Browsing by Author "Sanders, John"

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Laser Processed Condensing Heat Exchanger (LP-CHX) Test Article Design, Manufacturing, and Testing
(50th International Conference on Environmental Systems, 7/12/2021) Hansen, Scott; Wallace, Sarah; Zuhlke, Craig | Alexander, Dennis; Roth, Nick; Ediger, Aaron; Sanders, John; Izenson, Mike; Hamilton, Tanner
Current state-of-the-art Condensing Heat Exchangers (CHXs) require non-permanent coatings which have a history of degrading over time, becoming hydrophobic, and potentially contributing to dimethylsilanediol (DMSD) production on a spacecraft. Ultimately, this type of heat exchanger must be uninstalled and sent back to earth for refurbishment, which is not an option for spaceflight beyond low earth orbit. These significant technical issues must be solved for deep-space spaceflight. In continued pursuit of a high reliability CHX, a silver, dimpled sub-scale Laser Processed CHX (LP-CHX) was designed and manufactured. The LP-CHX does not require a coating, but rather relies only on a femtosecond laser processed silver surface for condensing. This paper highlights the design, development, manufacturing, and testing of the LP-CHX as well as the laser processing of the silver surfaces. Additionally, further microbial growth testing and long duration laser processed condensing tests are reported. These studies conclude that silver laser processed surfaces significantly minimize microbial growth and fungal growth when compared to plain silver and stainless steel metals.
Laser Processed Condensing Heat Exchanger Technology Development
(47th International Conference on Environmental Systems, 2017-07-16) Hansen, Scott; Wright, Sarah; Wallace, Sarah; Hamilton, Tanner; Alexander, Dennis; Zuhlke, Craig; Sanders, John
The reliance on non-permanent coatings in Condensing Heat Exchanger (CHX) designs is a significant technical issue to be solved before long-duration spaceflight can occur. Therefore, high reliability CHXs have been identified by the Evolvable Mars Campaign (EMC) as critical technologies needed to move beyond low earth orbit. The Functionalized Condensing Heat Exchanger project aims to solve these problems through the use of femtosecond laser processed surfaces, which have unique wetting properties and potentially anti-microbial growth properties. These surfaces were investigated to identify if they would be suitable candidates for a replacement CHX surface. Among the areas researched in this project include microbial growth testing, siloxane testing in which functionalized surfaces were exposed to an air stream of siloxanes, and condensation testing in which functionalized surfaces were condensed upon.
Lightweight, Durable PCM Heat Exchanger for Spacecraft Thermal Control
(47th International Conference on Environmental Systems, 2017-07-16) Izenson, Michael; Knaus, Darin; Cox, Jeff; Sanders, John
We have built and demonstrated a proof-of-concept thermal storage system using an innovative design that enables very high thermal storage per unit mass. Thermal storage is a key technology for future spacecraft because it can reduce the size of thermal management systems by smoothing out variations in the heat load and/or heat rejection environment. This approach reduces system mass by enabling designers to size active components based on a spacecraft’s average operating conditions instead of the least favorable conditions. Heat exchangers that contain phase-change material (PCM) enable thermal storage by freezing the PCM when extra heat rejection is available and thawing it when the heat loads are high. Low-mass PCM heat exchangers are difficult to design, however, due to the large amount of additional mass needed to provide a durable heat exchanger structure and to provide low-resistance pathways for heat conduction into or out of the PCM. Our PCM heat exchanger design is based on innovative heat exchanger fabrication techniques that enable essentially direct-contact heat exchange with the PCM through a very lightweight containment structure. We have fabricated a prototypical core sample and measured its energy storage performance using paraffin PCM in thermal cycle tests that simulate operation in low-lunar orbit. The tests demonstrate very high thermal energy storage per unit mass of heat exchanger (130 kJ/kg ) in the heat exchanger core, low pressure losses, and efficient heat transfer. Based on these results, we have produced a conceptual design of a full-size PCM heat exchanger based on requirements for a manned spacecraft in low Lunar orbit. The test results and design calculations show that the PCM heat exchanger can achieve an overall PCM mass fraction greater than 50% in a 3,700 kJ thermal storage unit.
Next-generation Spacecraft Humidity Control and Water Recovery System (SHOWRS) – Combining the Condensate Separator for Microgravity Conditions (COSMIC) and Laser-Processed Condensing Heat Exchanger (LP-CHX)
(2024 International Conference on Environmnetal Systems, 2024-07-21) Jacobi, Robert; Joyce, Connor; Sanders, John; Zuhlke, Craig
Spacecraft temperature and humidity control systems (THCS) are an essential part of environmental control and life support systems (ECLSS) for all human spaceflight missions. Crew perspiration and respiration releases approximately 50% of consumed water into the cabin atmosphere, so failing to recover water from the atmosphere necessitates the transport of large quantities of water from Earth. The Spacecraft Humidity Control and Water Recovery System (SHOWRS) described herein combines Paragon Space Development Corporation's patented COndensate Separator for MIcrogravity Conditions (COSMIC) and Edare and UNL's Laser-Processed Condensing Heat Exchanger (LP-CHX) into a THCS that functions equally well in micro, partial or full gravity to provide high-efficiency water recovery for sustainable, long-duration human habitation and exploration missions in Low-Earth Orbit (LEO), in cislunar space, on the Moon, on Mars, and in deep space. This paper discusses the SHOWRS system specifications and advantages compared to state-of-the-art THCS, showing the substantial benefits in performance, size, and power over alternative technologies. We describe the empirical, analytical, integrated COSMIC sizing and performance model that couples principal design and operating parameters to predict power draw as a function of condensate loads, airflow rates, and differential pump pressure. The paper also highlights the thermal, anti-microbial, and anti-fungal properties of the laser-processed silver condensing surfaces at the core of the LP-CHX and the resulting superior performance and longevity.