Kuongorora kweEntropy muMainjiniya eThermodynamic Maitiro
Muinjiniya, thermodynamics ihwaro hwakakosha hwekunzwisisa kuti simba rinofamba sei uye rinoshanduka sei mukati memasisitimu—kubva kumainjini ekupisa mukati nematurbine emhepo kusvika kumacompressor nemasisitimu efiriji. Zvisinei, kunze kwekuverenga simba nekushanda zvakanaka kune pfungwa huru inowanzo tsanangura miganhu yekushanda kwemaitiro: entropy. Entropy haisi ye "qualitative disorder" chete, asi zvehunyanzvi, huwandu hunobatsira mainjiniya kuongorora divi remaitiro, kuyera kusachinjika, uye kuverenga basa rakarasika mumasisitimu chaiwo. Chinyorwa chino chinokurukura ongororo ye entropy mumasisitimu einjiniya ethermodynamic, kubva pakutsanangurwa kwayo kusvika pakushandiswa kwayo kumaindasitiri.
1. Kunzwisisa Entropy uye Zvainoreva Panyama
Mu thermodynamics yekare, entropy ibasa remamiriro ezvinhu iro shanduko yaro inotsanangurwa senzira inodzokororwa nehukama:
\[
dS = \frac{\delta Q_{rev}}{T}
\]
apo \(dS\) iri shanduko mu entropy, \(\delta Q_{rev}\) iri kupisa kunodzoserwa shure, uye \(T\) iri tembiricha yakakwana (Kelvin). Sezvo entropy iri basa remamiriro ezvinhu, shanduko mu entropy inongoenderana nemamiriro ekutanga neekupedzisira, kwete panzira yemaitiro. Izvi zvakakosha zvikuru muinjiniya nekuti zvinobvumira mainjiniya kuverenga shanduko mu entropy kunyangwe kune maitiro chaiwo, asingadzoserwe shure, vachishandisa nzira dzekufungidzira dzinodzoserwa pakati pemamiriro maviri akafanana.
Zvinorehwa ne entropy zvine chekuita nemaitiro ehurongwa ekufamba kuenda kumamiriro ezvinhu anogona kunge aripo, pamwe nekuyera "kupararira" kwesimba. Mukuita kweinjiniya, entropy inowanzoshandiswa ku:
1. Sarudza kana maitiro acho angangoitika ega.
2. Ongorora mwero wekusachinjika uye mhando yemaitiro acho.
3. Verengai kushanda kwepamusoro kwedzidziso (muganhu wakakodzera).
2. Mutemo Wechipiri weThermodynamics neEntropy Production
Kuongororwa kwe entropy kwakabatana zvikuru neMutemo wechipiri weThermodynamics. Kune system yakaparadzana, entropy haimbodziki:
\[
\Delta S_{total} \ge 0
\]
Kune masisitimu chaiwo, entropy yakazara inosanganisira entropy yesisitimu nenzvimbo dzakaipoteredza. Kana maitiro ari:
– Inodzoserwa kumashure, wobva \(\Delta S_{total} = 0\)
– Hazvidzoreki, wobva \(\Delta S_{total} > 0\)
Pfungwa huru pano ndeyekugadzirwa kwe entropy (\(S_{gen}\)), iyo inomiririra entropy "inogadzirwa" nekuda kwemasimba asingadzoreki akadai sekukweshana, kutamiswa kwekupisa pamusoro pemusiyano wekupisa wakaganhurirwa, kusanganiswa kwemvura, turbulence, kuwedzera kwakasununguka, uye kusawirirana kwemakemikari. Muchimiro che entropy balance yesystem ye control volume, izvi zvinogona kunyorwa seizvi:
\[
\frac{dS_{cv}}{dt} = \sum \dot{m}_{in}s_{in} – \sum \dot{m}_{out}s_{out} + \sum \frac{\dot{Q}}{T} + \dot{S}_{gen}
\]
ne \( \dot{S}_{gen} \ge 0\). Kune mainjiniya, kukosha kwe \( \dot{S}_{gen} \) chiratidzo chemhando yemaitiro: kana yakakura, kurasikirwa kwakawanda kunoitika.
3. Entropy muBasic Thermodynamic Process
Mukuongorora kweinjiniya, maitiro anowanzo shandiswa senzira dzekuita kuti kuverenga kuve nyore. Mamwe maitiro ekutanga uye hukama hwawo ne entropy ndeaya anotevera:
a. Maitiro eIsothermal (T inogara iripo)
Munzira ye isothermal inodzokororwa, shanduko mu entropy ine chekuita zvakananga nekupisa/kubuda:
\[
\Delta S = \frac{Q_{rev}}{T}
\]
Maitiro aya anoenderana nekuongorora mainjini eCarnot uye mamwe matanho ekudzvanya/kuwedzera anononoka zvikuru.
b. Maitiro eIsentropic (S inoramba iripo)
Maitiro e isentropic inzira yakanaka iyo inogona kushandiswa mu adiabatic uye inodzoserwa. Zvikamu zvakawanda zveinjiniya, zvakaita sema turbine, ma compressor, uye ma nozzles, zvinowanzofungidzirwa kuti isentropic kuti zviverenge kushanda kwakanaka. Muchokwadi, maitiro ari muzvikamu izvi anenge ari adiabatic asi haadzoreki, saka entropy inowanzo kuwedzera. Kutsauka kubva pamaitiro e isentropic kunoshandiswa kutsanangura kushanda kwe isentropic.
c. Maitiro eAdiabatic Asingadzokerike
Mukuita kwe adiabatic chaiyo, hapana kutamiswa kwekupisa (\(Q=0\)), asi entropy inogona kuwedzera nekuda kwekusachinjika kwemukati:
\[
\Delta S = S_{gen} > 0
\]
Muenzaniso unowanzoonekwa ndewekudzvinyirirwa kwegasi nekukweshana nekuvhiringika.
d. Maitiro eIsobaric neIsochoric
Kune maitiro ekumanikidzwa nguva dzose kana maitiro ehuwandu hunogara huripo, shanduko ye entropy inogona kuverengerwa uchishandisa data reproperty (matafura esteam, matafura egasi akakodzera) kana specific heat equation:
- Kune magasi akakodzera:
\[
\Delta s = c_p \ln\left(\frac{T_2}{T_1}\right) – R\ln\left(\frac{P_2}{P_1}\right)
\]
kana
\[
\Delta s = c_v \ln\left(\frac{T_2}{T_1}\right) + R\ln\left(\frac{v_2}{v_1}\right)
\]
4. Kushandiswa kweEntropy Analysis muEngineering Equipment
a. Turbine neCompressor
Mu turbine yakanaka, kuwedzera kwemvura kunoita kuti pave nekushanda kwakanyanya panguva ye isentropic process. Ma turbine chaiwo anowana kuwedzera kwe entropy nekuda kwekukweshana uye turbulence, zvichikonzera kusashanda chaiko. Kushanda zvakanaka kwe isentropic kwe turbine kunowanzotsanangurwa sehuwandu hwebasa chairo nebasa re isentropic. Kusiyana neizvi, mu compressor, kusadzoreka kunoita kuti basa chairo rive rakakura kupfuura rakakodzera.
b. Chinochinja Kupisa (Chinochinja Kupisa)
Zvishandiso zvinochinja-chinja kupisa zvinowanzofungidzirwa kuti hazviite basa uye zvinoshanda zvakatsiga. Kunyangwe zvichifungidzirwa kuti zvine adiabatic maererano nenzvimbo yakapoteredza, kugadzirwa kwe entropy kunoitika nekuda kwekutamiswa kwekupisa pamusoro pemusiyano wetembiricha wakaganhurirwa. Dhizaini yakanaka inovavarira kuderedza musiyano wetembiricha yemunzvimbo, kuderedza kusachinjika, uye kudzikisa \(S_{gen}\).
c. Vharuvhu Yekuvhuvhuta
Maitiro ekudhonza (semuenzaniso, mumavharuvhu ekuwedzera efriji) anowanzoonekwa seasingachinji (\(h\)), asi entropy inowedzera. Kuongorora kweEntropy kunobatsira kunzwisisa kuti kudhonza inzira isingadzoreki uye inokonzera kurasikirwa nebasa rinogona kuitwa. Nokudaro, mune mamwe masisitimu, mudziyo wekuwedzera unotsiviwa neexpander kuti utore basa uye kuderedza kusadzoreka, kunyangwe zvichikonzera kuomarara kwakanyanya.
d. Masisitimu ekuisa mufiriji nekupisa
Muchikamu chekutonhodza, ongororo ye entropy inobatsira kuongorora mashandiro e compressor, mhando ye condensation/evaporation process, uye manyuko ekusachinjika anoderedza COP (Coefficient of Performance). Dhayagiramu ye \(Ts\) inobatsira zvikuru pakuona kuwedzera kwe entropy mumaitiro chaiwo ekudzvanya uye ekupwanya.
5. Kushanda nesimba, Kushanda nesimba, uye Kurasikirwa Nebasa
Muinjiniya, entropy inowanzobatanidzwa nepfungwa ye exergy, inova chiyero chesimba guru rinogona kushandurwa kuita basa rinobatsira kana sisitimu ikabatana nenzvimbo yekutarisa. Kurasikirwa nebasa nekuda kwekusachinjika kwakabatana zvakananga nekugadzirwa kwe entropy kuburikidza ne:
\[
\dot{W}_{lost} = T_0 \dot{S}_{gen}
\]
apo \(T_0\) iri tembiricha yemhepo. Hukama uhwu hwakasimba zvikuru: chero entropy inogadzirwa inomiririra kurasikirwa ne "basa rinogona kuitwa." Nokudaro, kugadzirisa masisitimu emaindasitiri kunowanzo tarisa pakuderedza \( \dot{S}_{gen} \) muzvikamu zvinotonga, zvakaita semacompressor, macombustors, kana maheat exchangers ane musiyano mukuru wetembiricha.
6. Ts Diagram seChishandiso Chekuongorora
Dhayagiramu yetembiricha-entropy (\(Ts\)) ichishandiso chakakosha chekuona. Nzvimbo iri pasi pekongiri yemaitiro anodzokororwa padhayagiramu ye\(Ts\) inomiririra kutamiswa kwekupisa \(Q_{rev}\). Dhayagiramu iyi inoita kuti zvive nyore kune mainjiniya kuona:
- Maitiro acho anowanzo shandurwa zvishoma (curve yacho "yakanaka" uye haiwedzere entropy).
- Kusachinjika kwakadini kuripo mukudzvanywa, kuwedzeredzwa, uye kuwedzerwa/kubviswa kwekupisa.
- Kuenzanisa kutenderera kwakakodzera vs kutenderera chaiko.
7. Kesimpulan
Kuongorora ma "entropy" mu "engineering thermodynamic processes" inzira yakakosha yekunzwisisa nekuvandudza mashandiro ema "energy systems". "Entropy" inobatsira kubatanidza Mutemo Wechipiri weThermodynamics nezviri kuitika mumunda: hapana maitiro anogona kudzoserwa shure, uye kusachinjika kwese kunogadzira "entropy" uye kunoderedza kushanda kunogona kuitika. Kuburikidza ne "entropy balances", mainjiniya vanogona kuona kwavanobva kurasikirwa, kuongorora kushanda kwe "isentropic" kwe "fluid machines", kuongorora mhando yemagadzirirwo e "heat exchanger", uye kubatanidza kugadzirwa kwe "entropy" nekurasikirwa kwe "exergy". Pakupedzisira, kuziva pfungwa ye "entropy" hakusi kungodiwa kwedzidzo chete asi chishandiso chinoshanda chekugadzira masisitimu e "thermal" anoshanda zvakanaka, asingashandise simba zvakanyanya, uye akavimbika mumashandisirwo emaindasitiri emazuva ano.
