Xa sithetha kwi-physics kunye ne-thermodynamics ye Umjikelo weCarnot sithetha ngokulandelelana kweenkqubo ezenzeka kwi-injini yeCarnot. Sisixhobo esifanelekileyo esineenkqubo zohlobo oluthile ezinokubuyela umva. Oku kuthetha ukuba xa ezi nkqubo zenzekile, imeko yokuqala inokuphinda iqale. Olu hlobo lweemoto luthathelwa ingqalelo kwi-physics njengeyona moto ifanelekileyo kwaye isetyenziselwa ukukwazi ukucwangcisa ezinye iinjini.
Kule nqaku siza kukuxelela yonke into ofuna ukuyifumana malunga nomjikelezo weCarnot kunye neempawu zayo eziphambili.
Iimpawu eziphambili
Sithetha ukuba olu hlobo lwe-injini luthathwa njengenjini efanelekileyo. Oku kunjalo kuba isilela ekuchithweni kwamandla, ngenxa yokungqubana nomhlaba okanye umoya kwaye akukho luhlobo lwe-viscosity. Zonke ezi mpawu okanye okungathandekiyo kuvela kuyo nayiphi na injini yokwenene, ukusukela oko akunakwenzeka ukuguqula amandla ashushu abe ngumsebenzi osetyenziswayo nge-100%. Nangona kunjalo, imfumba yeCarnot inokulinganisa zonke ezi meko ukuze zikwazi ukusebenza ngcono kwaye zibalo ngendlela elula.
Xa uthenga injini, siyenza ukuqala kwinto ekwaziyo ukwenza umsebenzi. Umzekelo, izinto eziphambili ezisetyenzisiweyo yirhasi, ipetroli okanye umphunga. Xa ezi zinto zinakho ukwenza umsebenzi ziphantsi kotshintsho kwiqondo lobushushu noxinzelelo, zivelisa umahluko othile kumthamo wazo. Ngale ndlela, i-piston inokuhanjiswa ngaphakathi kwesilinda ukuze iimoto zihambe.
Yintoni umjikelo weCarnot?
Lo mjikelo wenzeka ngaphakathi kwenkqubo ebizwa ngokuba yi-Carnot engine. Kule injini kukho igesi efanelekileyo efakwe kwisilinda kwaye inikwe ipiston. I-piston inxibelelana nemithombo eyahlukeneyo kumaqondo obushushu ahlukeneyo. Kule nkqubo kukho iinkqubo ezithile esinokuthi sizishwankathele kula manyathelo alandelayo:
- Isixa esithile sobushushu sinikezelwa kwisixhobo. Eli nani lobushushu livela kwindawo yokugcina ubushushu obuphezulu.
- Imoto yenza umsebenzi ngenxa yolu bushushu obuya kubonelelwa
- Olunye ubushushu luyasetyenziswa kanti olunye luyachithwa. Inkunkuma idluliselwa kwitanki ye-thermal ekwiqondo lobushushu elisezantsi.
Nje ukuba sibonile zonke iinkqubo, siza kubona ukuba ngawaphi amanqanaba omjikelo weCarnot. Uhlalutyo lwezi nkqubo lwenziwa ngokusebenzisa umzobo apho uxinzelelo kunye nomthamo kulinganiswa. Injongo yeinjini kunokuba kukugcina inombolo yetanki ipholile ngokukhupha ubushushu kuyo. Kule meko siza kuthetha ngomatshini wokupholisa. Ukuba, ngokuchaseneyo, injongo kukuhambisa ubushushu kwindawo yokugcina amanzi ngenombolo enye, sithetha ngempompo yobushushu.
Ukuba sihlalutya uxinzelelo kunye nomzobo wevolumu sibona ukuba utshintsho kuxinzelelo nakubushushu benjini luboniswa phantsi kweemeko ezithile zilandelayo:
- Logama nje iqondo lobushushu ligcinwa rhoqo. Apha sithetha ngenkqubo ye-isothermal.
- Akukho tshintsho lobushushu. Kulapho sinokufudumeza ubushushu.
Iinkqubo ze-Isothermal kufuneka zidityaniswe kunye kwaye oku kufezekiswe ngenxa yokugqalwa kwe-thermal.
Amanqanaba omjikelo weCarnot
Kwindawo yokuqala sinokuqala ngayo nayiphi na indawo yomjikelo apho igesi ineemeko ezithile zoxinzelelo, umthamo kunye nobushushu. Oku kunye negesi kuya kuhamba kuthotho lweenkqubo eziya kuthi zikhokelele ekubeni zibuyele kwiimeko zokuqala. Nje ukuba igesi ibuyele kwimeko yayo yokuqala, yayikwimeko efanelekileyo ukuqala omnye umjikelo. Le miqathango inikwa ixesha elide njengamandla angaphakathi ekugqibeleni afanayo namandla angaphakathi ekuqaleni. Oku kuthetha ukuba amandla alondoloziwe. Sele siyazi ukuba amandla awenziwanga okanye atshatyalaliswe, kodwa aguqulwe kuphela.
Isigaba sokuqala somjikelo weCarnot sisekwe kulwandiso lwe-isothermal. Kweli nqanaba le nkqubo ifunxa ubushushu ukusuka kwidama lokushisa elingu-1 kwaye iyaqhubeka nokwandiswa okungafaniyo. Ngenxa yoko, umthamo wegesi uyanda kwaye uxinzelelo luyancipha. Nangona kunjalo, iqondo lobushushu lihlala lizinzile okoko xa igesi iyanda iyaphola. Ke ngoko, siyazi ukuba amandla alo angaphakathi ahlala ehleli ngokuhamba kwexesha.
Kwinqanaba lesibini sine Ukwandiswa kwe-adiabatic. I-Adiabatic ithetha ukuba le nkqubo ayifumani okanye ilahle ubushushu. Oku kufezekiswa ngokubeka igesi kwindawo yokufudumeza ubushushu njengoko kubonisiwe apha ngasentla. Ke ngoko, kulwandiso lwe-adiabatic ivolumu iyonyuka kwaye uxinzelelo luyancipha lude lufike kwixabiso eliphantsi.
Kulo Inqanaba lesithathu sine-isothermal compression. Apha sisusa ubushushu kwaye inkqubo idibana nenombolo ye-2 yetanki eshushu, eya kuba kubushushu obuphantsi. Ngesi sizathu, inkqubo inoxanduva lokuhambisa ubushushu benkunkuma obungasetyenziswanga kule tanki ye-thermal. Njengoko ukukhutshwa kobushushu, uxinzelelo luqala ukwanda kunye nevolumu ukunciphisa.
Okokugqibela, kwinqanaba lokugqibela lomjikelo weCarnot sineUxinzelelo lwe-adiabatic. Apha sibuyela kwinqanaba lokufakwa kwe-thermal yinkqubo. Uxinzelelo lwonyusa ivolumu iyancipha de ifike kwiimeko zokuqala kwakhona. Ke ngoko, umjikelo ukulungele ukuqala kwakhona.
Ukushokoxeka
Njengoko bekutshiwo ngaphambili, i-injini yeCarnot ilungiselelwe. Oku kuthetha ukuba inemiqobo ukusukela Iimoto ezizezokwenene azinakho ukusebenza kwe-100%. Siyazi ukuba oomatshini ababini beCarnot banobuchule obufanayo ukuba bobabini basebenza ngamachibi afanayo ashushu. Le ngxelo ithetha ukuba ndiyikhathalele into esiyisebenzisayo, kuba ukusebenza kuya kuzimela ngokupheleleyo kwaye akunakuphakanyiswa.
Isiphetho esivela kuhlalutyo lwangaphambili kukuba umjikelo weCarnot ngowona uphambili wenkqubo ye-thermodynamic enokufikelelwa ngokufanelekileyo. Oko kukuthi, ngaphaya koko, akuyi kubakho injini inokusebenza ngokukuko. Siyazi ukuba inyani yokugquma ubushushu ayigqibeki kwaye amanqanaba e-adiabatic awakho, kuba kukho ukutshintshiselana ngobushushu nangaphandle.
Kwimeko yemoto, ibhlokhi yeenjini iyatshisa kwaye kwelinye icala, umxube wepetroli kunye nomoya awuziphathi ngokuchanekileyo, unxibelelana ngokufanelekileyo. Ungakhankanyi ezinye zezinto kubangele ukuncipha okukhulu kwintsebenzo.
Ndiyathemba ukuba ngolu lwazi ungafunda ngakumbi malunga nomjikelo weCarnot kunye neempawu zayo.