CC BY
40
- load factor from I ;
- total power factor cos 9. And with block Micro logic H further available:
- total value of the phase and power factor cos 9;
- the harmonic distortion on current and voltage;
- coefficient of current K and average to K;
- intensified coefficients of current and voltage;
- all basic components of harmonics on each phase;
- phase shift the main components of the current and voltage harmonics;
- power and distortion coefficients on each phase;
- amplitude and phase shift 3-51 order harmonics current and voltage.
Access to all counters for the maximum and minimum values is provided if there are additional data transfer functions for COM dispatch system.
The Master pact circuit (2, 5, 6, 7-performances) to protect the mains leads are implemented:
- protection against overloading, triggered by the current value of the current. Thermal memory: thermal "image» before and after the trip.
- Protection against short circuits - selective circuits (MCP) and the instantaneous current cutoff. Select the state function I 2t (enabled or disabled) in setting time protection with low exposure time.
Blocks of the control and management Micro logic 6, 7th performance also include:
- protection against short-circuits- protection type "No balance" or "return of current in accordance with current earth lead" (fig.2). Select the State function I 2t (enabled or disabled) in the setting time;
- but block of the control and management Micro logic 7th performances:
- differential current protection of zero sequence (Vigi).
References:
1. The Rules of the device of electrical installations. The seventh edition. Section 1. Chapter 1.7. // - Moscow: Power Service, - 2006. - P. 439.
2. Solovyov A. L. Guidelines on choice of features and setting protection of electrical equipment with the use of microprocessor terminal to series Sepam manufactured by Schneider Electric. // St. Petersburg Institute of energy development of management and specialists of the Ministry of the Russian Federation, - 2005. - P. 69.
3. Zhalilov R. B. Digital relays: regulatory framework application, brief description // Chief power engineer, - 2007. - P. 14-17. April.
4. Merlin Gerin. Circuit breakers and disconnectors for power transfer in low voltage networks. - 2007 catalog. - Moscow. Informational support center.
5. Zhalilov R. B. About one way of protecting consumers of electricity in the networks of 0.4 kV // Electrical equipment, - 2008. - P. 29-35, February.
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-99-102
Ikramova Malika,
Scientific Research Institute of Irrigation and Water Problems
Akhmedkhodjaeva Ifoda, Khodjiev Alisher, Tashkent Institute of Irrigation and Melioration E-mail: malika.ikramova56@gmail.com
The Amudarya river basin water resources management issues: case study
Abstract: The Amudarya is one of the main water resources involving all Central Asian countries and playing a key role in their development. The most recent period ofwater scarcity is impacting negatively on the socio-economics of the region. Water deficit is bound to increase, especially in the light of climate change and by increases in the demand for food production. In the paper currant water availability state is analyzed.
Keywords: River basin, water resources management, reservoir sedimentation, water loss
Introduction
The Amudarya runoff is mainly generated within Tajikistan (72,8%) and partly in Afghanistan and Uzbekistan (Fig.1). However, water consumption by the riparians is not divided according to their share of generation which is a potential cause of conflict of interests for these countries.
The fate of the river runoff depends on human demands. In reality the entire hydrological cycle and water quality have been changed due to interaction between the river and the territories which is characterized, on the one hand, by water withdrawal for human consumption, industrial and irrigation water require-
ments all of which have a rising trend and, on the other, by the return of water to the river containing pollutants.
At the present time the runoff is controlled by two main reservoirs (the Nurek and the Tuyamuyun) and by several intersystem reservoirs which play an important role in seasonal water storage.
The problems arising in the basin are connected to the development of hydropower in the upper region, increasing water demands, pollution and water losses. The ecological crisis in the region is intensifying and increasing social problems in the Aral Sea region, mainly due to the imperfect water management.
a b
Figure 1. The division of Amudarya runoff (a) and water consumption by the riparian countries (b)
Figure 2. Increased irrigation in the basin
Water loss and pollution. Irrigation in the basin, based on well-developed irrigation and drainage systems with its inevitable return flows, is the main source of ecological pollution and water losses in the basin. Evaporation and seepage losses from the Amudarya and reservoirs also represent a significant contribution to losses. At present it is very difficult to identify these contributions. Estimated water losses in sections of the river can be accounted for as follows: upper stream to Kerki - 1,2 km 3 a year; middle stream from Kerki
to Tuyamuyun - 3,6 km 3 a year; lower stream - 1,4 km 3 a year. The most up to date investigations indicate that the losses vary between 7 and 13 km 3 a year which amounts to 20-40% of the total water withdrawal, i. e. there is a significant imbalance. Technical water loss in the system and on the irrigated fields is also significant due to low efficiency of the irrigation systems and technology. Annual average water delivered to the fields and consumed water amount is presented in Fig. 3.
Figure 3. Comparison between the irrigation water delivered and actual consumption in the lower reaches of the Amudarya River
The total volume of salt transported by the river reaches is about 30-40 Million tons a year which negatively influences crop production as well as the environment. In the Vakhsh-Pyanj section of the river 7-9 Million Tons enter, whilst in the Kerki-Tuyamuyun section - 13-16.5 Million Tons of salt inflow to the river from the drain-collectors. Cotton loss due to this case varies from 20% to 60% depending on soil salinity. Due to this situation, the irrigated lands are in a poor condition. Over 20% of them are rated as being in a very bad condition due to high salinity and
high levels of ground water. Crop productivity in Karakalpakstan is 4-5 times lower than it is in the other regions; crop losses account for 15-20% of the productive capacity and, moreover, has a decreasing trend (Fig.4).
Water scarcity and pollution impact negatively on human activity, particularly in the lower reaches of the river where the main occupations are cropping and processing (40%). Ecological issues have brought to and social issues as unemployment and diseases, poverty and migration.
Figure 4. Crop productivity trends in
Water accumulation capacity of THC reservoirs. Irrigated agriculture in the Lower reaches of the Amudarya depends on reducing due to siltation capacity of the 4 reservoirs (Channel, Kaparas, Koshbu-lak and Sultansanjar) of the Tuyamuyun Hydro Complex (THC). The reservoirs filling was started in 1981. During 35 years' operation period the reservoirs have been deformed significantly and lost almost 40% of operational capacity. The field investigations of the reservoirs have been carried out regularly by Scientific Research Institute of Irrigation and Water Problems (ex.SANIIRI) and the last by the Bathometric Center of the MAWR in 2008. The field investigations and data provided by the THC Management Unit allowed analyzing of accumulation and removal processes in the Channel reservoir. Analysis of the measurement data has resulted that the total designed reservoir capacity loss dynamics for the period 1995— 2015 show that average annual sedimentation volume for operation period consists of average 22.0 Mio m3 a year. The most intensive accumulation of sediments took place in 1991-1992 (222 Mio m3) and in 1998 (108 Mio m3). Maximum removal of sediments has been observed in 1986 (135 Mio m3) at the 20,8km3 runoff, 1997 (56 Mio m3) at the runoff of 18,3 km3 and 2000-2001 (110 Mio m3) at the runoff of 18,7.
Khorezm and Karakalpakstan regions
Conclusion
The above-mentioned issues are caused by major disadvantages in the system of management. Despite significant progress in the management of water resources, leading to positive experiences of economic cooperation, many organizational regulations still need to be improved in the basin. The following technical issues such as low data reliability and available water resources assessment, drought damage, inexact information about actual water withdrawal and water deficits, ineffective irrigation systems all contribute to a decline in the effective use of water resources.
The following actions must be taken to address these problems: introduce a reliable forecasting system; improve water accounting systems and the water metering status of the hydrological services; increase the efficiency of the irrigation systems and improve watering techniques and technologies.
Investigations, carried out by researchers of the Scientific Research Institute of Irrigation and Water Problems, present that the above-mentioned actions will provide significant positive economic, social and ecological benefits. The urgent and long-term actions list and expected efficiency of its application at the lower reaches of the Amudarya River is indicated in Table 1.
Table 1. - Expected efficiency gains and recoupment due to water loss reductions
Expected efficiency Khorezm Karakalpakstan
Irrigated land productivity increase due to a reduction of water salinity, USD/ha a year 56.33 49.40
Productivity increases due to the elimination of waterlogging: % of gross output 12 15
USD/ha a year 169.00 148,13
Collector-drainage system: operational cost reduction, USD/ha a year 12.50 12.50
Reduction in the costs of drinking and industrial water supply, USD/ha a year 24.46 31.02
Reduction in the cost of ecological and natural protection would be applied to the irrigated lands, water bodies and adjacent territories in the basin, USD/ha a year 10.19 10.34
Expected profit for an irrigation systems efficiency increase to 90%, USD/ha a year 589.17 502.02
The estimated benefit of the long-term actions fluctuates around 464 USD/ha in all the irrigated lands of the Amudarya Basin. Improvement of the existing water resources management system of the Amudarya Basin must be directed towards optimal satisfaction of the
needs of providing high quality water to all consumers. This must consider the situation existing at the present and likely to exist in the future. To achieve this situation, the affected entities need to coordinate their actions for the benefit of the economy of the nations will be required.
References:
1. Ikramova, at all. Water-land resources use efficiency increase in the Lowers of Amudarya. Research report, - Tashkent, Saniiri, - 2008, - 197 p.
2. Kambarov F.at all. Water use analyses in Khorezm region and crop watering estimation. Saniiri, - Tashkent, - 2003, - 203p.
3. Resolution of the Cabinet of the Ministry of UZB "Irrigated lands reclamation program for - 2001-2010", - Tashkent, - 2001, - 15 p.
4. Ismagilov Kh. A., Cann E. K. Channel processes on the river. Amu Darya in the conditions of water resources management//Extreme hy-drological events in the Aral-Caspian region: Tr. Interdisciplinary Scientific Conference. October 19-20, - 2006. - M., - 2006. - P. 255-260.
5. Kayumov O. Develop and implement measures to improve the flow regulation of the Tuyamuyun reservoirs in the interests of irrigation and water supply to the population of the lower reaches of the Amu Darya. Research Report, Saniiri, - 1989, - Tashkent. - P. 178.
6. Sorokin A. Management of water and alluvial regimes of the Amudarya river basin: tools and assessment // Extreme hydrological events in the Aral-Caspian region: Tr. Interdisciplinary Scientific Conference. October 19-20, - 2006. - M., - 2006. - From 289-293.
DOI: http://dx.doi.org/10.20534/ESR-17-3.4-102-104
Sukhrob Telyaev Kudratillayevich, Junior Researcher of laboratory "Ion plasma technologies and Thermo multiphase systems", department of Engineering Physics,
Tashkent State Technical University named after Islam Karimov, Tashkent, Republic of Uzbekistan.
Iskandarov Asilbek Akrom ugli, Bachelor, department of Thermal Engineering, Tashkent State Technical University named after Islam Karimov, Tashkent, Republic of Uzbekistan.
E-mail: asilbek.iskandarov17@gmail.com
Measurement of coefficient of convective heat transfer based on silicon oxide nanofluid in the cylindrical channel
Abstract: Coefficient ofheat transfer is investigated experimentally in nanofluidits flow in the cylindrical channel. The nanofluid has been prepared on the basis of distilled water and nanoparticle SiO2 Concentration of nanoparticles was varied ranging from 0.5 to 5% by volume. Significant intensification of heat transfer is established. At particle concentrations above 0.5%, the nanofluid was Non-Newtonian. Consequently, estimates of the rheological parameters of the nanofluid and coefficient ofthermal conductivity. Keywords: Thermal conductivity, nanofluid, viscosity, laminar-turbulent transition, coefficient of heat transfer.
Attempts to use liquid using microparticles for objectives of heat exchange intensification are known since the mid 70 's. On the way to achieve significant effects failed because large particles of sediment quickly enough. The liquid in which the component is dispersed nanoparticles (nanofluid), deprived of this shortcoming. Early experiments have shown that even small additives nanopar-ticles to fluids can lead to significant growth in its thermal conductivity and heat transfer and critical heat flow can be increased many times (see, for example, [1-4]).
Despite the huge amount of work, in which thermal conductivity of nanofluid and their heat transfer is studied, the results are often contradictory. In most works of increasing heat transfer using nanoparticles. There are, however, and publications, which demonstrates its decrease when you add nanoparticles [5]. There is a need to further study of all specified processes. The key in this issue is not thermal conductivity of nanofluid, that's its heat transfer coefficient. In this work for water based nanofluid and nanoparticle, SiO2 is experimentally studied.
Through pump fluid from the tank served in a heated area, after which enters the thermostat. Flow in the circuit is governed by Voltage transformer system. Plot is a heated copper cylindrical pipe with a wall thickness of 1 mm, diameter of 15 mm and a length of 1 m as the heater uses a coiled up on a nichrome channel thread thickness 0.1 mm with an overall resistance 320 n. Channel with the heater is insulated. Heating power regulated power source Lauda Alpha A 24. For measurement of the local temperature channel on its walls at equal distances from each other docked 6 Chromel-Copel thermocouples. As a heat carrier, a nanofluid was used based on distilled water and SiO2 nanoparticles with volume concentration y, equal to 0.5, 0.75, 1.5, 2, 3 and 5%. For preparation of a nano-
fluid applied standard two-step process and used SiO2 powder production of "Evonik Industries AG ", (63403 Hanau, Germany). Spherical nanoparticles, the bulk density of the powder equal to 2.2 g/cm 3. The average size of the nanoparticles was 12 nm. After add the required amount of water tank of nanopowders to destroy conglomerates nanoparticles fit in an ultrasonic mixer UZDN-4. Liquid consumption path changed from 50 to 550 g/min these ranges correspond to a laminar flow for all carriers, except water and nanofluid with concentration of 0.5%. In the last case, laminarturbulent transition occurs since the flow of about 400 g/min. Thus, three liquids laminar flow regime had taken place, and the fourth is laminar and transition. Conducted measurements showed that adding nanoparticles significantly increase local and convective heat transfer coefficients of the fluid medium. The degree of this extend rises with increasing concentration of nanoparticles. At low flow quantity (up to about 300 g/min), when with certainty we can talk about laminar flow mode as for the nanofluid, and water, the extent of this increase are growing almost proportional to the bulk concentration of nanoparticles. With further increase in consumption observed the rise in the average heat transfer coefficient of water. Starting with 350 g/min flow quantity average heat transfer coefficient of water compared with the corresponding coefficient for nanofluid with small concentrations of nanoparticles, and then begins to exceed them. At the expense of the order of400 g/min average heat transfer coefficient ofwater becomes higher than 2 per cent of a nanofluid. Such behaviour is associated with the turbulence of the water flow. This also indirectly indicates, that turbulence of nano-fluids at given flow quantity does still not occur. Laminar-turbulent transition is determined by the number of Reynolds. Given the expense of variation values for water and nanofluid can be associated
