Physics presentation on the history of the creation of a capacitor. Capacitors, their role and functions. is equal to one if, when imparting charges to them
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Completed by: Dima Karetko, student 10 “A” Supervisor: Popova Irina Aleksandrovna, physics teacher Belovo 2011 Municipal educational institution “Secondary school No. 30 Belovo” Capacitors Miiproekt in physicsSlide 2
Plan Introduction Capacitors Basic parameters of a capacitor Classification of capacitors Application of capacitors Conclusion Literature
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Introduction You can find a system of conductors of very high electrical capacity in any radio receiver or buy it in a store. It's called a capacitor. Now you will find out how they work similar systems and what their electrical capacity depends on.
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Capacitors A capacitor is a two-terminal network with a certain capacitance value and low ohmic conductivity; device for storing electric field energy.
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Basic parameters of a capacitor: 1) Capacity: capacitance appears in the designation of a capacitor, while the actual capacitance can vary significantly depending on many factors. Real capacity is determined by electrical properties. 2) Specific capacitance is called the ratio of capacitance to the volume (or mass) of a dielectric. 3) Rated voltage - the voltage value indicated on the capacitor at which it can operate under specified conditions during its service life while maintaining parameters within acceptable limits. 4) Polarity: Many oxide dielectric (electrolytic) capacitors operate only with the correct voltage polarity due to the chemical characteristics of the interaction of the electrolyte with the dielectric.
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Classification of capacitors Vacuum capacitors (plates without dielectric are in vacuum). Capacitors with gaseous dielectric. Capacitors with liquid dielectric. Capacitors with a solid inorganic dielectric: glass (glass-enamel, glass-ceramic), mica, thin-layer inorganic films. Capacitors with solid organic dielectric: paper, metal-paper, film. Electrolytic and oxide-semiconductor capacitors (Such capacitors differ from all other types primarily by their huge specific capacitance). Permanent capacitors are the main class of capacitors that do not change their capacity. Variable capacitors- capacitors that allow a change in capacitance. Trimmer capacitors are capacitors whose capacitance changes during one-time or periodic adjustment.
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Application of capacitors Capacitors are used to build various circuits with frequency-dependent properties. When a capacitor is quickly discharged, a high-power pulse can be obtained, for example, in photo flashes. Since a capacitor can retain a charge for a long time, it can be used as a memory element or an electrical energy storage device. In industrial electrical engineering, capacitors are used to compensate reactive power and in higher harmonic filters. Transducer(IP) small movements: a small change in the distance between the plates has a very noticeable effect on the capacitance of the capacitor. IP of air humidity (a change in the composition of the dielectric leads to a change in capacitance) IP of wood humidity In relay protection and automation circuits, capacitors are used to implement the logic of the operation of some protections.
(lat. condenso - compact, thicken) - a heat exchanger, a heat exchanger in which the condensation process is carried out, the process of phase transition of the coolant from a vapor to a liquid state due to heat removal by a colder coolant.
Operating principle
The condenser usually receives superheated coolant vapors, which are cooled to saturation temperature and, condensing, pass into the liquid phase. To condense steam, it is necessary to remove heat from each unit of its mass equal to the specific heat of condensation. Depending on the
cooling medium (coolant), condensers can be divided into the following types: water-cooled, water-air (evaporative) cooling, air-cooled, cooled by boiling refrigerant in the evaporator condenser, cooled by the process product. The choice of capacitor type depends on the application conditions.
Application
Condensers are used in thermal and nuclear power plants to condense exhaust steam from turbines. In this case, for every ton of condensing steam there are about 50 tons of cooling water. Therefore, the need for thermal power plants and especially nuclear power plants for water is very high - up to 600 thousand m³/hour.
In refrigeration units, condensers are used to condense refrigerant vapors, such as freon. In chemical technology, condensers are used to obtain pure substances (distillates) after distillation.
The principle of condensation is also successfully used to separate mixtures of vapors of various substances, since their condensation occurs at different temperatures.
Varieties
Based on the principle of heat exchange, capacitors are divided into mixing (mixing) and surface capacitors. In mixing condensers, water vapor is in direct contact with cooling water, and in surface condensers, the working fluid vapors are separated
wall from the cooling fluid. Surface capacitors are divided according to
following features:
in the direction of coolant flows: direct-flow, counter-flow and with transverse coolant flow;
according to the number of changes in the direction of movement of the coolant - into single-pass, double-pass, etc.;
by the number of series-connected housings - single-stage, two-stage, etc.
by design: shell and tube, plate, etc.
Refrigerator condenser "Minsk-10"
Pasteurizer
Pasteurization process represents bringing the temperature of the product to a certain technological requirements value and holding it at this temperature for some time, as well as subsequent cooling of the product to storage temperature.
Pasteurization is carried out using special equipment - a pasteurizer.
The scope of application of this equipment is pasteurization (heat treatment) and cooling in the flow of various food products: pasteurization of milk, cream, juices, wine, beer, kvass, etc.
Pasteurization modes always mean the ratio of holding time at pasteurization temperature and the actual pasteurization temperature. In relation to the dairy industry: Aseptic pasteurization - 4 seconds 137 degrees Celsius. Non-aseptic pasteurization has a wide variety of parameters, for example, raw materials for the production of yogurt are usually pasteurized at the following parameters: holding time 300 seconds, temperature 97 degrees Celsius. If the raw material has previously been subjected to bactofugation, then much more can be used soft modes, for example, a shutter speed of 120 seconds and a temperature of 67 degrees Celsius.
Types of pasteurizers
Based on the type of operating cycle, pasteurizers can be divided into periodic (discrete) and continuous.
Discrete pasteurizers Due to high operating costs, they are rarely used in industry, for example, autoclaves in the canning industry.
Continuous pasteurizers widely used in the dairy, juice, and brewing industries. Discrete pasteurizers in currently widely used in the production of ketchups.
Based on the type of raw materials processed, pasteurizers can be divided into pasteurizers of liquids, pasteurizers and pasteurizers of packaged products.
By type of pasteurization conditions - aseptic (sterile) and non-aseptic (non-sterile). Aseptic pasteurizers can be divided into pasteurizers with direct heating of the product (usually sterile steam), and with heating of the product using a heat exchange unit ("hot circuit"). In pasteurizers with direct heating of the product, the product is cooled in vacuum chambers (deaerators), in pasteurizers with the product heated using a heat exchange unit - in the regeneration section of the heat exchanger (not always, there are designs in which cooling is performed with circulating/ice water).
Plate pasteurizers are used for heat treatment of products with low viscosity (milk, juices, tea, drinks, etc.) in a thin-layer continuous flow.
Tubular pasteurizers are used to process products of varying degrees of viscosity (milk, milk drinks, cream, ice cream mixtures, creams, mayonnaise, ketchup, etc.) in a closed flow. Tubular heat exchangers compare favorably in price and are simpler to manufacture compared to plate heat exchangers. Using the installation makes it possible to process the product at high pressure, temperature, and speed; and also completely eliminate the penetration of one environment into another. The installation has good thermal activity.
Scraper pasteurizers are used for pasteurization and cooling of products with high viscosity (heavy cream, curd mixture, ice cream mixture, tomato paste, ketchup). Scraped surface heat exchangers ensure uniform heating or cooling of the product due to its forced mixing in the heat exchanger channel.
Evaporator
- a heat exchanger in which the process of phase transition of a liquid coolant into a vapor and gaseous state is carried out due to the supply from a hotter coolant. This hot fluid is usually water, air, brine or
gaseous, liquid or solid technological products. When the phase transition process occurs on the surface of a liquid, it is called evaporation. If the process occurs throughout the depth of the liquid with the formation of steam bubbles, then this is called boiling. A phase transition can occur with either a homogeneous liquid or a mixture of liquid components.
Application
In thermal power engineering, the evaporator is designed to produce a distillate that replenishes the loss of condensate in steam power plants. There are evaporators heated by flue gases leaving boiler units. The steam produced in such evaporators can be used both to replenish condensate losses and for heat supply. High-capacity evaporators are used at nuclear power plants located near seas and oceans for desalination of sea water. Evaporators, sometimes called desalinators, are installed on seagoing vessels. And are the main elements refrigeration units, in which a refrigerant is evaporated, intended for direct (or through brine) cooling of refrigeration chambers.
Classification
Based on the nature of the cooled medium (according to its intended purpose), evaporators for cooling liquid coolants and technological products are distinguished; for cooling air and gaseous process products, i.e. when direct
heat exchange between the cooled object and the refrigerant; for cooling solid technological products; evaporators-condensers.
Depending on the circulation conditions of the cooled liquid, evaporators can be of closed or open type. Closed type evaporators are called evaporators with
closed circulation system of cooled liquid pumped by a pump. These include shell-and-tube and shell-and-coil evaporators. Evaporators open
type are called evaporators with an open level of cooled liquid, the circulation of which is created by a stirrer. These include vertical tube and panel evaporators.
Based on the nature of the refrigerant filling, evaporators are divided into flooded and non-flooded. The latter include irrigation, shell-and-tube with boiling in pipes, as well as coil evaporators with top liquid supply.
Evaporators are also divided into groups depending on the surface on which the refrigerant boils: in the intertube space (shell-and-tube flooded and irrigating) or inside pipes and channels (shell-and-tube with boiling in pipes, vertical-tube and panel). The last division is important from the point of view of choosing a model for calculating the heat transfer of a boiling liquid.
Based on the nature of the refrigerant movement, evaporators with natural and forced circulation are distinguished.
Operating principle
A shell-and-tube evaporator consists of a wide horizontal cylinder (casing), inside of which there are tube sheets. These gratings are a series of thin copper tubes, through which coolant (water) flows. The diameter of such tubes, on average, is 20–25 cm, in them
The coolant moves at a speed of up to 2 m/s. In the space between the tube sheets there is boiling refrigerant. Nozzles are attached to both edges of the grille, which are connected
to the water cooling system. To increase heat transfer, the outer part of the grille has fins. During operation, the refrigerant moves through the tubes from the bottom of the evaporator upward. During its movement, it cools the water, which circulates from the outside of the tubes. Dividing partitions inside the cylinder provide moving water with a speed of 0.5 to 3 m/s.
The design of a plate evaporator consists of several rows of one-dimensional steel plates, connected to each other according to the “herringbone” principle. The coolant and refrigerant in such an evaporator do not move parallel to each other, but towards each other, each inside its own independent circuit. Compared to other types of evaporators, plate evaporators have a number of undeniable advantages: they are small in size; less susceptible to breakdowns, and in case of malfunctions they are resistant to freezing; have high performance.
9th grade 5klass.net
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The purpose of the lesson:
Form the concept of electrical capacity; Enter new characteristic– electrical capacity of the capacitor, and its unit of measurement. Consider the types of capacitors and where they are used
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Let's repeat... Option 1 1) Who and when was the theory created? electromagnetic field and what is its essence. 2) List the types of electromagnetic waves. Infrared radiation, its properties and effects on the human body. Option 2 1) What is called electromagnetic wave?. What are the main properties of an electromagnetic wave? 2) List the types of electromagnetic waves. X-ray radiation, its properties and effect on the human body.
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A capacitor consists of two conductors separated by a dielectric layer, the thickness of which is small compared to the size of the conductors. The electrical capacity of the capacitor is equal to where q is the charge of the positive plate, U is the voltage between the plates. The electrical capacity of a capacitor depends on its geometric design and the electrical permittivity of the dielectric filling it and does not depend on the charge of the plates. Capacitor
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The electrical capacitance of two conductors is the ratio of the charge of one of the conductors to the potential difference between this conductor and the neighboring one. The unit of measurement of capacitance is farad – [F] You need to know this:
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The electrical capacity of a flat capacitor is equal to where S is the area of each of the plates, d is the distance between them, ε is the dielectric constant of the substance between the plates. It is assumed that the geometric dimensions of the plates are large compared to the distance between them. Remember that...
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Capacitor energy
W = qU/2 W=q2 /2C U
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Types of capacitors
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Currently, paper capacitors are widely used for voltages of several hundred volts and a capacity of several microfarads. In such capacitors, the plates are two long strips of thin metal foil, and the insulating spacer between them is a slightly wider paper strip impregnated with paraffin. One of the covers is covered with paper tape, then the tapes are tightly rolled into a roll and placed in a special case. Such a capacitor, having the size of a matchbox, has a capacity of 10 μF (a metal ball of such capacity would have a radius of 90 km). Paper capacitor
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Ceramic capacitor Ceramic capacitors are used in radio engineering. The dielectric in them is special ceramics. The linings of ceramic capacitors are made in the form of a layer of silver applied to the surface of the ceramic and protected with a layer of varnish. Ceramic capacitors are manufactured with capacities ranging from units to hundreds of picofarads and voltages from hundreds to thousands of volts.
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Variable capacitor.
Write down the device of the capacitor
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Write down what their electrical capacity is.
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APPLICATION OF CAPACITORS
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What is the electrical capacity of the capacitor if the charge of the capacitor is 10 nC and the potential difference is 20 kV. And now the task...
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A 10 µF capacitor was given a charge of 4 µC. What is the energy of a charged capacitor. And now the task...
Pieter van Muschenbrouck ()
What is a capacitor? Capacitor (from Latin condense “to compact”, “to thicken”) is a two-terminal network with a certain capacitance value and low ohmic conductivity; device for storing electric field energy. A capacitor is a passive electronic component. Typically consists of two plate-shaped electrodes (called plates) separated by a dielectric whose thickness is small compared to the dimensions of the plates.
Properties of a capacitor Capacitor in a circuit direct current can conduct current at the moment it is connected to the circuit (the capacitor is charged or recharged); at the end of the transition process, no current flows through the capacitor, since its plates are separated by a dielectric. In an alternating current circuit, it conducts alternating current oscillations through cyclic recharging of the capacitor, closing with the so-called bias current of the direct current circuit with a bias current
In terms of the complex amplitude method, a capacitor has a complex impedance:complex amplitude impedance method The resonant frequency of a capacitor is equal to: Resonant frequency When a capacitor in an alternating current circuit behaves like an inductor. Therefore, it is advisable to use a capacitor only at frequencies at which its resistance is capacitive in nature. Typically, the maximum operating frequency of a capacitor is about 23 times lower than the resonant inductor
Main parameters. Capacity The main characteristic of a capacitor is its capacitance, which characterizes the capacitor’s ability to accumulate electric charge. The designation of a capacitor indicates the value of the nominal capacitance, while the actual capacitance can vary significantly depending on many factors. The actual capacitance of a capacitor determines its electrical properties. So, according to the definition of capacitance, the charge on the plate is proportional to the voltage between the plates (q = CU). Typical capacitance values range from a few picofarads to hundreds of microfarads. However, there are capacitors with a capacity of up to tens of farads. capacitanceelectric chargecharge voltagefarad The capacitance of a flat capacitor consisting of two parallel metal plates of area each, located at a distance d from each other, in the SI system is expressed by the SI formula
To obtain large capacities, capacitors are connected in parallel. In this case, the voltage between the plates of all capacitors is the same. The total capacity of a battery of parallel-connected capacitors is equal to the sum of the capacitances of all capacitors included in the battery. If all parallel-connected capacitors have the same distance between the plates and the same dielectric properties, then these capacitors can be represented as one large capacitor, divided into fragments of a smaller area. At serial connection capacitors, the charges of all capacitors are the same, since they are supplied from the power source only to the external electrodes, and on the internal electrodes they are obtained only due to the separation of charges that previously neutralized each other. The total capacity of a battery of series-connected capacitors is equal to
Specific capacity. Capacitors are also characterized by specific capacitance, the ratio of capacitance to the volume (or mass) of the dielectric. The maximum value of specific capacitance is achieved with a minimum thickness of the dielectric, but at the same time its breakdown voltage decreases.
Energy Density The energy density of an electrolytic capacitor depends on the design. The maximum density is achieved with large capacitors, where the mass of the housing is small compared to the mass of the plates and electrolyte. For example, an EPCOS B4345 capacitor with a capacity of µF x 450 V and a mass of 1.9 kg has an energy density of 639 J/kg or 845 J/l. This parameter is especially important when using a capacitor as an energy storage device, followed by its instant release, for example, in a Gauss gun.
Rated voltage Another equally important characteristic of capacitors is the rated voltage - the voltage value indicated on the capacitor at which it can operate under specified conditions during its service life while maintaining parameters within acceptable limits. The rated voltage depends on the design of the capacitor and the properties of the materials used. During operation, the voltage on the capacitor should not exceed the rated voltage. For many types of capacitors, as the temperature increases, the permissible voltage decreases, which is associated with an increase in the thermal speed of charge carriers and, accordingly, a decrease in the requirements for the formation of electrical breakdown. temperature charge carrier speed
Polarity Many oxide dielectric (electrolytic) capacitors operate only when the voltage polarity is correct due to the chemical characteristics of the interaction of the electrolyte with the dielectric. When the voltage polarity is reversed, electrolytic capacitors usually fail due to chemical destruction of the dielectric with a subsequent increase in current, boiling of the electrolyte inside and, as a result, the possibility of explosion of the housing. electrolytic electrolyte explosion
