Mathematical model of a maneuvering nanosatellite with a heliothermal propulsion system and a flywheel orientation and stabilization system

Author(s):  
Z.S. Zhumaev

The paper considers a possibility of using a heliothermal propulsion system for constructing constellations of nanosatellites in the CubeSat format. Such a propulsion system implies direct heating of the working fluid by focused solar radiation. In comparison with electric jet engines, the proposed propulsion has orders of magnitude higher thrust, which makes it possible to build a constellation of nanosatellites in low Earth orbit in less than 6 days. In comparison with electrothermal motors, the presented solution achieves higher efficiency of converting the energy of solar radiation into the thermal energy of the working fluid. The spacecraft motion was simulated taking into account the mutual influence of the propulsion system, the orientation and stabilization system, the power supply system, as well as the passage of the shadow sections of the orbit in which there is a loss of electrical and thermal energy.

2020 ◽  
pp. 4-11
Author(s):  
Андрей Владимирович Погудин ◽  
Сергей Викторович Губин

The subject of the research in the article is the process of preparing the working fluid for launching an engine installation with an electric heating engine. The goal is to minimize the time for preparing the working fluid for launch by developing an algorithm for thermostating and barostating of elements of a propulsion system with limited power of the power supply system. Tasks: analysis of the structure of a propulsion system with an electric heating engine, selection of an installation control controller, the formation of an algorithm for preparing the working fluid for the first launch, the study of the reserve time for preparing the working fluid for launch with limited power supply system, the formation of an algorithm for minimizing the starting time. The methods used are: circuit analysis, energy balance and algorithmic analysis. The following results were obtained: the structural diagram of the propulsion system was analyzed, a control unit based on the Arduino Leonardo controller was selected, the first start-up algorithm was compiled, which consisted of the barostatting of the tank, thermostatting of the steam generator, barostatting of the receiver, and thermostatting of the electric heating engine; A start-up cyclogram with reduced time was constructed, an algorithm with a minimum start-up time of the propulsion system was formed. The scientific novelty of the results is as follows: the procedures included in the algorithm for preparing the working fluid for the first launch of the propulsion system are formed, a cyclogram for preparing the working fluid for the first launch is constructed, a cyclogram for reducing the time for preparing the working fluid for the first launch of the installation is constructed based on the energy balance of power consumption with limitation power plant output parameters, an algorithm for reducing the preparation time of the working fluid for the first launch of a propulsion system with an electric heating engine was built, the value of the start time was established by the modified first start algorithm with limited values of the power supply system.


2019 ◽  
Vol 18 (3) ◽  
pp. 29-37 ◽  
Author(s):  
I. V. Belokonov ◽  
A. V. Ivliev ◽  
A. M. Bogatyrev ◽  
A. A. Kumarin ◽  
I. A. Lomaka ◽  
...  

This paper presents the results of theoretical and experimental research of a prototype of a propulsion system for periodical low-Earth orbit correction of research-and-educational nanosatellites. For that purpose, the prototype is to provide at least 20 m/s relative velocity for a 3U CubeSat with a mass not exceeding 4.5 kg. The personnel and environment safety were taken into account during testing and operation along with the ability to be launched as an associated payload by a “Soyuz”-series launch vehicle or from the ISS. An electro-thermal propulsion system (ResistoJet) was designed with “nonfreezing” mixture of ethanol and distilled water used as the working fluid. It is shown that a standard vehicle power system is capable of initiating one corrective thrust impulse per orbit with flight velocity change of about 0.1 m/s by introducing pulse energy storage units and allocating sufficient time for their charging in the flight profile. The propulsion system prototype was tested in atmospheric conditions. For that purpose shortened “atmospheric” nozzles were used. Testing was carried out using a zero-torque test-bench with high-speed cameras. The measured thrust value was in agreement with the calculated value of 44 mN.


Author(s):  
Monica F. Bonadies ◽  
Mahmood Mohagheghi ◽  
Mark Ricklick ◽  
J. S. Kapat

Solar thermal power plants have been constructed over the past two decades to reduce harmful emissions and provide a long-term solution for oil independent electricity generation. Of the solar power plant solutions, Rankine cycle based machines have most widespread uses. This study focuses on the modeling of a solar retrofit to a typical combined cycle power plant. The goal is to operate the plant 17 hours per day, making use of thermal storage capability so that the plant may operate even during a portion of the night time. The plant will be located in Orlando, Florida to take advantage of the abundance of sun in that geographic location. On the cycle side, the amount of solar collectors, the working fluid, and the turbine are considered. The thermal storage system, on the other hand, must be designed based upon a balance between cost and storage density. A decision will be made from existing sensible heat solid storage materials. The storage material evens out the energy supplied to the turbine working fluid between the peak solar radiation of the day time and the absence of solar radiation at night. This plant can be implemented in two ways: as a completely newly constructed power plant or as an addition to a HRSG (Heat Recovery Steam Generation) configuration, which can be retrofitted to an existing combined cycle power plant to increase its overall efficiency. In this study, the addition of a solar air collection system with a storage unit to a HRSG combined cycle power plant is proposed. The HRSG will be designed using a series of energy balances for each component. This proposed plant will then be compared with a similar solar plant to examine its feasibility in terms of land area. The storage unit devised comprises 1377 m3 and stores approximately 3900 GJ of thermal energy, which equates to 8 hours of run time when solar radiation is not available. The benefit of this addition to the plant is that the storage reduces the gas turbine run time necessary to provide hot gas to the HRSG. The total cost of the storage medium is approximately $8 million.


2011 ◽  
Vol 4 (10) ◽  
pp. 2273-2292 ◽  
Author(s):  
S. Schweitzer ◽  
G. Kirchengast ◽  
V. Proschek

Abstract. LEO-LEO infrared-laser occultation (LIO) is a new occultation technique between Low Earth Orbit (LEO) satellites, which applies signals in the short wave infrared spectral range (SWIR) within 2 μm to 2.5 μm. It is part of the LEO-LEO microwave and infrared-laser occultation (LMIO) method that enables to retrieve thermodynamic profiles (pressure, temperature, humidity) and altitude levels from microwave signals and profiles of greenhouse gases and further variables such as line-of-sight wind speed from simultaneously measured LIO signals. Due to the novelty of the LMIO method, detailed knowledge of atmospheric influences on LIO signals and of their suitability for accurate trace species retrieval did not yet exist. Here we discuss these influences, assessing effects from refraction, trace species absorption, aerosol extinction and Rayleigh scattering in detail, and addressing clouds, turbulence, wind, scattered solar radiation and terrestrial thermal radiation as well. We show that the influence of refractive defocusing, foreign species absorption, aerosols and turbulence is observable, but can be rendered small to negligible by use of the differential transmission principle with a close frequency spacing of LIO absorption and reference signals within 0.5%. The influences of Rayleigh scattering and terrestrial thermal radiation are found negligible. Cloud-scattered solar radiation can be observable under bright-day conditions, but this influence can be made negligible by a close time spacing (within 5 ms) of interleaved laser-pulse and background signals. Cloud extinction loss generally blocks SWIR signals, except very thin or sub-visible cirrus clouds, which can be addressed by retrieving a cloud layering profile and exploiting it in the trace species retrieval. Wind can have a small influence on the trace species absorption, which can be made negligible by using a simultaneously retrieved or a moderately accurate background wind speed profile. We conclude that the set of SWIR channels proposed for implementing the LMIO method (Kirchengast and Schweitzer, 2011) provides adequate sensitivity to accurately retrieve eight trace species of key importance to climate and atmospheric chemistry (H2O, CO2, 13CO2, C18OO, CH4, N2O, O3, CO) in the upper troposphere/lower stratosphere region outside clouds under all atmospheric conditions. Two further species (HDO, H218O) can be retrieved in the upper troposphere.


Energies ◽  
2017 ◽  
Vol 11 (1) ◽  
pp. 37 ◽  
Author(s):  
Jose Rogada ◽  
Lourdes Barcia ◽  
Juan Martinez ◽  
Mario Menendez ◽  
Francisco de Cos Juez

Power plants producing energy through solar fields use a heat transfer fluid that lends itself to be influenced and changed by different variables. In solar power plants, a heat transfer fluid (HTF) is used to transfer the thermal energy of solar radiation through parabolic collectors to a water vapor Rankine cycle. In this way, a turbine is driven that produces electricity when coupled to an electric generator. These plants have a heat transfer system that converts the solar radiation into heat through a HTF, and transfers that thermal energy to the water vapor heat exchangers. The best possible performance in the Rankine cycle, and therefore in the thermal plant, is obtained when the HTF reaches its maximum temperature when leaving the solar field (SF). In addition, it is necessary that the HTF does not exceed its own maximum operating temperature, above which it degrades. The optimum temperature of the HTF is difficult to obtain, since the working conditions of the plant can change abruptly from moment to moment. Guaranteeing that this HTF operates at its optimal temperature to produce electricity through a Rankine cycle is a priority. The oil flowing through the solar field has the disadvantage of having a thermal limit. Therefore, this research focuses on trying to make sure that this fluid comes out of the solar field with the highest possible temperature. Modeling using data mining is revealed as an important tool for forecasting the performance of this kind of power plant. The purpose of this document is to provide a model that can be used to optimize the temperature control of the fluid without interfering with the normal operation of the plant. The results obtained with this model should be necessarily contrasted with those obtained in a real plant. Initially, we compare the PID (proportional–integral–derivative) models used in previous studies for the optimization of this type of plant with modeling using the multivariate adaptive regression splines (MARS) model.


2013 ◽  
Vol 12 (2) ◽  
pp. 197-204
Author(s):  
Karolina Brzezińska ◽  
Andrzej Szychowski

The paper analyses the influence of the rotational flexibility of beam-column connection on the roof plane rigidity of the longitudinally braced frame-purlin cover of the solid wall hall. The cover is adapted to obtain thermal energy from solar radiation. The roof cover is then provided in the form of a transparent glass barrier which requires considerable roof plane rigidity. The analysis aimed to compare the roof plane rigidity of the frame-purlin cover to those of space structures and truss-purlin covers, depending on the type of longitudinal bracing and rotational rigidity of the beam-column connection. The investigations were conducted for three types of roof plane bracing and different rigidity indexes of the beam-column connection (from u=0 – pin connection, through u=0.25; 0.5; 0.75 – semi-rigid connection, to u=1 – rigid connection). In the transfer of horizontal forces, the interaction of the rigidity of frames with flexible nodes (beam-column) with longitudinal roof plane bracings supported by lateral bracings of gable walls was observed. The highest roof plane rigidity was demonstrated by 2X-shaped and K-shaped braces with rigid nodes at frame corners.   


2013 ◽  
Vol 10 (4) ◽  
pp. 1253-1261 ◽  
Author(s):  
Baghdad Science Journal

The effects of solar radiation pressure at several satellite (near Earth orbit satellite, low Earth orbit satellite, medium Earth orbit satellite and high Earth orbit satellite ) have been investigated. Computer simulation of the equation of motion with perturbations using step-by-step integration (Cowell's method) designed by matlab a 7.4 where using Jacobian matrix method to increase the accuracy of result.


Concentrating Solar Power (CSP) focuses sunlight in order to use the heat energy of the sun. In a central receiver system configuration, many mirrors (heliostats) individually track the sun and reflect the concentrated solar energy onto a receiver on top of a tower. The receiver contains the working fluid which is heated by the concentrated solar radiation. The useful energy that absorbed by the water flows through the receiver in solar tower plant depending on the angle between the solar rays and the position of heliostat in the region of work. Heliostat will reflect the incident solar radiation in the direction of the receiver founded in the top of the tower, in order to get a maximum incident solar radiation on the heliostat reflection area. Because of the cosine factor loss effect due to the sun position is variable along the day from sunrise to sunset, which must be in a minimum value, therefore an automated tracking system with dual axes as a control system with sensors had been built and used to stay the sunrays incident on the receiver, and enable the heliostat to flow the sun where it was


Author(s):  
Mustafa Aktaş ◽  
Meltem Koşan ◽  
Erhan Arslan ◽  
Azim Doğuş Tuncer

The integrated usage of solar energy systems, heat pump applications, and thermal energy storage units is an effective way for heating systems due to their sustainability and stability in operations. In this study, a novel direct solar-assisted heat pump with thermal energy system has been designed which uses the solar collector as the evaporator of the heat pump. Besides, two-dimensional transient numeric analyses have been conducted for the thermal energy storage unit using the ANSYS Fluent 16.2 commercial software package. With this direct system, the heat required for heating systems is supplied from the condenser with the heat received from the solar collector of the working fluid. For an effective and high performance system, the solar collector is designed as a double-pass which provided superheating of the working fluid. It is aimed to store the surplus energy from the solar energy in the thermal energy storage unit and to operate the system continuously and efficiently in both sunny and overcast weather conditions. Furthermore, the system has been analyzed theoretically and the results show that coefficient of performance may improve. As a result, this newly designed system can be successfully applied for thermal applications.


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