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…
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…
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…
The generation of fuel through solar energy is a technique based on generating chemical reactions using solar radiation. These chemical processes allow the generation of energy that would otherwise come from a source of fossil fuel or nuclear energy.
A great advantage of the generation of solar fuels is that they can be transported and stored easily. However, adding a step in the generation of electric power (fuel generation) implies a reduction in efficiency: adding an additional step between the storage of energy and the production of electricity drastically decreases the…
In engineering a heat exchanger (or simply an exchanger) is an apparatus in which thermal energy is exchanged between two fluids that have different temperatures.
From the thermodynamic point of view, heat exchangers can be assimilated to open systems that work without exchanging work; in other words, they exchange matter and heat with the outside, but they do not exchange jobs.
In the solar thermal industry the heat exchanger is used to transfer the heat captured through the solar radiation that is found from fluid that circulates through the solar collectors to another…
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially, using the energy of solar radiation.
Photosynthesis occurs in plants, algae, and some groups of bacteria, but not in archaea. Photosynthetic organisms are called "photoautotrophs," but not all organisms that use light as an energy source effect photosynthesis, since "photoheterotrophs" use organic compounds, not carbon dioxide, as a carbon source. In plants, algae and cyanobacteria, photosynthesis uses carbon dioxide and water, releasing oxygen as a waste product. photosynthesis is crucial…
In thermodynamics an adiabatic wall is a wall that does not allow the transfer of heat from one side to another. An adiabatic wall does not let out or enter any heat.
Adiabatic walls are theoretical concepts because if in case tehey would exist they would be a perfect thermal insulation. At present, any thermal insulation, however good it may be, always allows some transfer of heat energy. Adiabatic process
An adiabatic process is a process in which the system does not exchange heat with its surroundings. An isentropic process is an adiabatic process that is also reversible.…
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 isobaric process is a change in the state of a certain amount of matter in which the pressure does not change, but one or more of its state variables. An example of this is air in a cylinder with a freely movable piston to which heat is supplied. Due to the increase in temperature, the volume will increase, but the pressure will remain constant.
The isobaric process is governed by Charles's law. The Frenchman Jacques A. Charles (1742-1822) was the first to make measurements about gases that expand when their temperature increases. Examples of isobaric processes…
Petroleum is a complex non-homogeneous mixture of hydrocarbons, composed / formed by hydrogen and carbon. The kinds of petroleums are very different from each other, can be from yellow and liquid to black and viscous. These differences are due to the relationships between the types of hydrocarbons. It is a non-renewable natural resource, raw material for numerous materials and products and, as a fossil fuel, the main primary energy source in the world.
The chemical components of petroleum are separated and obtained by distillation through a refinery process. From it different products…
Fossil fuels are often spoken of as a type of negative, polluting energy, harmful to the environment. Fossil fuels are considered a non-renewable energy source due to the difficulty of regeneration.
Currently, fossil fuels are the most widely used energy source in the world. It is used to generate electrical energy but above all it is also used to generate mechanical energy (cars, heat engines, etc.)
The theory that fossil fuels formed from the fossilized remains of dead plants by exposure to heat and pressure in the earth's crust for millions of years was first introduced…
Polycrystalline or polysilicon silicon is a material made of misaligned (polycrystalline) silicon glass. It occupies an intermediate position between amorphous silicon, in which there is no long-range order, and monocrystalline silicon.
This type of material is very important for the construction of photovoltaic panels and solar energy in general. The combination of silicon, together with solar radiation, makes it possible to take advantage of the photovoltaic effect and generate electricity.
This material has discrete metallic characteristics if strongly n-type doped. It often…
Monocrystalline silicon is the base material for the silicon chips used in practically all current electronic equipment. In the field of solar energy, monocrystalline silicon is also used to manufacture photovoltaic cells due to its ability to absorb radiation.
Monocrystalline silicon consists of silicon in which the crystalline lattice of the entire solid is continuous, does not break at its edges and is free of any grain limit. Monocrystalline silicon can be prepared as an intrinsic semiconductor that is composed only of very pure silicon, or can be doped by the addition of other elements…
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…
Coal is a fossil fuel that is used to obtain fossil energy through its combustion. The thermodynamic properties of coal allow obtaining a large amount of heat energy during its combustion process.
Coal is a natural resource limited. The generation of coal is a process of several million years, while the consumption of this energy resource is very fast. For this reason, coal is considered a non-renewable source of energy.
Coal is a sedimentary rock of organic origin, black or dark brown. It is used mainly as a fossil fuel because of its high calorific value…
Fracking, or hydraulic fracture, is an Anglo-Saxon term that is used to refer to a technique to increase the extraction of fossil fuels natural gas and oil from soil.
Hydraulic fracturing or geotechnical fracking is the exploitation of the pressure of a fluid, typically water, to create and then propagate a fracture in a layer of rock in the subsoil. Fracking is carried out after a drilling in a rock formation containing hydrocarbons (oil or natural gas). The objective is to increase the permeability. Improving permeability improves the production of oil or gas contained in the subsoil…
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…
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…
At the end of the 17th century, the Earth was conceived as a molten mass with a solid crust as a result of its cooling. It was not until the 19th century that the first calculations of the age of the Earth based on its thermal evolution were drawn up, and the term geothermal was first defined as the scientific discipline that studies earth's heat, origin of this heat, distribution and use.
Precisely, the use of this thermal energy is what has led to the development of geothermal energy. Geothermal energy allows us to take advantage of the heat energy inside the Earth in different applications,…
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.
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…
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…
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…
The photovoltaic cells are responsible for converting solar radiation into electrical energy in the form of direct current. Photoelectric cells are an indispensable element for this type of renewable energy.
There are different types of photoelectric cells depending on the nature and characteristics of the materials used. The most common type is the crystalline silicon cell (Si). This material is cut into very thin disc-shaped, monocrystalline or polycrystalline sheets, depending on the manufacturing process of the silicon bar.
The first crystalline cell that was manufactured…
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…
In the field of renewable energies, there are other renewable technologies in the development phase. Cellulosic ethanol, geothermal energy from hot and dry rock and marine energy are technologies that can complement traditional photovoltaic solar energy, wind energy or hydropower, for example.
However, these technologies are not yet sufficiently developed or have limited commercialization. Many of these new sources of renewable energy have great potential, but they still have a long way to go in research and development.
There are numerous organizations within the academic…
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.…
Solar energy allows to take advantage of the energy that comes from solar radiation. One way to take advantage of sunlight is to convert the radiation into electrical energy (photovoltaic solar energy) or thermal energy (solar thermal energy). Photovoltaic solar energy requires a chemical process to obtain a continuous current, while solar thermal energy only requires a thermodynamic process.
The characteristics of solar energy imply certain advantages with respect to other sources of energy. Mainly if the other sources of energy are non-renewable energies that come from fossil fuels.…