A supercritical CO2 thermoacoustic pump is a novel device driven by periodic pressure oscillations from a thermoacoustic engine, which employs check valves to rectify the oscillatory flow for directed transport of the working fluid. Given the inherent advantages of thermoacoustic engines, including no moving parts and structural simplicity, it is essential to develop check valves of simplicity and high reliability to preserve these system-level benefits. This work proposes and evaluates two check valve concepts through numerical and experimental studies. The first is a no-moving-part check valve based on topology optimization. It generates optimized solid flow-disturbing structures within a design domain to achieve rectification via asymmetric flow resistance. Numerical results indicate that orifice-like structures within the flow path are a key contributor to enhanced diodicity. However, experiments reveal that under the high-amplitude pressure oscillations typical of thermoacoustic pumps, its performance remains limited. The second concept incorporates a simple spherical moving element (ball-type check valve). Its performance was significantly improved by optimizing the valve seat profile, adding a low-stiffness spring, and controlling the ball stroke. Consequently, this design delivers rectification performance comparable to the reference precision check valve. In summary, this study delineates two design pathways for check valves in supercritical CO2 thermoacoustic pumps: a fully no-moving-part approach and a simple moving-part approach. The former suits applications prioritizing ultimate reliability and maintenance-free operation, while the latter offers improved rectification with only a modest complexity increase. The conclusions provide clear guidance for optimizing check valves in thermoacoustic pumps and related devices.
Guo et al. (Fri,) studied this question.
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