A Stirling engine is a heat engine operating cyclic compression and expansion of air or other gas, the fluid works at different temperature levels, such that a net conversion of heat energy to mechanical energy occurs.Originally conceived in 1816 by Robert Stirling designed as a first mover to rival the steam engine, in practice its use for home applications fell by almost a century. Stirling engines have high efficiency, when compared to steam engines, and easily to be applied to any source of heat. These advantages are making returns the interest in these engines, and their application in collectors systems of renewable energies.

 

Stirling engine powered by candels.

 

The Stirling engine is the only one capable of approaching (theoretically it reached) the maximum theoretical yield known as Carnot efficiency, so, as far as thermal performance engines are concerned, is the best choice.

ADVANTAGES

– The heat input is external, so that the combustion conditions are flexible.

– Works with any heat source, not only by burning, so you can use heat sources such as solar, geothermal, nuclear, biological, etc..

– Most Stirling engines have the mechanisms and the heat sink together, and therefore require less lubrication and last longer than alternative machines.

– The mechanisms are simpler than other alternatives machines, these is no need valves, the burner can be simplified.

– They can be built for run quietly without air consumption for submarine propulsion or operation in space.

– They are extremely flexible and can be used for cogeneration in winter and cooling in summer.

DISADVANTAGES

– Stirling engines require heat exchanger inlet and outlet, which must contain working fluid at high temperature and withstand the corrosive effects of the heat source and the atmosphere. This represents a rise in the price of the machine.

– Engines running with small thermal differentials are very large compared to the work done because of the exchangers.

– A Stirling engine can not start instantly, you must first “warm” the engine. This is true of all external combustion engines, but smaller than others such as the steam engine. It is best used in engines that require a constant speed.

 

STIRLING ENGINES IN THE XXI CENTURY

NASA itself is very interested in this type of converters has devoted significant energy and economic efforts in the development of applications that incorporate different engine models. In the Internet http://www.grc.nasa.gov/WWW/tmsb/stirling/doc/stirling_animation.html  we can see interesting animations of different engine models.

Solar Stirling engines have been used for decades, but has not reached mass market until 2010. Sean Gallagher, Vice President of Market Strategy and Regulatory Affairs for SES, says the reason they have taken so long to commercialize this technology, it is more logistical and economic problem that because of the technology itself.

In 2010 this technology for the first demonstration plant of 1.5MW in Maricopa Arizona is employed, using 60 disks SunCatcher Stirling technology. This plant is the first commercial example of this type of system and paves the way for the construction of solar plants with Stirling technology 1.5GW in California and Texas.

Until date today there are many plants that are operating in different geographical parts of the world, and marketing is available to anyone interested in using this wonderful technology.

 

Stirling disks, for generate energy.

NASA Stirling Engine

Striling Disk. Parts

 

 

Stirling Engines for submarines.

 

PELTIER  EFFECT

 

Peltier effect is the production or absorption of heat caused by the passage of current through the contact of both metals or a metal and a semiconductor. The Peltier effect was discovered in 1834 by French physicist JCA Peltier emerged on the basis of the discovery of the German physicist TJ Seebeck in 1821.

The essence of the Peltier effect, involves passing a current from a continuous source of electricity through a circuit formed by two conductors of different nature to give one of its unions absorbs heat and releases it otherwise. The heat gives the hot spot will be the sum of the electrical energy supplied to the thermocouple and the heat absorbed by the cold source. These thermal elements are configured in this way, constitute a refrigerating machine.

Currently, one of its most common uses is as part of the CPU cooling computers.
It is also used in home dehumidifying equipment, because this system generates less noise than the compression system and is more compact.

 

 

 

http://www.ecotec2000.de/espanol/stir2.htm

Ventajas y Desventajas de los Motores Stirling

http://www.sc.ehu.es/sbweb/fisica_/estadistica/termodinamica/stirling/stirling.html

http://eltamiz.com/2007/08/30/%C2%BFque-es-el-efecto-peltier/

http://www.ecured.cu/index.php/Efecto_Peltier

http://www.aulastecnopole.com/trabajos/Memoria_SAUL-FERNANDO.pdf

The  last week experiment consisted of measuring the amount of solar energy emitted by a particular device. For the experiment, we follow a series of steps which consisted of the following. First we had to mount the device, which consisted of a solar cell, voltage probe, a flashlight and some different colored filters. Once we assemble the device, we were ready to go.

Our goal was to find the relationship between the voltage and intensity of light emitted, to do different measurements performed during X time, and at different distances. The process was the following, we placed the light source attached to the photovoltaic cell, and we were going by increasing distance and taking data of the results.
The result we got was that as we were going distancing of solar cell, the voltage that we gained was diminishing.

These results collected are in the chart that I show below:

 

 

Once we had completed this step, we returned to do the same, but this time add a little variation. Consisted to add color filter to the light, to see if this affected the amount of voltage that the solar cell was able to collect.
The results were as follows, the colors allow more light to pass through it, ie lighter colors, were the more voltage generated due to the greater amount of light intensity that allowed to pass. In the opposite case, the darker colors, gave inferior results.
Below, we can see a graph in which we observe the relationship between color, light intensity and voltage.

In this lab we were charged with the duty of running a generator powered off of our own bodily energy. For this lab we used the Lego Mindstorm technology and software to power and capture our results.

In this experiment we were asked to explore Faraday’s law. The law states that changing magnetic fluxes through coiled wires generate electricity currents and voltage. Our assignment was to measure the voltage produced shaking an old flashlight. We hooked up the equipment to lab view and became working.When the generator was shaken weakly it produced very little voltage. When shaken hardly the voltage produced was much higher.  Our data shows that the voltage increases the higher the number of shakes. Whether the movement was small or large there was always something produced. The magnet that was in the generator was what produced the voltage.

After doing the procedure, here’s the data my partner and I came up with, it was impossible to me to get the excell file, so I attach pictures of the screen:

 

Here we can see the sum of squares,

The numerator of this fraction involves a sum of squared deviations from the mean. The formula for this total sum of squares is

Σ (xi – x̄)2.

Here the symbol x̄ refers to the sample mean, and the symbol Σ tells us to sum the differences (xi – x̄) for all i.

 

 

The Sum of Square is also needed to square the voltage.  Each sum of square data plot represented 30 data points

 

 

Our finding was simple, as we increased the number of shakes, the voltage was increased, just as logic would tell us, but again, the theory was proven by practice.

What is Solar Energy?

 

Solar power is a source of energy from renewable sources, obtained from the use of electromagnetic radiation from the Sun

Solar radiation reaching the Earth has been harnessed by humans since ancient times, using different technologies that have evolved over time from conception. At present, heat and sunlight can be exploited by collectors and photovoltaic cells, thermal collectors or heliostats, which can transform into electrical or thermal energy. It is a so-called renewable energy or clean energy, which can help solve some of the most pressing problems facing humanity.

The different solar technologies are classified into passive or active depending on how you capture, convert and distribute solar energy. Active technologies include the use of photovoltaic panels and thermal collectors to gather energy. Among the passive techniques, different techniques are framed in bioclimatic architecture: the orientation of buildings to the Sun, selecting materials with favorable thermal mass or having properties for light scattering, and the design of spaces through natural ventilation.

In this small diagram, we can see how solar energy works

 

 

Innovation and Development of Solar Energy.Why we should use Solar Energy?

 

The use of solar energy in Europe is having in recent years a rapid growth. This is due to the need to replace fossil fuels with other renewable energy, intended to reduce emissions that cause the greenhouse effect and the interest that the European Community has set the development of this type of energy so, the most dynamic markets are England, France and Germany, which have growth rates between 40 and 70%.

Recently been created European Platform for Solar Thermal Technology, dedicated to the development of such energy, for this, measures such as tax cuts that encourage solar installations are made.

The most optimistic forecasts predict that long-term solar thermal energy can cover up to 50% of heating needs in Europe. If the actions are effective, it could end up saving more than 100 billion euros annually by 2020 and about 780 million tons of carbon dioxide that would stop launching into the atmosphere.

All these measures would mean that by 2020, the total energy savings could reach 27% in the home, 30% in the commercial sector, 26% in transport and 25% in manufacturing

 

Innovation in Spain

 

Spain is among the European countries with the highest number of sunshine hours, to which European commitments come together in renewable energy installation and the strategic desirability of reducing the large foreign energy dependence and increase energy independence.

All this contributed to Spain was initially one of the first countries in the world in research, development and utilization of solar energy. Thanks to favorable legislation, in 2008 Spain was one of the countries with the most installed photovoltaic power in the world, with 2,708 MW installed in a single year.

 

CSP Plant

Gemasolar is a CSP plant with thermal storage in molten salts.

Gemasolar is the first commercial solar thermal power plant  with a central tower receiver technology  and molten salt storage system. It is a solar field of 185 Ha housing the receiver on a tower 140 m high, the power island and 2,650 heliostats, each of 120 m2, distributed in concentric rings around the tower.

The most innovative aspects of this plant, owned by the company Torresol Energy, are the molten salt receiver, the heliostat pointing mechanism and control system, in addition, the storage system can produce electricity for 15 hours without sunlight (for night or on cloudy days). Thanks to this storage capacity, solar energy becomes manageable and can be supplied according to demand. The plant has already reached a fully1 day of uninterrupted supply to the network using thermal transfer technology.

Gemasolar, 19.9 MW, is capable of delivering 110 GWh per year, which can supply power to 27,500 homes. This plant has been operational since May 2011. The official opening was held in October 2011.

 

 

 

http://www.prosun.org/es/ue-solar-sostenible/energia-solar-para-el-futuro-de-europa.html

http://www.energia-solar.org.es/m-energia-solar-europa.html

http://twenergy.com/energia-solar

http://www.torresolenergy.com/TORRESOL/plantas.html