Brazed-plate heat exchangers (BPHEs) serve as essential recuperators in organic Rankine cycle (ORC) systems, which convert waste heat and low-grade thermal resources into electricity. However, the complex corrugated internal passages that enhance heat transfer also create a computational barrier: simulating a full-scale BPHE requires approximately 200 million mesh cells, making routine CFD analysis impractical for engineers and manufacturers.
Researchers have now introduced a validated domain-reduction strategy that cuts the computational mesh to just 4.5 million cells—a 44-fold reduction—while preserving prediction accuracy. The method isolates a single exchange unit (one vapor channel and one liquid channel separated by a heat-transfer plate) and further simplifies the geometry by truncating to the fully developed flow region and approximating the corrugation profile with a trapezoidal shape.
Validation was conducted using experimental data from a micro-scale ORC test rig operating with refrigerant R134a across five steady-state conditions, covering mass-flow rates from 0.08 to 0.22 kg/s and Reynolds numbers spanning 500 to 18,500. Temperature predictions from the reduced-domain CFD matched experimental measurements to within 1–10%, demonstrating reliable accuracy.
From this validated platform, the researchers derived single-phase Nusselt-number correlations applicable to the liquid phase (500 < Re < 1400) and vapor phase (6000 < Re < 18,500). These correlations provide engineers with design-oriented tools to estimate heat-transfer performance without running full CFD simulations.
The approach significantly accelerates preliminary assessment of BPHE recuperators during the design phase, reducing the barrier to CFD adoption in ORC development. Broader industrial applicability will require validation across additional geometries, operating conditions, and model formulations, but this foundation establishes a practical pathway for computational thermal design in distributed power and industrial waste-heat recovery applications.
