Advanced Mechanical Design and Efficiency Analysis of Waste Heat Recovery Systems

Abstract

Industrial manufacturing, power generation, and heavy chemical processingplants dissipate more than one-third of their primary energy inputs as low-grade and high-grade waste heat through exhaust gases, cooling waterstreams, and structural radiation. Waste Heat Recovery Systems (WHRS),particularly those based on Organic Rankine Cycles (ORC) and advancedshell-and-tube heat exchangers, present a highly viable pathway towardreducing thermodynamic irreversibility, improving overall plant thermalefficiency, and curbing greenhouse gas emissions. This research paperpresents a comprehensive study on the advanced mechanical design andthermal efficiency analysis of an optimized ORC-based WHRS integrated intoan industrial cement manufacturing facility. A multi-variable analytical modelcoupled with three-dimensional Computational Fluid Dynamics (CFD) andFinite Element Analysis (FEA) was established to evaluate structural integrity, aerodynamic flow behavior, and heat transfer performance across varying operating parameters. The mechanical design features a specialized helical baffle configuration within the primary gas-to-fluid heat exchanger to mitigate standard pressure-drop penalties while maximizing structural resonance safety under high-velocity exhaust conditions. The performance efficiency analysis demonstrates that optimizing working fluid selection (R245fa versus Cyclopentane) and mechanical baffle pitch angles yields a peak thermal efficiency increase from 14.2% to 18.7%, with an overall network output of 1.24 MW from a 7.5 MWth waste heat stream. Structural evaluation validates that the peak von Mises stress (112.4 MPa) remains well below the allowable yield limit for high-temperature structural steel (ASTM A387 Grade 22), ensuring an operating lifespan exceeding 15 years under cyclical thermal loads. The results provide highly granular, journal-level guidelines for engineering deployment, demonstrating that modern numerical optimization can effectively resolve the classical trade-off between heat transfer enhancement and fluid pumping power requirements. KEYWORDS: Waste Heat Recovery Systems (WHRS), Organic Rankine Cycle (ORC), Mechanical Design Optimization, Computational Fluid Dynamics (CFD), Thermal Efficiency Analysis, Shell-and-Tube Heat Exchanger.