Calculation of flue gas condensation amount below the dew point
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Hello everyone, has anyone encountered a situation where the flue gas contains (unsaturated) water vapor, the temperature of the flue gas is not at the dew point, but the temperature of the pipe walls might be below the dew point? In such cases, how should the heat transfer rate and the amount of condensation be calculated? The flue gas is outside the tube, while cooling water is inside the tube.
The situation you mentioned actually involves heat conduction and phase change calculations. First, it is necessary to determine the water vapor partial pressure of the flue gas and the corresponding dew point temperature. The dew point can be determined by consulting the gas phase diagram or using relevant formulas. In your case, since the tube wall temperature is below the dew point of water vapor, the water vapor in the flue gas will condense on the tube wall. The key here is to calculate the amount of condensation on the pipe wall surface. The calculation steps can be as follows: 1. **Calculate the dew point temperature**: Determine the dew point temperature using the partial pressure of water vapor in the flue gas and relevant physical property data. 2. **Calculating the condensation amount**: The condensation amount can be estimated using calculation methods for phase-change heat transfer, based on the flue gas flow rate, the pipe wall area, and the temperature difference between the flue gas and the pipe wall. This usually involves calculating heat flux and mass transfer coefficients. 3. **Heat transfer calculation**: Latent heat is released during the condensation process, and this amount of heat can be calculated using the volume of condensate and the latent heat of water. The specific formula may need to be adjusted according to your specific application scenario and parameters. In engineering applications, calculations can usually be carried out using relevant heat and mass transfer software, or by looking up appropriate empirical formulas in engineering handbooks. If specific calculation steps or examples are needed, more parameters can be provided, such as the components of the flue gas, flow rate, pipe size, and other information. .
Thank you! I’ve also looked up a lot of information, but in cases involving condensation, the temperature must be below the dew point; otherwise, condensation shouldn’t occur theoretically. Even if the wall temperature reaches the dew point, the overall temperature of the flue gas is much higher than that dew point, so any amount of condensed liquid would evaporate