A thermocouple is used to measure the temperature of hot air flowing in a duct whose...
A thermocouple is used to measure the temperature of hot air flowing in a duct whose walls are maintained at Tw = 500 K. The thermocouple shows a temperature reading of Tt h = 850 K. Assuming the emissivity of the thermocouple junction to be 0.6, and the convection heat transfer coefficient to be 60 W/m2 · K,
(a) draw the thermal resistance network, and
(b) determine the actual temperature of the air.
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A thermocouple is used to measure the temperature of hot air
flowing in a duct whose...
Solve the differential equation analytically Suppose a thermocouple is to be used to measure the temperature of a hot gas flowing through a duct. The thermocouple junction is initially at ambient tem...
Solve the differential equation analytically
Suppose a thermocouple is to be used to measure the temperature of a hot gas flowing through a duct. The thermocouple junction is initially at ambient temperature Ti-25°C before it is inserted into the gas stream. Hot duct wall Tsur 400°C Gas stream Junction, Tt) 1,-25°C, D p 8500 kg/m3 T 200°C 0.7 mm 400 Jkg.K Approximating the thermocouple junction as a sphere and using the lumped capacitance model, an energy balance on the thermocouple...
The temperature of air in a duct is measured by a thermocouple as shown. It's to find the he...
The temperature of air in a duct is measured by a thermocouple
as shown.
It's to find the heat flux of the thermocouple
problem 8.5 Problem 8.5 The temperature of air in a duct is measured by a thermocouple, as shown. The tip of the thermocouple is a d-2 mm diameter sphere of metallic alloy, having thermal conductivity of k-60 W/m-K, and emissivity, 0.6 . The thermocouple wires are thin and long. The duct walls are at T- 130 C....
Problem 3 A portable thermocouple is used to measure the air temperature inside of a sauna....
Problem 3 A portable thermocouple is used to measure the air temperature inside of a sauna. The sauna is unbearably hot and a person can only stay for 20 seconds, during which the temperature reading keeps on changing and a steady temperature is not reached. Leaving the thermocouple reader in the sauna for extended period of time has been deemed too risky for an electronics device Fortunately, a transient heat transfer model can be used to extract the temperature in...
Problem 5: The temperature of air flowing through a 25-cm-diameter duct whose inner walls are at...
Problem 5: The temperature of air flowing through a 25-cm-diameter duct whose inner walls are at 320° C is to be measured using a thermocouple soldered in a cylindrical steel well of 1.2-cm OD with an oxidized exterior, as shown in the accompanying sketch. The air flows normal to the cylinder at a mass velocity of 17,600 kg/h m1 . If the temperature indicated by the thermocouple is 200°C, estimate the actual temperature of the air Air 17,600 kg/h m2...
4- A steel strip of thickness 6-12 mm is annealed by passing it through a large fumace whose wall...
4- A steel strip of thickness 6-12 mm is annealed by passing it through a large fumace whose walls are maintained at a temperature Tw corresponding to that of combustion gases flowing through the fumace (Iw Tp). The stip, whose density, spcific thermal conductivity, and emissivity are 79 kg/m3, cp -640 J/kg K, k 30 W/m K and 0.7, respectively, is to be heated from 300°C to 600°C Furnace walls, Combustion gases For a unifom convection coefficient of h-100 W/m2...
1. (10 points) A spherical thermocouple junction 1 mm in diameter is inserted in a combustion...
1. (10 points) A spherical thermocouple junction 1 mm in diameter is inserted in a combustion chamber to measure the temperature of the products of combustion. The hot gases are at 1000 K and have a velocity of 5 m/s. The thermocouple junction has an emissivity of 50% and the cooled walls of the combustor are at 500 K. The properties of the thermocouple junction are: p = 9000 kg/m”, Cp = 500 J/kg:K, k = 100 W/mK. The properties...
3) A rectangular HVAC duct of cross-section 20 cm X 20 cm and 12 m long...
3) A rectangular HVAC duct of cross-section 20 cm X 20 cm and 12 m long is made of 3.5 mm thick sheet metal that is used to deliver hot air at 60°C with an average velocity of 4 m/s. The thermal resistance of the duct is negligible, and the outer surface of the duct, whose emissivity is 0.305, is exposed to the cold air at 10 C in the room, with a convection heat transfer coefficient of 10 W/m²....
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...
The temperature of a flowing gas is to be measured with a thermocouple junction and wire...
The temperature of a flowing gas is to be measured with a thermocouple junction and wire stretched between two legs of a sting, a wind tunnel test fixture. The junc- tion is formed by butt-welding two wires of different material, as shown in the schematic. For wires of diame- ter D = 125 pm and a convection coefficient of h = 700 W/ m K, determine the minimum separation distance between the two legs of the sting, L=L +L, to...
A rectangular forced air heating duct is suspended from the ceiling of a basement whose air...
A rectangular forced air heating duct is suspended from the ceiling of a basement whose air and walls are at a temperature of ∞T∞=Tsur= 5°C. The duct is 15 m long, and its cross section is 350 mm × 188 mm. (1) For an uninsulated duct whose average surface temperature is 50°C, estimate the rate of heat loss from the duct. The surface emissivity and convection coefficient are approximately 0.5 and 4 W/m2·K, respectively. (2) If heated air enters the...
Solve the differential equation analytically
Suppose a thermocouple is to be used to measure the temperature of a hot gas flowing through a duct. The thermocouple junction is initially at ambient temperature Ti-25°C before it is inserted into the gas stream. Hot duct wall Tsur 400°C Gas stream Junction, Tt) 1,-25°C, D p 8500 kg/m3 T 200°C 0.7 mm 400 Jkg.K Approximating the thermocouple junction as a sphere and using the lumped capacitance model, an energy balance on the thermocouple...
The temperature of air in a duct is measured by a thermocouple
as shown.
It's to find the heat flux of the thermocouple
problem 8.5 Problem 8.5 The temperature of air in a duct is measured by a thermocouple, as shown. The tip of the thermocouple is a d-2 mm diameter sphere of metallic alloy, having thermal conductivity of k-60 W/m-K, and emissivity, 0.6 . The thermocouple wires are thin and long. The duct walls are at T- 130 C....
Problem 3 A portable thermocouple is used to measure the air temperature inside of a sauna. The sauna is unbearably hot and a person can only stay for 20 seconds, during which the temperature reading keeps on changing and a steady temperature is not reached. Leaving the thermocouple reader in the sauna for extended period of time has been deemed too risky for an electronics device Fortunately, a transient heat transfer model can be used to extract the temperature in...
Problem 5: The temperature of air flowing through a 25-cm-diameter duct whose inner walls are at 320° C is to be measured using a thermocouple soldered in a cylindrical steel well of 1.2-cm OD with an oxidized exterior, as shown in the accompanying sketch. The air flows normal to the cylinder at a mass velocity of 17,600 kg/h m1 . If the temperature indicated by the thermocouple is 200°C, estimate the actual temperature of the air Air 17,600 kg/h m2...
4- A steel strip of thickness 6-12 mm is annealed by passing it through a large fumace whose walls are maintained at a temperature Tw corresponding to that of combustion gases flowing through the fumace (Iw Tp). The stip, whose density, spcific thermal conductivity, and emissivity are 79 kg/m3, cp -640 J/kg K, k 30 W/m K and 0.7, respectively, is to be heated from 300°C to 600°C Furnace walls, Combustion gases For a unifom convection coefficient of h-100 W/m2...
1. (10 points) A spherical thermocouple junction 1 mm in diameter is inserted in a combustion chamber to measure the temperature of the products of combustion. The hot gases are at 1000 K and have a velocity of 5 m/s. The thermocouple junction has an emissivity of 50% and the cooled walls of the combustor are at 500 K. The properties of the thermocouple junction are: p = 9000 kg/m”, Cp = 500 J/kg:K, k = 100 W/mK. The properties...
3) A rectangular HVAC duct of cross-section 20 cm X 20 cm and 12 m long is made of 3.5 mm thick sheet metal that is used to deliver hot air at 60°C with an average velocity of 4 m/s. The thermal resistance of the duct is negligible, and the outer surface of the duct, whose emissivity is 0.305, is exposed to the cold air at 10 C in the room, with a convection heat transfer coefficient of 10 W/m²....
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...
The temperature of a flowing gas is to be measured with a thermocouple junction and wire stretched between two legs of a sting, a wind tunnel test fixture. The junc- tion is formed by butt-welding two wires of different material, as shown in the schematic. For wires of diame- ter D = 125 pm and a convection coefficient of h = 700 W/ m K, determine the minimum separation distance between the two legs of the sting, L=L +L, to...
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