Phello ea Mocheso Bokhoni ba Enjene ea Mocheso
Enjene ea mocheso ke sesebelisoa se fetolang matla a mocheso hore e be mosebetsi oa mechine. Mehlala e mengata: lienjene tsa mouoane lifemeng tsa motlakase, lienjene tsa ho chesa ka hare likoloing, liturbine tsa khase lifofaneng, esita le litsamaiso tsa motlakase tsa sejoale-joale tse thehiloeng potolohong ea thermodynamic. Ho sa tsotellehe mefuta-futa ea tsona, lienjene tsohle tsa mocheso li sebetsa ka molao-motheo o le mong: li ntša mocheso mohloling oa mocheso o phahameng, li fetola o mong oa oona hore e be mosebetsi, 'me li hana mocheso o setseng ho o isa tikolohong ea mocheso o tlase. Ntlha ea bohlokoa ka ho fetisisa e khethollang hore na mocheso ona o fetoloa mosebetsi o mokae ke mocheso. Sengoloa sena se hlahloba kamoo mocheso o amang katleho ea lienjene tsa mocheso, ka bobeli ho latela pono ea khopolo-taba ea thermodynamic le mokhoa oa boenjiniere.
Khopolo ea motheo ea katleho ea enjene ea mocheso
Bokgoni ba enjene ya mocheso hangata bo hlahiswa e le karolelano ya mosebetsi wa letlowa o hlahiswang ke enjene le mocheso o monngwang mohloding wa mocheso. Ka kakaretso:
\[
\eta = \frac{W}{Q_{in}} = 1 – \frac{Q_{out}}{Q_{in}}
\]
ka:
– \( \eta \) = bokgoni ba mocheso,
– \( W \) = mosebetsi o hlahisitsoeng ka netweke,
– \( Q_{in} \) = ho kenya mocheso (ho monngoa ho tsoa polokelong e chesang),
– \( Q_{out} \) = mocheso o hanetsoe (ho ea letamo le batang).
Ho tsoa ho equation ena, ho ka bonoa hore bokgoni bo tla eketseha haeba karolo ya mocheso o hanetsweng \(Q_{out}\) e le nyane ho feta mocheso o kentsweng \(Q_{in}\). Mona ke moo mocheso o bapalang karolo ya bohlokwa haholo, hobane tataiso ya "tshekamelo" ya phetiso ya mocheso le moedi wa kgopolo-taba wa phetoho ya mocheso hore e be mosebetsi di laolwa ke phapang ya mocheso pakeng tsa mohlodi wa mocheso le sinki ya mocheso.
Bokgoni bo boholo: Moeli oa Carnot le karolo ea mocheso
Ho thermodynamics, enjene e loketseng ea mocheso e nang le bokhoni bo phahameng ka ho fetisisa bakeng sa matamo a mabeli mochesong o itseng e bitsoa enjene ea Carnot. Bokgoni ba Carnot bo hlophisitsoe ka tsela ena:
\[
\eta_{Carnot} = 1 – \frac{T_c}{T_h}
\]
ka:
– \(T_h\) = mocheso oa letamo le chesang (ho Kelvin),
– \(T_c\) = mocheso o batang wa letamo (ho Kelvin).
Foromo ena e fana ka thuto ea bohlokoa: katleho ea enjene ea mocheso e khethoa ke karolelano ea mocheso, eseng phapang ea mocheso feela. Ho na le litsela tse peli tse ka sehloohong tsa ho eketsa katleho e phahameng ho latela Carnot:
1. Eketsa mocheso oa mohloli oa mocheso \(T_h\)
Haeba \(T_h\) e eketseha ha \(T_c\) e ntse e tsitsitse, joale \(T_c/T_h\) ea fokotseha e le hore bokgoni bo eketsehe.
2. Ho theola mocheso oa letamo le batang \(T_c\)
Haeba \(T_c\) e fokotseha ha \(T_h\) e ntse e tsitsitse, bokgoni le bona bo a eketseha hobane karolelano \(T_c/T_h\) e a fokotseha.
Kaha mocheso o tlameha ho hlaloswa ho Kelvin, dipalo tsa bokgoni di tlameha ho sebedisa sekala se feletseng. Mohlala, haeba \(T_h = 800 \, K\) le \(T_c = 300 \, K\), jwale:
\[
\eta_{Carnot} = 1 – \frac{300}{800} = 1 – 0{,}375 = 0{,}625
\]
Bokgoni bo boholo ba khopolo-taba ke 62,5%. Lienjine tsa lefats'e la nnete li tla lula li le tlase ho feta boleng bona ka lebaka la tahlehelo e fapaneng.
Ke hobane'ng ha mocheso o khetholla moeli oa katleho?
Ka 'mele, enjene ea mocheso e sebetsa ka lebaka la gradient ea mocheso: mocheso o "phalla" ka boiketsetso ho tloha mochesong o phahameng ho ea mochesong o tlase. Ho fetola phallo ena ea matla a mocheso hore e be mosebetsi o lebisitsoeng (mohlala, motsamao oa piston kapa potoloho ea turbine), sistimi e tlameha ho sebetsa lipakeng tsa mocheso o mabeli. Molao oa Bobeli oa Thermodynamics o bolela hore ho ke ke ha khoneha ho fetolela mocheso oohle o monyelitsoeng hore o sebetse ntle le ho hana o mong oa oona ho o kenya polokelong e pholileng. Ka mantsoe a mang, boteng ba \(T_c\) ke "theko" e lokelang ho lefshoa.
Ha phapang e kgolo maemong a mocheso pakeng tsa mohlodi wa mocheso le sinki ya mocheso (haholo-holo, ha karolelano e le nyane \(T_c/T_h\)), monyetla wa ho fetola mocheso o mong hore o sebetse pele matla a setseng a qetella a hanetswe.
Tšusumetso ea ho eketsa mocheso oa mohloli oa mocheso (Th) enjeneng ea 'nete
Ha e le hantle, ho eketsa \(T_h\) hangata ke leano la mantlha la ho ntlafatsa bokgoni ba dipolante tsa motlakase le dienjene tsa dikoloi. Mehlala e kenyeletsa diturbine tsa kgase le dipolante tsa mouoane tse bohlokwa haholo: ho eketsa mocheso wa ho kena ha turbine ka kakaretso ho ntlafatsa bokgoni ba potoloho.
Leha ho le jwalo, keketseho ya \(T_h\) e tobane le mefokolo ya boenjiniere:
1. Matla a thepa le ho hanyetsa mocheso
Likarolo tse kang mahare a turbine, likamore tsa ho tuka, le liphaephe tsa boiler li tlameha ho mamella mocheso o phahameng haholo. Maemong a mocheso o phahameng, thepa e ka ba le ho thekesela (ho fetoha butle), ho oxidation, ho bola ho chesang, le tahlehelo ea matla a mechini.
2. Litlhoko tsa ho pholisa likarolo
Li-turbine tsa khase tsa sejoale-joale, mahare a turbine a pholisoa ka moea kapa sistimi ea ho pholisa ea ka hare. Pholiso ena e thusa thepa hore e phele, empa e ka boela ea fokotsa bokhoni hobane matla a mang a sebelisoa bakeng sa sistimi ea ho pholisa 'me phallo e ba thata le ho feta.
3. Keketseho ea tahlehelo ea ho se fetohe
Maemong a mocheso o phahameng, lits'ebetso tse ling (mohlala, ho chesa ha 'nete, ho kopanya, ho ferekane, phetiso ea mocheso holim'a liphapang tse kholo tsa mocheso) li ka eketsa entropy le ho fokotsa bokhoni ba 'nete ha li bapisoa le bokhoni bo loketseng.
Leha ho le jwalo, mekgwa ya theknoloji e ntse e tswela pele ho ntshetsa pele dintlafatso ho \(T_h\) ka ntshetsopele ya thepa (di-superalloy, di-ceramics), dikobo tse thibelang mocheso, le meralo e rarahaneng ya ho phodisa.
Phello ea ho fokotsa mocheso oa letamo le batang (Tc)
Ho theola \(T_c\) le hona ho eketsa bokgoni, empa hangata ho thata ho feta kamoo ho bonahalang kateng. Difemeng tsa motlakase, \(T_c\) hangata ho amana le mocheso wa metsi a pholileng kapa moya o potolohileng. Kaha tikoloho e ke ke ya "etswa e batang" ka boithatelo, phokotso ya \(T_c\) e lekanyetswa ke:
1. Tlelaemete le mocheso oa tikoloho
Li-power plant tse libakeng tse chesang hangata li na le \(T_c\) e phahameng, kahoo bokhoni boa fokotseha ha bo bapisoa le li-power plant tse libakeng tse pholileng.
2. Theknoloji ea Condenser le litsamaiso tsa ho pholisa
Li-condenser tse betere li ka tlisa mocheso oa mosi haufi le mocheso o potolohileng, empa li ke ke tsa feta moeli oo ntle le litšenyehelo tse phahameng le ho rarahana.
3. Meeli ea sekhahla sa phetisetso ea mocheso
Ho theola \(T_c\) e sebetsang hantle ho bolela ho eketsa bokgoni ba ho tlosa mocheso. Sena se hloka sebaka se seholo sa phetisetso ya mocheso, phallo e phahameng ya sephodisang, kapa mekgwa e ikgethang ya ho phodisa—tseo kaofela di amang ditjeo le tshebediso ya matla a dikokonyana (dipompo, difene).
Moelelong oa enjene ea ho chesa ka hare ea koloi, "tanka e batang" e ka utloisisoa e le sistimi ea ho pholisa ea enjene le tikoloho e e potolohileng. Boemo ba leholimo bo chesang hangata bo baka hore mocheso oa ts'ebetso o eketsehe, e leng se ka fokotsang katleho le ho eketsa kotsi ea ho kokota kapa ho chesa haholo.
Bokgoni bo botle bo loketseng khahlano le bokgoni ba sebele: phello ya mocheso hodima tahlehelo
Leha Carnot e fana ka meeli e phahameng ka ho fetisisa, mechine ea 'nete e tobana le mathata a mang:
– Khohlano ea mechine (li-shaft, li-piston, li-bearing) e fetolang mosebetsi hore e be mocheso.
– Tahlehelo e sa batleheng ea phetisetso ea mocheso tikolohong.
– Ho tuka ho sa fellang dienjeneng tsa ho tuka ka hare, kahoo ha se matla ohle a dikhemikhale a fetolwang mocheso o thusang.
– Tahlehelo ea phallo ea metsi (ho theoha ha khatello) liphaepheng, li-valve, li-heat exchanger.
– Ho se fetohe ka lebaka la lits'ebetso tse sa fetoheng, pherekano le ho kopanya.
Mocheso o amana haufi-ufi le tahlehelo ena. Mohlala, phapang e kholo ea mocheso ho sesebelisoa sa ho fapanyetsana mocheso e ka potlakisa phetiso ea mocheso, empa hangata sena se eketsa ho se fetohe ka lebaka la tlhahiso e kholo ea entropy. Sena se bolela hore moralo oa mocheso o tlameha ho leka-lekanya litlhoko tsa ts'ebetso le ho fokotsa ho se fetohe.
Mehlala ea ts'ebeliso: Lipotoloho tsa Rankine le Brayton
Setsing sa motlakase sa mouoane (Rankine cycle), ho eketsa mocheso le khatello ea mouoane o kenang ka turbine (mohlala, ho futhumatsa haholo kapa ho ba le tšusumetso e matla) hangata ho eketsa katleho. Ka lehlakoreng le leng, ho sebelisa condenser e sebetsang hantle ho theola khatello/mocheso oa mouoane o ntšang mosi le hona ho eketsa katleho, leha ho na le meeli ea tikoloho.
Liturbineng tsa khase (potoloho ea Brayton), katleho ea eketseha ha mocheso oa ho kena ha turbine o ntse o eketseha. Ho feta moo, mekhoa e kang ho nchafatsa, ho pholisa le ho futhumatsa hape e laola boemo ba mocheso ho fokotsa litšila le ho eketsa mosebetsi oa letlooa. Potoloho e kopaneng, e sebelisang mocheso oa mosi oa turbine ea khase ho hlahisa mouoane potolohong ea Rankine, ke mohlala o hlakileng oa leano la ho ntlafatsa mocheso: mocheso mochesong o mahareng o neng o senngoa pele joale o sebelisoa ho hlahisa mosebetsi o mong.
Qetello
Mocheso ke phetoho ea bohlokoa e khethollang katleho ea enjene ea mocheso. Ka khopolo-taba, katleho e phahameng e lekanyelitsoe ke katleho ea Carnot, \(\eta = 1 – T_c/T_h\), e leng se bontšang hore katleho e ea eketseha ha mocheso oa mohloli oa mocheso o eketseha le/kapa mocheso oa letamo le batang o fokotseha. Ha e le hantle, ho eketsa \(T_h\) ho lekanyelitsoe ke bokhoni ba thepa, litlhoko tsa ho pholisa, le tahlehelo ea ho se fetohe; ha ho fokotseha \(T_c\) ho lekanyelitsoe ke mocheso o potolohileng le bokhoni ba sistimi ba ho hana mocheso. Ka hona, ho ntlafatsa katleho ea enjene ea mocheso ha se taba feela ea ho "etsa hore e chese haholo" kapa "ho etsa hore e bata haholo," empa ho e-na le hoo ke taba ea ho ntlafatsa sistimi ea mocheso ka kakaretso - ho khetha thepa, ho rala li-exchange tsa mocheso, ho laola tahlehelo, le ho sebelisa mocheso maemong a fapaneng a mocheso. Ka ho utloisisa kamano pakeng tsa mocheso le katleho, re ka rala lienjene tsa mocheso tse bolokang matla haholoanyane, tse tšepahalang haholoanyane, le tse mosa haholoanyane tikolohong.
Haeba o lakatsa, nka fetola sengoloa sena hore e be mofuta: (1) thuto e eketsehileng ka litšupiso le li-equation tse ling, (2) e tsebahalang haholo bakeng sa baithuti ba sekolo se phahameng, kapa (3) e shebaneng le mehlala ea lienjine tsa likoloi kapa lifeme tsa motlakase.
