Мундарижа

1. 
   249-GURUX TALABASI ABDUSATTOROV NODIRBEKNING ICHKI YONUV DVIGATELLARI FANIDAN
   

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2. 
   AMALIY MASHG'ULOTLARI
   

3. 
   DVIGATELNING ISSIQLIK HISOBI
   

Dvigatelning ishchi tsiklini issiqlik bo’yicha hisoblash modernizatsiya qilinayotgan yoki Yangidan loyixalanayotgan dvigatelning asosiy ishchi parametrlarini aniqlashga, Shuningdek yaratilayotgan dvigatelning indikator va effektiv ishchi ko‘rsatkichlarini baholashga imkon beradi.

Dvigatelning issiqlik hisobi uchun quyidagi dastlabki ma’lumotlar zarur buladi: Dvigatelning turi, nominal quvvati, tirsakli valning aylanishlar soni, siqish darajasi, taktlilik koeffitsienti, havoning ortiqchalik koeffitsienti, havoning harorati, bosimi, yoqilg’ining turi, uning pastki solishtirma Yonish issiqligi, o’rtacha elementar tarkibi.

1. 
   Ishchi jismning parametrlari.
   

1 kg yoqilg’ini to’la yonishi uchun kerak bo’lgan havoning nazariy miqdori:

L_H = 10.23*(8/3*C + 8*H₂ -O₂), kg.

Bunda: C, N₂, О₂ — 1 kg yoqilg’i (dizel) da mos ravishda uglerod, vodorod va kislorodning miqdor nisbati:

Benzin uchun: C = 0,857 kg, H₂ = 0,133 kg, О₂ = 0.01

L_H = 10.23*(8/3*C + 8*H₂ -O₂) =1/0.23*(8/3*0.857+8*0.133-0.01)=14.518 kg

1 kg yonilg’ining to’la yonishi uchun kerak bo’lgan havoning nazariy miqdori kilomollarda.

L_H = L¹_H/^, kmol

Bunda: ц_х — havo miqdorini kilogramdan kmolga o’tkazish koeffitsienti:

• 
  = 28,96.
  

L_H = L¹_h/v = 14.518/28.96=0.5013

Yangi zaryadning haqiqiy miqdori:

Dizelli dvigatel uchun: m_i =a*L_Hs , kmol.

Bunda a -havoning ortiqchalik koeffitsienti (topshiriqda berilgan).

M₁ = a*L_H = 0,93*0.5013=0.466 ^km°

Yonish maxsulotlarning umumiy miqdori.

Dizelli dvigatel uchun:

M₂ = a*L_H + H₂/4+O₂/32+0.21L^ *(1 -a), kmol

M₂ = a*L_H + H₂/4 + O₂/32+0.21L_H *(1 -a) = 0,93*0.50+0.133/4+0.01/32+0.21*0.50 (1-0,93)=0.50

Yonuvchi aralashmani molekulyar o’zgarishining kimyoviy koeffitsienti.

А = м 2/ м

2. 
   Kiritish jarayoni
   

Kiritishda zaryadning zichligi.

p_t=p,*10⁶/(r,*T0) , kg /m Bunda: R_X — havo uchun solishtirma gaz doimiyligi. R_X = 287 kg grad.

T₀ - tashqi muhit harorati, K (topshiriqda berilgan).

p_k = P₀ *10⁶/(R_x * T0) =0.1 *10⁶/(287*296)=0.1 *10⁶/84952=1.18 kg/m³

Kiritishda bosimning yo’qotilishi.

AP = (C² + ) * (C^² * p_k *10^-6) / 2, mPa.

Bunda: S va Z_kir- mos ravishda zaryad tezligining so’nishi va kiritish sistemasining qarshilik koeffitsientlari.

c² + z = 2,5... 4

С + Z =2.5 qabul qilamiz.

Skir- zaryadni kiritish sistemasining eng kichik qismidan o’tish tezligi.

C²kir = 50 ... 130 m/s.

2

С kir=50 qabul qilamiz

AP_a = (C² + Z_KUP)*(С_кир² * p_k *10^-6) / 2 = 2.5 * 50²*1.18*10^-6/2=0.0037 mPa Kiritish jarayoni oxiridagi bosim.

P = P -AP , mPa.

a 0 a¹

P = P-AP = 0.1-0.0037=0.096

a 0 a

To’ldirish koeffitsienti

4v = TS - P,)/[(T₀ + AT)(s- 1)P]

Bunda s - dvigatelning siqish darajasi (Topshiriqda berilgan).

AT- Yangi zaryad haroratini kiritish kollektori, klapan va boshqa detallarning issiqligi hisobiga ortishi:

AT= 10...25 K AT=10 K

rj_v= T₀(sP_a -P_r)/[(T₀ + AT)(s- 1)P₀] = 296(17*0.096-0.115)/((296+10)*(17-1)*0.1)) =0.920

Qoldiq gazlar koeffitsienti

r = P'T^PTn. (s- 1)]

Bunda P_r - qoldiq gazlar bosimi, mPa

P_r = 0,1...0,2 mPa y = PT /[^P0^TrVy (£ -1)]= 0.115*296/((0.1*893*0.920(17-1)) =0.025 Kiritish jarayoni oxiridagi harorat

T +AT

T =

P t + AT

1 --^*(1 - ¹ + ) £ P„ T

Bunda T_r - qoldiq gazlar xarorati, K (topshirqda berilgan)

1 + AT _ 296 +10 _

^a = P T + AT ~ 0 115 296 +10 =^306/((1-

1 _- *(1 _- ^To + ^A1 ) 1 ^{0 115} *(1 _- ²⁹⁶ +¹⁰)

£ P_a T_r 17*0.096 893

(0.0704*0.^a658))=306^r/0.953=320.81

Dizelli dvigatellar uchun: T_a = 320... 360 K bo’lishi kerak.

1.3.Siqish jarayoni.

Politropik siqishning o’rtacha ko’rsatkichini quyidagi eipirik formula orqali aniqlash mumkin:

Dizelli dvigatellar uchun: n=1.41- (100/П_н)-0.01 Bunda n_H- tirsakli valning aylanishlari soni (Topshiriqda berilgan).

n 1=1.41 - (1 00Mh-0.01=1.41-(100/5000)-0.01=1.38

Siqish jarayoni oxiridagi bosim:

Pc = Pa *£ⁿ¹ , mPa P_c = P_a *£ = 0.096*17¹³⁸=4,8 MPa

T_c = T_a * £

Siqish harorati:

1 = T_a *£^{n1 -1} = 320,18*17^138-1=941.49 K

4. 
   Yonish jarayoni.
   

Dizelli dvigatellar uchun:

Yonish jarayoni oxiridagi haroratni Yonishning benzinli dvigatel uchun issiqlik balansi tenglamasidan foydalanib topish mumkin:

M_PT = + 8.314*A)T_c + Q l((oL_H(1 -y))
Dizelli dvigatellarda suyuq yoqilg’ining Yonish maxsulotlari uchun o’zgarmas bosimdagi o’rtacha molekulyar issiqlik sig’imi quyidagicha topiladi:

V_PPz = (20.2 + 0.92/ a) + (15.5 +13.8/ a) *10^-4 T_z + 8.314, kJ/kmolK

V_PPz = (20.2 + 0.92/a) + (15 . 5 +13 . 8/a) *10^-4 T_z + 8.314 =21.189+0.00303T_z

Siqish oxiridagi zaryadning (havoning) o’rtacha molekulyar isssiqlik

sig’imi:

V_v = 20.16 +1.74 *10^-3T_c, kJ/kmolK V_v = 20.16 + 1.74*10^-3T_c = 20.16+1.74*10^-3*941.49 =21.798kJ/molK

Qoldiq gazlarning mollar soni:

M = a*y* L_H , kmol M = a*y* L_H = 0,93*0.025*0.50=0.012 kmol

Siqish oxiridagi Yonishgacha bo’lgan gazlarning mollar soni:

M = aL_H + M_r , kmol M =aL_H + M = 0,93*0.50+0.012=0.478

Gazlarning yonishdan keyingi mollar soni

M = M ⁺ M_r , kmol

M₂(_a=₁)=C/12+H₂/2+0.79aL_H (manba S.Qodirov O.SalimovDvigatellar va avtomobil nazariyasi 149-bet)

Mz = M2 + M_r =

C/12+H₂/2+0.79aL_H+M_r=0.857/12+0.133/2+0.79 *0.50 *0,93+0.012=0.511

Ishchi aralashmani molekulyar o’zgarishining hisobiy koeffitsienti

P = M_z / Mc

p = M_z /M_c = 0.511/0.478=1.07

Issiqlikdan foydalanish koeffitsienti £ (topshiriqda berilgan) va topilgan qiymatlarni dizelli dvigatel uchun yonish tenglamasiga qo’yib yonish oxiridagi haroratni topamiz.

Hisoblab topilgan va qabul qilingan qiymatlarni yonish tenglamasiga qo’yib, dizelli dvigatel uchun yonish oxiridagi harorat T_z topiladi.

VT = V + 8.314* X)T_c + Q /((aL_H (1 - _r))

1.07*(21.189+0.00303T_z)*T_z=(21.798+8.314* 1.85) 941.49 +

0.89*42500/((1*0.50(1-0.025))=71154

0.00324T_z²+22,676T_z=71154

• 
  b ±л/b² - 4ac
  

^z 2a

-22,676±422,676² -4*0.00309*(-71154)

= 2358K

2*0.00324

Yonish iarayoni oxiridagi nazariy maksimal bosim:

P₂=h*P_c,mP a

P₂ =A* P_c=1.85*4,8=8,89 MPa

Yonish jarayoni oxiridagi haqiqiy maksimal bosim:

P_ZI = 0.85P_z, mPa

P_ZI = 0.85P_z = 0.85*8,89=7,55MPa

Bosimning ko’tarilish darajasi:

Я = Pz / Pc ,

X = P₂ / P_c = 1.85 X = 1.85 qabul qilamiz.(manba T.O. Almataev Transport vositalarini ichki yonuv dvigatellari 44-bet)

4. 
   Kengayish jarayoni
   

Politropik kengayishning o’rtacha ko’rsatkichini quyidagi empirik formula yordamida topamiz:

Benzinli dvigatellar uchun:

n2=1,22+(130/n)-0.01 n₂=1,22+130/n)-0.01=1.22+(130/5000)-0.01=1.236

Kengayish oxiridagi bosim:

P_B = P_Z / Sⁿ, mPa P_B = P_Z / Sⁿ² = 8,89/11,73^L236=0.423 MPa

S-so’ngi kengayish darajasi.

S=e/p = s * A*T_c/J3 *T_z=17*1.85*941,49/1.07*2358=11,73

Kengayish oxiridagi harorat:

T_R = T₇ l S"^2-1, K

B ^ Z

T_B = T_Z l S"^2-1 = 2358/11,73^1236-1=1319.29 K

4. 
   Dvigatelning indikator ko’rsatkichlari
   

Tsiklning nazariy o’rtacha indikator bosimi:

Benzinli dvigatellar uchun:

1

1

1

Up- 1)+-^p (1

1)

⁽¹ _7n;_'⁾

S^}

£ -1

ⁿ2 ^{- 1}

n -1

2

£

4,8

1 85*1 45 1.85(1.45 -1) + (1

1

1

(1 "

1.38-1 17

— )

71.38-1'

1.236

17 -1

1.236 -1 11,73 =1.23 MPa

Ф_т =0,92...0.97 -kirrasiz va kirrali indekator diagrammalar yuzalarining nisbatini belgilaydigan koeffitsient. cp_T =0.94 deb qabul qilib, tsiklning haqiqiy o’rtacha indikator bosimini topamiz:

P = (p_TP_i, mPa

P =^_TP^. = 0.94*1.23=1,15

Indikator foydali ish koeffitsienti (FIK):

er = P_taL^l_H ^/(QnP_kri_v⁾

Г = paL}_Hl(Q_n pr ) = 1,15*0,93*14.52/(42500*1.18*0.920) *10³=0.337

Yoqilg’ining indikator solishtirma sarfi:

g_t = ³.⁶*^103/(Qnr⁾, gkVt soat = 3.6 *10³ /(Q_nr) = 3.6*10³/(42500*0.000337)=250.13 gkVt soat

4. 
   Dvigatelning effektiv ko’rsatkichlari
   

Porshenning o’rtacha tezligi:

C_П = S*n_H /(3*10⁴), m/s C_П = S*n_H l(3*10⁴) = 108,54*5000/3*10⁴=18,09 m/s

Dizelli dvigatel uchun o’rtacha bosimning mexanik yo’qotishlarga sarflanadigan qismi:

P_M = 0,105 + 0,013C_n, mPa
P_M = 0,105+ 0,013С_П = 0.105+0.013*18,09=0.32 mPa С_я=18,09 m/s С_я=18,09 m/s deb qabul qilamiz.

O’rtacha effektiv bosim:

^Pe = ^Pi ^{- P}m, mPa

P, = Pr - Pm = 1,15-0.32=0.83

Mexanik foydali ish koeffitsienti