Browsing by Author "Wang, Dan"

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Graphene-Copper Hybrid Thermal Straps for Cryogenic Instruments and Optical Systems
(2024 International Conference on Environmnetal Systems, 2024-07-21) Wang, Dan; Hall, Timothy; Snyder, Stephen; Inman, Maria; Godwin, Jessica; Roberts, Nick
The development of next generation materials with enhanced thermal and/or electrical conductivity will be beneficial for both terrestrial and space applications, ranging from thermal links for conduction cooling of cryogenic instruments and optical systems, mirror substrates for space telescopes, coolant tubes for heat exchangers and deployable radiators, space landing systems, to high powered electronics and beyond. The cryogenic cooling systems are essential for the advancement of terrestrial and space's science goals, which enable new capabilities on sensors, detectors, and accelerators, such as for near- and mid-IR instruments on SmallSats and CubeSats for Earth and Lunar observations, for cooling of far- and mid-IR optics, and for extracting heat dissipation of superconducting radio frequency cavity. High conductive thermal straps play a critical role in balancing heat dissipation and reaching the operating temperature of the instruments. The sluggish conduction cooling rate of conventional thermal straps made from copper, aluminum, or graphite hinders the application of thermal straps on the cryogenic cooling systems. Within this context, we will discuss an efficient, scalable, manufacturing-ready approach to produce high conductive graphene-copper hybrid foils and demonstrate their application in thermal straps for the conduction cooling of cryogenic instruments and optical systems. This technology utilizes the intrinsic physiochemical, thermal, and mechanical properties of graphene and copper matrix, combined with advanced electrodeposition techniques for hybrid material fabrication. An innovative manufacturing process based on the use of pulsed electric fields and the combination of electrodeposition and electrophoretic deposition (EPD), have been developed for controlled, reproducible, scalable production of graphene-copper hybrid foils/coatings. The hybrid exhibited enhanced conductivity and mechanical strain for fast conduction cooling processes. Next step, we will work on the thermal strap fabrication using synthesized graphene-copper hybrid foils and their performance evaluation. Acknowledgements: The financial support of DOE SBIR program through grant No. DE-SC0021676 (Phase I&II) is acknowledged.
In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection
(50th International Conference on Environmental Systems, 7/12/2021) Vijapur, Santosh; Hall, Timothy; Taylor, E. Jennings; Radhakrishnan, Rajeswaran; Wang, Dan; Snyder, Stephen; Skinn, Brian; Cabrera, Carlos; Duarte, Armando Pe�a
Disinfection needs to meet the personal hygiene requirements of interplanetary travel community in space vehicles is currently accomplished through the use of pre-packaged, disposable, wetted wipes, which represent an appreciable carry-along mass and disposal burden. There is a stated need to develop a system that could use onboard utilities to create on demand disinfectants thereby reducing the astronaut�s dependence on earth-based supplies and further eliminating storage and disposable problems. Within this context, we are developing an in-situ approach to electrochemically generate hydrogen peroxide disinfectant utilizing onboard life support supplies (Air/Water) to eliminate many of the surface contaminants present in closed living systems. As discussed within our 2018 paper we have demonstrated the potential to produce up to 1 w/w% peroxide with DI water and oxygen utilizing our optimized system. This paper will build upon that work and discuss the results from our zero-gravity flight test and system scale-up activities. Furthermore, the system has been shown to be amenable to utilize various water streams (DI, RO, and Tap water) with or without I or Ag additions as well as air or pure oxygen supplies. Finally, we have scaled the system to produce up to 6 L per day of 1 w/w% peroxide and are working to increase the output concentration up to 6 w/w% peroxide. The peroxide generation system offers a more economical and practical alternative, with the disinfectant solution being generated on demand and in-situ; and applied to reusable cloths, reducing both the carried and disposed mass associated with the disinfection process. The peroxide generation system demonstrates a strong potential to address a critical need of disinfection within ISS and will also be able to address Earth-based needs in various settings such as hospitals, restaurants, movie theatres, among many others. Acknowledgements: Financial support of NASA Contracts NNX16CA43P, NNX17CJ12C, and 80NSSC20C0070.
In-Situ Resource Utilization for Electrochemical Generation of Hydrogen Peroxide for Disinfection
(49th International Conference on Environmental Systems, 2019-07-07) Vijapur, Santosh; Hall, Timothy; Taylor, E. Jennings; Wang, Dan; Snyder, Stephen; Skinn, Brian; Cabrera, Carlos; Peña Duarte, Armando; Sweterlitsch, Jeffrey
Technological innovations are essential to enable energy-efficient maintenance of closed air, water, and waste systems for interplanetary travel with limited resupply options and microgravity living conditions. One particular need for the interstellar travel community is disinfection to meet personal hygiene requirements. At present, surface disinfection in space vehicles is accomplished through the use of pre-packaged, disposable, wetted wipes, which represent an appreciable carry-along mass and disposal burden. Therefore, next-generation system should use onboard utilities to create on demand disinfectants thereby reducing the astronaut’s dependence on earth based supplies and further eliminating storage and disposable problems. Within this context, we are demonstrating a technology to generate disinfectants that can neutralize or eliminate many of the contaminants while improving system maintenance and disinfection. Specifically, we are exploring an electrochemical system for generating hydrogen peroxide, a well-established disinfectant with non-toxic decomposition products (viz., oxygen and water), that is safe enough for human contact to be sold commercially as a 3 w/w% solution. This concept is founded on the electrochemical reduction of oxygen to hydrogen peroxide using readily available on-board supplies of oxygen and water. Initial trials confirmed that the developed system utilizing oxygen and RO water can generate >1 w/w% peroxide concentration. The proposed hydrogen peroxide generation system offers a more economical and practical alternative, with the disinfectant solution being generated on demand and in-situ; and applied to reusable cloths, reducing both the carried and disposed mass associated with the disinfection process. A zero gravity flight test is scheduled for March 2019 to validate the technology in microgravity environments. The specific application of interest to this program is crew contact surfaces in space vehicles, but this approach could be utilized for waste water disinfection, heat exchanger biofouling remediation, and laundry applications. Acknowledgements: Financial support of NASA Contracts No. NNX16CA43P and NNX17CJ12C are acknowledged.