Combined Plant and Control Design for a Flash Boiling Cooling System

Flash boiling is a phase change cooling mechanism with the potential to meet stringent transient thermal management performance specifications across a range of applications. However, the dynamics of flash boiling are extremely fast and nonlinear and therefore create challenges in modeling and controlling a novel cooling system based on flash boiling. More specifically, the system is not only underactuated, but without the ability to measure vapor transport, sensing is limited too. Therefore, in this work we propose the use of combined plant and control design, or co-design, optimization to design both key process parameters and an optimal open loop control signal for this batch process. We use first principles to derive a nonlinear dynamic model of the system that captures both the pressure dynamics and vapor mass transport dynamics of the two-phase mixture created during the flash boiling process. We then formulate and solve a nonlinear co-design optimization problem and demonstrate efficacy of the proposed approach through simulation results.