Performance enhancement of an industrial desuperheater using a Ross Low-Low-Pressure-Drop (LLPD) static mixer

This study numerically investigates integrating a Ross Low-Low-Pressure Drop (LLPD) static mixer—which utilizes semi-elliptical panels joined at a 120^∘angle to achieve efficient mixing with minimal flow resistance—to enhance the thermal performance and operational robustness of an industrial desuperheater. A coupled Eulerian–Lagrangian framework is employed, combining the turbulence model with a Discrete Phase Model (DPM) to resolve the interaction between the carrier gas flow and dispersed water droplets. The impact of the LLPD mixer on the flow field, droplet dynamics, and heat and mass transfer is systematically assessed against a conventional (no-mixer) configuration. The LLPD mixer induces a strong swirling motion that substantially amplifies turbulent kinetic energy (by up to a factor of 12) and axial vorticity (by up to a factor of 130), leading to markedly improved mixing. As a result, the average particle-based heat transfer coefficient increases by approximately 35% and the desuperheating efficiency approaches 100%, compared with about 78% for the conventional design. A key outcome is the marked reduction in performance sensitivity to the initial droplet diameter. In the LLPD configuration, outlet temperature variations are limited to about 1 K, compared with up to 7 K in the baseline case, corresponding to efficiency variations of only ±2.7% versus ±29.4% for the no-mixer configuration. These findings demonstrate that the LLPD static mixer provides a highly effective and robust passive solution for improving desuperheater performance, offering enhanced thermal efficiency and strong resilience to fluctuations in atomization quality, albeit at the cost of an increased pressure drop.