Buy Stirling Engine Solar
The solar concentrator, or dish, gathers the solar energy coming directly from the sun. The resulting beam of concentrated sunlight is reflected onto a thermal receiver that collects the solar heat. The dish is mounted on a structure that tracks the sun continuously throughout the day to reflect the highest percentage of sunlight possible onto the thermal receiver.
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The engine/generator system is the subsystem that takes the heat from the thermal receiver and uses it to produce thermal to electric energy conversion. The most common type of heat engine used in dish/engine systems is the Stirling engine. A Stirling engine uses the heated fluid to move pistons and create mechanical power. The mechanical work, in the form of the rotation of the engine's crankshaft, drives a generator and produces electrical power.
Theoretically, the stirling engine can perform to full Carnot Cycle efficiency, but there has been no success in practice. Depending on the configuration, efficiency typically hovers around 25-30%. It can run on a temperature difference as little as 7 ͦ C, with diminished power output, of course. The engine can also be supplied with mechanical power to reverse its cycle and be used as a heat pump.
The stirling cycle has four steps involved in its operation, illustrated in the animation below.1. Heating: Energy is transferred from the heat source to the working fluid through the hot heat exchanger. This causes the pressure of the working fluid to increase within the fixed volume contained by the piston. The bulk of the fluid is contained in the hot cylinder at this time.2. Expansion: At a certain point, the pressure within the cylinder becomes high enough to displace the power piston. The power piston turns the crankshaft which results in a power output. The working fluid will continue to expand until the pressure inside the cylinder reaches equilibrium with the pressure applied by the piston.3. Cooling: On the cold side, energy is transferred from the working fluid to a heat sink through the cold heat exchanger. This causes a pressure decrease in the cold side. At this point, the working fluid is mostly inside the cold cylinder.4. Compression: At a certain point, the pressure within the cylinder becomes low enough to displace the displacement piston, sending the cooled fluid back to the hot cylinder. The working fluid will continue to compress until the pressure inside the cylinder reaches equilibrium with the pressure applied by the piston.
The presence of the regenerator is really what distinguishes a Stirling engine from a simple hot air engine. There can be many different piston/cylinder configurations. Here are the three most common types:
A Swedish technology company has installed a new solar electricity generation system in South Africa's sun-soaked Kalahari desert, saying it's not only the most efficient system of its kind in the world, but it doubles the efficiency of standard solar panels.
The system, which features a pair of huge, 12-metre mirror dishes, runs on a Stirling engine - a type of closed-cycle regenerative heat engine that was invented way back in 1816, and uses trapped gas instead of water to propel the internal pistons and flywheel. The dishes are slowly rotated throughout the day to capture the maximum amount of solar rays and focus them into a specific point, which kicks the Stirling engine into gear.
Adopted by the Swedish military for use in their submarines almost three decades ago, Stirling engines have since been touted as the perfect match for renewable energy systems because they can function with almost any heat source, are quiet to run, and don't take up much space. Swedish-based company, Ripasso Energy, licensed the technology from the military, and together with their colossal parabolic mirror dishes, the system requires just 2 hectares to produce a megawatt of energy.
"This is the only working small-scale concentrated solar energy system of its kind in the world. Thirty-four percent of the Sun's energy hitting the mirrors is converted directly to grid-available electric power, compared to roughly half that for standard solar panels. Traditional photovoltaic panels are able to turn about 23 percent of the solar energy that strikes them into electricity, but this is cut to around 15 percent before it is usable by the grid."
The challenge now is to show the potential of the system in environments where sunlight isn't as abundant. It's all very well for a solar system to work brilliantly in the middle of a desert, but it needs to be able to work in an urban environment in order to make an actual difference. But this team is no stranger to setting records using solar technology, so hopefully they'll figure it out.
The Concentrator Photovoltaic, or CPV, is often viewed as the most efficient tool for retrieving solar energy to power various systems. The primary purpose of a CPV is to keep the solar radiation focused on the solar cells, therefore, accumulating the solar radiation. Creating the environment, in which the transformation of solar power into heat energy becomes a possibility, the device in question should be viewed as one of the means of introducing a policy of sustainable use of resources into the contemporary industry realm.
The primary structure of a CPV system is rather simple. The funnel lenses serve as the primary tool for capturing the solar energy and focusing it in the cells. The secondary optics allows magnifying the effect of the sun radiation, therefore, helping retrieve the necessary amount of energy. Finally, the cell assembly creates the environment, in which the process of receiving energy becomes a possibility. The cell assembly consists of a secondary concentrator and an electrical contact between the cell itself and its prismatic cover, the solder with a copper heat spreader, and a conductive adhesive supported by a module housing. The housing, in its turn, performs the function of a container for the cells and the optics.
It should be noted, though, that the use of CPV is only possible in specific areas that can provide an environment favorable for the further accumulation of solar energy. Understandably enough, the tool in question is only applicable in the areas that provide exposure to large doses of solar radiation; particularly, it is required that the Direct Normal Irradiance (DNI) doses should reach 2,000 kWh/m2a at the very least [1]. Otherwise, the adoption of the CPV system is unlikely to be successful.
Phillips et al. [1] specify two types of CPV, which are currently used as the primary means of collecting solar energy, based on their capacity. The High Concentration PV and the Low Concentration one differ primarily in the concentration ratio 300 to 1,000 and less than 100 correspondingly), the tracking type (solely two-axis one or the one inviting an opportunity for using either one- or two-axis approach), and the type of converter (III-V multi-junction solar cells or c-Si/other cells correspondingly). It should also be borne in mind that the above options allow for a significant reduction in the costs for the cells since the technology used to create the items in question has become quite popular and, therefore, reproducible.
It should also be borne in mind that the CPV system must be positioned appropriately so that its assets could be used to their full potential. Du et al. (2012) point specifically to the fact that the construction needs to be tilted at 35 so that it could capture all the light and produce as much energy as possible. As the experiment set by the authors of the article has shown, the solar intensity peaked at 1019 W/m2, which allowed the construction to retrieve an impressive amount of solar energy. With the difference between the temperature of the fixed solar cell and the ambient environment ranging from 20 C to 23 C, the cooling water extracted a large amount of heat from the cells.
In other words, the experiment has shown that the current preference for the use of solar cells with the cooling system to the fixed cells use is fully justified as the former provides a much better output. Therefore, the application of the CPV system requires the usage of cooling systems that create the environment, in which CPV can be used to its maximum capacity.
To compare the Stirling engine to the CPV tool, one must carry out a foray into the history of its creation first. Another innovative tool that allowed revolutionizing the very concept of generating power, the Stirling engine was supposed to provide has recently been renovated and upgraded to retrieve power from solar energy.
Because of its universal structure that permits its application in a variety of domains, the Stirling engine is used in rather specific domains such as submarines for generating the necessary amount of power. Nevertheless, the basic components of the engine remain basically the same. The system rests on a stump, which serves as the foundation for the crankcase. The latter contains the crankshaft, which is activated by the drive mechanism, and the connecting rod that makes the piston rod move.
The crankshaft and the piston rod are activated by the drive shaft. The piston rod seal, which is a specimen of a hydraulic seal, connects the driveshaft to the cylinder block, therefore, activating the latter as the former starts the motion. The volume of the gas in the cylinder increases as the preheater is activated, or drops as the cooler are set into motion. Therefore, once the fuel injector supplies the fuel, and the fuel lighter triggers the creation of gas, the Stirling engine is started [3]. The structure described above allows for retrieving the maximum energy possible from the amount of fuel supplied to the engine.
While the transfer from obtaining energy from the traditional sources to the extraction of solar energy has altered some of the elements of the Stirling engine, the general structure and properties remain in their places. Among the primary changes that occurred to the structure, the addition of the solar receiver needs to be brought up. According to the description provided, the receiver contains an insulated cavity; the latter, in its turn, has the aperture needed for the sunlight to enter [3]. It should be noted, though, that focused solar energy is not acceptable in the specified case; herein lies the need for the slew shield. The latter serves as the means of protecting the PCU. As soon as the hydrogen in the heater heads reaches the temperature of 600 C, the engine is set into motion. 041b061a72
