logistic_guy
Senior Member
- Joined
- Apr 17, 2024
- Messages
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here is the question
In an industrial process, products of combustion at a temperature and pressure of \(\displaystyle 2000\) K and \(\displaystyle 1\) atm, respectively, flow through a long, \(\displaystyle 0.25\)-m diameter pipe whose inner surface is black. The combustion gas contains \(\displaystyle CO_2\) and water vapor, each at a partial pressure of \(\displaystyle 0.10\) atm. The gas may be assumed to have the thermophysical properties of atmospheric air and to be in fully developed flow with \(\displaystyle \dot{m} = 0.25\) kg/s. The pipe is cooled by passing water in cross flow over its outer surface. The upstream velocity and temperature of the water are \(\displaystyle 0.30\) m/s and \(\displaystyle 300\) K, respectively.
(a) Determine the pipe wall temperature, \(\displaystyle T_s\).
(b) Determine the heat flux, \(\displaystyle q_{total}\).
Hint: Emission from the pipe wall may be neglected.
my attemv
i've to use the energy balance equation to solve this question (a)
\(\displaystyle \epsilon_g \sigma T_g^4 + h_1(T_g - T_s) = h_2(T_s - T_{\infty})\)
the pipe wall temperature is \(\displaystyle T_s\)
\(\displaystyle \epsilon_g:\) emissivity of the gas
\(\displaystyle \sigma:\) Stefan-Boltzmann constant
\(\displaystyle T_g:\) temperature of the gas
\(\displaystyle T_s:\) temperature of the surface
\(\displaystyle T_{\infty}:\) temperature of the surroundings
\(\displaystyle h_1:\) convective heat transfer coefficient related to the gas
\(\displaystyle h_2:\) convective heat transfer coefficient related to the water
i understand the main two ingredients in the questions is carbon dioxide \(\displaystyle CO_2\) and water \(\displaystyle H_2O\)
i think a lot of information is missing like the mean of the pipe length \(\displaystyle L_c\) due to radiaion, not given
and there's no enough information to find it
i need this information to solve the emissivity of carbon dioxide \(\displaystyle \epsilon_c\) and the emissivity of water \(\displaystyle \epsilon_w\)
which necessary to find \(\displaystyle \epsilon_g\) also calculating \(\displaystyle h_1\) and \(\displaystyle h_2\) need a lot of information which is not given
for example what is Reylond's numbers \(\displaystyle Re_1\) and \(\displaystyle Re_2\)?
In an industrial process, products of combustion at a temperature and pressure of \(\displaystyle 2000\) K and \(\displaystyle 1\) atm, respectively, flow through a long, \(\displaystyle 0.25\)-m diameter pipe whose inner surface is black. The combustion gas contains \(\displaystyle CO_2\) and water vapor, each at a partial pressure of \(\displaystyle 0.10\) atm. The gas may be assumed to have the thermophysical properties of atmospheric air and to be in fully developed flow with \(\displaystyle \dot{m} = 0.25\) kg/s. The pipe is cooled by passing water in cross flow over its outer surface. The upstream velocity and temperature of the water are \(\displaystyle 0.30\) m/s and \(\displaystyle 300\) K, respectively.
(a) Determine the pipe wall temperature, \(\displaystyle T_s\).
(b) Determine the heat flux, \(\displaystyle q_{total}\).
Hint: Emission from the pipe wall may be neglected.
my attemv
i've to use the energy balance equation to solve this question (a)
\(\displaystyle \epsilon_g \sigma T_g^4 + h_1(T_g - T_s) = h_2(T_s - T_{\infty})\)
the pipe wall temperature is \(\displaystyle T_s\)
\(\displaystyle \epsilon_g:\) emissivity of the gas
\(\displaystyle \sigma:\) Stefan-Boltzmann constant
\(\displaystyle T_g:\) temperature of the gas
\(\displaystyle T_s:\) temperature of the surface
\(\displaystyle T_{\infty}:\) temperature of the surroundings
\(\displaystyle h_1:\) convective heat transfer coefficient related to the gas
\(\displaystyle h_2:\) convective heat transfer coefficient related to the water
i understand the main two ingredients in the questions is carbon dioxide \(\displaystyle CO_2\) and water \(\displaystyle H_2O\)
i think a lot of information is missing like the mean of the pipe length \(\displaystyle L_c\) due to radiaion, not given
and there's no enough information to find iti need this information to solve the emissivity of carbon dioxide \(\displaystyle \epsilon_c\) and the emissivity of water \(\displaystyle \epsilon_w\)
which necessary to find \(\displaystyle \epsilon_g\) also calculating \(\displaystyle h_1\) and \(\displaystyle h_2\) need a lot of information which is not given
for example what is Reylond's numbers \(\displaystyle Re_1\) and \(\displaystyle Re_2\)?