For the conversion of fossil energy into electrical energy, the technology of a thermal power plant is often used. At the moment in which a thermal power station is fossil fuels fossilized from a source of non-renewable energy generation.
A thermal power plant (or thermoelectric plant) is a plant that generates electricity by transforming heat. Historically heat energy is converted into electricity by transferring heat to a working fluid and then transforming the energy of this fluid into mechanical energy. Finally, mechanical energy is transformed into electricity. The…
According to the first law of thermodynamics, every process that occurs in a given system must satisfy the principle of conservation of energy, including the flow of heat.
states, in other words, that any process whose sole purpose is to create or destroy energy, is impossible, that is, it denies the existence of a first-class perpetual motion machine.
However, the first law does not tell us anything about the…
In thermodynamics, an isothermal process is a thermodynamic transformation at constant temperature, that is, a variation of the state of a physical system during which the temperature of the system does not change with time. Devices called thermostats can maintain a constant temperature value.
The isothermal transformation of a perfect gas is described by Boyle's law which, in a pressure-volume diagram (or Clapeyron's plane), is represented by a branch of the equilateral hyperbola. Isotherm of a perfect gas Calculation of heat and work exchanged
For isothermal gas…
Thermodynamics is the branch of classical physics that studies and describes the thermodynamic transformations induced by heat and work in a thermodynamic system, as a result of processes that involve changes in the temperature and energy state variables.
Classical thermodynamics is based on the concept of macroscopic system, that is, a portion of physical mass or conceptually separated from the external environment, which is often assumed for convenience that is not disturbed by the exchange of energy with the system. The state of a macroscopic system that is in equilibrium conditions…
The applications of photovoltaic solar energy are many and varied. In this field, they include from large power generation plants through photovoltaic panels, to small solar calculators.
A first way to classify the applications of photovoltaic solar energy is to distinguish the applications connected to the electrical network and the isolated installations.
The use of photovoltaic panels in isolated buildings is very useful since the investment needed to place solar panels on the roof of a farm, a chalet in the mountain or in a hotel in a secluded spot, is much less than what it…
An inverter is an electronic device. The function of the inverter is to change a DC input voltage to a symmetrical AC output voltage, with the magnitude and frequency desired by the user. The inverters use in a great variety of applications, from small power supplies for computers, to industrial applications to control high power. The inverters are also used to convert the direct current generated by photovoltaic solar panels, accumulators or batteries, etc., into alternating current and thus be able to be injected into the electrical network or used in isolated electrical installations.…
An inverter is an electronic device. The function of the inverter is to change a DC input voltage to a symmetrical AC output voltage, with the magnitude and frequency desired by the user. The inverters use in a great variety of applications, from small power supplies for computers, to industrial applications to control high power. The inverters are also used to convert the direct current generated by photovoltaic solar panels, accumulators or batteries, etc., into alternating current and thus be able to be injected into the electrical network or used in isolated electrical installations.
In the beginnings of photovoltaic solar energy, the electrification facilities used electricity for consumption at the same voltage and with the same form that they received from photovoltaic solar panels and accumulators, that is, at 12, 24, 48 volts in direct current. This made a big difference with the users who had electricity distribution network or generator sets at 220 volts alternating current.
The appliance market has adapted to the majority of users and we can find any appliance with 220 volts of alternating current. Therefore, getting reliable, quality, and reasonably…
We refer to the photovoltaic effect in everything related to obtaining energy through the action of light.
The most used light source for photovoltaic installations is that coming from the Sun, that is, solar energy. Although there are small devices, such as calculators, that can work with artificial light. Photovoltaic solar energy
Solar photovoltaic energy is a methodology for obtaining electrical energy thanks to photoelectric cells. It is a renewable energy since its energy source, the Sun, is considered inexhaustible.
Photoelectric cells are the main component…
In thermodynamics, a thermodynamic cycle is a circuit of thermodynamic transformations performed on one or more intended devices. The objective of these transformations is to obtain work from two sources of heat at different temperatures, or conversely, to produce through the contribution of work the passage of heat from the source of lower temperature to higher temperature.
Obtaining work from two thermal sources at different temperatures is used to produce movement, for example, in thermal engines or alternators used in the generation of electrical energy. Performance is…
The flat plate solar collector is a type of solar thermal panel whose objective is to transform solar radiation into thermal energy. This type of solar collector has a good cost / effectiveness ratio in moderate climates and adapts correctly to a large number of applications of solar thermal energy (heating of sanitary water, heating of swimming pools, support for heating, preheating industrial fluids , etc.).
We can distinguish two basic types of flat plate solar collectors, depending on the configuration of the absorber: the "grid type" parallel, in the vertical and horizontal…
The Stirling engine was invented in 1816 by Robert Stirling, a Scottish priest. The goal was to get a less dangerous engine than the steam engine.
The operation of the Stirling engine is based on the expansion and contraction of a gas that can be helium, hydrogen, nitrogen or air. This gas is forced to cycle cyclically from a cold source where it contracts to a hot source where it expands. It is considered as a thermal engine (thermodynamic engine) due to the presence of a temperature gradient between the two thermal sources.
Originally, the Stirling engine was conceived as an…
The watt (symbol: W) is the power unit of the International System, it is the amount of energy in joules that is converted, used or dissipated in one second. It is a derived unit that takes its name from the engineer, inventor and constructor of Scottish instruments James Watt, for his contribution to the development of the steam engine, which was one of the triggers of the beginning of the Industrial Revolution.
The watt unit was adopted by the Second Congress of the British Association for the Advancement of Science in 1889, which meant its international recognition as a power unit,…
A thermodynamic process is the evolution of certain properties, which are called thermodynamic properties, in relation to a particular thermodynamic system. In order to study a thermodynamic process, it is required that the system be in thermodynamic equilibrium at the initial and final point of the process; that is, that the magnitudes that undergo a variation when passing from one state to another must be completely defined in their initial and final states.
In this way thermodynamic processes can be interpreted as the result of the interaction of one system with another…
The solar thermal energy consists of the use of the energy coming from the Sun to transfer it to a medium that carries heat, generally water or air.
Among the different applications of solar thermal energy there is the possibility of generating electrical energy. The current technology allows heating water with solar radiation to produce steam and then obtain electrical energy.
Although the principle of operation is very similar there are two main applications of solar thermal energy:
- Use of solar thermal energy in homes and small installations…
In physics, in particular in thermodynamics, heat is defined as the contribution of transformed energy as a result of a chemical or nuclear reaction and transferred between two systems or between two parts of the same system. This energy is not attributable to a job or a conversion between two different types of energy. Heat is, therefore, a form of transferred energy and not a form of energy contained as internal energy.
As the energy is exchanged, the heat is measured in the International System in joules. In practice, however, it is often still used as the unit of measurement of calories,…
In thermodynamics, the internal energy is the total energy contained in a thermodynamic system.
The internal energy is the energy that is needed to create the system. According to this definition, the energy to displace the environment of the system, any energy related to external force fields (potential energy, gravitational energy, etc.) or any energy associated with the movement (for example, kinetic energy) is excluded from the internal energy. .
The internal energy of a system can be modified by exercising a work on it or by heating it (providing thermal energy). If we look…
In electricity, the rated voltage of an electrical device is the voltage that must not be exceeded in normal operation. The nominal adjective is because that tension usually serves to characterize the device, to name it. The nominal value indicates the theoretical or ideal value of anything that can be quantified, as opposed to the real value, which is what is obtained in a given measurement.
Another definition of rated voltage: The rated voltage is the specific potential difference for which a device or installation is designed.
As it is a nominal value it implies that the voltage…
The first law of thermodynamics was announced by Julius Robert von Mayer in 1841. It is the principle of conservation of energy.
Definition of the first law of thermodynamics: The total energy of an isolated system is neither created nor destroyed, it remains constant. Energy only transforms from one type to another. When one energy class disappears, an equivalent quantity of another class must be produced.
A body can have a certain speed with what has kinetic energy. If it loses speed, this kinetic energy that it loses becomes another type of energy, whether it is potential energy…
What is entropy? Entropy (S) is a thermodynamic quantity originally defined as a criterion for predicting the evolution of thermodynamic systems.
Entropy is a function of extensive character state. The value of entropy, in an isolated system, grows in the course of a process that occurs naturally. Entropy describes how a thermodynamic system is irreversible.
The meaning of entropy is evolution or transformation. The word entropy comes from the Greek. Entropy in the world of physics
In physics, entropy is the thermodynamic magnitude that allows us to calculate the…
The constant price increases in electricity rates are reflected in the monthly bills of our home and therefore, more and more people are looking for alternatives to electricity and natural gas in order to save a few euros at the end of the month . One of these alternatives that has been implemented for a few years in Spain is self-consumption from solar panels .
With the installation of solar panels and the use of solar radiation, it is possible to generate electricity and / or heat in the home in a clean and renewable…
Thermodynamics is mainly based on a set of four laws that are universally valid when applied to systems that fall within the constraints implicit in each.
The first principle that was established was the second law of thermodynamics, as formulated by Sadi Carnot in 1824. The 1860 already established two "principles" of thermodynamics with the works of Rudolf Clausius and William Thomson, Lord Kelvin. Over time, these principles have become "laws." In 1873, for example, Willard Gibbs claimed that there were two absolute laws of thermodynamics in his graphical methods in fluid thermodynamics.…
Geothermal energy is a long-term source of energy worldwide. With the geothermal energy stored in the top three kilometers of the Earth's crust, theoretically, the current energy demand could be covered for more than 100,000 years. However, only a small part of this energy is technically usable and the effects on the earth's crust during extensive heat dissipation are not yet clear.
When geothermal energy is used, a distinction is made between direct use, that is, the use of heat in itself, and indirect use, the use for conversion into electricity in a geothermal power plant. With the…
A turbine is a turbomachine that converts the flow energy of a fluid (liquid or gas) into mechanical energy by means of a system of rotating blades. This mechanical energy can be used to power another machine or an electric generator.
The turbine name was proposed by Claude Burdin during an engineering contest in 1828. This name comes from the Latin turbine, which means Foucault current.
A simple turbine consists of a single rotor with blades, which provide energy exchange with the flow. The first examples of turbines are wind turbines and water mills, that is, for wind…
One kilowatt (kw) is a power unit in current use, equivalent to 1000 watts (w).
One watt (w) is a power unit of the international system equivalent to one joule per second.
If we express the watt in units used in electricity, we can say that a watt is the electric power produced by a potential difference of 1 volt and an electric current of 1 ampere (1 volt ampere).
Frequently the watt hour (Wh) is also spoken as an energy unit. The watt hour is a practical unit of energy equivalent to the energy produced by a power of one watt for one hour. Common errors related…
A thermodynamic system is a portion of the material space, separated from the rest of the thermodynamic universe (that is, from the external environment) by means of a real or imaginary control surface (or edge), rigid or deformable.
A thermodynamic system can be the seat of internal transformations and exchanges of matter and / or energy with the external environment (that is, everything external to the system that interacts with it). Classification of thermodynamic systems
Within thermodynamics there are three main types of thermodynamic systems: open, closed and isolated.…
A solar thermal collector is a component of a solar thermal installation. A solar collector is a type of solar panel responsible for capturing solar energy and transforming it into heat. It is also called the solar thermal collector.
The solar collector is the basic element of this renewable energy source.
From solar collectors there are many types. The solar collector used will depend on the use that is going to be given. For example, if we want to heat a pool to a temperature of 25-28ºC, in the spring, we need a simple sensor, since the ambient temperature will easily be…
A thermodynamic property is a characteristic or a particularity that allows the changes of the work substance, that is to say, changes of energy.
The thermodynamic properties can be classified as intensive and extensive. They are intensive those that do not depend on the amount of matter of the system (pressure, temperature, composition). Extensive ones depend on the size of the system (mass, volume). Thermodynamic variables
The thermodynamic variables are the magnitudes…
The geothermal heat pump is an air conditioning system for buildings that exploits the heat exchange with the superficial subsoil, by means of a heat pump. Since the heat in the subsoil comes largely from the interior of the Earth, geothermal energy of low enthalpy is classified as a source of renewable energy, although the heat pump itself consumes electricity, generally produced from other sources of energy (for example, fossil fuels).
The heat pump allows the exchange of heat between a "source" at a lower temperature than the "well", or the point where the heat is introduced. In a…
Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the limits of the laws of thermodynamics.
Chemical thermodynamics involve not only laboratory measurements of various thermodynamic properties, but also the application of mathematical methods for the study of chemical questions and the spontaneity of processes.
The structure of chemical thermodynamics is based on the first two laws of thermodynamics. From the first law of thermodynamics and the second law of thermodynamics, four equations…
Hydropower is a source of renewable energy or alternative energy. This renewable energy exploits the transformation of gravitational potential energy, possessed by a certain mass of water at a certain elevation, in kinetic energy to overcome a certain difference in height. The mechanical energy obtained can be used directly to rotate the shaft of a turbine or in some application or machine that works using hydropower. The most common is to use this kinetic energy to generate electrical energy. In this case, we talk about hydroelectric power.
In hydroelectric power, the kinetic energy…
Although in principle it seems that in an installation of photovoltaic solar energy just need solar modules and batteries, there is a key element in these facilities is what ensures that, in the charging process as in the discharge accumulators, is made so that they are always within the correct operating conditions: the charge controller.
Solar panels are designed so that they can give a higher than the end voltage battery charging voltage. This ensures that the solar panels are always able to charge the battery, even when the temperature of…
In the autonomous electricity supply facilities, it is necessary to store the energy captured during the hours of solar radiation in order to cover supply during the hours when there is no (daily cycle and seasonal cycle).
- Electric batteries have a very important and fundamental to the proper functioning and duration of a solar photovoltaic installation function.
- They must have sufficient capacity to ensure supply of electricity during periods of clouds (autonomy of installation).
- It is reversible electrochemical systems…
Solar thermal energy is a way to harness the heat of solar energy from to get heat. Of the different techniques to convert solar radiation into thermal energy, in this section, we explain high-temperature solar thermal energy.
We refer to high-temperature solar thermal energy to those solar systems that use solar collectors that work at temperatures above 500ºC. In this type of installations, once the solar radiation has been transformed into heat energy, the next objective is to transform this heat into electrical energy.
Renewable energy is energy that comes from virtually inexhaustible natural sources. They are considered inexhaustible either because of the large amount of energy they contain or because they can be regenerated naturally.
Among the main advantages of renewable energies we highlight the following:
Renewable energies are respectful with the environment and do not pollute. In this sense, they are safer and pose fewer health risks than other sources of non-renewable energy. The more energy generated by clean energies will need to generate fossil energy mes and decrease,…
In the design of passive solar buildings, windows, walls and floors are made to collect, store and distribute solar energy in the form of heat in the winter and reject solar heat in the summer. This is called passive solar design because it does not involve the use of mechanical and electrical devices.
The key to designing a passive solar building is to make the most of the local climate by performing a precise site analysis. The elements to be considered include the placement and size of the window, and the type of glazing, thermal insulation, thermal mass and shading. Passive solar…
Photovoltaic solar energy consists of the direct transformation of solar radiation into electrical energy. This type of energy is often referred to directly as photovoltaics.
This transformation in electrical energy is achieved by taking advantage of the properties of semiconductor materials through photovoltaic cells. The base material for the manufacture of photovoltaic panels is usually silicon. When sunlight (photons) hits one of the faces of the solar cell, it generates an electric current. This generated electricity can be used as an energy source.
We have two definitions of electricity depending on whether ns refer to physical phenomena on a macroscopic scale or on a microscopic scale.
With the term electricity we refer generically to all physical phenomena in a macroscopic scale that involves one of the fundamental interactions, the electromagnetic force, with particular reference to electrostatics. At the microscopic level, these phenomena are due to the interaction between charged particles on a molecular scale: the protons in the nucleus of atoms or ionized molecules and the electrons. The typical macroscopic effects of such…
A mini-hydraulic power plant is a power plant that uses hydropower for the production of electricity. They are characterized by the fact of having a reduced installed power. Its small size implies the use of structures of much smaller size than a normal dam. These mini-hydraulic plants are safer, thanks to the smaller volume of water in the basin, and which also have a lower environmental impact and landscape.
There is no globally accepted limit for which a hydroelectric plant is defined as mini-hydraulic. According to the ESHA (European Association of Small Hydroelectric Power Plants),…
An adiabatic process is a thermodynamic process in which the system does not exchange heat with its surroundings. An adiabatic process may also be isentropic, which means that the process may be reversible.
The adiabatic process provides a rigorous conceptual basis for the theory used to expose the first law of thermodynamics and, as such, is a key concept in thermodynamics.
The term adiabatic refers to elements that impede the transfer of heat with the environment. An isolated wall is quite close to an adiabatic limit. Hence the adiabatic wall term appears.
A process that…