Entropy

Chirevo chaicho chemutemo wechipiri wethermodynamics hachigone kutsanangurwa kune ese maitiro asingadzoreki, saka tinoda chirevo chakazara. Chirevo ichi chinotarisirwa kutsanangura maitiro ese asingadzoreki anoitika muchadenga. Chirevo chakazara chemutemo wechipiri wethermodynamics chakagadzirwa pakati pezana remakore rechi19, kuburikidza nehuwandu hunonzi entropy (S). Entropy yakatanga kuunzwa naClausius uye yakagadzirwa kubva kuCarnot cycle (injini yakakwana yemacalorie). Sekureva kwaClausius, shanduko dzeentropy dzinoitika nesystem, apo system inowana kupisa kwakawedzerwa (Q) patembiricha yakajairika, iyo inomiririrwa ne equation:

ΔS = Kuchinja kweEntropy, Q = Kupisa, T = Temperature

Entropy huwandu hunoratidza mamiriro emuviri wemuviri wesystem zvekuti haugone kuzivikanwa zvakananga. Izvo zvinogona kuverengerwa shanduko dze entropy chete. Zvakafanana nekuchinja kwesimba remukati mumutemo wekutanga wethermodynamics.

Muenzaniso 1:

Gasi riri mugaba rinokura nekukurumidza. Kuchinja kwegasi entropy kuri…

Solutions

Munguva yeadiabatic process, hapana kupisa kunopinda kana kubuda musystem (gas). Sezvo Q = 0 saka ΔS = 0. System entropy inogara iripo. Ko nezve adiabatic compression? Munguva ye adiabatic compression, hapana kupisa kunopinda kana kubuda musystem (Q = 0). Saka, entropy yesystem inogara iripo.

Muenzaniso 2:

Injini yeCarnot inotora kupisa kwe2000 J pa500 K, inoburitsa kupisa pa350 K. Verenga kupisa kunoburitswa, uye shanduko mu entropy yese yedenderedzwa rimwe chete.

Solutions

T_H = 500K

Q_H = 2000 J

T_L = 350K

Q_L = ….. ?

Kana sisitimu ikagamuchira kupisa, Q inenge yakanaka, kana sisitimu ikaburitsa kupisa, Q inenge isina kunaka.

Munguva imwe chete, injini yeCarnot inopinda mumaitiro maviri e isothermal anodzoserwa (kuwedzera kwe isothermal + kudzvanywa kwe isothermal) uye maitiro maviri e adiabatic anodzoserwa (kuwedzera kwe adiabatic uye kudzvanywa kwe adiabatic). Munguva yekuwedzera nekudzvanywa, hapana kupisa kunopinda kana kubuda musystem (Q = 0). Sezvo Q = 0, entropy inochinja panguva ye adiabatic process = 0.

Munguva yekuwedzera kwe-isothermal, injini inotora kupisa (Q) kwe2000 J patembiricha (T) 500 K. Nekuti injini inotora kupisa, saka Q yakanaka. Kuchinja kwe entropy yemuchina panguva yekuwedzera kwe-isothermal ndekwekuti:

Munguva yekudzvanywa kwe isothermal, injini inoburitsa kupisa (Q) kusvika 1400 J patembiricha ye (T) 350 K. Nekuti injini inoburitsa kupisa, saka Q inenge iri negative. Kuchinja kwe entropy yemuchina panguva yekudzvanywa kwe isothermal ndekwekuti:

Kuchinja kwese kwe entropy = 4 J / K – 4 J / K = 0

Muenzaniso 3:

Injini inotora 600 J yekupisa patembiricha ye300 °C, inoburitsa kupisa patembiricha ye100 °C. Inoverenga kupisa kunoburitswa, uye inochinja mu entropy yese kwechikamu chimwe chete.

Solutions

T_H = 300K

Q_H = 600 J

T_L = 100K

Q_L =?

Munguva imwe chete, injini yeCarnot inopinda mumaitiro maviri e isothermal anodzoserwa (kuwedzera kwe isothermal + kudzvanywa kwe isothermal) uye maitiro maviri e adiabatic anodzoserwa (kudzvanywa kwe adiabatic uye kuwedzera kwe adiabatic). Munguva yekuwedzera nekudzvanywa kwe adiabatic, hapana kupisa kunopinda kana kubuda musystem (Q = 0). Nekuti Q = 0 saka entropy inochinja panguva ye adiabatic process = 0.

Munguva yekuwedzera kwe-isothermal, injini inotora kupisa (Q) kwe600 J patembiricha ye (T) 300 K. Nekuti injini inotora kupisa, saka Q yakanaka. Kuchinja kwe entropy yemuchina panguva yekuwedzera kwe-isothermal ndekwekuti:

Munguva yekudzvanywa kwe isothermal, injini inoburitsa kupisa (Q) 200 J patembiricha (T) 100 K. Nekuti injini inoburitsa kupisa, saka Q inenge iri negative. Kuchinja kwe entropy yemuchina panguva yekudzvanywa kwe isothermal ndekwekuti:

Kuchinja kwese kwe entropy = 2 J / K – 2 J / K = 0

Zvichibva pamuenzaniso nhamba 2 nemuenzaniso nhamba 3, shanduko ye entropy yese yemaitiro anodzoserwa = 0. Mumaitiro anodzoserwa, entropy yese inogara yakadaro.

Muenzaniso 4:

Aizi ye2 kg pa 0 °C inonwisa kupisa, saka inonyunguduka. Verenga shanduko yechando. (Kupisa kwekubatana kwemvura = 3.34 x 10⁵ J / Kg)

Solutions

Huwandu hwechando = 2 kg

Kupisa kwechando = 0 ^oC + 273 = 273 K

Kupisa kwekubatana kwemvura = 3.34 x 10⁵ J / Kg

Kupisa kunodiwa kuti 2 kg yechando inyunguduke mumvura:

Q = mL

Q = (2 kg)(3.34 x 10⁵ J/Kg)

Q = 6.68 x 10⁵ J

Q = 668 x 10³ J

Munguva yekunyunguduka (chando chichienda kumvura), tembiricha inogara iripo. Sezvo tembiricha ichigara iripo, saka shanduko yechando inonzi:

Muenzaniso 5:

Mvura pa26 °C inosanganiswa nemvura pa22 °C. Huremu hwemvura i2 kg. Verenga shanduko ye entropy yemvura. Mvura inopisa nemvura inotonhora zvinosanganiswa mumudziyo wakavharwa zvakanaka uye wakadzivirirwa. Kutamiswa kwekupisa inzira isingadzoreki.

Solutions

^{Kupisa chaiko yemvura (c) =} 4180 J/Kg C^o

Huremu hwemvura = 2 kg

Huremu hwemvura hwakafanana, saka tembiricha yekupedzisira = 24 ^oC (26 ^oC + 22 ^oC / 2 = 48 ^oC / 2 = 24 ^oC).

Huwandu hwekupisa hunoburitswa nemvura inopisa kana tembiricha yadzikira kubva pa26 °C kusvika 24 °C ndehwekuti:

Q = mc ΔT = (2 kg) (4180 J / kg C^o) (26 ^oC - 24 ^oC) = (2 Kg) (4180 J / kg C^o) (2 ^oC) = 16720 J

Huwandu hwekupisa hunotorwa nemvura inotonhora kana tembiricha yakwira kubva pa22^oC - 24^oC ndiyo:

Q = mc ΔT = (2 kg) (4180 J / kg C^o) (24 ^oC - 22 ^oC) = (2 kg) (4180 J / kg C^o) (2 ^oC) = 16720 J

Kuchinja kwe entropy yese = kuchinja kwe entropy yemvura inopisa + kuchinja kwe entropy yemvura inotonhora

ΔS= ΔMvura inopisa + ΔMvura inotonhora yeS

ΔS = Q/T + Q/T

Avhareji yekupisa kwemvura inopisa = (26) ^oC + 24 ^oC) / 2 = 50 ^oC / 2 = 25 ^oC —- 25 + 273 = 298 K

Avhareji yekupisa kwemvura inotonhora = (22) ^oC + 24 ^oC) / 2 = 46 ^oC / 2 = 23 ^oC —- 23 + 273 = 296 K

Mvura inopisa inoburitsa kupisa, saka Q haina kunaka. Mvura inotonhora inotora kupisa, saka Q ine kunaka.

ΔS= ΔMvura inopisa + ΔMvura inotonhora yeS

ΔS = -Q/T + Q/T

ΔS = -16720/298 + 16720/296

ΔS = -56.107 + 56.486

ΔS= 0.379 J/K

Total entropy yakawedzera ne0.379 J/K

Kunyange zvazvo chikamu che entropy chesystem chichidzikira (-56.107 J/K), chikamu che entropy chesystem chinowedzera muhuwandu hwakawanda (+ 56.486 J / K) zvekuti huwandu hwe entropy hunogara huchiwedzerwa (+ 0.379 J / K).

Kuwedzera kwe entropy yese mukuita kusingadzoreki hakungoshandi chete pakuchinjisa kupisa pakati pemusanganiswa wemvura inopisa neinotonhora wakaongororwa pamusoro apa, asiwo kunoshanda kune ese masayendisiti akaongorora. Total fixed entropy kana maitiro acho akaitika nenzira inodzoserwa shure. Kana maitiro acho akaitika nenzira isingadzoreki, saka total entropy inogara ichikwira.

Maitiro ese echisikigo muhupenyu hwedu hwezuva nezuva haachinjiki saka entropy yese inofanira kuwedzera. Izvi zvinopfupikiswa mumutsara unotevera:

Mukuita kusingadzoreki, entropy yese yehurongwa nenzvimbo yakapoteredza iri kuramba ichikura.

Chirevo ichi chirevo chakajairika chemutemo wechipiri wethermodynamics. Mutemo wechipiri wethermodynamics wakasiyana nemimwe mitemo yefizikisi. Kazhinji, mitemo yefizikisi inotaurwa maererano nemaequation (mutemo waNewton) kana muchimiro chemutemo wekusingaperi (mutemo wekuchengetedza simba).