Chemical Engineering - Heat Transfer - Discussion
Discussion Forum : Heat Transfer - Section 1 (Q.No. 45)
45.
Pick out the wrong statement.
Discussion:
1 comments Page 1 of 1.
Boddhi said:
2 years ago
In the case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply when a temperature cross occurs."
The statement is incorrect. In a 1-2 shell and tube heat exchanger, a temperature cross occurs when the hot and cold fluids switch positions within the heat exchanger. It means that at some point along the length of the heat exchanger, the cold fluid becomes hotter than the hot fluid.
When a temperature cross occurs, the log mean temperature difference (LMTD) correction factor value decreases rather than increases sharply. The LMTD correction factor is used to account for the deviation from the ideal counterflow or parallel flow patterns in a heat exchanger. In a temperature cross scenario, the LMTD correction factor is less than 1, indicating that the actual heat transfer rate is lower than that predicted by using the LMTD for counterflow or parallel flow.
The statement is incorrect. In a 1-2 shell and tube heat exchanger, a temperature cross occurs when the hot and cold fluids switch positions within the heat exchanger. It means that at some point along the length of the heat exchanger, the cold fluid becomes hotter than the hot fluid.
When a temperature cross occurs, the log mean temperature difference (LMTD) correction factor value decreases rather than increases sharply. The LMTD correction factor is used to account for the deviation from the ideal counterflow or parallel flow patterns in a heat exchanger. In a temperature cross scenario, the LMTD correction factor is less than 1, indicating that the actual heat transfer rate is lower than that predicted by using the LMTD for counterflow or parallel flow.
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