Lamulo Loyamba la Thermodynamics mu Kusanthula Makina Amakampani
Kumbuyo kwa phokoso la ma turbine, kutentha kwa zitofu za boiler, ndi kugunda kwa ma compressor m'mafakitale, pali mfundo imodzi yofunika yomwe nthawi zambiri imakhalapo: Lamulo Loyamba la Thermodynamics. Lamuloli ndi maziko omvetsetsa momwe mphamvu imayendera ndi kusintha komwe kumachitika mkati mwa makina amafakitale. Mwa kulidziwa bwino, mainjiniya amatha kuwerengera zofunikira za mafuta, kuwerengera momwe zimagwirira ntchito, kupanga makina ozizira, komanso kuzindikira kutayika kwa mphamvu mu zida zopangira. Nkhaniyi ikufotokoza malingaliro, ma equation ofunikira, ndi zitsanzo za momwe Lamulo Loyamba la Thermodynamics limagwiritsidwira ntchito posanthula makina amafakitale.
1. Kumvetsetsa Lamulo Loyamba la Thermodynamics
Lamulo Loyamba la Thermodynamics kwenikweni ndi lamulo losunga mphamvu. Mphamvu sizingapangidwe kapena kuwonongedwa; zimatha kusamutsidwa kuchokera ku dongosolo lina kupita ku lina kapena kusinthidwa kuchokera ku mawonekedwe ena kupita ku ena. Ponena za thermodynamics, mitundu ya mphamvu yomwe nthawi zambiri imakambidwa ndi iyi:
– Kutentha (kutentha, Q): mphamvu yomwe imasamutsidwa chifukwa cha kusiyana kwa kutentha.
– Ntchito (W): mphamvu imasamutsidwa chifukwa cha mphamvu yomwe imayambitsa kusamuka, mwachitsanzo ntchito ya shaft pa turbine kapena compressor.
– Mphamvu yamkati (U): mphamvu ya microscopic mu chinthu (chogwirizana ndi kutentha, gawo, ndi kuyanjana kwa mamolekyulu).
- Zowonjezera zofunika ku dongosolo la kayendedwe ka madzi: mphamvu ya kinetic (KE) ndi mphamvu ya potential (PE).
Mwachidule, Lamulo Loyamba limati: kusintha kwa mphamvu ya dongosolo ndi kofanana ndi mphamvu yolowera kupatula mphamvu yotuluka.
2. Machitidwe a Thermodynamic mu Makina Amafakitale
Mu kusanthula makina a mafakitale, nthawi zambiri timasankha imodzi mwa mitundu iwiri ya machitidwe:
1. Dongosolo lotsekedwa
Unyinji sudutsa malire a dongosolo, koma mphamvu (kutentha/ntchito) imatha kusamutsa. Chitsanzo: silinda-pistoni m'njira zina (monga mayeso a labotale kapena njira zapadera).
2. Tsegulani dongosolo / voliyumu yowongolera
Mphamvu ndi kulemera zimatha kudutsa malire. Izi zimapezeka kwambiri m'mafakitale: ma turbine, ma compressor, mapampu, ma boiler, ma condenser, ma heat exchangers, nozzles, ma diffuser, ndi mapaipi.
Zipangizo zambiri zopangira zinthu zimasanthulidwa ngati kuchuluka kowongolera pansi pa mikhalidwe yokhazikika, zomwe zikutanthauza kuti kuchuluka kwa madzi ndi mphamvu zake sizisintha pakapita nthawi.
3. Chiwerengero Chachikulu cha Lamulo Loyamba la Thermodynamics
3.1. Kwa makina otsekedwa
Equation yoyambira:
\[
\Delta E = Q – W
\]
kumene \(\Delta E\) imaphatikizapo kusintha kwa mphamvu yamkati, ya kinetic, ndi ya potential. Nthawi zambiri, kusintha kwa mphamvu ya kinetic ndi ya potential kumanyalanyazidwa kotero kuti:
\[
\Delta U = Q – W
\]
Kutanthauzira: kulowa kwa kutentha kumawonjezera mphamvu yamkati, pomwe ntchito yochitidwa ndi dongosolo imachepetsa mphamvu yamkati (kutengera ndi chizindikiro, koma dongosolo lonse la uinjiniya ndi: kulowa kwa Q kuli bwino, kuchoka kwa W (kopangidwa ndi dongosolo) kuli bwino).
3.2. Kwa makina otseguka (kulamulira voliyumu)
Kuti munthu azitha kuyenda bwino nthawi zonse, njira yomwe imagwiritsidwa ntchito nthawi zambiri ndi iyi:
\[
\dot{Q} – \dot{W} = \dot{m}\left[(h_2-h_1) + \frac{V_2^2 – V_1^2}{2} + g(z_2-z_1)\right]
\]
Zambiri:
– \(\dot{Q}\): kutentha kosinthira (kW)
– \(\dot{W}\): liwiro la ntchito (kW), nthawi zambiri mu mawonekedwe a ntchito ya shaft
– \(\dot{m}\): kuchuluka kwa madzi (kg/s)
– \(h\): enthalpy yeniyeni (kJ/kg)
– \(V\): liwiro la kuyenda (m/s)
– \(z\): kukwera (m)
Mu makina ambiri a mafakitale, kusintha kwa elevation ndi kinetic energy ndi kochepa poyerekeza ndi kusintha kwa enthalpy, kotero zimakhala zosavuta kuti:
\[
\dot{Q} – \dot{W} \pafupifupi \dot{m}(h_2-h_1)
\]
Ndi mawonekedwe osavuta awa omwe amapangitsa Lamulo Loyamba kukhala lothandiza kwambiri: ndi deta ya inlet-outlet enthalpy yokha, titha kuwerengera kutentha kapena mphamvu zomwe zimafunika pa shaft.
4. Kugwiritsa Ntchito mu Makina Amafakitale
4.1. Turbine ya nthunzi kapena turbine ya gasi
Ma turbine amasintha mphamvu ya kutentha ya madzi kukhala ntchito ya shaft. Pa turbine yokhazikika, nthawi zambiri imaganiziridwa kuti ndi adiabatic (\(\dot{Q}\approx 0\)):
\[
-\dot{W} \pafupifupi \dot{m}(h_2-h_1)
\]
Popeza \(h_2 < h_1\) (kuchepa kwa enthalpy), ndiye \(\dot{W}\) ndi mphamvu yabwino yopangidwa. Kuchokera apa, mphamvu ya turbine ikhoza kuwerengedwa ngati kuchuluka kwa kuyenda kwa mass ndi kuchepa kwa enthalpy zimadziwika kutengera matebulo a nthunzi kapena deta ya katundu wa gasi. Ubwino wa mafakitale: kuwerengera mphamvu yotulutsa, kuwunika momwe turbine isentropic imagwirira ntchito, ndi kuwerengera momwe nthunzi imagwiritsidwira ntchito pa kWh. 4.2. Kompresa wa mpweya Kompresa imafuna ntchito ya shaft kuti iwonjezere kupanikizika kuti enthalpy iwonjezereke (\(h_2>h_1\)). Kwa kompresa wa adiabatic:
\[
\dot{W}_{in} \pafupifupi \dot{m}(h_2-h_1)
\]
Izi zikutanthauza kuti kuchuluka kwa mphamvu zamagetsi zomwe compressor imafuna kumatsimikiziridwa ndi kuwonjezeka kwa enthalpy, komwe kumakhudzidwa ndi chiŵerengero cha kupanikizika, kutentha kwa kulowa, ndi magwiridwe antchito a compression.
Ubwino wa mafakitale: kudziwa zofunikira pa injini, kuwerengera ndalama zogwiritsira ntchito mphamvu yokakamiza, ndikuyerekeza ma compressor a gawo limodzi ndi ma multistage ndi intercooling.
4.3. Pampu yamadzimadzi
Mapampu amawonjezera kuthamanga kwa madzi. Pa madzi osagwedezeka, kusintha kwa enthalpy nthawi zambiri kumayesedwa ndi:
\[
w_p \pafupifupi v \Delta p
\]
pomwe \(v\) ndi voliyumu yeniyeni (m³/kg) ndipo \(\Delta p\) ndi kukwera kwa kuthamanga. Chifukwa \(v\) ndi yaying'ono, ntchito ya pampu pa kg nthawi zambiri imakhala yocheperapo kuposa ya compressor ya gasi.
Ubwino wa mafakitale: kukula kwa pampu ndi injini, kusanthula kutayika kwa mutu, ndi kuwunika momwe mphamvu imagwiritsidwira ntchito m'mapaipi.
4.4. Boiler (boiler ya nthunzi)
Boiler imasamutsa kutentha kuchokera ku kuyaka kupita ku madzi kuti ipange nthunzi. Kuti muwongolere voliyumu yokhazikika pogwiritsa ntchito shaft yaying'ono (\(\dot{W}\approx 0\)):
\[
\dot{Q}_{in} \approx \dot{m}(h_{out}-h_{in})
\]
Kuwerengera kumeneku kumathandiza kudziwa kutentha komwe kumafunika kuti pakhale kuchuluka kwa nthunzi yomwe yaperekedwa. Kuphatikiza apo, zofunikira za mafuta zitha kuwerengedwa poganizira momwe mafuta amayakira bwino komanso kuchuluka kwa mphamvu ya mafuta.
Ubwino wa mafakitale: kuwunika mphamvu za boiler, kukonzekera mphamvu, ndi kuwononga mphamvu ndi kukonza bwino chuma.
4.5. Chokonzetsera
Kondensa imachotsa kutentha kuchokera ku nthunzi mpaka itasungunuka kukhala madzi. Ngati palibe ntchito ya shaft:
\[
\dot{Q}_{out} \approx \dot{m}(h_{in}-h_{out})
\]
Kukula kwa \(\dot{Q}_{out}\) kumatsimikizira kufunikira kwa madzi ozizira kapena mphamvu ya nsanja yozizira.
Ubwino wa mafakitale: kapangidwe ka makina oziziritsira, kuwongolera kutentha kwa njira, ndi kuyang'anira kuipitsidwa kwa zinthu m'makina osinthira kutentha.
4.6. Chosinthira kutentha
Mu chosinthira kutentha, mitsinje iwiri imasinthira kutentha, ndipo nthawi zambiri imaganiziridwa kuti ndi ya adiabatic poyerekeza ndi malo ozungulira (\(\dot{Q}_{surroundings}\approx 0\)) ndipo siigwira ntchito:
\[
\dot{m}_h(h_{h,in}-h_{h,out}) = \dot{m}_c(h_{c,out}-h_{c,in})
\]
Chiyerekezo ichi ndi mtundu wa Lamulo Loyamba lomwe ndi lofunika kwambiri powerengera kuchuluka kwa kutentha ndi kutsimikizira magwiridwe antchito a zida m'munda.
5. Kugwiritsira Ntchito Mphamvu Moyenera ndi Kuzindikira Zinyalala
Lamulo Loyamba silinena mwachindunji momwe makina alili abwino (ndiye gawo la Lamulo Lachiwiri ndi lingaliro la entropy), koma ndi lamphamvu kwambiri pa:
- Pangani mphamvu yokwanira ya magawo onse a ntchito.
- Dziwani kutayika kwa kutentha chifukwa cha kutenthetsa kosakwanira, kutuluka kwa nthunzi, kapena kuyaka kosakwanira.
- Kuyeza momwe kutentha kumagwirira ntchito mosavuta, mwachitsanzo:
- Kugwiritsa ntchito bwino kwa boiler: mphamvu yothandiza ya nthunzi / mphamvu ya mankhwala ya mafuta.
– Kugwiritsa ntchito bwino kwa jenereta ya turbine: kuchepetsa mphamvu zamagetsi / nthunzi.
– Dziwani zinthu zofunika kwambiri pakusunga: zida zomwe zili ndi \(\dot{Q}\) kapena \(\dot{W}\) zazikulu nthawi zambiri zimakhala cholinga chachikulu pakukonza bwino.
Mu kafukufuku wa mphamvu, mainjiniya amasonkhanitsa kutentha, kuthamanga, kuchuluka kwa madzi, ndi deta ya mphamvu zamagetsi kenako n’kujambula kuchuluka kwa mphamvu zomwe zikubwera ndi zomwe zikubwera. Kusiyana kwa mphamvu zomwe zili m’magetsi nthawi zambiri kumasonyeza mavuto a zida, kuipitsidwa, kutuluka kwa madzi, kapena malingaliro osagwira ntchito.
6. Chitsanzo Chachifupi cha Momwe Mungaganizire (Popanda Manambala Ovuta)
Tiyerekeze kuti turbine imalandira nthunzi yokhala ndi enthalpy yambiri ndipo imatulutsa nthunzi yokhala ndi enthalpy yochepa. Ngati nthunzi ikudziwika, ndiye kuti mphamvu ya turbine imagwirizana bwino ndi \(\dot{m}(h_1-h_2)\). Ngati mphamvu yeniyeni ndi yochepa kwambiri, mainjiniya adzafufuza njira zotsatirazi:
- Kugwira ntchito bwino kwa turbine kumachepa (kuwonongeka kwa tsamba, kukokoloka kwa nthaka, kutayika kwa madzi),
- nthunzi ikutuluka kudutsa chisindikizo,
- malo olowera madzi sali okonzedwa bwino (kutsika kwa kuthamanga kwa magazi/kutentha),
- kukhalapo kwa kutentha kosafunikira kapena kusintha kwa kayendedwe ka madzi.
Kufufuza konseku kumayambira mu Lamulo Loyamba: "kodi mphamvu imapita kuti?"
7. Mapeto
Lamulo Loyamba la Thermodynamics ndi chida chofunikira kwambiri komanso chogwiritsidwa ntchito kwambiri pakuwunika makina amafakitale. Pogwiritsa ntchito mphamvu zofananira pa ma turbine, ma compressor, mapampu, ma boiler, ma condenser, ndi ma heat exchangers, mainjiniya amatha kuwerengera mosamala zofunikira pa kutentha, mphamvu ya shaft, kutulutsa ntchito, ndi katundu woziziritsa. Ngakhale kuti kugwiritsa ntchito mphamvu moyenera kumafuna Lamulo Lachiwiri, Lamulo Loyamba likadali poyambira pakupanga, kugwiritsa ntchito, ndi kukonza mphamvu za zomera zamakono.
Ngati mukufuna, nditha kuwonjezera mtundu wa nkhaniyi womwe uli ndi maphunziro a manambala (monga kuwerengera mphamvu ya turbine/compressor kapena ma balance a mphamvu ya boiler) yokhala ndi masitepe atsatanetsatane ndi matebulo oyenera a katundu.
