CC BY
20
BicHHK njAEA
Takayshvili. Later this approach began to develop inresearching of the Siberian Energy Institute (now the Institute of Energy named after L.A.Melentyev).Many scientists such as M. Rozkin,A. Ionin, A. Merenkov, E.Sennova, V. Sidlerand otherswere working onreliability's problems.General theoretical methods to ensure the reliability of technical systems, special techniques that can be effectively used in systems of power were worked out byYu.N.Rudenko.
Researchobjective.Reliability can be determined as an gas tube heaters property to perform the prescribed functions in the prescribed volume at certain conditions of operation. Ensuring reliability of heat supply systems with gas tube heaters is one of the most important requirements to them as at the design stage and during operation. The article provides an answer the question: «Can we all scientific - methodical achievements of the reliability of large systems of energy transfer to the research of decentralized heating systems, heating systems with tube heaters?».
Conclusions.It is considered the heat supply systems with gas tube heaters. During operation any energy object can be found in different states, determined by the states of its components. The states characterizing reliability are operating, inoperable and limit states. The classification of statesfor reliability definition is given.
A part of tube of the heater is heated (the temperature of the outer surface of the tube can reach 450 - 650°C). In the desing of the heaters you should consider changing the length of the pipe due to thermal expansion of the material with temperature and the proper selection and placement of fixture. Design and installation of heaters must be performed by the way when the pipe could move freely within the value calculated elongation.Failure - free operation indice of reliability that can be used to study of heat supply systems with tube gas heatersreliability was proposed.Methodandmathematicalmodelofindicecalculationarepresented.
REFERENCES
1. Rudenko Yu. N. Nadezhnost sistem energetiki / Yu. N. Rudenko, I. A. Ushakov // M. : Nauka, 1989. - 325 s.
2. Nadezhnost sistem energetiki i ih oborudovaniya: Spravochnik: v 4-h t. T. 3: Nadezhnost sistem gazo- i neftesnabzheniya / M. G. Suharev, S. G. Babaev, A. M. Beylin, [i dr].; pod red. M. G. Suhareva. - M. : Nedra, 1994. - Kn.2. - 287 s.; T. 4: Nadezhnost sistem teplosnabzheniya / E. V. Sennova, A. V. Smirnov, A. A. Ionin i dr. - Novosibirsk: Nauka, 2000. - 351 s.
3. Ionin A. A. Nadezhnost sistem teplovyih setey / A. A. Ionin. - M. : Stroyizdat, 1989.-268 s.
4. Nadezhnost sistem energetiki. Terminologiya: Sb. rekomenduemyih terminov. - M. : Nauka, 1980. - Vyip. 95. - 44 s.
5. Irodov Vyacheslav. Raschet temperaturnyih udlineniy infrakrasnogo trubchatogo gazovogo obogrevatelya / Valeriya Tkacheva, Leontina Solod // Theoretical Foundations of Civil Engineering. -2011. - V.19. - P. 381-386.
6. Danishevskiy V. V. Termouprugoe napryazhenno - deformirovannoe sostoyanie korpusa gazovoy gorelki / V. F. Irodov, V. V. Tkacheva // Stroitelstvo, materialovedenie, mashinostroenie: Sb. nauchn. trudov. - D. : PGASA. - 2013. -Vyip. 70. - S. 84-92.
7. Normyi rascheta na prochnost elementov reaktorov, parogeneratorov, sosudov i truboprovodov atomnyih elektrostantsiy, opyitnyih i issledovatelskih yadernyih reaktorov i ustanovok. - M. : Metallurgiya, 1973. - 408 s.
UDC 519.6
SIMULATION OF THE ATMOSPHERE POLLUTION IN THE CASE OF ACCIDENTS
E. Gunko, Cand. of Techn. Sc., Do.
Dnepropetrovsk National University of Railway Engineering
Key words:atmosphere pollution, numerical simulation, pollutant dispersion
Introduction.The prediction of the concentration of the toxic gas in the atmosphere is the main information which is necessary to know in the case of toxic gas release after accidents. This information is very important to assess the danger level after the accident and to organize the protectionor evacuation of the population. To solve this problem it is necessary to calculate the toxic gas dispersion in the atmosphere. The emergency service is in need nowadays of the effective tool to
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solve this problem.
Literature review.In Ukraine two models are widely used to predict the threat in the case with accidents with the toxic substance emissions. This the empirical model adopted by the Ukrainian authorities [7] and Gaussian plume model (in some case the analytical model of the instant ejection) [10; 11]. Both models allow to calculate the size of the hitting area but they can't take into account the different types of ejections [3; 10; 11]. Therefore, it is important to develop CFD models having more capabilities to simulate the process of the atmosphere pollution after toxic substances ejections[1; 4; 5].
The purpose.The main purpose of this work is the development of the effective numerical model which is more effective than the standard model and can be used for monitoring problems in the case of accidents with toxic substances.
Governing equations.To simulate the process of pollutant (toxic chemical substances) transfer in the atmosphere the transport equation is used [6]:
dC duC dvC dwC
- + -
- + -
- + -
dt dx cy dz
CC \ d ( dC
+°c=—\mx— |+—
dx V dx ) dy
Uy^T
, ' Cy.
d
dC
dz \z dz ,
+
(1)
+
X Q (t)s(x - x, )s(y - y, )â(z - z, )
where u, v, w are the velocity components in x, y and z direction respectively; C is the concentration of toxic substance;
ois the parameter taking into account the process of toxic gas decay;
fa fa, juzare the coefficients of turbulent diffusion in x, y and z direction respectively;
xi,yi,zi are the coordinates of point source of emission;
Qi(t) is the intensity of pollutant emission;
ô(x - xi )(y - yt )(z - zj ) is Dirac's delta-function.
In the developed numerical model, the following profile of velocity component u and coefficient of diffusion juz is used [2]:
u = u
( z ^ "
Uz = k1
( z ^ m
v zi y
(2)
v zi y
where uj is the velocity at height zj; £;=0,2; «=0,16; m~1. The transport equation is used with the following boundary conditions [6; 9]: -inlet boundary: C\Met = CE , where CE is the known concentration (very often CE = 0); -outlet boundary: in numerical model the condition C(i +1, j, k ) = C(/', j, k) is used (this boundary condition means that we neglect the process of diffusion at this plane).
Numerical integration of the equations.To develop the numerical model the following splitting of equation (1) is carried out [1]:
d c d uc d vc d wc
— +-+-+-+ ac = 0,
d t d x d x d z
d c ~dt
d x
U
d c d x
\
+ -
d_
d y
Uy
d c d y
\
+ -
d_
d z
Uz
d c
J~z
f=Z a (()s(r - r).
The following approximation of the first order derivatives is fulfilled [9]:
aC qf - c"
ijk
dt
At
(3)
(4)
(5)
(6)
duC du C du C -=-+-
dx
dx
dx
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dvC dv+C dv C
dy dy dy 5wC 5w+C dw C
dz dz dz
+ u + U _ u — \u\ + v + IV _ v — Ivl w + Iwl _ w —
where: U =-—; U =—-— ; v =—— ; v =-—; w+=-; w =-—
2 2 2 2 2 2
+ + cn+1 + Cn+1
du C ui+1, j,k cijk _ uijk ci—1, j,k L+ cn+1 — = C ,
dx Ax
_ — rn+1 — rn+1
du C ui+1, j, k Ci+1, j, k — uijk Cijk = n+1
~ = LxC ,
= LyC
d x Ax
dv+C + Cn+1 + Cn+1 vi,j+1k"ijk ~yijkLi,j—1,k
dy Ay
dv~C — Cn+1 - Cn+1 vi,j+l,k"i,j+1,k —vijk"ijk
dy Ay
dw+C + nn+1 + n+1 wi, jk+1Cijk — wijk"i, j ,k—1
dz Az
dw C — nn+\ — n n+1 wi,j ,k+1Ci j ,k+1 — wijk"i j ,k
= LyC
= LzC
= L~zCn+l. dz Az
Thesecondorder deriveties areapproximated as following:
d f P"\ Cn+1 — Cn+1 Cn+1 — Cn+1
^dX(»■ f) " ^ — ^ "-V^ = ^ +
d ( dC) ""+1 — ""+1 ""+1 — ""+1
d n ~n j+1,k j ~ 1,1,k jl,k = M — Cn+1 + M + Cn+1
~ Vy— - tty,-7-2--Vy2-—2-= Myy" + Myy" ,
dy dy J » Ay2 Ay
P f Pr\ Cn+1 — Cn+1 Cn+1 — Cn+1
I f) - ~ —n- =^ + M'zz""
where fj,x = , etc.
1 A+A+1
In these formulae L+, L—, LLy, L—, L+, Ly,M+,M—, etc. are the notations of the difference operators.
After the approximation the solution of the difference equation is splitted in 4 steps:
- at the first step k = — : 4
Cj —"j 1
+1 L+L+C + L+Ck )+-C" = 0; At 2Vx y z ' 2 j
- at the second step k = n +1; c = n +1:
2 4
Ck — Cc i
jk jk
+1 L + L—Ck + L—Ck)+ -Ck = 0 ; At 2V x y z ' 2 j
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3 1 - at the third step k = n H—; c = n H—:
4 2
Ck — Cc
^ijk ^ijk
1 (m - Cc + M+jCk + M - Cc + M + Ck + M - Cc + M+Ck );
O ^ xx yy yy zz zz '
At 2
3
- at the fourth step k = n + 1; c = n + —:
4
Ck — Cc 1 / \
-Jt-=1 (M—Ck +M+rrCc +M — Ck + M + Cc + M — Ck + M+Cc).
At 2 xx yy yy zz zz /
At the fifth step the influence of the sources of toxic gas emission is taken into account [9]:
5 n+1 5 n
Ci, j,k—Ci, j,k = Q, jt"+12) ^ (7)
At ti AxAyAz l'
On the basis of the developed model the code was created using FORTRAN language.
Fig.1. Sketch of the computational domain: Fig.2. Concentration of NH3, t=11min(1 -
(Railway bridge near settlement «Igren») C=24 mg/m3; 2 - C=53mg/m3)
A - position of the toxic gas emission
Fig.3. Concentration of NH3, t=32 min(1 - C=18mg/m3; 2 - C=43mg/m3)
Results. The developed model was used to solve the following problem. It is suppose that the emission of NH3 takes place as the result of the accident at the railway near the railway bridge
Вюник ПДАБА
«Samarskij» (Fig.1). The settlement «Igren» is situated near the railway bridge. That is why it is very important to predict the level of the atmosphere pollution after the accident.
The scenario of the problem was as following. At time t=0 the short term emission, during 25 min of NH3 takes place. The wind speed is 5 m/s. The aim of the calculation was to obtain the dimensions of the contaminated area near the settlement «Igren». The results of the numerical experiments are shown below.
As it is clear from figures2 - 3 the toxic gas plume very quickly reaches the buildings of «Igren» settlement. The plume has the specific geometrical form as a result of the short term emission. The concentration in the plume is much higher than the hitting concentration which is equal to 20 mg/m3for NH3. It means that it is necessary to develop measures to protect the population in settlement «Igren».
The computational time to solve the problem was about 15 sec. So the developed model can be used to predict very quickly the concentration field in the case of accidents.
REFERENCES
1. Антошкина Л. И. Оценка экологического риска при авариях с химически опасными веществами / Л. И.Антошкина, Н. Н.Беляев, Е. Ю. Гунько. - Д.: Наука и образование, 2008. -136 с.
2. Берлянд М. Е. Современные проблемы атмосферной диффузии и загрязнения атмосферы / М. Е. Берлянд. - Л.: Гидрометеоиздат, 1975. - 448 с.
3. Бруяцкий Е. В. Теория атмосферной диффузии радиоактивных выбросов / Е. В. Бруяцкий.- К.: Институт гидромеханики НАН Украины, 2000. - 443 с.
4. Гунько Е. Ю. Моделирование загрязнения атмосферы при испарении жидкости из грунта / Е. Ю. Гунько // Вюник Дншропетр.нац.ун-ту затзн.трансплм.акад. В. Лазаряна. - 2007. - № 19. - С. 35-39.
5. Гунько Е. Ю. Оценка риска токсичного поражения людей при аварийном выбросе химически опасного вещества / Е. Ю. Гунько // Вюник Дншропетр.нац.ун-ту залiзн.трансп.iм.акад. В. Лазаряна. - 2008. - № 20. - С. 87-90.
6. Марчук Г. И. Математическое моделирование в проблеме окружающей среды / Г. И. Марчук. - М.: Наука, 1982. - 320 с.
7. Методика прогнозування наслщюв виливу (викиду) небезпечних хiмiчних речовин при аварiях на промислових об'ектах i транспорт - К.: 2001. - 33 с.
8. Самарский А. А. Теория разностных схем / А. А. Самарский. - М.: Наука, 1983. - 616 с.
9. Численное моделирование распространения загрязнения в окружающей среде / М. З. Згуровский, В. В. Скопецкий, В. К. Хрущ[и др.]. - К.: Наук. думка, 1997. - 368 с.
10. Hanna S. Hybrid Plume Dispersion Model (HPDM) Improvements and Testing / S. Hanna, J. Chang // College on Atmospheric Boundary Layer and Air Pollution Modelling: 16 May-3 June 1994. - № SMR/760-4. P. 1491-1508.
11. Tirabashi T. Analytical Air Pollution Advection and Diffusion Models / T. Tirabashi // College on Atmospheric Boundary Layer and Air Pollution Modeling. - 16 May-3 June 1994. -№ SMR / 760-9.
SUMMARY
Постановка задачи Внаслщок надзвичайних ситуацш техногенного характеру вщбуваеться штенсивне забруднення атмосфери. Прогнозування процесу розповсюдження забруднювача е важливим при прийнятп адекватних ршень тд час локалiзацii зон забруднення та лшвщацп наслщюв аваршних ситуацш з хiмiчно небезпечними речовинами.
Аналiз проблеми дослщження.Анатзсучасних методiвпрогнозування
забрудненняатмосферитсля аваршз небезпечнимиречовинами показав наявнють суттевих недолшв, а саме: вони не враховують вплив будiвель на процес переносу небезпечних речовин в атмосфер^ параметри метеоситуацп та потребують великих втрат часу на отримання результату прогнозування. Таким чином, постае необхщнють у створенш чисельних моделей, що дозволяють комплексно врахувати перелiченi вище чинники та швидко виконувати розрахунки.
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Для практичного застосування вкрай важливо мати стшю чисельш алгоритми, яю дозволяли б розраховувати забруднення атмосфери для широкого кола аваршних ситуацiй. Тому в данш роботi для прогнозу аваршного забруднення атмосфери застосовано неявну поперемшно-трикутну рiзницеву схему. Ця схема мае особливють - вона е неявною за побудовою, але розрахунок значення концентрацп здiйснюеться за явною схемою - метод «бегущего счета».
Мета дослщження. Метою дослщження е розробка ново! ефективно! 3-D чисельно! моделi для розрахунку розсiювання токсичних газiв в атмосферi, яка враховуе вплив будiвель на процес переносу забруднювача в атмосферi, параметри метеоситуаци, легка в користуванш та для отримання результату прогнозування потребуе 10-15 секунд.
Висновки. Розроблено ефективну чисельну модель для моделювання тривимiрного процесу забруднення атмосфери у разi надзвичайних ситуацш на базi гiдродинамiчноl моделi потенщально! течи i тривимiрного рiвняння переносу домшки, якi враховують вплив в^рового потоку на перенос забруднювача i хiмiчний розпад забруднюючо! речовини.
Розробленумодельбуло використанодлярозрахункузони ураження в селiтебнiй зош у випадку аварпз викидомтоксичних газiв поблизу залiзничного мосту. Представлено результатирозрахунюв, що iлюструють ефективнiсть розроблено1 3-D моделi прогнозування розсiювання забруднювача в атмосфера На основi проведених розрахунюв показано, що у випадку аваршно1 ситуаци можливе швидке та небезпечне забруднення атмосфери в селтебнш зош.
REFERENCES
1. Antoshkina L. I. Otsenka ekologicheskogo riska pri avariyah s himicheski opasnyimi veschestvami / L. I.Antoshkina, N. N.Belyaev, E. Yu.Gunko. - D. : Nauka i obrazovanie, 2008. - 136 s.
2. Berlyand M. E. Sovremennyie problemyi atmosfernoy diffuzii i zagryazneniya atmosferyi / M. E. Berlyand. - L. : Gidrometeoizdat, 1975. - 448 s.
3. Bruyatskiy E. V. Teoriya atmosfernoy diffuzii radioaktivnyih vyibrosov / E. V.Bruyatskiy. -K. : Institut gidromehaniki NAN Ukrainyi, 2000. - 443 s.
4. Gunko E. Yu. Modelirovanie zagryazneniya atmosferyi pri isparenii zhidkosti iz grunta / E. Yu. Gunko // Visnyk Dnipropetr. nats. un-tu zalizn. transp. im. akad. V. Lazaryana. - 2007. - № 19. - S. 35 - 39.
5. Gunko E. Yu. Otsenka riska toksichnogo porazheniya lyudey pri avariynom vyibrose himicheski opasnogo veschestva / E. Yu. Gunko // Visnyk Dnipropetr. nats. un-tu zalizn. transp. im. akad. V. Lazaryana.. - 2008. - № 20. - S. 87 - 90.
6. Marchuk G. I. Matematicheskoe modelirovanie v probleme okruzhayuschey sredyi / G. I. Marchuk. - M. : Nauka, 1982. - 320 s.
7. Metodika prognozuvannya naslldklv vilivu (vikidu) nebezpechnih hImlchnih rechovin pri avariyah na promislovih ob^ktah i transporti. - K. : 2001. - 33 s.
8. Samarskiy A. A. Teoriya raznostnyih shem / A. A. Samarskiy. - M. : Nauka, 1983. - 616 s.
9. Chislennoe modelirovanie rasprostraneniya zagryazneniya v okruzhayuschey srede / M. Z. Zgurovskiy, V. V. Skopetskiy, V. K. Hrusch, N. N. Belyaev. - K. : Nauk. dumka, 1997. - 368 s.
10. Hanna S. Hybrid Plume Dispersion Model (HPDM) Improvements and Testing / S. Hanna, J. Chang // College on Atmospheric Boundary Layer and Air Pollution Modelling: 16 May - 3 June 1994. - № SMR/760 - 4. P. 1491 - 1508.
11. Tirabashi T. Analytical Air Pollution Advection and Diffusion Models / T. Tirabashi // College on Atmospheric Boundary Layer and Air Pollution Modeling. - 16 May - 3 June 1994. -№ SMR / 760 - 9.
