Space thermo acoustic radio-isotopic power system: Space TRIPS

Proceedings of the VIII International Scientific Colloquium "Modelling for Materials Processing", 2017

In this paper are presented a new results of testing travelling wave thermoacoustic (TAc) generator, coupled with alternating current magnetohydrodinamic (MHD) generator in FP7 project "Space Trips". This project relates to experimental testing of radioisotopic-feeded electrical power supply system for deep space applications. There are analized and described experimental graphs of thermoacoustic generator like pressure oscillation amplitude as a function of mean pressure and temperature. A certain extrapolation of them had been performed. Also a thermoacoustic excitation graph is plotted, where are shown critical values when acoustic power generation starts to generate soundwave.

Sustainability

Electricity production is a major problem for deep space exploration. The possibility of using radioisotope elements with a very long life as an energy source was investigated in the framework of an EU project “SpaceTRIPS”. For this, a two-stage system was tested, the first in which thermal energy is converted into mechanical energy by means of a thermoacoustic process, and the second where mechanical energy is converted into electrical energy by means of a magnetohydrodynamic generator (MHD). The aim of the present study is to develop an analytical model of the MHD generator. A one-dimensional model is developed and presented that allows us to evaluate the behavior of the device as regards both electromagnetic and fluid-dynamic aspects, and consequently to determine the characteristic values of efficiency and power.

"Magnetohydrodynamics" journal article, 2020

Thermoacoustic-to-MHD energy conversion is a potential key technology for energy production in deep Space, due to the absence of moving mechanical parts or electrical contacts. This technology has been developed by a team of scientists from different institutes and companies from France, Italy, Latvia and Germany. Experimental results of the prototype built at the Institute of Physics, University of Latvia, are presented in this paper. It summarizes the results of several TAc-alone experimental sessions, indicating the required temperature difference and working gas mean pressure. These are the necessary parameters needed for the induction of acoustic power. The paper also discusses the operational experience gained in a preliminary water simulation for the MHD-alone experiment.

Conference paper: "2020 IEEE 61st International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)", 2020

This paper discusses the results of theoretical and experimental investigation of magnetohydrodynamic generator with liquid metal working body. This electric machine is used to convert mechanical energy, supplied by thermoacoustic engine, to an AC form of electrical energy. The purpose of this technology is an electricity production in deep Space, potentially suitable for long term missions far away from Sun.

Energy Conversion and Management, 2022

The generation of electricity in space is a major issue for space exploration, and among the viable alternatives, nuclear power systems appear to present a particularly suitable solution, especially for deep space exploration. Recent developments in thermoacoustic engine and liquid metal magnetohydrodynamic (LMMHD) generator technologies have shown that thermoacoustically-driven LMMHD generators are a promising thermal-to-electrical converter option for space nuclear reactors. In order to improve the power density and capacity of current thermoacoustically-driven LMMHD generators, a novel three-stage looped thermoacoustically-driven LMMHD generator is proposed and investigated in this work. A numerical model of the integrated system including a lumped parameter sub-model for the LMMHD generator is developed and validated. Using this model, the effect of key geometric and operating parameters on the operation and performance of the proposed system are investigated numerically, and acoustic field distributions are presented. The results indicate that when the heat source and sink temperatures are 900 K and 300 K, respectively, a thermal-to-electric efficiency of 27.7% with a total electric power of 4750 W can be obtained at a load factor of 0.92. This work provides guidance for the design of similar systems and contributes to the development of a new thermal-to-electrical conversion technology for space applications.

Proceedings of Meetings on Acoustics, 2017

Investigation on acoustic radiation characteristics of an open-air traveling-wave thermoacoustic generator The acoustic radiation impedance of an Open-air Traveling-wave ThermoAcoustic Generator (OTTAG) composed of a looped tube and a resonator was theoretically described. The acoustic radiation characteristics versus different resonator types and input heating powers of this OTTAG are experimentally investigated. The comparisons of sound pressure level (SPL) at 1m far away from the open end of the resonator were carried out in an anechoic chamber, a semi-anechoic chamber and a normal laboratory under different heating power. The results showed that the difference in a normal laboratory between the anechoic chamber and semi-anechoic chamber was lower than 1.5%. The maximum SPL at 1m far away from the open end of the resonator was up to 100.1 dB ref 20μPa. This OTTAG would be used as a newly basic acoustic source for low frequency and long-range noise experiments and industrial sources and vibration.

E3S Web of Conferences, 2017

To support the development of a Radioisotope Power Source (RPS) for exploration missions into deep space based on 241 Am, the European Commission's Joint Research Centre (JRC) has recently launched an exploratory research project, scheduled for a period of two years. It aims at finding innovative solutions for higher performance, safety and reliability of such a device. In addition, it will serve as a start-up platform for this field of research and enable identification of research areas, where JRC can significantly complement and support the already existing activities in Europe. The project is divided into several subtasks and will investigate-safety related properties of americium (oxide) as a heat source,-compatibility of americium compounds with cladding and structural materials,-properties of alternative americium compounds,-properties of advanced thermoelectric materials. The new exploratory research project will be introduced together with an overview on the available facilities and capabilities of JRC in this domain. Alternative americium forms with potential improved stability versus the oxides are discussed and innovative thermoelectric materials based on actinides are introduced.

The Department of Energy (DOE) and the NASA Glenn Research Center are developing a Stirling converter for an advanced radioisotope power system to provide spacecraft onboard electric power for NASA deep space missions. This high-efficiency converter is being evaluated as an alternative to replace the much lower efficiency radioisotope thermoelectric generator (RTG). The current power requirement (six years after beginning of mission (BOM) for a mission to Jupiter) is 210 W(sub e) (watts electric) to be generated by two separate power systems, one on each side of the spacecraft. Both two-converter and four-converter system designs are being considered, depending on the amount of required redundancy.

Thermoacoustic engines are energy conversion devices that convert thermal energy into mechanical work in the form of sound wave (gas oscillation). The sound wave is generated by thermal interaction between working gas and porous medium (regenerator) that possesses a large axial temperature gradient. Waste heat or solar thermal energy can be used as the heat source and noble gases or other inert gases such as air can be employed as the working gas, so that the thermoacoustic engines act as environmentally benign machines. The sound energy output can then be harnessed to drive a linear alternator to generate electricity. This paper presents experimental characterization of a traveling-wave loopedtube thermoacoustic engine with air working gas at various pressures including the onset temperature difference (the temperature difference between the regenerator ends required to start producing the sound), the harmonic frequencies and the pressure amplitudes of the generated sound waves. In this experiment, an electric heater is used as the heat source which supplies heat into the regenerator hot end. The experiment is carried out by measuring the temperatures at regenerator ends and sound pressure amplitudes at several points along the looped-tube. The measurements are performed at different charged pressures of air inside the looped-tube in the range of 100 kPa-400 kPa. It is found that the smallest onset temperature difference is 417 C which is obtained at charged pressure of 200 kPa. In addition, the second harmonic sound wave is dominantly generated at air pressure of 100 kPa, while the first harmonic (fundamental mode) sound wave dominates at 200 kPa, and the third harmonic shows up at other higher pressures. Moreover, the pressure amplitudes of the three harmonics are linearly getting higher along with the increasing charged pressure. The highest pressure amplitude of the first harmonic is 7 kPa, whereas those of the second and third harmonics are 4.8 kPa and 1.1 kPa, respectively, which are achieved at 400 kPa charged pressured. Furthermore, the sound frequencies are not significantly affected by the charged pressure variation, those are around 96 Hz, 192 Hz, and 289 Hz for the first, second, and third harmonics, respectively.

Energy Procedia, 2011

The thermo-acoustic generators offer a unique means of converting thermal energy into mechanical energy without any moving parts and without fluid circulation. They are comparable to the Stirling engine with the advantage of much greater simplicity. They are therefore natural candidates for special uses where interventions are limited. The problem to solve is transforming the mechanical energy into electrical energy. MHD generators offer excellent opportunities in this area, particularly by using the mechanisms of induction. The work concerns the combination of a thermo-acoustic generator with an induction generator of a new concept for obtaining electric current with adjustable voltage and current strength, delivered at the thermo-acoustic wave frequency. The system has been subjected to numerical simulation. However, an experimental program is being studied in collaboration with industrial and academic partners. The exploitation of the process by using a solar collector (parabolic or cylindrically-parabolic) is envisaged with the aim to produce electricity, for example, in isolate villages