Improved CFD simulation of water hammer caused by condensation with an enhanced phase change model

Condensation-Induced Water Hammer (CIWH) is a unique occurrence frequently observed within steam systems. In the context of steam piping and equipment, when steam undergoes condensation, it experiences a phase transition from gas to liquid. This transformation results in a sudden reduction in liquid volume, subsequently triggering a pressure shock wave within the piping—thus giving rise to condensation-induced water hammer. In this research, we employ numerical simulations to replicate the phenomenon of condensation-induced water hammer in a horizontal pipe. We employ the enhanced phase change model (L-H model) in combination with the CFD software FLUENT. The model is validated against experimental data from PMK-2. Moreover, we conduct a localized sensitivity analysis, varying parameters such as pipe diameter, inlet water temperature, inlet mass transfer rate (mass flow rate), and system pressure. This endeavor aids in gaining a deeper comprehension of the intricacies of condensation-induced water hammer. Our findings indicate that augmenting the high-temperature pipe diameter, inlet water temperature, and inlet mass flow rate leads to an escalation in both peak pressure and mass transfer rate within the flow field. Conversely, enlarging the low-pressure pipe diameter, inlet water temperature, and inlet mass flow rate results in irregular fluctuations in peak pressure and mass transfer rate within the flow field. Furthermore, elevating the system pressure leads to a reduction in both peak pressure and mass transfer rate within the flow field. The utilization of numerical simulations to analyze condensation-induced water hammer has substantial implications for engineers tasked with designing safer and more dependable systems. This knowledge equips them to implement appropriate measures for mitigating the impacts of water hammer phenomena. Furthermore, this study furnishes critical insights into the stability of liquid transport and piping systems across a spectrum of industries, including the energy sector, water supply systems, process engineering, and beyond.