Thermo-economic analysis of low-grade heat driven multi-effect distillation based desalination processes

We examine the economic viability of three multi-effect distillation (MED) based processes against the MED as a benchmark, when they are driven by low grade heat. We model and compare the Boosted MED (BMED), Flash Boosted MED (FBMED) and Distributed Boosted MED (DBMED) processes with the MED in terms of waste heat performance ratio, specific capex and opex. All three new configurations generate significantly higher productions than MED with higher capex and opex investment. We provide the corresponding cash-flow analyses using such financial metrics as the Net Present Value (NPV) and Internal Rate of Return (IRR). This study leads to the conclusion that the DBMED process is the superior scenario up to an interest rate of 12.5% at 65 °C heat source supply temperature which then drops to 8.4% at 90 °C heat source supply temperature. Also, the analysis shows for the high interest rates (above 8.4% at 90 °C), MED has higher NPV compared to other MED based processes.