Pumped Two-Phase Quality Sensor
Pumped two-phase (P2P) cooling systems are a commonly used thermal architecture that offers significant performance benefits over single-phase systems such as higher heat transfer coefficients and reduced fluid flow rates. A major challenge seen by P2P systems is the desire for optimal steady-state operation despite transient changes in heat load, which can be mitigated by sensing the quality of the two-phase flow present in the system. ACT has developed a novel, capacitance-based P2P quality sensor capable of registering across a quality range of 0 to 1 with a high degree of accuracy. The developed sensor solution is non-invasive as it allows the fluid to flow through without additional pressure drops or other flow disturbances. It is a simple and robust design, which is inexpensive and scalable to various tube diameters and working fluids.
Advanced P2P Evaporator
Pumped Two-Phase (P2P) systems are known for their ability to transport high heat loads by evaporating and condensing a coolant that flows through channels adjacent to the heat source. These systems rely on flow boiling, which has a limitation on the maximum heat flux achieved and can be affected by flow instabilities. Capillary systems, another thermal architecture, also rely on evaporation but from wicked structures rather than flow channels. In such devices, they can achieve heat fluxes as high as 1000W/cm² but are limited by the liquid supply to the wick. ACT’s Advanced P2P Evaporator, referred to as the Hybrid Evaporator, merges the benefits of mechanically pumped systems with those related to capillary evaporation from wicked structures. This combination results in a thermal management system capable of addressing high heat fluxes and transporting high heat loads, thereby outperforming existing two-phase systems. Recently, ACT has demonstrated significant size, weight, and power (SWaP) reduction when switching from a channel-cooled P2P system to a Hybrid P2P system.
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Plasma-Powder De-Oxidation
Plasma, the fourth state of matter, is a highly reactive state that can be used to enhance or assist various chemical processes. Low-temperature plasma (LTP) creates a set of circumstances that enable chemical reactions without the adverse effects of material decomposition, melting, agglomeration, or sintering. One such chemical reaction is the reduction of metal oxides to form metal and water (MxOy → M+ H2O). Metal particles are used in a host of applications including energetic materials and 3D printing (i.e., additive manufacturing). When used (or even stored or transported) for these applications, the inherently thin layer of metal oxide on each particle surface grows, thereby changing the chemical and mechanical properties of the powders and any macro-scale parts manufactured from those powders. ACT is currently developing an LTP process that can reduce metal oxides from metal powders. Oxide content can be reduced as a pre-treatment prior to utilization/fabrication processes or as a post-treatment recycling process afterward. Oxides can be removed from metals and metalloids including copper, aluminum, steel, nickel alloys, and boron. If desired, ACT can also apply a plasma-enhanced chemical vapor deposition (PECVD) technique immediately after the LTP metal oxide reduction to passivate the reduced oxide particles. This PECVD passivation layer protects the particles from reoxidation during transport and storage in ambient conditions.
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