Consider a parallel-flow heat exchanger, which is used to cool oil from 70°C to 40°C using water available at 30°C. The outlet temperature of the water is 36°C. The rate of flow of oil is 1 kg/s. The specific heat of the oil is 2.2 kJ/kg K. The overall heat transfer coefficient U = 200 W/m2 K.
The logarithmic mean temperature difference can be calculated simply using its definition:
- Area of Heat Exchanger
To calculated the area of this heat exchanger, we have to calculate the heat flow rate using mass flow rate of oil and LMTD.
The required area of this heat exchanger can be then directly calculated using general heat transfer equation:
Example – Problem with Solution. Calculation of Heat Exchanger