Methods of Mass-Flow Characterization of Water-Glycol Mixtures Through Micro/Nano-Channels

The design of a novel micro-propulsion system for small satellites of the nano-satellites class (1–10kg) that is low-cost, non-toxic, non-flammable, and no-pressurized at launch conditions is currently being developed at the University of Arkansas. The goal of the present micro-propulsion system is to achieve milli-Newton thrust levels with specific impulses on the order of 100s. The proposed propellant is the water-propylene glycol. However, little data is available for its fluid and thermal characteristics at the gaseous state, nor the evolution of similar mixtures through micro/nano-channels. This paper will present experimental methods of measuring the mass flow rate of the water-glycol mixtures through micro/nano-channels. A MEMS fluidic chamber fabricated with a nano-channel is used to quantify the mass flow through optical tracking of liquid interfaces confined in the chamber. The dimensions of the channels are designed with the purpose to act as a passive throttling valve that prevent liquid-phase fluids from entering into the nozzle in order to achieve a simple water-based cold-gas propulsion system.