Multi-effect Distillation Seawater Desalination System Thermal-Dynamic Calculation Research

With economic development, population growth and over-exploitation ofgroundwater resources, the shortage of freshwater has restricted the sustainabledevelopment of China society and economy. Desalination as a new supply of wateris one of the key way to solve the water scarcity problem. To developenergy-efficient technology is our prerequisite for our desalination business.Multi-effect distillation(MED) desalination is the rapid development of thermaltechnology; particularly used in the independent water and power production projects.Low-temperature multi-effect distillation technology is the future direction for thedevelopment of seawater desalination.The main MED thermal process include seawater(brine), steam and distillateflow, heat transfer, evaporation, condensation; thermal calculation of these processesis the basic content of performance analysis, optimization, and design. And also thethermal calculation is the research and development foundation of desalinationtechnology.In this paper, the calculation method for the heat and mass transfer within theevaporation process, the process of condensation heat, mass transfer and pressuredrop in the MED horizontal tube falling film evaporators has been carried out. Afterthe detailed analysis and comparison, the suitable engineering application ofcomputational model has been got. The internal thermodynamic analysis of theprocess in detail has been done. For the practical engineering application, the mainthermodynamic parameters have been decided. The thermal process model andMED thermal performance calculation method has been established.