen at 25 degrees Celsius in W to 2 decimal places. 4)calculate the total resistance (R) for the refrigerator in K/W to 4 decimal places
A 10-cm diameter pipe is covered by 2 layers of lagging. The insidelayer is 4 cm thick and has a coefficient of thermal conductivity of 0.08W/m-K. The outside layer is 3cm thick and has a coefficient of thermalconductivity of 0.15 W/m-K. The steam main conveys steam apressure of 1.7 MPa with 25 C superheat. The outside temperature ofthe lagging is 27 C. If the steam main is 30 m long, determine theinterface temperature of the lagging and overall coefficient of heattransfer based on outside area.