Consider a parallel-flow heat exchanger 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, and 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 calculate the area of this heat exchanger, we have to calculate the heat flow rate using the mass flow rate of oil and LMTD.
The required area of this heat exchanger can be then directly calculated using the general heat transfer equation:
Example – Problem with Solution. Calculation of Heat Exchanger