Articles techniques et présentations

Accurately modelling heat exchangers with complex heat transfer phenomena is critical for system optimization and improvement. In this abstract, we present a simulation of a heat exchanger for the supercritical water gasifiation (SCWG) of aqueous waste using the COMSOL Multiphysics® software. Supercritical conditions are crucial in various industrial processes, such as power generation or chemical production. One interesting application of supercritical water is in the process of recycling material from aqueous waste. iGas Energy has developed a process that returns nutrients, valuable substances, and energy contained in aqueous wastes such as liquid manure, sewage sludge, fermentation residues, etc. through SCWG. The simulation considers phase change and thermophysical properties such as density, specific heat, and thermal conductivity of the supercritical fluid, which vary significantly with temperature and pressure near the critical point. The heat exchanger geometry, including customized plates, and appropriate boundary and operating conditions are defined in COMSOL Multiphysics®. The simulation uses an appropriate fluid flow and heat transfer interface that considers both solid and fluid heat transfer modes. The supercritical fluid is defined as a function, and ramping is applied to improve convergence. The simulation results provide insights into the temperature, velocity, and pressure distribution, enabling optimization of the heat exchanger's design and operating conditions.