This paper presents results of a novel expansion device refrigerant flow control mechanism called vortexcontrol. The key advantage of this control mechanism is being far less vulnerable to clogging thanconventional expansion devices since the flow control is achieved without having to adjust thecross-sectional flow area in order to achieve the desired modulation effect. Vortex flow control is seen asparticularly promising when applied to transcriticalR744 ejectors, where flow control of the motive nozzle isknown to substantially impact ejector and cycle efficiencies. Vortex control can potentially offer theadvantage that overall ejector efficiency is less impacted than designs where a needle is used to modulate themotive nozzle flow. The effects of operating conditions were investigated experimentally. It is shown thatvortex flow control appears to be feasible for two-phase ejectors using R744 and similar flow modulationranges as with needle control were achieved.
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