A thermocouple at 20 °C is suddenly placed into a 60 °C water bath. The thermocouple...
A thermocouple at 20 °C is suddenly placed into a 60 °C water bath. The thermocouple is covered by a brass sphere that is 10 mm in diameter. The density of brass is 8500 kg/m3 and the specific heat is 0.385 kJ/kg-°C. The heat transfer coefficient is determined to be 1900 W/m2 °C.
For the same system as the previous question, determine the 90% rise time.
For the same system, calculate the time it would take to reach 40 °C.
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A thermocouple at 20 °C is suddenly placed into a 60 °C water
bath. The thermocouple...
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...
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...
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?
1. A thermocouple, which contains a solid copper wire, diameter of 0.1 cm. initially at 150...
1. A thermocouple, which contains a solid copper wire, diameter of 0.1 cm. initially at 150 °C, is suddenly immerse duct, which is 40 °C. The resulting time-versus-temperature profile of the thermocouple is as follows: d in a duct to measure the temperature of the fluid in the Time (s) Temperature (C) 0 27 94 150 125 100 75 Calculate the mean heat transfer coefficient between the fluid in the duct and the surface of the thermocouple For copper, density...
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...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched in a large bath having a constant temperature of 320 K with a convection heat transfer of 75 W/m2.K. The thermophysical properties of the sphere material are: p=400 kg/mº, c=1600 J/kg-K, and k=1.7 W/mK. (Use characteristic length Lc=VIA to determine applicability of lumped method; Use radius of the sphere for one term approximation) a) Calculate the time required for the surface of the sphere...
A long steel bar (20 mm diameter) at 455°C is placed horizontally in a water bath...
A long steel bar (20 mm diameter) at 455°C is placed horizontally in a water bath at 100°C under atmospheric pressure. (a) Estimate the initial heat transfer rate per unit length of the bar to the water when it is initially placed in water. You may assume emissivity of the steel bar to be 1. (b) What type of heat transfer mechanism is present when the bar has cooled to 110°C.
A long steel bar (20 mm diameter) at 455°C is placed horizontally in a water bath...
A long steel bar (20 mm diameter) at 455°C is placed horizontally in a water bath at 100°C under atmospheric pressure. (a) Estimate the initial heat transfer rate per unit length of the bar to the water when it is initially placed in water. You may assume emissivity of the steel bar to be 1. (b) What type of heat transfer mechanism is present when the bar has cooled to 110°C.
On a summer day, the air temperature is 36°C and the relative humidity is 20%. Water...
On a summer day, the air temperature is 36°C and the relative humidity is 20%. Water evaporates from the surface of a lake at a rate of 0.20 kg/h per square metre of water surface area. The temperature of water is 25°C. (a) Determine the mass transfer coefficient. (10 marks) (b) Determine the convective heat transfer coefficient. (10 marks) (c) Determine the net heat loss (in W/m2) from the lake. (5 marks) The specific volume of water vapour at 25°C...
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...
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...
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...
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?
1. A thermocouple, which contains a solid copper wire, diameter of 0.1 cm. initially at 150 °C, is suddenly immerse duct, which is 40 °C. The resulting time-versus-temperature profile of the thermocouple is as follows: d in a duct to measure the temperature of the fluid in the Time (s) Temperature (C) 0 27 94 150 125 100 75 Calculate the mean heat transfer coefficient between the fluid in the duct and the surface of the thermocouple For copper, density...
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...
7. (20 pts) A sphere with 30 mm in diameter initially at 800 K is quenched in a large bath having a constant temperature of 320 K with a convection heat transfer of 75 W/m2.K. The thermophysical properties of the sphere material are: p=400 kg/mº, c=1600 J/kg-K, and k=1.7 W/mK. (Use characteristic length Lc=VIA to determine applicability of lumped method; Use radius of the sphere for one term approximation) a) Calculate the time required for the surface of the sphere...
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...
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