Proposal for clean energy generation using a thermodynamic closed-cycle to convert sun light radiation to mechanical work.
Nowadays, the energy production came in different forms, there is a major percent in the world that is produced by fossil fuels, as well as, the automotive sector is engaged with the oil as the main power, under those circumstances, there is a large budget invested to research in new forms of energy production for extend the oilfields life, reduce the climate exchange effects and supply the demand of the humanity in electricity terms. This post is an overview of how the design and thermodynamics offers an innovate way to generate energy as a response to the energy needs.
This work was done in 2015 with a great team of physical engineering students, Camila Orozco, Liceth Uchima and the leadership of Juan Botero in the National University of Colombia.
I would like to explain in a straightforward way the science behind this work, in fact, the major technology have been used in energy generation is the internal combustion engine, which works in base of oil derivates, when the science started to research in energy 200 years ago, there was a fight between the internal and external combustion engines, for power efficiency reasons this fight was won by the first type of engine, and the science behind the second type was reserved to be explored in our days due all the environmental reasons explained, so as a part of external combustion engines was develop the Stirling cycle named by his inventor, the main difference between the two types of develops is the way that it use the source of energy.
The Stirling engine cataloged as a external type use the source of energy outside of the mechanisms of it, the source is external, in fact, if it is used with a fuel it should be burned outside of the engine, instead, the internal combustion engine burn the fuel into the cylinders, consequently, the main benefits of power generation of Stirling are that could be used with lot of energy sources available as: radiation, oil fuels, sun light, and others, this fact is amazing because without the need of changes in mechanisms, the engine may work with a variety of power sources, therefore, the possible applications of this science could be huge, from farms to space exploration.
In the first place, the team started to research over the time the possible applications of Stirling cycle, looking that in a high percent of the cases it was used to energy generation, and the possible goal to accomplish was build a machine that use the sun light and convert it to mechanical work, indeed, the reason of use the sun for this purpose is due the environmental conditions of Colombia, we have this incredible source of energy almost all the year for being near to the ecuador center, hence, the develop of a prototype could lead to solve a huge energy problem in communities far away from the principal cities. There are towns in Colombia that don’t have access to electricity and clean water sources, in consequence, the health conditions is not good for the people leading to propagate diseases.
Referring to the develop, this engine is the alpha type composed by two cylinders, the first one is the expansion cylinder and it is maintained at high temperature due the sun radiation that is gathered with a parabolic trough on the top of it, while the fluid of work is heated in one side, the other cylinder works as a compressor cooling the air, in the middle of the way between the two cylinders we could find the regenerator where the fluid passes in each cycle composed by a matrix of metal fine wire working as a heat exchange, the next image shows the main parts of the design.
After the design, maths, physics and thermodinamics stuff, the design was done in Solid Edge ST6 student version, the objetive is build the project and continue the research after all solving the problems that could occur in the way, the next images shows the design and the mechanical movement that makes possible the expansion and compression of the air, as well as the heat exchanger. All the mechanical parts was done by the team in a mechanical laboratory of the physics department at the university, using lathes, milling machines, and aluminium melting system.
The problem of gather the solar light in an small area to increase the infrared radiation on it to get high temperatures was solved with a parabolic trough of TV satellite streaming, we had a low budged and at the final this solution worked really good, in fact, the sun was gathered on the top of the expansion cylinder covered with also an aluminum external cylinder that ensures that light bounces at least twice in the heat cylinder.
The prototype was build complete, the mechanical system worked really good with incredible synchrony, also the right temperature was achieved with the colector system, however, the cylinder clearances for managing air flow was a headache, we tried nylon rings to insulate the volume of the internal cameras, but when the system started to compress the air and the pistons start to go along their way the air started to reduce the pressure due filtering, the project stopped at this time for budget problems.
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