PROJECT: Phase-Change Heat Transfer under Centrifugal Force in Applications to Adjustable Heat Transfer Wall
PI: Sunwoo Kim, Associate Professor, UAF
Boiling and condensation provides high heat flux (> 10,000 W/m2). The working principle of thermal siphons is based on the high heat transfer capability by phase-change heat transfer (PCHT). Heat is transferred from one end, where the liquid phase boils, to the other end where the vapor phase condensates. Despite the superiority of PCHT, the thermal control systems designed for space missions do not take full advantage due to the absence of gravity. Effective PCHT requires good contact between the liquid and the hot surface and of the vapor and the cold surface. On earth, gravity separates liquid from vapor. In space, another force must be used for the selective separation of liquid and vapor. This research will investigate the use of centrifugal force for effective PCHT. The goals of this work are to study phase-change heat transfer under centrifugal force and to design adjustable heat transfer walls for space and earth applications. When a liquid-vapor mixture flows in a curved tube, the centrifugal force pushes the liquid to the outside wall, leaving the vapor on the inside curve. With a hot outside wall and a cold inside wall, a cycle of evaporation and condensation occurs at a high heat transfer rate. The effect of centrifugal force on the PCHT in a curved flow path will be explored through a mathematical model. The model will be used to predict the fluid motion and heat transfer, necessary for designing adjustable heat transfer walls.
PROJECT: Ground validation of satellite measurements of HCHO columns at northern high latitudes
PI: Jingqiu Mao, Associate Professor, UAF
As a beacon of global climate change, the Arctic region has undergone dramatic temperature and ecological changes over the past century. The rate has accelerated in recent decades. A major unknown is how these changes will impact biosphere-atmosphere exchange and subsequently feedback on Arctic climate and air quality. Satellite observations of formaldehyde (HCHO), an oxidation product of biogenic volatile organic compounds, serve as a powerful tool to improve our understanding on biosphere-atmosphere exchange on regional and global scales. HCHO columns can now be observed from space by several satellite sensors including OMI on Aura (2004-), GOME-2 on MetOp-A (2006-), OMPS on SUOMI-NPP (2011-), GOME2 on MetOp-B (2012-) and TROPOMI on Sentinel-5 (2017-). But there appear to be large uncertainties and inconsistencies among these satellite sensors, due to instrument sensitivities, retrieval algorithms and other factors. This proposal aims to address some of these concerns by providing ground validation of HCHO columns for these satellite sensors at northern high latitudes. Together with a graduate student and another faculty member at UAF (Prof. William Simpson), we will use two ground instruments (Pandora and MAXDOAS), to evaluate satellite observations of HCHO columns in both boreal forests and tundra regions. From there we will develop a long-term record of satellite HCHO observations, to better understand biosphere-atmosphere exchange at high latitudes in past and future decades.
PROJECT: Development of infrared payload for UAS for multi-spectral mapping of landscape and detecting changes in thermal intensity for wildland fires and volcanic activity
PI: Peter Webley, Research Faculty, UAF
Direct observations of the thermal output from wildland fires and volcanic activity are critical to provide the inputs for modeling forecasts of their future location and impact. Manned airborne and satellite remote sensing data can provide thermal infrared temperature maps but are often saturated, cannot record the full range of temperatures, or are too coarse to capture subtle changes. This Research Infrastructure Development (RID) proposal focuses on building the capability to perform unmanned aircraft system (UAS) observations using a thermal infrared (TIR) camera with accompanying narrow band and neutral density filters. We will work with UAS collaborators at two National Aeronautics and Space Administration (NASA) centers (Jet Propulsion Laboratory and Ames Research Center) who will advise our team on tailoring our system design to the interest and needs of NASA as well as be ready for flight campaigns in Alaska. The outcome of our project will be to develop a TIR payload with inter-changeable filters that can be used for mapping hot volcanic targets as well as wildland fires and detect volcanic gases and aerosols in the TIR.
PROJECT: Estimating exospheric neutral Hydrogen densities near the subsolar magnetopause
PI: Hyunju Connor, Assistant Professor, UAF
SMILE (Solar wind – Magnetosphere – Ionosphere Link Explorer) is a soft X-ray imaging spacecraft funded by NASA, ESA, and China, and scheduled to launch in 2021. Its wide field-ofview soft X-ray images of the Earth’s dayside magnetosphere will provide innovative approaches to understand the global solar wind – magnetosphere interaction. Soft X-ray is emitted when solar wind plasma steals an electron from the Earth’s exospheric neutral Hydrogen. The neutral Hydrogen density is a key controlling parameter of the near-Earth soft X-ray signals that are also referred to as Solar Wind Charge Exchange (SWCX) signals. High neutral Hydrogen density produces strong SWCX signals, and thus helps to obtain high-cadence, high-resolution soft Xray images that are necessary for the SMILE mission. This study will support the SMILE mission by estimating neutral Hydrogen density near the subsolar magnetopause where the soft X-ray signals reach a peak. The density at this location hasn’t been fully understood due to the lack of the dayside observations. This project suggests using the strong SWCX events observed from the XMM-Newton astrophysics mission. These observations are considered contaminated by astrophysicists who study interstellar X-ray signals. The noise for astrophysicists becomes the signal for this proposed study. Using the unique XMM-Newton dataset, this project will estimate dayside neutral densities from solar maximum to solar minimum. The project outcome will advance our knowledge of the Earth’s dayside exosphere and its response to the solar cycle. Additionally, the estimated densities will be directly used to predict the strength of near-Earth soft X-ray signals, thus helping the SMILE team to plan their spacecraft mission.