A New Power System For Satellites Based On Power-mems-modules Using Micro Turbines And The Rankine-cycle-process
- Paper number
IAC-07-C3.2.06
- Author
Mr. Daniel Schubert, Technical University of Berlin, Germany
- Year
2007
- Abstract
Since 1996 the power demand of GEO satellites has increased immensely. This increased power demand is needed for power extensive applications like telecommunication, navigation and earth observation. Solar cells are producing the necessary electrical power through photovoltaic power conversion. Often large solar arrays are needed in order to provide enough power to the satellite. A reason for this is the relatively low efficiency of solar cells.
The present work examines the feasibility of the deployment of Power-MEMS (Micro-Electro-Mechanical System) for space power applications. Power-MEMS are micro fabricated machineries that offer a high development and market potential in many areas. The core subject of the work is the use of a micro turbine in combination with a micro generator, named MTG-Module (Micro-Turbine-Generator). This module is designed for an electrical power output of 10 Watt. The working principle is the Clausius-Rankine-Cycle, which is also known as the so-called steam cycle. This solar dynamic power module uses a Cassegrain collector system to concentrate the solar energy on a micro receiver. The collector system consists of a primary and a secondary mirror. The micro receiver is located in the focal point of the secondary mirror and is build up of many micro channels (diameter of one channel between 50-100 µm). Within these specially built micro channels a fluid is heated up until it evaporates. The hot steam impels a micro-turbine-generator combination. On the backside of the module a condensator/ radiator helps the steam to condensate again, before the fluid can be transported back to the receiver (done by a micro pump). The final goal is the implementation of many modules into a solar panel (10 to 20 MTG-Modules per m²) as well as to achieve a higher overall efficiency than the solar cells.
The work comprises the thermo dynamical calculation of the Clausius-Rankine-Cycle with the organic fluid Toluene (C7H8). In addition to this an evaluation of the different subsystems, like the evaporator, the pump, the turbine-generator combination and the radiator was undertaken. All these subsystems are considered as micro machineries (approx. weight of each subsystem only about several grams each). A calculation of the special honeycomb-shaped mirror system of the Cassegrain collector was also done.
The work was carried out at the Technical University of Berlin, Institute of Space Technology, under the guidance of Professor Klaus Briess.
- Abstract document