Thermophotovoltaic energy in space applications: Review and future potential

CubeSats provide a cost effective means to perform scientific and technological studies in space. Due to their affordability, CubeSat technologies have been diversely studied and developed by educational institutions, companies and space organizations all over the world. The CubeSat technology that is surveyed in this paper is the propulsion system. A propulsion system is the primary mobility device of a spacecraft and helps with orbit modifications and attitude control. This paper provides an overview of micro-propulsion technologies that have been developed or are currently being developed for CubeSats. Some of the micro-propulsion technologies listed have also flown as secondary propulsion systems on larger spacecraft. Operating principles and key design considerations for each class of propulsion system are outlined. Finally, the performance factors of micro-propulsion systems have been summarized in terms of: first, a comparison of thrust and specific impulse for all propulsion systems; second, a comparison of power and specific impulse, as also thrust-to-power ratio and specific impulse for electric propulsion systems.

https://www.mdpi.com/2226-4310/4/4/58/pdf

An Overview of Cube-Satellite Propulsion Technologies and Trends

Convection effect on the melting process of nano-PCM inside porous enclosure

Ultra high temperature latent heat energy storage and thermophotovoltaic energy conversion

Pore-scale investigation of gravity effects on phase change heat transfer characteristics using lattice Boltzmann method

Computational Evaluation of a Latent Heat Energy Storage System

: A bi-modal solar thermal system capable of providing propulsive and electric power to a spacecraft has been identified as a promising architecture for microsatellites requiring a substantial _V . The use of a high performance thermal energy storage medium is the enabling technology for such a configuration and previous solar thermal studies have suggested the use of high temperature phase change materials (PCMs) such as silicon and boron. To date, developmental constraints and a lack of knowledge have prevented the inclusion of these materials in solar thermal designs and analysis has remained at the conceptual stage. It is the focus of this ongoing research effort to experimentally investigate using both silicon and boron as high temperature PCMs and enable a bi-modal system design which can dramatically increase the operating envelope for microsatellites. This paper discusses the current progress of a continued experimental investigation into a molten silicon based thermal energy storage system. Using a newly operational solar furnace facility, silicon samples have been melted and results indicate that volumetric expansion during freezing will be the primary difficulty in using silicon as a PCM. Further experimental studies using different materials and test section fill factors have identified potentially reliable experimental conditions at the expense of energy storage density. In addition to conducting experiments, a concurrent computational effort is underway to produce representative models of the experimental system. The current models generally follow experimental results; however, difficulties still remain in determining high temperature material properties and material interactions. This paper also discusses the future direction of this research effort including modeling improvements, analysis of convective coupling with phase change energy storage and potential facility improvements.

Experimental Investigation of Latent Heat Thermal Energy Storage for Bi-Modal Solar Thermal Propulsion

The thermal energy storage and thermal-to-electric conversion components of a satellite power system were analyzed computationally. A phase- change material provided the energy storage while thermophotovoltaic cells converted the thermal energy to electrical. The phase-change mechanics were modeled and the associated system temperatures determined throughout the orbit. Using an equivalent circuit model for low-bandgap thermophotovoltaic diodes, those temperatures were then used to predict the maximum power output of the thermophotovoltaic cells. The system was modeled at five different altitudes. Two different thermophotovoltaic cells, gallium antimonide (GaSb) and gallium indium arsenide antimonide (GaInAsSb), were evaluated, and the system was analyzed when there were no voids in the phase-change material and when there were voids present. For all situations evaluated, the GaInAsSb cell produced significantly more power, but experienced greater variation in performance. The presence of voids in the phase-change material significantly lowered the power available during eclipse.

Numerical power output predictions for low-bandgap thermophotovoltaic cells coupled with a latent-heat energy storage system

: Solar thermal propulsion offers a unique combination of high thrust and high specific impulse levels that can provide competitive advantages relative to traditional satellite propulsion systems In order to enhance the functionality of this technology, thermal storage combined with a means of thermal-to-electric conversion is suggested, with the idea of providing a dual-mode power and propulsion system based on thermal energy A system including silicon (moderate performance) or boron (high performance) phase change material for storing energy, an insulating containment system consisting of boron nitride, carbon bonded carbon fiber, and vacuum gap insulation is proposed, with thermophotovoltaics used for electrical conversion A laboratory solar concentration system has been constructed and experiments to directly heat small quantities of candidate materials have begun, so that the nature and challenges of this system can be evaluated A modeling effort to optimize the solar receiver/absorber/converter system is also underway and will be discussed

High Energy Advanced Thermal Storage for Spacecraft Solar Thermal Power and Propulsion Systems

Thermophoretic force on a sphere in rarefied gas is studied experimentally and computationally for Knudsen numbers on the order of 0.1. Both experiment and numerical modeling have shown the force maximum for a Knudsen number of about 0.3 based on the sphere diameter. The measured and computed maxima agree within the error bars of the experiment and simulation. The phenomenon of negative thermophoresis, where the force on the sphere acts in the direction of temperature gradient (cold to hot) is established numerically and, for the first time, experimentally.

Rebecca N. Webb

Papers

Computational Evaluation of a Latent Heat Energy Storage System

Experimental Investigation of Latent Heat Thermal Energy Storage for Bi-Modal Solar Thermal Propulsion

Numerical power output predictions for low-bandgap thermophotovoltaic cells coupled with a latent-heat energy storage system

High Energy Advanced Thermal Storage for Spacecraft Solar Thermal Power and Propulsion Systems

Repulsion and attraction caused by radiometric forces