I am currently working on desalination project for my final year. The design is based on flashing of hot liquid in low pressure vessel and then condensing the extracted the steam to produce pure water.
The problem I am facing is that there doesn't seem to be any thermodynamic data (under saturation dome) available for saline water. The need for saturation data is because I need to calculate the required mass flow rate based on daily desalination goal.
For example, if the goal is to produce 100 L/day with average sunlight of 8 hrs, then desalination rate must be 0.0035 kg/s. If I know the quality (percentage of steam produced) of the liquid gas mixture, I can easily calculate the mass flow rate of saline water corresponding to desalination goal.
The only data I could find related to this problem was from a MIT resource Thermophysical properties of seawater, but unfortunately it only provides a single value for enthalpy at any given saturation temperature or pressure.
Right now, I can see only three options:
- Use steam table, and consider the values an approximation and incorporate the error produced in my design by slightly overdesigning
- Consider the enthalpy of seawater (from MIT resource) as enthalpy of saturated liquid (i.e. $h_f$), and enthalpy of vapor (from steam table) as $h_g$ and then perform my calculations
- Thirdly, I could take the enthalpy of seawater (from MIT resource) as the value that is halfway between $h_f$ and $h_g$ (from steam table), and then calculate the approximated value of $h_f$.
$h_f=$ Enthalpy at saturated liquid line; $h_g=$ Enthalpy at saturated vapor line
Any help/guidance in this regard will be highly appreciated