Chemical Engineering - Process Equipment and Plant Design - Discussion
Discussion Forum : Process Equipment and Plant Design - Section 1 (Q.No. 9)
9.
With increase in the number of shell passes, the value of FT
Discussion:
5 comments Page 1 of 1.
Chayanika said:
2 years ago
The correction factor of Logarithmic Mean Temperature Difference (LMTD) is used to correct for the deviation of the actual temperature distribution from the idealized temperature distribution assumed in the calculation of the LMTD. This deviation can occur when the flow of one fluid is non-uniform or when there is a significant variation in the heat transfer coefficient along the heat exchanger length (especially in cross-flow).
The correction factor is a dimensionless quantity that is used to modify the LMTD equation to account for the deviation from the idealized temperature distribution. It is denoted by the symbol F and is defined as the ratio of the actual temperature difference to the idealized temperature difference.
The correction factor depends on the specific heat exchanger geometry, the fluid flow rates and properties, and the heat transfer coefficients. It can be calculated using empirical correlations, numerical simulations, or experimental data.
In practice, the correction factor is used to modify the LMTD equation to obtain a more accurate estimate of the heat transfer rate in a heat exchanger. This can be particularly important for complex or non-uniform flow configurations where the deviation from the idealized temperature distribution is significant.
When there are multiple shells passes, the flow of the fluid is distributed over a larger area, resulting in a more uniform temperature distribution and a smaller deviation from the idealized temperature distribution.
As a result, the correction factor of LMTD decreases with an increase in the number of shell passes. This means that the actual temperature difference between the hot and cold fluids is closer to the idealized temperature difference, and the heat transfer rate is more accurately predicted by the LMTD method.
So, option B is the correct answer.
The correction factor is a dimensionless quantity that is used to modify the LMTD equation to account for the deviation from the idealized temperature distribution. It is denoted by the symbol F and is defined as the ratio of the actual temperature difference to the idealized temperature difference.
The correction factor depends on the specific heat exchanger geometry, the fluid flow rates and properties, and the heat transfer coefficients. It can be calculated using empirical correlations, numerical simulations, or experimental data.
In practice, the correction factor is used to modify the LMTD equation to obtain a more accurate estimate of the heat transfer rate in a heat exchanger. This can be particularly important for complex or non-uniform flow configurations where the deviation from the idealized temperature distribution is significant.
When there are multiple shells passes, the flow of the fluid is distributed over a larger area, resulting in a more uniform temperature distribution and a smaller deviation from the idealized temperature distribution.
As a result, the correction factor of LMTD decreases with an increase in the number of shell passes. This means that the actual temperature difference between the hot and cold fluids is closer to the idealized temperature difference, and the heat transfer rate is more accurately predicted by the LMTD method.
So, option B is the correct answer.
Mohit said:
6 years ago
Correction factor for lmtd.
Vishal aher said:
7 years ago
What is Ft? Please explain.
Amit said:
7 years ago
What is Ft here?
Patel Nilesh Kumar said:
1 decade ago
If Q and U fix then Ft inversely proportional to the Area and number of passes increase the Area decrease so Ft increases.
Examples:
1 passes - A.
2 passes - A/2.
Examples:
1 passes - A.
2 passes - A/2.
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