Characteristics of Two Phase Fluids as Microthruster Propellant

2009 ◽  
Author(s):  
John Lee ◽  
Adam Huang
Keyword(s):  
Attitude Control ◽  
Orbital Elements ◽  
Two Phase ◽  
Multiple Points ◽  
Limited Ability ◽  
Small Satellites ◽  
Orbital Maneuvers ◽  
Orbital Maneuver ◽  
R 134A ◽  
Micro Propulsion

Nano- and picosatellites are small satellites that are a more affordable alternative to larger satellites. Nanosats are satellites with a mass ranging from 1kg to 10kg while picosats have a mass that ranges from 0.1kg to 1kg. In addition to their cost, the smaller satellites have the advantage that they are able to carry out missions that would be difficult for a larger satellite. These advantages include using formations to gather data from multiple points and in-orbit inspection of larger satellites. Nano/picosats can be fabricated or procured for under $25k and launched into space for around another $40–60k which makes the total pre-mission expenditures for the satellite under $100k. Currently these satellites have a limited ability to orient themselves and cannot perform orbital maneuvers. For example a satellite could potentially use electro-magnetically charged coils in conjunction with earth’s magnetic field to orient themselves. The problems with the current methods of orientation are they are extremely slow to damp out oscillations due to low power (minutes) and cannot execute out of orbit maneuvers. Once a satellite is deployed from its launcher it is on a set orbit and cannot change its orbital elements on-command for the duration of its mission, limiting their use for science missions. Thus, it would be extremely beneficial for the nano- and pico-satellite community if a micro propulsion system capable of full-authority attitude control and orbital maneuver is developed. This paper describes the limiting characteristics of the refrigerant-based propellant (such as 1,1,1,2-Tetraflurorethan <R-134a> or 1,1-difluoroethane <R-152a>) for the cold gas systems that is currently under development.

Microthruster Knife-Edge Thrust Stand

2009 ◽  
Author(s):  
John Lee ◽  
Adam Huang
Keyword(s):  
Attitude Control ◽  
Cost Effective ◽  
Knife Edge ◽  
Razor Blade ◽  
Small Satellites ◽  
Orbital Maneuvers ◽  
Direct Technique ◽  
Thrust Measurement ◽  
Micro Propulsion ◽  
Thrust Stand

Nano- and picosatellites are small satellites that are a more affordable alternative to larger satellites. Nanosats are satellites with a mass ranging from 1kg to 10kg while picosats have a mass that ranges from 0.1kg to 1kg. In addition to their cost, the smaller satellites have the advantage that they are able to carry out missions that would be difficult for a larger satellite. These advantages include using formations to gather data from multiple points and in-orbit inspection of larger satellites. Nano/picosats can be fabricated or procured for under $25k and launched into space for around another $40–60k which makes the total pre-mission expenditures for the satellite under $100k. Currently these satellites have a limited ability to orient themselves and cannot perform orbital maneuvers. For example a satellite could potentially use electro-magnetically charged coils in conjunction with earth’s magnetic field to orient themselves. The problems with the current methods of orientation are they are extremely slow in damping out oscillations due to low power and cannot execute out of orbit maneuvers. Thus, once a satellite is deployed from its launcher it is on a set orbit and cannot change its orbital elements on-command for the duration of its mission, limiting their use for science missions. Thus, it would be extremely beneficial for the nano- and pico-satellite community if a micro propulsion system capable of full-authority attitude control and orbital maneuver is developed. This paper describes the development of a cost-effective thrust stand for cold gas micro thruster development work. The thrust stand design is a static pendulum supported by a razor blade knife edge sitting on top of a silicon V-groove chip. The thrust measurement used is direct technique using a 1-axis strain gauge load cell at 25gm full-scale and resolutions in the order of 10 micro-g. Future possibilities include implementing a electromagnetic force compensation balance to improve sensing resolution.

Micro-Propulsion System of a Thermospheric Explorer CubeSat

2009 ◽  
Author(s):  
Bogdan Udrea ◽  
Adam Huang ◽  
Russell Cosgrove ◽  
Richard Doe ◽  
John Malsbury
Keyword(s):  
Circular Orbit ◽  
Attitude Control ◽  
Specific Impulse ◽  
Propulsion System ◽  
Preliminary Design ◽  
Two Dimensional ◽  
Orbital Maneuvers ◽  
Total Impulse ◽  
Initial Attitude ◽  
Micro Propulsion

The major design driver for the Dipping Thermospheric Explorer (DipTE) CubeSat mission is that the satellite shall fly a significant amount of orbit arcs at altitudes of 300km and below. It is assumed that the DipTE satellite will be released in a circular orbit above the altitudes of scientific interest for the mission. A propulsion system will be employed to make the orbit elliptic and satisfy the design driver. The apogee of the elliptic orbit will be at the altitude of the initial circular orbit. The inclination of the orbit will stay the same. A few design iterations of the mission converged to a satellite configuration capable of storing 0.375 kg of propellant, and a propulsion system with a specific impulse Isp of 86 s. About 90 % of the total impulse of 313 Ns stored on board was budgeted to perform orbital maneuvers, with a 1 N thruster orbital maneuvering thruster (OMT). The remainder of 10% of the propellant mass has been budgeted for attitude control maneuvers, such as those performed during detumbling and initial attitude acquisition. The attitude control maneuvers are performed with the thrusters of a reaction control system (RCS). The 12 two-dimensional (2D) microthrusters of the RCS produce 40 mN each and are installed such that they provide three-axis control of the spacecraft. This paper describes the preliminary design of the propulsions system.

Two-phase flow regimes of condensing R-134a at low mass flux in rectangular microchannels

2017 ◽  
Vol 84 ◽  
pp. 92-103 ◽  
Author(s):  
Michael A. Vanderputten ◽  
Tabeel A. Jacob ◽  
Maria Sattar ◽  
Nouman Ali ◽  
Brian M. Fronk
Keyword(s):  
Mass Flux ◽  
Two Phase Flow ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Rectangular Microchannels ◽  
Low Mass ◽  
R 134A

scholarly journals Three-axis air-bearing based platform for small satellite attitude determination and control simulation

2005 ◽  
Vol 3 (03) ◽  
Author(s):  
J. Prado ◽  
G. Bisiacchi ◽  
L. Reyes ◽  
E. Vicente ◽  
F. Contreras ◽  
...  
Keyword(s):  
Attitude Control ◽  
Attitude Determination ◽  
Center Of Mass ◽  
Measurement Unit ◽  
Simulation Platform ◽  
Air Bearing ◽  
Small Satellites ◽  
Main Components ◽  
Free Environment ◽  
And Control

A frictionless environment simulation platform, utilized for accomplishing three-axis attitude control tests in small satellites, is introduced. It is employed to develop, improve, and carry out objective tests of sensors, actuators, and algorithms in the experimental framework. Different sensors (i.e. sun, earth, magnetometer, and an inertial measurement unit) are utilized to assess three-axis deviations. A set of three inertial wheels is used as primary actuators for attitude control, together with three mutually perpendicular magnetic coils intended for desaturation purposes, and as a backup control system. Accurate balancing, through the platform’s center of mass relocation into the geometrical center of the spherical air-bearing, significatively reduces gravitational torques, generating a virtually torque-free environment. A very practical balancing procedure was developed for equilibrating the table in the local horizontal plane, with a reduced final residual torque. A wireless monitoring system was developed for on-line and post-processing analysis; attitude data are displayed and stored, allowing properly evaluate the sensors, actuators, and algorithms. A specifically designed onboard computer and a set of microcontrollers are used to carry out attitude determination and control tasks in a distributed control scheme. The main components and subsystems of the simulation platform are described in detail.

scholarly journals Investigation of Separated Two-Phase Thermosiphon Loop for Relieving the Air-Conditioning Loading in Datacenter

Energies ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 105 ◽  
Author(s):  
Hafiz Daraghmeh ◽  
Mohammed Sulaiman ◽  
Kai-Shing Yang ◽  
Chi-Chuan Wang
Keyword(s):  
Temperature Distribution ◽  
Energy Saving ◽  
Air Conditioning ◽  
Energy Savings ◽  
Filling Ratio ◽  
Two Phase ◽  
System Pressure ◽  
Optimum Energy ◽  
Free Cooling ◽  
R 134A

This study investigates the feasibility of using R-134a filled separated two-phase thermosiphon loop (STPTL) as a free cooling technique in datacenters. Two data center racks one of them is attached with fin and tube thermosiphon were cooled by CRAC unit (computer room air conditioning unit) individually. Thermosiphon can help to partially eliminate the compressor loading of the CRAC; thus, energy saving potential of thermosiphon loop was investigated. The condenser is a water-cooled design and perfluoroalkoxy pipes were used as adiabatic riser/downcomer for easier installation and mobile capability. Tests were conducted with filling ratio ranging from 0 to 90%. The test results indicate that the energy saving increases with the rise of filling ratio and an optimum energy savings of 38.7% can be achieved at filling ratios of 70%, a further increase of filling ratio leads to a reduction in energy saving. At a low filling ratio like 10%, the evaporator starves for refrigerant and a very uneven air temperature distribution occurring at the exit of data rack. The uneven temperature distribution is relieved considerably when the evaporator is fully flooded. It is also found that the energy saving is in line with the rise of system pressure. Overfilling of the evaporator may lead to a decline of system pressure. A lower thermal resistance occurs at high filling ratios and higher ambient temperature.

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