Recovering energy from low-grade saturated industrial steam remains a significant thermodynamic challenge because of the dominance of latent heat, which makes conventional sensible-heat recovery systems ineffective. To make use of this underused resource, this study introduces a tri-generation system that combines an Organic Rankine Cycle (ORC), a Humidification–Dehumidification (HDH) desalination unit, and a silica-gel Adsorption Cooling System (ACS) in a fully decoupled parallel setup. The ORC acts as a thermal conditioner, capturing a large amount of latent energy from the steam source, converting it into electricity, and producing a steady 85°C subcooled condensate stream that powers the HDH and ACS units. The system is designed to operate effectively across a wide range of conditions (source temperatures from 90 to 150°C and steam qualities from 0.05 to 0.97), ensuring its versatility for various real-world applications. A hybrid MATLAB–Engineering Equation Solver (EES) computational framework was utilized to simulate the multi-physics integration. The model reliability was established through subsystem-level validation against experimental datasets, yielding a Mean Absolute Percentage Error (MAPE) of less than 7.5% for individual components. Thermodynamic analysis reveals that ORC performance is susceptible to steam quality; net power output surges from 213 kW to 1299 kW at 150°C as steam quality rises from 0.05 to 0.97. Notably, the ORC thermal efficiency remains stable across varying loads, driven by flowrate scaling rather than state-point shifts. Regarding the bottoming cycles, the HDH unit was optimized at a Mass Ratio (MR) of 2, achieving a peak Gain Output Ratio (GOR) of ≈1.8. Crucially, a unified optimal operating window was identified within the 20–30% heat allocation range, where desalination performance aligns with the ACS maximum Coefficient of Performance (COP ≈ 0.5). Consequently, the integrated framework amplifies the Energy Utilization factor (EUF) for overall system from a baseline of 7.27% (stand-alone ORC) to a peak of 53.09% at 90°C (compared to 33.2% at 150°C) under the water-prioritized Configuration A (95% HDH / 5% ACS allocations with maximum seawater flow), effectively converting the entire latent heat content into valuable outputs. The techno-economic assessment demonstrates exceptional commercial viability. At high steam quality (0.97), the Levelized Cost of Electricity (LCOE) drops to 0.0094 $/kWh at 150°C and 0.0128 $/kWh at 90°C. Additionally, Levelized Costs of Water (LCOW) and Cooling (LCOC) settle at 0.22–0.38 $/m3 and 0.036 $/kWh, respectively. Profitability analysis indicates rapid returns, with payback periods falling below 2 years for high-quality steam. Finally, addressing the dynamic nature of real-world operations, a comprehensive annual optimization was conducted for New Borg El-Arab City. By defining the Total Annualized Cost (TAC) as the sole objective function, the study evaluated 28,800 design combinations under variable monthly ambient temperatures and facility demands. This rigorous search identified the “Balanced Configuration” (150°C, 0.9, 40% HDH / 60% ACS allocation) as the global minimum-cost solution. This configuration, utilizing seawater and chilled water flow rates of 3 kg/s and 0.7 kg/s, respectively, offers the most robust strategy for satisfying dynamic facility demands while minimizing grid interaction. |
