26-04-2012, 04:27 PM
Newton's Law of Cooling
According_to_Newton.doc (Size: 166 KB / Downloads: 61)
Mean Temperature Difference
The the mean temperature difference in a heat transfer process depends on the direction of fluid flows involved in the process. The primary and secondary fluid in an heat exchanger process may
• flow in the same direction - parallel flow or cocurrent flow
• in the opposite direction - countercurrent flow
• or perpendicular to each other - cross flow
Logarithmic Mean Temperature Difference - LMTD
The rise in secondary temperature is non-linear and can best be represented by a logarithmic calculation. A logarithmic mean temperature difference is termed
• Logarithmic Mean Temperature Difference or LMTD or DTLM
LMTD can be expressed as