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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, thermal conductivity k240...
Problem 7.036 A long, cylindrical, electrical heating element of diameter D 10 mm, thermal conductivity k240 W/m- K, density p 2700 kg/m, and specific heat c900 J/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 1000 W/m....
A hollow aluminum sphere, with an electrical heater in the center, is used in tests to...
A hollow aluminum sphere, with an electrical heater in the center, is used in tests to determine the thermal conductivity of Insulating materials. The inner and outer radii of the sphere are 0.15 and 0.18 m, respectively, and testing is done under steady-state conditions with the inner surface of the aluminum maintained at 250°C. In a particular test, a spherical shell of Insulation is cast on the outer surface of the sphere to a thickness of 0.12 m. The system...
Please help me with this problem 2. A composite cylinder is formed by a long cylindrical...
Please help me with this problem
2. A composite cylinder is formed by a long cylindrical rod (A) and two concentric cylinders (tubes B and C). Tube B encloses trod A and its inner and outer radii are 20 mm and 40 mm, respectively. Tube C encloses tube B and its outer radius is 50 mm. A thin electrical heater is inserted between rod A and tube B. The rod (A) has a thermal conductivity of 2.5 w/m K, while...
5. Problem 3.54 (Textbook) (20 points) KNOWN: Diameter of electrical wire. Thickness and thermal conductivity of...
5. Problem 3.54 (Textbook) (20 points) KNOWN: Diameter of electrical wire. Thickness and thermal conductivity of rubberized sheath. Contact resistance between sheath and wire. Convection coefficient and ambient air temperature. Maximum allowable sheath temperature. FIND: Maximum allowable power dissipation per unit length of wire. Critical radius of insulation. SCHEMATIC: Air Wire Egen. D-2 mm Two Tini Tino To Ric = 3x10-4 m2-KW Insulation, t = 2 mm T= 20°C Ric Rcond conv k = 0.13 W/m-K Tmax = 50°C h...
A long cylindrical rod of diameter 220 mm with thermal conductivity 0.5 W/m-K expe riences uniform...
A long cylindrical rod of diameter 220 mm with thermal conductivity 0.5 W/m-K expe riences uniform volumetric heat generation of 25,000 W/m3. The rod is encapsulated by a circular sleeve having 7 W/m K. The outer surface of the sleeve is exposed to cross flow of air at 25°C with a convection coefficient of 25 W/m2-K. Find the temperature at the interface between the rod and sleeve, and on the outer surface. an outer diameter of 410 mm and thermal...
A long cylindrical rod of diameter 100 mm with thermal conductivity of 0.5 W/mK experiences uniform...
A long cylindrical rod of diameter 100 mm with thermal conductivity of 0.5 W/mK experiences uniform volumetric heat generation of 5.0 x 10 W/m². The rod is encapsulated by a circular sleeve having an outer diameter of 400 mm and a thermal conductivity of 4 W/mK. The outer surface of the sleeve is exposed to cross flow of air at 27°C with a convection coefficient of 25 W/m2K (a) Find the temperature at the Interface between the rod and sleeve...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A current is passed through the wire, resulting in a volumetric heat generation of q - 1.5 x 108 W/m3. The convection coefficient is h - 500 W/m2 - K, and the properties of the wire are ρ-8000 kg/m3, Cp-500 J/kg-K, and...
Steel balls 12 mm in diameter are annealed by heating to 1100 K and then slowly...
Steel balls 12 mm in diameter are annealed by heating to 1100 K
and then slowly cooling to 390 K in an air environment for which
?T?= 325 K and h= 20 W/m2·K. Assuming the properties of
the steel to be k= 40 W/m·K, ?= 7800 kg/m3, and c= 600
J/kg·K, estimate the time required for the cooling process.
Problem 5.007 Your answer is incorrect. Try again. Steel balls 12 mm iri diameter are annealed by heatin time required for...
2. To measure the speed of an airplane, a narrow strip heater is attached to the...
2. To measure the speed of an airplane, a narrow strip heater is attached to the wing of an airplane 0.01 m from the leading edge. A heat flux of 300 W/m²is electrically dissipated and the temperature difference between the heater and the surrounding air is measured to be 1 °C. Assume that the temperature of the wing is uniform. What is the speed of the aircraft? (Hint: Nux = 0.332Rex?Pr1/3) 1q" - 300 W/m² 0.01m Heater Properties of air...
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 +...
Problem 7.036 A long, cylindrical, electrical heating element of diameter D 10 mm, thermal conductivity k240 W/m- K, density p 2700 kg/m, and specific heat c900 J/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 1000 W/m....
A hollow aluminum sphere, with an electrical heater in the center, is used in tests to determine the thermal conductivity of Insulating materials. The inner and outer radii of the sphere are 0.15 and 0.18 m, respectively, and testing is done under steady-state conditions with the inner surface of the aluminum maintained at 250°C. In a particular test, a spherical shell of Insulation is cast on the outer surface of the sphere to a thickness of 0.12 m. The system...
Please help me with this problem
2. A composite cylinder is formed by a long cylindrical rod (A) and two concentric cylinders (tubes B and C). Tube B encloses trod A and its inner and outer radii are 20 mm and 40 mm, respectively. Tube C encloses tube B and its outer radius is 50 mm. A thin electrical heater is inserted between rod A and tube B. The rod (A) has a thermal conductivity of 2.5 w/m K, while...
5. Problem 3.54 (Textbook) (20 points) KNOWN: Diameter of electrical wire. Thickness and thermal conductivity of rubberized sheath. Contact resistance between sheath and wire. Convection coefficient and ambient air temperature. Maximum allowable sheath temperature. FIND: Maximum allowable power dissipation per unit length of wire. Critical radius of insulation. SCHEMATIC: Air Wire Egen. D-2 mm Two Tini Tino To Ric = 3x10-4 m2-KW Insulation, t = 2 mm T= 20°C Ric Rcond conv k = 0.13 W/m-K Tmax = 50°C h...
A long cylindrical rod of diameter 220 mm with thermal conductivity 0.5 W/m-K expe riences uniform volumetric heat generation of 25,000 W/m3. The rod is encapsulated by a circular sleeve having 7 W/m K. The outer surface of the sleeve is exposed to cross flow of air at 25°C with a convection coefficient of 25 W/m2-K. Find the temperature at the interface between the rod and sleeve, and on the outer surface. an outer diameter of 410 mm and thermal...
A long cylindrical rod of diameter 100 mm with thermal conductivity of 0.5 W/mK experiences uniform volumetric heat generation of 5.0 x 10 W/m². The rod is encapsulated by a circular sleeve having an outer diameter of 400 mm and a thermal conductivity of 4 W/mK. The outer surface of the sleeve is exposed to cross flow of air at 27°C with a convection coefficient of 25 W/m2K (a) Find the temperature at the Interface between the rod and sleeve...
A long wire with circular cross section and diameter D = 1 mm is submerged in an oil bath with temperature To 20。C. The wire is initially at temperature T = 20。C, the same temperature as the oil. A current is passed through the wire, resulting in a volumetric heat generation of q - 1.5 x 108 W/m3. The convection coefficient is h - 500 W/m2 - K, and the properties of the wire are ρ-8000 kg/m3, Cp-500 J/kg-K, and...
Steel balls 12 mm in diameter are annealed by heating to 1100 K
and then slowly cooling to 390 K in an air environment for which
?T?= 325 K and h= 20 W/m2·K. Assuming the properties of
the steel to be k= 40 W/m·K, ?= 7800 kg/m3, and c= 600
J/kg·K, estimate the time required for the cooling process.
Problem 5.007 Your answer is incorrect. Try again. Steel balls 12 mm iri diameter are annealed by heatin time required for...
2. To measure the speed of an airplane, a narrow strip heater is attached to the wing of an airplane 0.01 m from the leading edge. A heat flux of 300 W/m²is electrically dissipated and the temperature difference between the heater and the surrounding air is measured to be 1 °C. Assume that the temperature of the wing is uniform. What is the speed of the aircraft? (Hint: Nux = 0.332Rex?Pr1/3) 1q" - 300 W/m² 0.01m Heater Properties of air...
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 +...
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