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TECHNICAL SCIENCES
ALARM SENSOR FOR GEOTHERMAL ENERGY FACILITIES
UDC 620.97
Qoldashov Obbozjon Xokimovich
Doctor of Physical and Mathematical Sciences, Professor of the Scientific Research Institute "Physics of Semiconductors and Microelectronics" at the National University of Uzbekistan
Scientific Research Institute "Physics of Semiconductors and Microelectronics" at the National University of Uzbekistan
Komilov Abdullajon Odiljonovich
Assistant of the Fergana branch of the Tashkent University of Information Technologies
Ferghana Branch of Tashkent University of Information Technologies
Jumaev Javohir Abdurasulovich
2nd year student of the Department of 13.03.02 "Electric power and electrical engineering" of the Tashkent branch of the Moscow Power Engineering Institute
Tashkent Branch of the Moscow Power Engineering Institute
Annotation. Over the past decades, there has been an increased interest in alternative sources of renewable energy in nature: solar, geothermal, wind, etc. It should be noted that this interest is caused not only because of the annual increase in prices for traditional fuels (oil, coal, gas) and forecast data on the depletion of their reserves in the foreseeable future. It is also caused by the need to address issues of environmental protection from pollution and possible man-made disasters. For these reasons, many countries around the world are focused on a rational combination of traditional energy sources with renewable ones. At the same time, among renewable energy sources, the deep heat of the Earth occupies not the last place. It is enough to name countries such as Iceland, the Philippines, New Zealand, Indonesia, the USA, Italy, etc., where there are enormous thermal resources lying in relatively shallow layers of the earths crust.
Keywords: sensors, alarm system, geothermal energy, alternative sources of renewable and natural energy.
Аннотация. За последние десятилетия в мире возрос интерес к альтернативным источникам возобновляемой в природе энергии: солнечной, геотермальной, ветровой и др. Надо отметить, что этот интерес вызван не только из-за ежегодного роста цен на традиционные виды топлива (нефть, уголь, газ) и прогнозных данных по истощению в обозримом будущем их запасов. Он вызван также необходимостью решения вопросов защиты окружающей среды от загрязнения и возможных техногенных катастроф. По этим причинам во многих странах мира ориентируются на рациональное сочетание традиционных источников энергии с возобновляемыми. При этом среди возобновляемых источников энергии глубинное тепло Земли занимает не последнее место. Достаточно назвать такие страны, как Исландия, Филиппины, Новая Зеландия, Индонезия, США, Италия и др., где имеются колоссальные тепловые ресурсы, залегающие в сравнительно неглубоких пластах земной коры.
Ключевые слова: датчики, аварийная сигнализация, геотермальная энергетика, альтернативные источники возобновляемой и природной энергии.
Today, geothermal energy is actively developing in Uzbekistan. On the territory of Uzbekistan, forecast geothermal resources at accessible depths (up to 5-6 km) are 4-6 times higher than hydrocarbon resources. The main consumers of geothermal resources in the near and long term in Uzbekistan will undoubtedly be heat supply and, to a much lesser extent, electricity generation.
However, geothermal energy is not without drawbacks, as it is known that dangerous gases are released at geothermal wells, and therefore the control of these gases is relevant for the development and search for new sources of geothermal waters. When using these waters in the equipment of geothermal systems, deposits are observed, mainly of the poorly soluble salt CaCO3, in this regard, the control of the gas composition is relevant for their development and the search for new sources of geothermal waters [6-7].
Depending on the conditions of formation, as well as the chemical and gas composition, geothermal waters are divided into carbon dioxide, hydrogen sulfide, nitrogen, hydrogen sulfide-carbon dioxide, nitrogen-carbon dioxide, methane and nitrogen-methane. Geothermal waters of the Fergana Valley are classified as methane.
The presence on the territory of Uzbekistan of a large potential of resources of hydrothermal deposits with a gas factor requires the development of new technical and technological solutions for their effective use.
Exposure to geothermal gases, mainly methane, can occur at workplaces during emergency releases of geothermal fluid and maintenance work in a confined space, for example, inside pipelines, turbines and condensers. The severity of the risk of methane exposure may vary depending on the location of the facility and the properties of the reservoir being developed.
If there is a possibility that workers will be exposed to methane in dangerous concentrations, installation of methane concentration monitoring systems and alarm systems at geothermal energy facilities should be carried out.
The gas composition of geothermal waters is dominated by methane CH4, CO2, N2 and H2S. The absorption coefficients of gases entering the IR radiation region were calculated on the basis of spectroscopic information from the HITRAN-2008 database, the wavelength at the maximum absorption of infrared radiation by methane was 3.4 microns [10-11].
The principle of operation of the alarm sensor for geothermal energy facilities is as follows: the gas chamber is irradiated with two infrared LEDs emitting two different wavelengths, one of which corresponds to the maximum absorption of methane (F0λ1 = 3.4 microns), and the other weak (F0λ2 = 3.2 microns).
The gas chamber is irradiated with two radiation streams F0λ1 and F0λ2 at the reference and measuring λ2 wavelengths, respectively. The radiation fluxes that have passed through the gas chamber will be equal, respectively:
where: F0λ1 and F0λ2 are radiation fluxes incident on the gas chamber at wavelengths and, respectively.
where: F0λ1 and F0λ2 are radiation fluxes after passing through the gas chamber at wavelengths and, respectively: c1 is the concentration of a mixture of gaseous substances; L is the length of the optical path, i.e. the length of the gas chamber; c2 is the concentration of the gaseous substance;
K1 is the scattering coefficient of a mixture of gaseous substances;
K2 is the absorption coefficient of the gaseous substance being determined.
The radiation flux varies in time (t) according to the exponential law:
where: A is a constant coefficient corresponding to the initial value of the exponential pulse amplitude, N is the number of pulses from the beginning of the exponent to the moment of change of the photoelectric signal.
At the moment of equality of the radiation fluxes and we obtain that
from which it follows that:
where: te is the exponential time constant.
In the alarm sensor for geothermal energy facilities, LEDs with radiation spectra of 3.2 microns (reference) and LEDs with radiation spectra of 3.4 microns (working) are used.
Figure 1 shows a block diagram of an alarm sensor for geothermal energy facilities, which consist of a power supply unit 1, a generator 2, a frequency divider 3, a singlevibrator 4, an exponential function modulator 5, an emitter repeater 6, electronic keys 7 and 8, light-emitting diodes (9 and 10), gas chamber 11, photodiode 12, first differentiating device 13, threshold device 14, matching circuit 15, second differentiating device 16, counter 17.
The alarm sensor for geothermal energy facilities works as follows:
The rectangular pulse generator 2 generates pulses with the required repetition rate. These pulses from the antiphase outputs go to the input of the divider 3 frequencies and to the control inputs of the keys 7 and 8. Rectangular pulses from the output of the divider 3 frequencies go to the input of the single vibrator 4. Rectangular pulses with the required duration from the output of the single vibrator 4 enter the input of the exponent modulator 5, the output of which is connected via an emitter repeater 6 to the input of the electronic key 8, where a discrete exponential current pulse is formed, which flows through the emitting diode 9, causing a radiation flux according to the same law. The electronic key 7 switches to the pulses that fill the exponent in an antiphase manner.
Figure 3 shows the transfer function of the alarm sensor for geothermal energy facilities.
A current pulse flowing through a light-emitting diode 10 causes a luminous flux, the amplitude of which is constant. The radiation streams of LEDs that have passed through the gas chamber 11 are received by the photodiode 12. This signal is fed to the input of the first differentiating device 13, from the output of which the differentiated photoelectric signal enters the input of the threshold device 14.
Next, the signal from the output of the threshold device 14 is fed to one of the inputs of the matching circuit 15. A signal is sent to the other input of the coincidence circuit 15 from the output of the second differentiating device 16. From the moment of comparison, a number of pulses appear at the output of the coincidence circuit 15, which arrive at the counting input of the counter 17. At the beginning of the next exponent, the counter 17 receives rectangular pulses from the output of the singlevibrator 4 at the input "Zero setting" and the counter 17 is prepared for the next cycle.
Comparison of the amplitudes of the reference and measuring radiation fluxes using a threshold device ensures the accuracy of measurement of a geothermal gas monitoring device based on semiconductor emitters.
Literature
1. Akhmedov G. Ya. Protection of geothermal systems from carbonate deposits. M.: Scientific World, 2012.
2. Kiseleva S. V., Kolomiets Y. G., and O. S. Popel, «Assessment of solar energy resources in Central Asia,» Appl. Sol. Energy (English Transl. Solar Engineering), 2015, doi: 10.3103/S0003701X15030056.
PHOTOVOLTAIC EFFECT IN a-QUARTZ
UDC 548.1.024.5
Karimov Boxodir Xoshimovich
Candidate of Physical and Mathematical Sciences, Associate Professor of the Department of "Technological Education" of the Faculty of Physics and Technology of Fergana State University
Ferghana State University, Ferghana, Uzbekistan
Annotation. The anomalous photovoltaic effect observed earlier for LibO 3:Fes ferroelectrics is a special case of a more general FE existing in crystals without a center of symmetry and described by the third ai j k tensors.
Keywords: photovoltaic effect, ferroelectrics, tensor, tensor components.
Аннотация. Аномальный фотовольтаический эффект, наблюдавшийся ранее для сегнетоэлектриков Li bO3:Fe SbSJ, является частным случаем более общего ФЭ существующего в кристаллах без центра симметрии и описываемого тензорам третьего a
i j k
Ключевые слова: фотовольтаический эффект, сегнетоэлектрики, тензор, компоненты тензора.
The components of the aij tensor are nonzero for 20 acentric point symmetry groups. With uniform illumination by linearly polarized light of a homogeneous piezo crystal and ferroelectrics, a photovoltaic current arises in it. The sign and magnitude of the photovoltaic current depends on the orientation of the polarization vector of light with its components and Ul*, the direction of its propagation and the symmetry of the crystal.
In accordance with (I) and the symmetry of the point group, it is possible to write an expression for the photovoltaic current. Comparison of the experimental criminal dependence with (β) makes it possible to determine the photovoltaic tensor aajk or photovoltaic coefficients
(a* is the light absorption coefficient).
If the electrodes of the crystal are opened, the photovoltaic current generates a photovoltaic voltage of 103-105 B. the value of which can be several orders of magnitude greater than the band gap of piezo or ferroelectrics. There is no FE in centrosymmetric crystals.
We studied a-quartz, one of the more common crystalline forms of silica (SiO2). At tempratures up to 573o, there is a so-called "low-temperature" a-quartz. A-quartz crystals belong to the trigonal trapezohedral class of the trigonal system (point group of symmetry 32) and are often found in two known forms: right and left crystals. At normal pressure and temperature of 573o With a quartz turns into a hexagonaltrapezohedral class of the hexagonal system (point symmetry group 622).
The thirdorder axis in quartz is the optical axis of the crystal. One of the axes of the second order is the electric axis and the normal to both of these axes is the mechanical axis.
The symmetry of the quartz structure determines the symmetry of the properties of this crystal.
Quartz has the need to rotate the plane of the field, not only along the optical axis, but also in a direction perpendicular to it. It has been experimentally established that the ratio remains constant for wavelengths from 545 to 565 Nm and is equal to 054, i.e. the rotation of the plane in the directions perpendicular to the optical wasp is immeasurably two times less than that of the optical wasp. Despite all the "popularity" of quartz, both its properties have not yet been studied in detail.
In this paper, the results are presented, the effect of the polarization of light on
Af effect in natural crystal -quartz with natural coloring.
Figure 1 shows the angular instability of the photovoltaic current in a native a-quartz crystal with a natural color. The crystals were suspended in the impurity spectral region (l- 300500 nm, a2 = 2cm -1) at room temperature. Figure 1 shows two orientational angular dependence Jx (b) when illuminated in the direction of the a-z axis, while for a-quartz K11 = (13). 1013 A. cm (W) -1.
The illumination in the Zdirection reveals a noticeable deviation of Jx(b) from the theory. Perhaps this is due to the difference in the values of the optical activity coefficient of quartz for the Z and Ydirections. Attention is drawn to the very low value of the photovoltaic coefficient K11 in a-quartz. It characterizes the impurity centers responsible for the natural coloring of natural crystals and does not reflect the asymmetry of their own transitions. Unfortunately, a-quartz impurity centers have not been specifically investigated; this provides an independent task.