Direct Contact Ultrasonic Drying Rate and Efficiency Investigation for Spacecraft Solid Waste Management

Abstract

The goal of our study is to investigate the drying performance of the direct contact ultrasonic drying for bagged human solid waste relevant to the current waste management system at the ISS. Unlike the conventional thermal drying methods, the direct contact ultrasonic drying does not use heat nor evaporate water and therefore is not bound by the high energy input required for water vaporization. This novel method of drying mechanically removes water by shaking the object rapidly (on a micron-scale) using piezoelectric transducers. Water is removed in the form of cold mist (atomized water). By bypassing the evaporation process, the technology demonstrates a much higher efficiency and drying speed on a bagged human solid waste. In this paper, we will report the ultrasonic drying performance of the simulated feces on multiple piezoelectric transducers across a membrane under different configurations. The result of this study could potentially help to design a better solid waste management system for ISS.