Void Fraction Sensor for Packed-Bed Reactors in Microgravity

The innovative product resulting from this project is an instrument to measure void fraction in packed-bed reactors. As NASA pursues long-duration crewed missions, it will be necessary to adapt packed-bed chemical processing methods to reduced gravity to minimize the mass and volume of consumables carried from earth. Accurate measurement of void fraction is critical to (1) identify the flow regimes, and (2) quantify the liquid holdup for design and performance calculations. At present, there is no simple, easy-to-use instrument for microgravity. Capacitance-based sensors have several advantages including the potential to be very sensitive to liquid held up in the reactor, not intrude into the flow, and provide high rates of data sampling. With the conductive fluids used in reactors, a new signal-conditioning scheme is needed for capacitance-based measurements of void fraction. We will develop the new signal-conditioning scheme with an adapted version of a unique capacitance sensor previously developed at Creare. During Phase I we will prove the feasibility of the new signal-conditioning electronics using a multiphase flow facility. During Phase II we will develop the electronics package, adapt the sensor mechanical design to the configuration of packed-bed reactors, and demonstrate the prototype under packed-bed flow conditions.