Why log mean temperature difference is used?
The logarithmic mean temperature difference (also known as log mean temperature difference, LMTD) is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers.
What is LMTD and NTU?
The Number of Transfer Units (NTU) Method is used to calculate the rate of heat transfer in heat exchangers (especially counter current exchangers) when there is insufficient information to calculate the Log-Mean Temperature Difference (LMTD).
What is the significance of NTU?
NTU means number of transfer units. It signifies that the heat transfer capacity of a given heat exchanger. NTU signifies how much number of units of heat, the given heat exchanger is capable of transferring from one fluid to other.
What do you mean by LMTD & NTU method?
How do you calculate Cv valves?
Cv by definition is the number of gallons per minute (GPM) a valve will flow with a 1 psi pressure drop across the valve. For example a valve with a Cv of 10 will flow 10 GPM with a 1 psi pressure drop. The formula used to select the valve Cv with the specified differential pressure is: Cv=GPM/((SQ RT(∆P)).
What is Cv value of valve?
What is Cv value? The valve flow coefficient according to the JIS standard, represents the flow capacity in US gallons/minute of 60° F pure water when it is flowing through the valve with a pressure difference of 1 psi at the specified travel (operation range).
Why LMTD is used instead of normal temperature difference?
Because, LMTD is a temperature difference of hot fluid and cold fluid. It means LMTD is a driving force for the heat transfer. So there is a basic criteria that minimum temperature difference between hot fluid and cold fluid is 3degree for the shell and tube heat exchanger.
Why we use LMTD instead of arithmetic mean?
The log mean temperature difference (LMTD) is used to determine the temperature driving force for heat transfer in flow systems, most notably in heat exchangers. The use of the LMTD arises, straightforwardly, from the analysis of a heat exchanger with constant flow rate and fluid thermal properties.
