Refrigerant Vapor Quality Sensor

Navy SBIR 21.1 - Topic N211-090
ONR - Office of Naval Research - Ms. Lore-Anne Ponirakis -
Opens: January 14, 2021 - Closes: February 18, 2021 (12:00pm EDT)

N211-090 TITLE: Refrigerant Vapor Quality Sensor

RT&L FOCUS AREA(S): Directed energy; General Warfighting Requirements

TECHNOLOGY AREA(S): Ground / Sea Vehicles

OBJECTIVE: Develop a low-cost, high-speed sensor and instrumentation to measure refrigerant quality in an electronics cooling system.

DESCRIPTION: Two-phase cooling systems using pumped refrigerant loops are being developed to remove heat from high-powered electronic systems. These thermal systems would benefit from monitoring the relative mass fractions of liquid and vapor phases (quality) in a saturated mixture, for future system optimization and assurance of safe operation in harsh environmental and transient operational conditions. Capacitance and impedance techniques can be used for volume averaged void fraction measurements, but these techniques are limited by their relatively low spatial resolution and the accuracy of the reconstructed image, and are not readily available to utilize for platform applications. Laboratory experiments rely on complex, expensive instrumentation to measure quality, such as image analysis or liquid-vapor separators. Measurement of the spatial and temporal variation of quality also allow for a characterization of flow regimes, which can be used to predict heat transfer performance. Such techniques are not easily translated to fielded systems that may require hundreds of such sensors operating at frequencies greater than 100 Hz for integration into the control system.

The goal of this SBIR topic is to design and fabricate a non-invasive, high-speed instrument to measure refrigerant quality in an operational, military electronics cooling system. The electronics cooling system shall be able to use the instrument measured refrigerant quality as a controls parameters. The instrument shall be able to assess vapor qualities as high as 0.80 and operate under dynamic platform motion as defined by DOD-STD-1399/301a. The instrumentation shall be waterproof and vibration resistant and should be able to interface with control systems through standard software communication protocols such as Modbus.

PHASE I: Develop a design for an instrument to measure refrigerant vapor quality. The sensor should not exceed 25 lbs per-unit-weight and 1 cu ft volume size. Validate design performance through analytical modeling and subscale demonstration for vapor qualities up to 0.80. Ensure that the system maintains proper operation when subjected to ship motion dynamics (DOD-STD-1399/301a). Perform rough manufacturing cost analysis. Develop a Phase II plan.

PHASE II: Refine Phase I design and fabricate prototype instrument, including software interface to commercial platforms. Ensure that the system is capable of monitoring at least 10 independent sensors. Demonstrate operation in a pumped refrigerant loop using R134a over vapor qualities of 0.0 to 0.80. Perform more detailed manufacturing cost analysis.

PHASE III DUAL USE APPLICATIONS: Develop final design and manufacturing plans using the knowledge gained during Phases I and II in order to support transition of system to Navy platforms. Ensure that the final system meets Navy unique requirements, e.g., shock, vibration, and electromagnetic interference (EMI). The development of refrigerant quality sensors capable of operating under dynamic motion associated with shipboard installation has commercial applications that include cooling of electric vehicles and commercial vessels.


  1. Caniere, H., T'Joen, C., Willockx, A. and De Paepe, M. "Capacitance signal analysis of horizontal two-phase flow in a small tube." Exp. Thermal Fluid Sci. Volume 32, Issue 3, 2008, pp. 892–904.
  2. Valiorgue, P., Ritchey, S.N., Weibel, J.A. and Garimella, S.V. "Design of a non-intrusive electrical impedance-based void fraction sensor for microchannel two-phase flows." Meas. Sci. Technol. 25, 095301, 2014.
  3. Roman, A.J., Kreitzer, P.J., Ervin, J.S., Hanchak, M.S. and Byrd, L.W. "Flow Pattern Identification of Horizontal Two-Phase Refrigerant Flow Using Neural Networks." Int. Comm. Heat Mass Transfer 71, 2016, pp. 254-264.
  4. Department of the Navy, Naval Sea Systems Command, DOD-STD-1399/301a, "Ship Motion and Attitude." (21 July 1986).

KEYWORDS: Electronics Cooling; Two-Phase Cooling System; Vapor Quality; Pumped


The Navy Topic above is an "unofficial" copy from the overall DoD 21.1 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its 21.1 SBIR BAA pre-release on December 8, 2020, which opens to receive proposals on January 14, 2021, and closes February 18, 2021 at 12:00 p.m. ET.

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