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 single—vibrator – 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 single—vibrator – 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 ai 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*