Thermodynamic difference issue in seawater desalination
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What is the minimum possible temperature difference for heat transfer across each stage in the low-temperature multi-effect seawater desalination process? Also, what happens to the temperature difference as the efficacy increases? Thank you!
As far as I know now, the temperature difference for heat transfer over a distance is as low as 1.5 to 2 degrees Celsius. In multi-effect distillation at low temperatures, the maximum evaporation temperature of seawater is below 70 degrees Celsius. By making full use of the energy of the steam, the minimum temperature in the final condenser is generally around 40 degrees Celsius; in other words, the total temperature difference is about 30 degrees Celsius. As the number of effect stages increases, it is obvious that the temperature difference decreases. However, this also depends on the specific conditions of the project; if the number of effect stages is low, then the temperature at the last stage can be increased accordingly.