TYPES OF FLOWS
There are 2 types of flows that can be used in heat exchangers
Counter Current flow
Countercurrent exchange can achieve a greater amount of heat transfer than parallel
The temperature difference between the hot and cold fluid in the counter-current heat exchanger is maintained at a larger value compared to the co-current heat exchanger for a large part of the heat exchanger’s length
Our recommandation
Our recommandation
Counter current flow
The hot and cold fluid flow in opposite directions in the heat exchanger
This is a diagram of how counter current flow works. It shows the change in temperature from inlet to outlet of two fluids
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Red = hot
Blue =cold
This is a graph of how counter current flow works and the temperature of the different fluids from the inlet to the outlet
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Red = hot
Blue = cold
This is the expression for log mean temperature for a counter current heat exchanger.
"Log mean temperature is used to determine the temperature driving force for heat transfer in heat exchangers. LMTD is introduced due to the fact, the temperature change that takes place across the heat exchanger from the entrance to the exit is not linear."
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Source: https://www.thermal-engineering.org/what-is-logarithmic-mean-temperature-difference-lmtd-definition/
Co current flow
The hot and cold fluid flow in the same direction in the heat exchanger
This is a diagram of how co current flow works. It shows the change in temperature from inlet to outlet of two fluids.
The temperature difference between the hot and cold fluid decreases along the length of the heat exchanger from the inlet to the outlet. There is a decrease in heat transfer efficiency which requires a larger heat transfer area.
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Red = hot
Blue =cold
This is a graph of how cocurrent flow works and the temperature of the different fluids from the inlet to the outlet
​
Red = hot
Blue = cold
This is the expression for log mean temperature for a co current heat exchanger.
"Log mean temperature is used to determine the temperature driving force for heat transfer in heat exchangers. LMTD is introduced due to the fact, the temperature change that takes place across the heat exchanger from the entrance to the exit is not linear."
​
Source: https://www.thermal-engineering.org/what-is-logarithmic-mean-temperature-difference-lmtd-definition/