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2. To measure the speed of an airplane, a narrow strip heater is attached to the...
Problem Wall with Strip Heater The air inside a chamber is measured to be 50C and used to convectively heat a wall (h 2...
Problem Wall with Strip Heater The air inside a chamber is measured to be 50C and used to convectively heat a wall (h 20 w/m2 K). The wall (thermal conductivity of 4 W/m K) is 200 mm thick and has a uniform heat generation of 1000 W/m2. To prevent any heat generated within the wall from being lost to the outside of the chamber a very thin electrical strip heater is placed on the outer wall to provide a uniform...
Air at T=25°C and pressure P=1 bar flows over a square plate with a velocity V=1...
Air at T=25°C and pressure P=1 bar flows over a square plate with a velocity V=1 m/s. This plate has a length L= 1 m and it is heated over its entire length; the plate temperature is constant Tp=100°C. The following data are given. For air: dynamic viscosity: mu = 1.9*10–5 kg/(m.s); density: rho = 1.05 kg/m3; conductivity k = 0.03 W/(m K); Specific heat Cp = 1.007 kJ/(kg K); Prandtl number Pr = 0.7 For laminar flow over a...
5: Problem: Consider subsonic airflow past an airplane wing. Flow speed far ahead of the wing is ...
5: Problem: Consider subsonic airflow past an airplane wing. Flow speed far ahead of the wing is Uc The flow accelerates over the wing, reaching a maximum speed of Freestream density and temperature are poo-1.20 kg/m3 and T 300 K, respectively. Compute Moo and the percentage change in temperature at the point of maximum velocity for Uo50 m/sec and for 250 m/sec M.-0. 144, decrease by 0.4%, M. 0720, decrease by 10% Answer
5: Problem: Consider subsonic airflow past an...
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...
2. A separation column at a temperature of 100C is subjected for cooling for a certain...
2. A separation column at a temperature of 100C is subjected
for cooling for a certain period of time. If the separation column
is 1500 mm high and 18 cm in diameter, and eventually exposed to an
environment temperature of 35C, determine the following with a
neat diagram:
a) Heat Transfer Coefficient (in J/s m2C and kJ/s m2C)
b) Heat transfer Rate (in W and kW)
Assume the properties of air at mean temperature as density
(ρ) = 1.06 kg/m3,...
When using the apparatus from this experiment, the average heat flux at the heater surface is...
When using the apparatus from this experiment, the average heat flux at the heater surface is calculated to be 7.2 kW/m2 and the temperature difference between the heater surface and freestream fluid temperature is 70°C. Calculate the Nusselt number (assume thermal conductivity of air = 0.02587 W/m-K). Answer: 62.82
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, termal conductivity k = 240 w/m·K, density ρ = 2700 kg/m3, and specific heat cp-900 נ/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...
During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation,...
During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation, and evaporation for air velocities of 0.11<V< 0.33 m/s is determined experimentally and is expressed as h = 5.05 KairRe131D, where the diameter Dis 0.1 m. Oranges are cooled by refrigerated air at 5°C and 1 atm at a velocity of 0.3 m/s. Given: The thermal conductivity of the orange is given to be k = 0.50 W/m°C. The thermal conductivity and the kinematic...
During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation,...
During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation, and evaporation for air velocities of 0.11<V 0.33 m/s is determined experimentally and is expressed as h=5.05 kairRe13/D, where the diameter Dis 0.1 m. Oranges are cooled by refrigerated air at 5°C and 1 atm at a velocity of 0.3 m/s. Given: The thermal conductivity of the orange is given to be k = 0.50 W/m-°C. The thermal conductivity and the kinematic viscosity of...
A water heater consists of a copper tube that carries water through hot gas in a...
A water heater consists of a copper tube that carries water through hot gas in a furnace, as shown in Fig. 1. hot gas at T, = 500° th=0.033 inch h, = 25 W/m2K Poytube = 0.25 inch water at Tv = 30° h = 500 W/m2K kube= 300 W/m-K Figure 1: Copper tube in a water heater. The copper tube has an outer radius, ro,tube = 0.25 inch and a tube wall thickness of th=0.033 inch. The conductivity of...
Problem Wall with Strip Heater The air inside a chamber is measured to be 50C and used to convectively heat a wall (h 20 w/m2 K). The wall (thermal conductivity of 4 W/m K) is 200 mm thick and has a uniform heat generation of 1000 W/m2. To prevent any heat generated within the wall from being lost to the outside of the chamber a very thin electrical strip heater is placed on the outer wall to provide a uniform...
5: Problem: Consider subsonic airflow past an airplane wing. Flow speed far ahead of the wing is Uc The flow accelerates over the wing, reaching a maximum speed of Freestream density and temperature are poo-1.20 kg/m3 and T 300 K, respectively. Compute Moo and the percentage change in temperature at the point of maximum velocity for Uo50 m/sec and for 250 m/sec M.-0. 144, decrease by 0.4%, M. 0720, decrease by 10% Answer
5: Problem: Consider subsonic airflow past an...
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...
2. A separation column at a temperature of 100C is subjected
for cooling for a certain period of time. If the separation column
is 1500 mm high and 18 cm in diameter, and eventually exposed to an
environment temperature of 35C, determine the following with a
neat diagram:
a) Heat Transfer Coefficient (in J/s m2C and kJ/s m2C)
b) Heat transfer Rate (in W and kW)
Assume the properties of air at mean temperature as density
(ρ) = 1.06 kg/m3,...
When using the apparatus from this experiment, the average heat flux at the heater surface is calculated to be 7.2 kW/m2 and the temperature difference between the heater surface and freestream fluid temperature is 70°C. Calculate the Nusselt number (assume thermal conductivity of air = 0.02587 W/m-K). Answer: 62.82
Problem 7.036 A long, cylindrical, electrical heating element of diameter D = 10 mm, termal conductivity k = 240 w/m·K, density ρ = 2700 kg/m3, and specific heat cp-900 נ/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...
During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation, and evaporation for air velocities of 0.11<V< 0.33 m/s is determined experimentally and is expressed as h = 5.05 KairRe131D, where the diameter Dis 0.1 m. Oranges are cooled by refrigerated air at 5°C and 1 atm at a velocity of 0.3 m/s. Given: The thermal conductivity of the orange is given to be k = 0.50 W/m°C. The thermal conductivity and the kinematic...
During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation, and evaporation for air velocities of 0.11<V 0.33 m/s is determined experimentally and is expressed as h=5.05 kairRe13/D, where the diameter Dis 0.1 m. Oranges are cooled by refrigerated air at 5°C and 1 atm at a velocity of 0.3 m/s. Given: The thermal conductivity of the orange is given to be k = 0.50 W/m-°C. The thermal conductivity and the kinematic viscosity of...
A water heater consists of a copper tube that carries water through hot gas in a furnace, as shown in Fig. 1. hot gas at T, = 500° th=0.033 inch h, = 25 W/m2K Poytube = 0.25 inch water at Tv = 30° h = 500 W/m2K kube= 300 W/m-K Figure 1: Copper tube in a water heater. The copper tube has an outer radius, ro,tube = 0.25 inch and a tube wall thickness of th=0.033 inch. The conductivity of...
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