The ever-increasing demand for high-recovery thermal desalination systems has highlighted critical gaps in thermodynamic modeling accuracy, particularly regarding boiling point elevation (BPE) effects. This study comprehensively quantifies the systematic errors introduced by BPE neglect in multi-effect desalination (MED) systems. Three distinct MED technologies—conventional MED with external heat sources (geothermal, steam, hot water), MED with thermal vapor compression (MED-TVC), and MED with mechanical vapor compression (MED-MVC)—were modeled and evaluated across recovery ratios from 20 % to 88 % with feed salinity of 35 g/kg utilizing different configurations. The results reveal significant systematic deviations in vapor compression systems when BPE effects are neglected. MED-MVC systems demonstrate the most severe prediction errors, with total power consumption (TPC) underestimated by 37.8 % and second-law efficiency overestimated by 62.1 % at 88 % recovery ratio. MED-TVC systems show substantial yet slightly lower sensitivity, with TPC underestimation reaching 30.6 % and efficiency overestimation of 33.1 % under similar conditions. Conversely, conventional MED systems exhibit negligible sensitivity with errors consistently below 0.03 % across all recovery ratios and configurations. The economic implications are severe, with capital cost underestimations reaching $1.4 million for MED-MVC systems and annual energy cost miscalculations of $13.9 million for typical installations. Critical operating thresholds are established at 70 % recovery ratio for MED-MVC and 80 % for MED-TVC systems, beyond which BPE neglect creates commercially unacceptable prediction errors. This study establishes definitive evidence for mandatory BPE correction in high-recovery vapor compression MED applications and provides technology-specific sensitivity guidelines for accurate performance prediction and reliable economic projections in the rapidly expanding desalination industry. © 2025 Elsevier B.V.

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