In which case LMTD will be same for parallel and counter flow arrangement?

The same effect would be achieved without phase change if Cc >> Ch and the LMTD will remain the same for both parallel flow and counter flow exchangers. And in that case, LMTD should be replaced by DTa DTb, and the temperature profiles of the two fluids along Its length would be parallel straight lines.

What is LMTD and LMTD correction factor can LMTD be zero What happen if that condition occurs?

The LMTD is a logarithmic average of the temperature difference between the hot and cold feeds at each end of the double pipe exchanger. For a given heat exchanger with constant area and heat transfer coefficient, the larger the LMTD, the more heat is transferred.

Why is LMTD higher in counter flow?

The counterflow LMTD is used because it is undoubtedly believed that its value for two countercurrent streams is higher than when the same streams are arranged in concurrent flow.

Why LMTD of counter flow is greater than parallel flow?

Most classical heat transfer textbooks state that under an identical situation a counter flow heat exchanger has a higher value of LMTD than a parallel flow one. Consequently, for exactly the same inlet and outlet hot and cold fluid temperatures, the counter flow heat exchanger requires a smaller heat transfer area.

What does negative LMTD mean?

Zero LMTD means no further heat transfer is possible and if heat transfer is to be done than infinite area is required, which is not possible. Hope it will help you.

Why LMTD is used instead of arithmetic mean?

, Math Lover. We use LMTD instead of average temperature in heat exchanger because we concern about both inlet and outlet temperature of both hot and cold fluids . Because of which, LMTD came into use. In LMTD, we include all the inlet and outlet temperature of both hot and cold fluids.