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the standard technique, direct, inverse photogrammetric intersection, as well as the construction of strip and block phototriangulation. However, it should be remembered that the photo shows only the space in the camera's field of view. In this regard, the identification of the exact position and orientation of the camera should rely on well-known coordinates of the control points located throughout the measurement area.

Another feature of the processing of ground images is that the coordinates of the photographing centers and the control directions between the points of building structures, the distance between the points and the length of the photographing base can be additionally used as reference points.

So, e.g., the distance D between two points of a building structure i and j can be defined as a function of the coordinates of these points:

Dij2 Xi X j 2 Yi Yj 2 Zi Zj 2 . (21)

The distance D between the photographing point S and the point i of the object can be given by the expression:

Dsi2 Xs X j 2 Ys Yj 2 Zs Zj 2 . (22)

The length of the photographing basis B can also be determined using the coordinates of the two projection centers:

If the points i and j belong to the same vertical plane, (e.g., the corner of a building), they are given by the expression:

(24)

(25) The above equations are introduced into the general system of collinearity equations traditionally used for least squares processing. As a result of solving the general system of equations, the equalized values of the external orientation elements of the images and the coordinates of the control points of the structures are found.

In the normal case of shooting, the accuracy of determining the coordinates of points of building structures using a stereopair is pre-calculated using the formulas (26).

Y mX f mx,

(26)

Y mY b mp,

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Y mZ f my ,

where mx, my ,mp are the mean square errors of measurement of coordinates and longitudinal parallaxes of image points; Y is the distance to the survey object (value of the Y coordinate in the base coordinate system); b (the basis of photographing at the scale of the image) which is calculated by the formula:

Lx is the frame size along the x-axis, and P is the longitudinal overlap of stereo pair images, expressed in %.

Obviously, routinely performing such calculations in the field is challenging for surveyors. Thus for practical work it is necessary to make use of the currently existing numerous scientific and commercial software products for processing ground photographs, which allows one to calculate the spatialcoordinatesofanobject witha highdegree ofreliabilityunder almost any conditions. The use of modern software products for processing ground photographs transforms a computer monitor into a high-accuracy survey tool and addresses the problems that prevent surveyors from utilizing digital cameras in their work.

Conclusions. Photogrammetric methods for controlling deformations of structures have a few of advantages over geodetic ones [6, 12, 19]. Hence by means of the photogrammetric methods, a large number of construction points (including those in dangerous and hard-to-reach places) are recorded at one physical moment. This makes it possible to assess their mutual static and dynamic deformation, the presence of vibrations and other rapid processes, and simultaneously along all three axes of coordinates. The resulting images are reliable documentary evidence of the presence and magnitude of the recorded deformations. They make it possible at any time to conduct a second independent examination of the measurements which can be performed even several years after photographing the subject.

Photogrammetric methods make it possible to conduct measurements in the conditions of operating enterprises when vibration interference interferes with accurate geodetic measurements. The suggested control methods enable the use of conventional digital cameras as a practical geodetic measuring instrument, which will cause an increase in labor productivity, and in some cases, that in the accuracy of work at construction sites.

For greater reliability it is recommended that complex monitoring of deformations is performed using various visual and instrumental methods with photographic recording of all de-

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tected changes and supplementing them with modern research methods –– GPR and laser scanning, and ultrasonic and thermal imaging studies are eemployed to evaluate the damage zone of building structures.

All the control methods listed in the article were developed and tested on the buildings and structures of the VAST (Voronezh nuclear heat supply station), which was suspended in 1993 –– the buildings of the chemical water treatment plant and the water cooling system of the SVO, reactor departments No. 1 RD-1 and No. 2 RD-2.

References

1.Ageeva S. T., Novikova N. S., Netrebina Yu. S. Ispol'zovanie geodezicheskikh metodov pri issledovanii deformatsii zdanii i sooruzhenii [The use of geodetic methods in the study of deformations of buildings and structures]. Student i nauka, 2018, no. 1, pp. 48––53.

2.Bryn' M. Ya., Tolstov E. G., Nikitichin A. A., Reznik B., Yashchenko A. I., Evstaf'ev O. V., Kuchu-

mov V. A. Geodezicheskii monitoring deformatsii vantovykh mostov na osnove sputnikovykh tekhnologii [Ge-

odetic monitoring of cable-stayed bridge deformations based on satellite technologies]. Izvestiya peterburgskogo

universiteta putei soobshcheniya, 2009, no. 2, pp. 120––128.

3.Voronov A. A., Popov B. A. Kompleksnyi geotekhnicheskii monitoring zdanii i sooruzhenii Voronezhskoi atomnoi stantsii teplosnabzheniya (VAST) [Integrated geotechnical monitoring of buildings and structures of the Voronezh Nuclear Power Plant of Heat Supply(VAST)]. Student i nauka, 2018, no. 4 (7).

4.Epin V. V., Tsvetkov R. V., Shardakov I. N. Deformatsionnyi monitoring fundamentov zdanii metodom gidrostaticheskogo nivelirovaniya [Deformation monitoring of building foundations by hydrostatic leveling].

Inzhenerno-stroitel'nyi zhurnal, 2015, no. 3, pp. 21.

5.Zaitsev A. K., Marfenko S. V., Mikhelev D. Sh. e. a. Geodezicheskie metody issledovaniya deformatsii sooruzhenii [Geodesic methods for studying deformations of structures]. Moscow, Nedra Publ., 1991. 272 p.

6.Malyuchek T., Fedorova I. Primenenie fotogrammetricheskikh izmeritel'nykh sistem V-STARS v promyshlennosti [Application of V-STARS photogrammetric measuring systems in industry]. SAPR i grafika, 2014, no. 10 (216), pp. 98––101.

7.Mel'kumov V. N., Tkachenko A. N., Kazakov D. A., Khakhulina N. B. Perspektivy primeneniya geodezicheskikh metodov nablyudeniya za deformatsiyami pnevmaticheskikh opalubok [Prospects for the application of geodetic methods for monitoring the deformations of pneumatic formwork]. Nauchnyi vestnik Voronezhskogo gosudarstvennogo arkhitekturno-stroitel'nogo universiteta. Stroitel'stvo i arkhitektura, 2015, no. 1 (37), pp. 51––58.

8.Nikonov A. V. Osobennosti primeneniya sovremennykh geodezicheskikh priborov pri nablyudenii za osadkami i deformatsiyami zdanii i sooruzhenii ob"ektov energetiki [Features of the use of modern geodetic instruments in the observation of precipitation and deformations of buildings and structures of energy facilities].

Vestnik SGGA, 2013, no. 4, pp. 12––18.

9. Fedoseev Yu. E., Egorchenko E. A. Trebovaniya k geodezicheskoi informatsii pri monitoringe deformatsionnykh protsessov mostovykh sooruzhenii [Requirements for geodetic information when monitoring

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the deformation processes of bridge structures]. Inzhenernye izyskaniya, 2010, vol. December, pp. 50––57.

10.Shekhovtsov G. A., Shekhovtsova R. P. Sovremennye geodezicheskie metody opredeleniya deformatsii inzhenernykh sooruzhenii [Modern geodetic methods for determining deformations of engineering structures]. NizhnyNovgorod, NNGASU Publ., 2009. 156 p.

11.Yambaev Kh. K., Krylov V. I. O vozmozhnosti ispol'zovaniya sputnikovykh GPS/GLONASS izmerenii dlya kontrolya vertikal'nosti pri vozvedenii vysotnykh sooruzhenii [About the possibility of using satellite GPS / GLONASS measurements to control verticality during the construction of high-rise structures]. Izvestiya vuzov. Geodeziya i aerofotos"emka, 2009, vol. 4, p. 3640.

12.Yashchenko A. I., Burtsev A. V., Dorofeev A. A. Avtomatizirovannyi distantsionnyi monitoring istoricheskogo pamyatnika arkhitektury zdaniya «Srednie torgovye ryady», Krasnaya ploshchad', dom 5 [Automated remote monitoring of the historical architectural monument of the building "Sredniye shopping malls", Red Square, house 5]. Zhurnal Interekspo GeoSibir', 2011, no. 2, vol. 1, 8 p.

13.Kopáčik A., Kyrinovič P., Lipták I., Erdély J. Automated Monitoring of the Danube Bridge Apollo in Bratislava, TS01E –– Deformation Monitoring. FIG Working Week 2011 Bridging the Gap between Cultures Marrakech, Morocco, 18––22 May2011.

14.Bihter E. Evaluation of High-Precision Sensors in Structural Monitoring. Sensors. 2010 №10, р. 10803–– 10827.

15.Yigit O. C., Inal C., Yetkin M. Monitoring of tall building’s dynamic behavior using precision inclination sensors, 13th FIG Symposium on Deformation Measurement and Analysis, 14th IAG Symposium on Geodesy for Geotechnical and Structural Engineering. LNEC. Lisbon, 2008, may12––15.

16.Cranenbroeck J., Hayes D., Oh S. H., Haider M. Core Wall Control Survey –– The State of Art. 7th FIG Regional Conference Spatial Data Serving People, Land Governance and the Environment –– Building the CapacityHanoi, Vietnam, 19––22 October 2009.

17.Cranenbroeck J. V. State of the art in structural geodetic monitoring solutions for Hydropower dams. Interekspo Geo-Sibir', 2012.

18.Groten E., Mathes A., Uzel T. Dam monitoring by continuous GPS observations. Istanbul-94. Ist. Int. Symp. Deform. Turkey, Istanbul, Sept. 5––9, 1994. Abstr. Istanbul, 1994, p. 51.

19.Willfried S. Moderne Messverfahren in der Ingenieurgeodasie und ihr praktischer Einsatz. Flachenmanag. Und Bodenordn, 2002, no. 2, pp. 87––97.

20.Yanhua M., Lixin L., Hong Z. Automatic monitoring system concerning extra-highrise building oscillating based on measurement robot. Proceedings of the 2010 IEEE International Conference on Robotics and Biomimetrics. December 14—18, 2010, Tianjin, China. pp. 662—666.

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Russian Journal of Building Construction and Architecture

HEAT AND GAS SUPPLY, VENTILATION, AIR CONDITIONING,

GAS SUPPLY AND ILLUMINATION

DOI 10.36622/VSTU.2021.51.3.003

UDC697.911:66.096.5

A. V. Barakov1, V. Yu. Dubanin2, D. A. Prutskikh3, A. A. Nadeev4

DEVELOPMENT OF AN EVAPORATING TYPE AIR COOLER

FOR VENTILATION SYSTEMS

Voronezh State Technical University1, 2, 3, 4

Russia, Voronezh

1D. Sc. in Engineering, Prof. of the Dept. of Theoretical and Industrial Heat Power Engineering, tel. (473)243-76-62, e-mail: abarakov@cchgeu.ru

2Ph. D. in Engineering, Assoc. Prof. of the Dept. of Theoretical and Industrial Heat Power Engineering, tel. (473)243-76-62, e-mail: vdubanin@cchgeu.ru

3Ph. D. in Engineering, Assoc. Prof. of the Dept. of Theoretical and Industrial Heat Power Engineering, tel. (473)243-76-62, e-mail: dprutskikh@cchgeu.ru

4Ph. D. in Engineering, Assoc. Prof. of the Dept. of Theoretical and Industrial Heat Power Engineering, tel. (473)243-76-62, e-mail: anadeev@cchgeu.ru

Statement of the problem. The air supplied to the premises during the hot season must be cooled to comfortable temperatures. Due to the fact that additional energy consumption for this cooling is not provided, it is possible to use an evaporative-type air cooler. However, the currently known results of experimental and theoretical studies of such devices do not allow their design, which prevents their spread. The structure of such an apparatus is considered and its theoretical and experimental studies are carried out, theresults of which can be used for engineering calculation and design of such apparatus.

Results. An evaporative-typeair cooler designed bytheauthorsfor ventilation systemsis described. Atheoretical and experimental studyoftheair coolerhasbeen carried out. Analytical relationshipswereobtained for determining thetimeofmovement ofthematerial checker in the"wet" chamber oftheapparatus, thetemperature of the cooled air and the temperature of the checker in any section of the circulation loop. Empirical relationshipshavebeen obtained for theefficiencycoefficient ofthecooler anditshydraulicresistance.

Сonclusions. The obtained dependencies will serve as the basis for the development of a methodology for the design calculation of indirect-evaporative air coolers with a moving fluidized bed in the field of centrifugal forces.

Keywords: ventilation systems, air cooler, centrifugal fluidized bed, time, temperature, efficiency coefficient, hydraulic resistance.

Introduction. Supply and exhaust ventilation systems for industrial and public premises are known to be designed for comfortable and safe conditions in areas. The major issues associa-

© Barakov A. V., Dubanin V. Yu., Prutskikh D. A., Nadeev A. A., 2021

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ted with these systems emerge during the cold season when the outside air temperature exceeds the design temperature for ventilation, which is typically due to the lack of heat for the supply air. However, there can be some problems during the hot season as well when the outside air temperature is higher than the comfortable one, as the energy required to lower the temperature of the air entering the room is not provided in the system of ventilation and conditioning (SVK) data [18, 19]. It is possible to use renewable energy sources to reduce energy consumption for producing cold. One of these can be the method of water-evaporative cooling [14, 15, 17] relying on the thermodynamic non-uniformity of the atmospheric air. Its use in the air cooler for ventilation and air conditioning systems of industrial and public premises will allow energy saving reserves to be more completely utilized [8––10, 16].

1. Schematic diagram of the air cooler. One of the types of intermediate cooler is a nozzle which circulates in the annular channel layer of fluidized dispersed material. It has a high specific contact surface of the interacting phases and thereby a high intensity of heat and mass transfer between them. This nozzle is made of corrosion-resistant particles of various shapes with an equivalent diameter of 1 to 6 mm, which is central to their high wettability. Such a nozzle has a low cost and allows heat to continuously transfer from the main (cooled) air flow to the auxiliary (cooling) [1,2]. The schematic diagram of the indirect evaporative cooling apparatus is shown in Fig. 1 [11, 12].

Fig. 1. Schematic diagram of the air cooler

Its major element is an annular working chamber 1 with a central part of the conical shape 6 separated by two partitions 7 into a «dry» section 4 and a «wet» section 5. The partitions are made of overflow windows 8 for free circulation of dispersed material (nozzles) 2 with in-

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clined blades 3 serves to form a circulating fluidized bed. The nozzle 9 is designed to moisten the material in the «wet» section of the operating chamber.

The design of such an air cooler calls for a scientific basis for the development of methods for its design thermal and hydraulic calculations. This device was investigated in order to obtain ratios for identifying its design and operating parameters.

2. Modeling of the parameters of the air cooler. The time when the particles in the "wet" chamber dry out is given by the heat balance equation [3, 4]. Let us assume that as time passes, the volume of water d on the surface of the particle will decrease by dv.

q is the density of the heat flow; fч is the area of the surface of the wetted particle; tнас is the

r is the diameter of the particle; is the thickness of the water film on the particle surface. Convection is the major method of heat supply perceived by the particle surface. Therefore using the Newton-Richman law, the heat flux density is identified:

is the interphase thermal coefficient in the «wet» chamber; tв is the temperature of teh atmospheric air.

Assuming the insignificance of interfacial heat exchange through a thin surface water film of the particle, the heat transfer coefficient is given by the following criterion equation [6, 7, 13]:

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The solution of the system of differential equations of heat balance and Newton-Richman (in regards to the elementary volume of the fluidized layer) [5] made it possible to obtain an expression for the distribution of air temperature along the height of the layer of the dispersed nozzle

y is the coordinate; tв' ,tн' is the water and nozzle temperature at the inlet into the «dry»

chamber; tн is the nozzle temperature; fvн is the specific surface of the nozzle layer; is the porosity of the nozzle layer; в is the air density; cв is the air heat conductivity.

Significant movement of particles along the height of the fluidized layer during its motion enables us to conclude that there is a dependence of their temperature only in the longitudinal direction of the chamber (from the x coordinate) as shown in the following relation [5]:

mediate cooler; h is the height of the layer; х is the transverse coordinate.

3. Experimental study of the air cooler. Experimental studies have made it possible to assess the operability of the device and to evaluate one of its most important parameters, i.e., the coefficient of thermal efficiency. Two coaxial cylinders 0.3 m and 0.2 m with the height of 0.5 m form the body of the experimental air cooler. The outer case is made of polymethyl methacrylate for convenient visual observation of processes. The «dry» and «wet» chambers are formed by 2 vertical partitions. The height of the partitions is less than the height of the chambers, which allows the bottom of the device flow windows to be arranged. There is also a gas distribution grid made in the type of blinds. It is possible to change the angle of inclination of the blades in the range from 20 to 40 °. The air supply to each chamber of the device was carried by high-pressure fans, and its flow was measured by averaging tubes with multilimit micromanometers with an inclined tube MMN-240. The universal temperature regulator TPM138 in conjunction with the computer and thermocouples of the HC type served to measure and store in memory of the air temperatures in various points of the device. The nozzle

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was a particle of aluminozinc alloy ( н = 2850 kg/m3, dЭКВ = 2.6; 2.9; 4.6; and 5 mm) and quartz sand ( н = 2650 kg/m3, dЭКВ = 2.7 and 3.2 mm). For various experiments in the range of 0.5––3.5 kg, the weight of the nozzle was varied. A mechanical nozzle providing a water flow rate of 0.0004––0.0024 kg/sec moistened the dispersed material. The hydraulic resistance of the apparatus chambers was measured by differential pressure sensors connected to the TPM-138. The general view of the experimental air cooler installed in the scientific laboratory of the TPTE Department of the VSTU is shown in Fig. 2.

Fig. 2. Generalviewoftheexperimentalair cooler

The following experimental studies were conducted. A certain amount of nozzle was put into the device. Pressure fans were turned on. To ensure reliable movement (circulation) of the dispersed material in the chambers of the device, the flow rates of both air streams were regulated. Then, using the nozzle at the inlet to the «wet» chamber, the nozzle was wetted with water. Measurement oftemperatures and air flow rates (main and auxiliary flows, 12 points) as well as the hydraulic resistance of the setup chambers was performed only after the quasi-static mode had been set. Overall, more than 50 mode parametersofthe air cooler were examined.

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According to the measurement results, the thermal efficiency coefficient was calculated

the inlet to the «dry» chamber.

As a result of the analysis of the results, the major parameters central to the thermal efficiency of the air cooler were obtained. These include the air speed in the «dry» chamber of the device and the mass of the nozzle. The least squares approximation applied to the experimental data made it possible to obtain an empirical equation for calculating the thermal efficiency coefficient

M is the nozzle mass in the device, kg.

Fig. 3 shows some of the results of experimental and calculated data from (10). The standard deviation does not exceed 3 %.

kg

Fig. 3. Graph of the dependence of the efficiencycoefficient of the device on the nozzle mass and velocity of the major air flow:

The outcome of the subsequent statistical processing of the results of the experiment on the hydraulic resistance of the apparatus was the following empirical equation

Fig. 4 shows the results of experimental and calculated data based on (11). The standard deviation does not exceed 4 %.

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