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pts.) Consider a long resistance wire of radius ri-1.5 cm and thermal conductivity m'к in which...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is gene...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is generated uniformly in the wire as a result of resistance heating at a constant rate of 0.5 W/cm3. The wire is covered with polyethylene insulation with a thickness of 0.25 cm and thermal conductivity of ks 0.4 W/m K. The outer surface of the insulation is subjected to free convection in air at 20°C and a convection heat transfer coefficient of 2...
2-97 A long homogeneous resistance wire of radius r = 5 mm is being used to...
2-97 A long homogeneous resistance wire of radius r = 5 mm is being used to heat the air in a room by the passage of electric current. Heat is generated in the wire uniformly at a rate of 5 X 10' W/m as a result of resistance heating. If the temperature of the outer surface of the wire remains at 180°C. determine the temperature at r = 3.5 mm after steady opera- tion conditions are reached. Take the thermal...
P2) (50 pts.) A sphere of radius , and thermal conductivity of k=0.1 W/ mK is...
P2) (50 pts.) A sphere of radius , and thermal conductivity of k=0.1 W/ mK is generating heat at a constant rate in W/m] inside another sphere of radius ry. The radius of the internal sphere is a 10 cm and the radius of the outer sphere is 40 cm. The outer surface is exposed to ambient air at 27°C and a convection coethicient -30 W/m-K. The thermal conductivity of the external sphere is 6.0 W/m-K. If the temperature at...
A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal...
A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k0.15 W/m-K. Electrical measurements indicate that a current of 13 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T 30°C with a heat transfer coefficient of h 24 W/m2 K, determine the temperature at the interface of the wire and the plastic cover...
FIGURE P2-101 2-102 A long home r.= 0.6 cm and thermal cond used to boil water...
FIGURE P2-101 2-102 A long home r.= 0.6 cm and thermal cond used to boil water at atmosph electric current. Heat is gener result of resistance heating a generated is transferred to water at 10 an average heat transfer coe Assuming steady one-dir the differential equation and the boundary COI ong homogeneous resistance wire of radius rmal conductivity k = 15.2 W/m.K is being it atmospheric pressure by the passage of at is generated in the wire uniformly as a...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
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...
Problem 2: Consider a large plane slab of semi-thickness L = 0.3 m, thermal conductivity k...
Problem 2: Consider a large plane slab of semi-thickness L = 0.3 m, thermal conductivity k = 2.5 W/m K and surface area A = 20.0 m². Both sides of the slab is maintained at a constant wall temperature of 358°K while it is subjected to a uniform but constant heat flux of 950.0 W/m2 Evaluate the temperature distribution/profile within the wall. Calculate the heat flux and temperature at location x = 0.1m. Problem 3: Consider a 10.0 m long...
Consider a rectangular bar of thermal conductivity k W/m-K and total length 2L, as shown in...
Consider a rectangular bar of thermal conductivity k W/m-K and
total length 2L, as shown in the figure, is connected to a hot
surface that is at a temperature T1. The connection between the bar
and the surface is imperfect and results in a thermal contact
resistance of R’’ m2-K/W. The width of the rod into the depth of
the paper is W meters and the thickness of the rod is t meters. The
first section of the rod of...
The core is at 37C , skin-fat layer thermal conductivity k_s = 0.3 W/m-K, skin emissivity...
The core is at 37C , skin-fat layer thermal conductivity k_s =
0.3 W/m-K, skin emissivity E_s = 0.95, skin-fat thickness l_s = 3
mm, and convection coefficient ℎ_air = 2 W/m2 -K. The jacket has
thermal conductivity of k_j = 0.5 W/m-K, jacket emissivity E_j =
0.02, and jacket thickness l_j = 2 cm.
a) Write two energy balances, one at the skin-jacket interface
and another at the jacket-air interface. Can any of the terms in
your energy balances...
2-157 A long electrical resistance wire of radius r.-0.25 cm has a thermal conductivity kwire-15 W/m-K. Heat is generated uniformly in the wire as a result of resistance heating at a constant rate of 0.5 W/cm3. The wire is covered with polyethylene insulation with a thickness of 0.25 cm and thermal conductivity of ks 0.4 W/m K. The outer surface of the insulation is subjected to free convection in air at 20°C and a convection heat transfer coefficient of 2...
2-97 A long homogeneous resistance wire of radius r = 5 mm is being used to heat the air in a room by the passage of electric current. Heat is generated in the wire uniformly at a rate of 5 X 10' W/m as a result of resistance heating. If the temperature of the outer surface of the wire remains at 180°C. determine the temperature at r = 3.5 mm after steady opera- tion conditions are reached. Take the thermal...
P2) (50 pts.) A sphere of radius , and thermal conductivity of k=0.1 W/ mK is generating heat at a constant rate in W/m] inside another sphere of radius ry. The radius of the internal sphere is a 10 cm and the radius of the outer sphere is 40 cm. The outer surface is exposed to ambient air at 27°C and a convection coethicient -30 W/m-K. The thermal conductivity of the external sphere is 6.0 W/m-K. If the temperature at...
A 2.2-mm-diameter and 10-m-long electric wire is tightly wrapped with a 1-mm-thick plastic cover whose thermal conductivity is k0.15 W/m-K. Electrical measurements indicate that a current of 13 A passes through the wire and there is a voltage drop of 8 V along the wire. If the insulated wire is exposed to a medium at T 30°C with a heat transfer coefficient of h 24 W/m2 K, determine the temperature at the interface of the wire and the plastic cover...
FIGURE P2-101 2-102 A long home r.= 0.6 cm and thermal cond used to boil water at atmosph electric current. Heat is gener result of resistance heating a generated is transferred to water at 10 an average heat transfer coe Assuming steady one-dir the differential equation and the boundary COI ong homogeneous resistance wire of radius rmal conductivity k = 15.2 W/m.K is being it atmospheric pressure by the passage of at is generated in the wire uniformly as a...
2.) A plane wall is made of brick with a thermal conductivity of 1.5 W/(m-K). The wall is 20 cm thick and has a surface area of 10 m2. One side of the wall is exposed to outside air blowing against the wall resulting in a heat transfer coefficient of 20 W/(m2-K). The other side is exposed to an air-conditioned room with a convective heat transfer coefficient of 5 W/(m2-K). a. What are the thermal resistances corresponding to conduction through...
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...
Problem 2: Consider a large plane slab of semi-thickness L = 0.3 m, thermal conductivity k = 2.5 W/m K and surface area A = 20.0 m². Both sides of the slab is maintained at a constant wall temperature of 358°K while it is subjected to a uniform but constant heat flux of 950.0 W/m2 Evaluate the temperature distribution/profile within the wall. Calculate the heat flux and temperature at location x = 0.1m. Problem 3: Consider a 10.0 m long...
Consider a rectangular bar of thermal conductivity k W/m-K and
total length 2L, as shown in the figure, is connected to a hot
surface that is at a temperature T1. The connection between the bar
and the surface is imperfect and results in a thermal contact
resistance of R’’ m2-K/W. The width of the rod into the depth of
the paper is W meters and the thickness of the rod is t meters. The
first section of the rod of...
The core is at 37C , skin-fat layer thermal conductivity k_s =
0.3 W/m-K, skin emissivity E_s = 0.95, skin-fat thickness l_s = 3
mm, and convection coefficient ℎ_air = 2 W/m2 -K. The jacket has
thermal conductivity of k_j = 0.5 W/m-K, jacket emissivity E_j =
0.02, and jacket thickness l_j = 2 cm.
a) Write two energy balances, one at the skin-jacket interface
and another at the jacket-air interface. Can any of the terms in
your energy balances...
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