Problem 10.17
The temperature of a flowing gas stream is measured using a bare
thermocouple, which is a spherical metal bead 1.2 mm in diameter.
The properties of the metal are: denisty = 8000 kg/m^3, cp=450
J/kgK, and k= 25 W/mK. The film coefficient between the gas and the
metal is 310 W/m^2K. If the gas temperature suddenly changes from
200C to 210C, how long will it take for the thermocouple to reach
209C
?
Homework Answers
Add Answer to:
Problem 10.17
The temperature of a flowing gas stream is measured using a bare
thermocouple, which...
HW3: The temperature of a gas stream is measured with a thermocouple. The junction may be...
HW3: The temperature of a gas stream is measured with a thermocouple. The junction may be approximated as a sphere of diameter D=1 mm, k=20 W/(mK), p= 7800 kg/m² and Cp=0.4 kJ/(kgK). The heat transfer coefficient between the junction and the gas stream is h=100 W/(m²K). If the initial temperature of the thermocouple 20 C and gas stream temperature is 100 C, what will be reading of the thermocouple after t=10 seconds?
In an experiment, the temperature of a hot air sS stream is to be measured by...
In an experiment, the temperature of a hot air sS stream is to be measured by a thermocouple with a spherical junction. Due to the nature of this experiment, the response time of the thermocouple to register 99 percent of the initial temperature difference must be within 5s. The properties of the thermocouple junction are k 35 W/m-K, T 8500 kg/m3, and cp 320 J/kg-K The hot air has a free stream velocity and temperature of 3 m/s and 140°C,...
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...
part B ?? The heat transfer to a thermocouple bead is characterized by a heat transfer coefficient of: h- 100 W/m2C. The thermocouple bead can be approximated by a sphere with the following prope...
part B ??
The heat transfer to a thermocouple bead is characterized by a heat transfer coefficient of: h- 100 W/m2C. The thermocouple bead can be approximated by a sphere with the following properties: Diameter, D = 1 mm, Density, ρ = 10,000 kg/m3, Specific Heat, Cp-1001/kgK. 5. a. Find the time constant, t b. Would you recommend using this thermocouple to make temperature measurements on a system whose temperature is oscillating at 1 Hz?
The heat transfer to a...
3 Lumpy Junction A thermocouple junction, which may be approximated as a sphere, is to be...
3 Lumpy Junction A thermocouple junction, which may be approximated as a sphere, is to be used for temperature measurement in a gas stream. The convection coefficient between the junction surface and the gas is h = 200 W m-2 K-1. The junction properties are k = 35 W m-1 K-1, c = 500 J kg-1 K-1, and p = 8000 kg m-3. Determine the junction diameter needed for the thermocouple to have a time constant of t = 0.8...
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...
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...
5. A spherical thermocouple bead of diameter D = 0.002 m (i.e. 2 mm) on the...
5. A spherical thermocouple bead of diameter D = 0.002 m (i.e. 2 mm) on the tip of a wire is used to measure tempera- ture of a low-speed, hot gas flow in a duct (Fig. 2). The gas' approach speed is U. = 2 m/sec and its respective density and viscosity are p = 1 kg/m3 and v = 2 x 10-5 m2/s. The coefficient of drag for such moderate flows is well- approximated by the curve fit Cp...
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 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...
HW3: The temperature of a gas stream is measured with a thermocouple. The junction may be approximated as a sphere of diameter D=1 mm, k=20 W/(mK), p= 7800 kg/m² and Cp=0.4 kJ/(kgK). The heat transfer coefficient between the junction and the gas stream is h=100 W/(m²K). If the initial temperature of the thermocouple 20 C and gas stream temperature is 100 C, what will be reading of the thermocouple after t=10 seconds?
In an experiment, the temperature of a hot air sS stream is to be measured by a thermocouple with a spherical junction. Due to the nature of this experiment, the response time of the thermocouple to register 99 percent of the initial temperature difference must be within 5s. The properties of the thermocouple junction are k 35 W/m-K, T 8500 kg/m3, and cp 320 J/kg-K The hot air has a free stream velocity and temperature of 3 m/s and 140°C,...
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...
part B ??
The heat transfer to a thermocouple bead is characterized by a heat transfer coefficient of: h- 100 W/m2C. The thermocouple bead can be approximated by a sphere with the following properties: Diameter, D = 1 mm, Density, ρ = 10,000 kg/m3, Specific Heat, Cp-1001/kgK. 5. a. Find the time constant, t b. Would you recommend using this thermocouple to make temperature measurements on a system whose temperature is oscillating at 1 Hz?
The heat transfer to a...
3 Lumpy Junction A thermocouple junction, which may be approximated as a sphere, is to be used for temperature measurement in a gas stream. The convection coefficient between the junction surface and the gas is h = 200 W m-2 K-1. The junction properties are k = 35 W m-1 K-1, c = 500 J kg-1 K-1, and p = 8000 kg m-3. Determine the junction diameter needed for the thermocouple to have a time constant of t = 0.8...
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...
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...
5. A spherical thermocouple bead of diameter D = 0.002 m (i.e. 2 mm) on the tip of a wire is used to measure tempera- ture of a low-speed, hot gas flow in a duct (Fig. 2). The gas' approach speed is U. = 2 m/sec and its respective density and viscosity are p = 1 kg/m3 and v = 2 x 10-5 m2/s. The coefficient of drag for such moderate flows is well- approximated by the curve fit Cp...
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 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...
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