Lapho sikhuluma ku-physics nakuma-thermodynamics we Umjikelezo weCarnot sikhuluma ngokulandelana kwezinqubo ezenzeka enjinini yeCarnot. Kuyithuluzi elifanele eliqukethe izinqubo zohlobo oluthile kuphela ezingaguqulwa. Lokhu kusho ukuthi uma lezi zinqubo sezenzekile, isimo sokuqala singaqala kabusha. Lolu hlobo lwemoto lubhekwa kwi-physics njengemoto ekahle futhi lusetshenziselwa ukwazi ukuhlela amanye ama-motors.
Kulesi sihloko sizokutshela konke odinga ukukwazi mayelana nomjikelezo weCarnot nezimpawu zawo eziyinhloko.
Izici eziyinhloko
Sikhuluma ukuthi lolu hlobo lwenjini lubhekwa njengenjini ekahle. Lokhu kunjalo ngoba ayinakho ukuchithwa kwamandla, ngenxa yokushayisana nomhlabathi noma umoya futhi alukho uhlobo lwe-viscosity. Zonke lezi zici noma ukungahambi kahle kuvela kunoma iyiphi injini yangempela, ngoba akunakwenzeka ukuguqula amandla ashisayo abe umsebenzi ongasetshenziswa nge-100%. Kodwa-ke, inqwaba yeCarnot ingalingisa zonke lezi zimo ukuze ikwazi ukusebenza kangcono nokwenza izibalo ngendlela elula.
Lapho sithenga injini, siyenza siqala entweni ekwaziyo ukwenza umsebenzi. Isibonelo, izinto ezisemqoka ezisetshenziswayo igesi, uphethiloli noma umusi. Lapho lezi zinto ezikwazi ukwenza umsebenzi zingaphansi kwezinguquko ezahlukahlukene kokushisa nokucindezela, khiqiza ukuhlukahluka kwevolumu yabo. Ngale ndlela, i-piston ingahanjiswa ngaphakathi kwesilinda ukuze ibe nenjini.
Uyini umjikelezo weCarnot?
Lo mjikelezo wenzeka ngaphakathi kohlelo olubizwa nge-Carnot engine. Kule njini kukhona igesi ekahle evalelwe kusilinda futhi enikezwe ipiston. I-piston ixhumana nemithombo ehlukahlukene esemazingeni okushisa ahlukene. Kulesi simiso kunezinqubo ezithile esingazifingqa ngezinyathelo ezilandelayo:
- Inani elithile lokushisa linikezwa kudivayisi. Leli nani lokushisa livela echibini eliphakeme lokushisa elishisayo.
- Imoto yenza umsebenzi ngenxa yalokhu kushisa okuzonikezwa
- Okunye ukushisa kuyasetshenziswa kanti okunye kuyachithwa. Imfucuza idluliselwa ethangini lokushisa elisezingeni lokushisa eliphansi.
Lapho sesizibonile zonke izinqubo, sizobona ukuthi yiziphi izigaba zomjikelezo weCarnot. Ukuhlaziywa kwalezi zinqubo kwenziwa kusetshenziswa umdwebo lapho kukalwa khona ingcindezi nevolumu. Inhloso yenjini kungaba ukugcina ithangi lesibili lipholile ngokukhipha ukushisa kulo. Kulokhu sizobe sikhuluma ngomshini wokupholisa. Uma, ngokuphambene nalokho, inhloso ukudlulisa ukushisa echibini elishisayo njengenombolo eyodwa, khona-ke sikhuluma ngempompo yokushisa.
Uma sihlaziya ingcindezi nomdwebo wevolumu siyabona ukuthi izinguquko kwingcindezi nasekushiseni kwenjini zikhonjiswa ngaphansi kwezimo ezithile ezilandelayo:
- Uma nje izinga lokushisa ligcinwa njalo. Lapha sikhuluma ngenqubo ye-isothermal.
- Akukho ukudluliswa kokushisa. Yilapho esinokufakwa okushisayo khona.
Izinqubo ze-Isothermal zidinga ukuxhunyaniswa komunye nomunye futhi lokhu kufinyelelwa ngenxa yokufakwa okushisayo.
Izigaba zomjikelezo weCarnot
Lapho siqala khona singaqala nganoma iyiphi ingxenye yomjikelezo lapho igesi inezimo ezithile zengcindezi, ivolumu kanye nokushisa. Lokhu kanye negesi kuzodlula ochungechungeni lwezinqubo ezizokwazi ukuyibuyisela ezimeni zokuqala. Lapho igesi isibuyile ezimeni zayo zokuqala, yayisesimweni esifanele ukuqala omunye umjikelezo. Lezi zimo zinikezwa uma nje amandla angaphakathi ekugcineni elingana namandla angaphakathi ekuqaleni. Lokhu kusho ukuthi amandla ayalondolozwa. Sesivele sazi ukuthi amandla awadalwa noma abhujiswe, kepha aguqulwa kuphela.
Isigaba sokuqala somjikelezo weCarnot sisekelwe ekukhulisweni kwe-isothermal. Kulesi sigaba uhlelo ludonsa ukushisa okuvela echibini elishisayo 1 bese luyanda. Ngakho-ke, ivolumu yegesi iyanda futhi ingcindezi iyancipha. Kodwa-ke, izinga lokushisa lihlala lizinzile kusukela lapho igesi inweba iyaphola. Ngakho-ke, siyazi ukuthi amandla alo angaphakathi ahlala njalo ngokuhamba kwesikhathi.
Esigabeni sesibili sine- ukunwetshwa kwe-adiabatic. I-Adiabatic isho ukuthi uhlelo alutholi noma lilahlekelwe ukushisa. Lokhu kutholakala ngokubeka igesi ekufakweni kokushisa njengoba kukhonjisiwe ngenhla. Ngakho-ke, ekunwetshisweni kwe-adiabatic ivolumu iyakhula futhi ingcindezi iyancipha ize ifike kunani layo eliphansi.
Ku isigaba sesithathu sinokucindezelwa kwe-isothermal. Lapha sisusa ukwahlukanisa futhi uhlelo luhlangana nethangi lokushisa elingu-2, elizoba sezingeni lokushisa eliphansi. Ngalesi sizathu, uhlelo lubhekene nokudlulisa ukushisa kwemfucuza okungasetshenziswanga kuleli thangi elishisayo. Njengoba ukushisa kukhipha, ingcindezi iqala ukukhuphuka nevolumu yehle.
Ekugcineni, esigabeni sokugcina somjikelezo weCarnot sine-kokucindezelwa adiabatic. Lapha sibuyela esigabeni sokufakwa okushisayo ngohlelo. Ingcindezi inyusa ivolumu iyancipha ize ifinyelele ezimweni zokuqala futhi. Ngakho-ke, umjikelezo ulungele ukuqala futhi.
Ukulinganiselwa
Njengoba kushiwo ngaphambili, injini yeCarnot yenziwe kahle. Lokhu kusho ukuthi kunemikhawulo yayo kusukela ama-motors wangempela awasebenzi ngendlela eyi-100%. Siyazi ukuthi imishini emibili yeCarnot inokusebenza kahle okufanayo uma yomibili isebenza ngamachibi afudumele afanayo. Lesi sitatimende sisho ukuthi nginendaba nokuthi yini esiyisebenzisayo, ngoba ukusebenza kuzozimela ngokuphelele futhi akukwazi ukuphakanyiswa.
Isiphetho esisithola ekuhlaziyweni kwangaphambilini ukuthi umjikelezo weCarnot ungaphezulu kwenqubo ye-thermodynamic engafinyelelwa kahle. Lokho wukuthi, ngaphezu kwalokho, ngeke kube khona injini esebenza kahle kakhulu. Siyazi ukuthi iqiniso lokufakwa okushisayo alikaze liphelele futhi izigaba ze-adiabatic azikho, ngoba kukhona ukushintshana ngokushisa nengaphandle.
Endabeni yemoto, ibhlokhi yenjini iyashisa kanti ngakolunye uhlangothi, ingxube kaphethiloli nomoya ayiziphathi kahle, ukhuluma kahle. Ukungasho ezinye izici ukuthi kubangele ukuncipha okukhulu ekusebenzeni.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngomjikelezo weCarnot nezici zawo.