Kuverengwa kwebasa nesimba muThermodynamic Systems
Thermodynamics inodzidza hukama huripo pakati pekupisa, basa, nesimba mukati mehurongwa. Mukuita—ingava mumainjini emotokari, mafekitori emagetsi, macompressor emaindasitiri, kana kunyange mafiriji—pfungwa dzebasa nesimba ndizvo zvinonyanya kukosha pakuongorora kushanda zvakanaka kwehurongwa, zvinodiwa nesimba, uye kugona kugadzira kana kupinza simba. Chinyorwa chino chinokurukura kuti basa nesimba zvinoverengerwa sei muhurongwa hwethermodynamic, pfungwa huru dzavanoda, uye mienzaniso yekushandiswa kwadzo mumaitiro ekutanga.
1. Masisitimu, miganhu yemasisitimu, uye marudzi esimba
Tisati taita maverengero, tinofanira kutsanangura sisitimu (chikamu chiri kudzidzwa) nenzvimbo dzakakomberedza (kunze kwesisitimu). Miganhu yesisitimu inogona kuva chaiyo (madziro emudziyo) kana yekufungidzira. Kune mapoka matatu akajairika:
1. Sisitimu yakavharwa: huremu hahupfuure miganhu, asi simba rinogona.
2. Sisitimu yakavhurika (sisitimu yakavhurika/vhoriyamu yekudzora): huremu nesimba zvinogona kuyambuka miganhu.
3. Sisitimu yakaparadzana: hapana kuchinjana kwehukuru kana simba (yakanaka).
Simba mu thermodynamics rinoonekwa mumhando dzakasiyana-siyana:
– Simba remukati (U): simba re microscopic nekuda kwekufamba uye kudyidzana kwemamorekuru.
– Kinetic energy (KE): ine chekuita nekumhanya kukuru kwemvura/chinhu, \( KE = \frac{1}{2} m V^2 \).
– Simba rinogona kuwanikwa (PE): rine chekuita nekukwirira mumunda wegiravhiti, \(PE = mgz \).
– Simba rekuyerera muhurongwa hwakavhurika rinowanzoonekwa muchimiro che \( pv \) (nguva yekumanikidzwa kwevhoriyamu chaiyo).
Mukuongorora kwatinoita, tinosarudza kuti ndeipi simba rakakosha. Semuenzaniso, mutangi risingachinji, shanduko muKE nePE dzinowanzoregeredzwa. Zvisinei, muturbine kana nozzle, shanduko muKE dzinogona kuva dzakanyanya.
2. Basa mu thermodynamics
Basa ndiko kutamiswa kwesimba kunoitika nekuda kwemasimba anoshanda kuburikidza nekutama pamuganhu wesystem. Mu thermodynamics, chiratidzo chinowanzo shandiswa ndechekuti:
- Kushanda kwesystem kwakanaka (system inoshanda).
- Zvinowanikwa pabasa muhurongwa hazvina kunaka (nzvimbo inoshanda pahurongwa).
Mhando dzebasa dzakajairika:
1. Basa remuganhu: rinoitika kana vhoriyamu yehurongwa ichichinja.
2. Basa remugodhi: basa remakanika kuburikidza nemugodhi, semuenzaniso maturbine nemacompressor.
3. Basa remagetsi: masisitimu anoshanda kuburikidza nemagetsi nemagetsi.
4. Basa repamusoro nemamwe marudzi (semuenzaniso basa rechirimo).
2.1 Muganho webasa mumaitiro e quasi-static
Pamaitiro e quasi-static (kumanikidzwa pamuganhu wesystem kwakanyatsotsanangurwa), basa remuganhu rinotsanangurwa:
\[
W_b = \int_{V_1}^{V_2} p \, dV
\]
Kukosha kwebasa kunoenderana negwara remaitikiro, kwete mamiriro ekutanga neekupedzisira chete. Izvi zvakakosha: kunyangwe simba remukati riri basa remamiriro, basa harisi iro.
Dzimwe nyaya dzakajairika:
- Maitiro ekumanikidzwa nguva dzose (isobaric)
\[
W_b = p(V_2 – V_1)
\]
- Maitiro ehuwandu hwenguva dzose (isochoric)
Kubva \( dV = 0 \), ipapo \( W_b = 0 \).
– Maitiro ePolytropic \( pV^n = \text{constant} \)
Kune \( n \neq 1 \):
\[
W_b = \frac{p_2 V_2 – p_1 V_1}{1-n}
\]
Kune \( n = 1 \) (inonyatsokodzera gasi isotherm):
\[
W_b = mRT \ln\left(\frac{V_2}{V_1}\right)
\]
Kusarudzwa kwemuenzaniso wemaitiro (isobaric, isothermal, adiabatic, polytropic) kwakakosha zvikuru pakuona mhedzisiro yekuverenga, saka data kana fungidziro dzinofanira kutaurwa zvakajeka.
3. Kupisa uye hukama hwako nebasa
Kupisa (Q) ndiko kutamiswa kwesimba nekuda kwekusiyana kwekupisa. Muchiitiko chimwe chete ichi:
– \( Q > 0 \): kupisa kunopinda musystem.
– \( Q < 0 \): kupisa kunobuda muhurongwa. Mu thermodynamics, kupisa nebasa imhando dzekufambisa simba, kwete "simba rakachengetwa". Simba rakachengetwa rinoratidzwa kuburikidza ne \( U \), \( KE \), \( PE \), kana enthalpy \( H \). 4. Mutemo wekutanga weThermodynamics: hwaro hwekuverenga simba 4.1 Sisitimu yakavharwa Mutemo wekutanga unotaura kuchengetedza simba: \[ \Delta E = Q - W \] na \( E = U + KE + PE \). Saka: \[ \Delta U + \Delta KE + \Delta PE = Q - W \]
Mumatambudziko mazhinji, shanduko dziri mu \( KE \) uye \( PE \) diki zvekuti: \[ \Delta U = Q - W \] Izvi zvinopa hwaro hwekuverenga kupisa kana basa kana shanduko yesimba remukati ichizivikanwa (semuenzaniso, kubva patafura yezvivakwa kana equation yegesi yakakodzera). 4.2 Sisitimu yakavhurika (vhoriyamu yekudzora) uye equation yesimba rinoyerera zvakadzikama. Kune steady-flow, fomu yakakurumbira ndeiyi: \[ \dot{Q} - \dot{W}_s = \dot{m}\left( h_2 - h_1 + \frac{V_2^2 - V_1^2}{2} + g(z_2 - z_1) \right) \] Pano: - \( \dot{W}_s \) ibasa remubato panguva imwe neimwe. - \( h \) i enthalpy \( h = u + pv \), yakakosha zvikuru mumasisitimu akavhurika nekuti inosanganisira simba remukati nerekuyerera. Zvikamu \( \frac{V^2}{2} \) uye \( gz \) dzimwe nguva zvinogona kuregeredzwa, asi kune ma nozzles/diffusers kana masisitimu ane musiyano mukuru wekukwirira, zvikamu izvi zvinofanira kufungwa nezvazvo. 5. Nzira dzakajairika dzekuverenga basa nesimba. Mukugadzirisa matambudziko ethermodynamic, matanho akarongeka anobatsira kudzivirira zvikanganiso: 1. Tsanangura sisitimu (yakavharwa kana yakavhurika) uye dhirowa dhayagiramu iri nyore. 2. Sarudza maitiro (isobaric, adiabatic, isothermal, polytropic, nezvimwewo). 3. Nyora chiyero chesimba (Mutemo wekutanga) zvichienderana nerudzi rwesisitimu. 4. Ziva huwandu hwakaregeredzwa (semuenzaniso \( \Delta KE \approx 0 \)). 5. Shandisa hukama hwepfuma: matafura evapor, magasi akakodzera, kana ma equation estate. 6. Verenga basa kubva pa integral \( \int p\,dV \) kana kubva pa flow energy equation. 7. Tarisa mayuniti nezviratidzo (zvakanaka/zvakaipa zvichienderana netsika). Chikanganiso chinowanzoitika ndechekuvhiringidza tsananguro yebasa remuganhu muhurongwa hwakavharwa nebasa remugodhi muhurongwa hwakavhurika, uye kukanganwa kuti basa rinoenderana nenzira. 6. Mienzaniso yepfungwa dzinoshandiswa pamidziyo yethermodynamic 6.1 Maturbine Maturbine anoshandura simba remvura kuita basa remugodhi. Kuti rifambe zvakanaka, rinowanzo fungidzirwa kuti adiabatic (\( \dot{Q} \approx 0 \)) uye kuchinja kwehurefu kudiki: \[ \dot{W}_s \approx \dot{m}(h_1 - h_2) \]
Kana kumhanya kwekubuda kwakakwira zvakanyanya, saka shanduko musimba rekinetic inofanira kuiswa kuti ive nechokwadi chekuti simba rinofanotaurwa nemazvo. 6.2 MaCompressor MaCompressor anoda basa remugodhi kuti awedzere kumanikidzwa. Mumamiriro ezvinhu akakodzera eadiabatic, basa racho rine chekuita nekuwedzera kwe enthalpy: \[ w_s \approx h_2 - h_1 \] Muchokwadi, kurasikirwa kunoitika, saka isentropic efficiency inowanzo shandiswa kurondedzera mamiriro ezvinhu akakodzera uye chaiwo. 6.3 Cylinder–piston (closed system) Mukuwedzera kwegasi mupiston, basa remuganhu rinoverengerwa kubva munzvimbo iri pasi pecurve \( p \)-\( V \). Kana maitiro acho achikurumidza uye asiri quasi-static, kumanikidzwa kwemuganhu kunogona kusafanana, kuchida kungwarira nenzira iri nyore yekubatanidza kana kushandisa kumanikidzwa kwekunze. 7. Kukosha kwemuviri: basa, simba, uye kushanda zvakanaka Kuverenga kwebasa nesimba hakungoburitsi nhamba chete, asiwo kunopa kunzwisisa kwekuti simba rinotamiswa sei uye kuti kurasikirwa kunoitika kupi. Mumamiriro ekushanda zvakanaka: - Injini dzinopisa dzinovavarira basa guru rekubudisa kubva pakupisa kwekupinda. - Masisitimu efiriji anovavarira kutamiswa kwekupisa kwakanangana nekushanda kushoma. - Mumasisitimu emaindasitiri, kugadzirisa kunowanzo tarisa pakuderedza basa rekumanikidza, kudzoreredza kupisa kwakarasika, kana kuderedza kusadzoreka. Kunyange zvazvo Mutemo wekutanga uchivimbisa kuti simba "harirasikirwi," mhando yesimba inogona kudzikiswa nekusadzoreka—iyo inozoongororwa zvakadzama neMutemo wechipiri nepfungwa ye entropy. Zvisinei, sehwaro, kugona Mutemo wekutanga uye kuverenga basa nesimba idanho rekutanga rakakosha. Mhedziso Kuverenga kwebasa nesimba mumasisitimu e thermodynamic kunotanga nekutsanangurwa kwesisitimu, kuona mafomu esimba akakodzera, uye kushandisa Mutemo wekutanga weThermodynamics. Kune masisitimu akavharwa, chinangwa chikuru chinowanzo kuve pakuchinja kwesimba remukati nebasa remuganhu \( \int p\,dV \). Kune masisitimu akavhurika, enthalpy ndiyo yakakosha, uye ongororo inoitwa uchishandisa steady-flow energy equation, iyo inosanganisira basa re shaft uye shanduko dzinogona kuitika mu kinetic uye potential energy. Nenzira yakarongeka uye kunzwisisa nzira yemaitiro, kuverenga uku kunogona kushandiswa kuongorora nemazvo uye kugadzira zvishandiso zvakasiyana-siyana zvesimba. Kana ndichida, ndinogona kuwedzera mienzaniso yakazara yenhamba (semuenzaniso, kuwedzera kwegasi repolytropic kana simba returbine rine data re enthalpy) kuti chinhu chacho chishande zvakanyanya.
