WATER RECOVERY WITH THE HEAT MELT COMPACTOR IN A MICROGRAVITY ENVIRONMENT

The Heat Melt Compactor is a proposed utility that will compact astronaut trash, extract the water for eventual re-use, and form dry square tiles that can be used as additional ionizing radiation shields for future human deep space missions. The Heat Melt Compactor has been under development by a consortium of NASA centers. The downstream portion of the device is planned to recover a small amount of water while in a microgravity environment. Drop tower low gravity testing was performed to assess the effect of small particles on a capillary-based water/air separation device proposed for the water recovery portion of the Heat Melt Compactor. KEY WORDS: Life Support, Heat Transfer, Condensation 1. INTRODUCTION In order to complete long-term human deep space missions, many resources are required to support humans and logistics operations of the spacecraft. Due to the isolation of the spacecraft from earth, and the impracticality of periodic resupply from earth, solutions must be found for providing all the resources. The ideal solution to provide those resources is to reuse and repurpose the resources. Among the efforts to develop such technology to reuse resources is the heat melt compactor (HMC) project. The HMC separates water from trash used by astronauts by evaporating the water within the compactor and then condensing it downstream from the compactor [1]. The water is then condensed and separated from the gas and residual vapor in a dedicated condenser and dedicated separator, or in a combined condenser/separator. The water is then directed to a water re-processing unit for chemical purification and processing, which makes the water useable. This paper discusses one aspect of the separator unit: the operation in microgravity with particles that may possibly degrade a capillary-based separator. The main challenge in separating the liquids from the gases arises because of the lack of gravity while in space. On Earth, the greater density of liquids compared to gases causes the liquids to sink to the bottom of a container while the gases rise. However, in space, where there is no gravity to separate the two phases alternate forces must be applied such as capillary action. The capillary separator and HMC have been investigated by other researchers [2], [3]. A concern for using a capillary separator is contamination with small solid particles that may impede the capillary-driven liquid flow through the separator and cause the separator to be inefficient or non-functional. This paper reports on the observation of silicone oil mixed with solid glass beads inside a wedge while in microgravity conditions. The testing device is called an angular liquid bridge (ALB) vessel. The ALB was an experiment performed on board the MIR space station by astronauts in order to examine capillary flow in microgravity. The ALB hardware was an astronaut training unit and brought out of storage for this drop tower testing. Microgravity