Njira za Thermodynamic: Isothermal Adiabatic Isochoric Isobaric

Njira za Thermodynamic: Isothermal Adiabatic Isochoric Isobaric

Pali njira zinayi za thermodynamic, zomwe ndi Isothermal, isochoric, isobaric ndi adiabatic.

Njira Yotenthetsera (kutentha kosalekeza)

Mu njira ya isothermal, kutentha kwa dongosolo kumakhala kofanana. Mwachiphunzitso, dongosolo lowunikidwa ndi mpweya wabwino. Kutentha kwa mpweya wabwino kumagwirizana mwachindunji ndi mphamvu yoyenera ya mpweya wamkati (U = 3/2 n RT). T sikusintha, kotero U sikusinthanso. Chifukwa chake, ngati igwiritsidwa ntchito ku njira ya isothermal, lamulo loyamba la equation ya thermodynamic limakhala:

Δ U = Q – W

Mphamvu yamkati siisintha, kotero Δ U = 0.

0 = Q – W

Q = W

Kutengera ndi equation iyi, mu njira ya isothermal (kutentha kosalekeza), kutentha (Q) komwe kumawonjezeredwa ku dongosololi kumagwiritsidwa ntchito ndi dongosololi kuchita ntchito (W).

Kusintha kwa kuthamanga ndi kuchuluka kwa dongosolo mu njira ya isothermal kukuwonetsedwa ndi graph ili pansipa:

Voliyumu yoyamba ya dongosolo = V₁ (voliyumu yaying'ono) ndi kuthamanga kwa dongosolo = P₁ (kupanikizika kwakukulu). Kuti kutentha kwa dongosolo kukhale kokhazikika, kutentha kukawonjezeredwa ku dongosolo, dongosolo limakula ndikugwira ntchito pa chilengedwe. Dongosolo likagwira ntchito pa chilengedwe, voliyumu ya dongosolo imasintha kukhala V₂ (kuchuluka kwa voliyumu ya dongosolo kumawonjezeka) ndi kusintha kwa kuthamanga kwa dongosolo ku P₂ (kuchepa kwa kuthamanga kwa dongosolo). Mawonekedwe a graph ndi opindika chifukwa kuthamanga kwa dongosolo sikusintha nthawi zonse panthawiyi. Kuchuluka kwa ntchito yomwe yachitika dongosolo = malo okhala ndi mthunzi.

Njira ya Adiabatic

Mu ndondomeko ya adiabatic, palibe kutentha komwe kumawonjezeredwa ku dongosolo kapena kutuluka mu dongosolo (Q = 0). Njira za Adiabatic zitha kuchitika m'makina otsekedwa bwino. Pa makina otsekedwa bwino, nthawi zambiri sipamakhala kutentha komwe kumalowa mu dongosolo kapena kutuluka mu dongosolo. Njira za Adiabatic zitha kuchitikanso m'makina otsekedwa omwe sali okhaokha.

Pankhaniyi, njirayi iyenera kuchitika mwachangu kuti kutentha kusayende kupita ku dongosolo kapena kutuluka mu dongosolo. Ngati ikugwiritsidwa ntchito pa njira ya adiabatic, lamulo loyamba la Thermodynamic equation lidzasintha:

Δ U = Q – W

Palibe kutentha komwe kuli mkati kapena kunja kwa dongosolo, kotero Q = 0.

Δ U = 0 – W

Δ U = -W

Ngati dongosolo lakanikiza mwachangu (ntchito yachitika pa dongosolo), ndiye kuti ntchito ndi yoipa. Chifukwa W ndi yoipa, ndiye kuti U ndi yoipa (mphamvu mu dongosolo imawonjezeka). Mosiyana ndi zimenezi, ngati dongosolo likukulirakulira mofulumira (dongosolo limagwira ntchito), ndiye kuti W ndi yoipa. Popeza W ndi yoipa, U ndi yoipa (mphamvu mu dongosolo imachepa). Mphamvu mu dongosolo (mpweya wabwino) ndi yofanana ndi kutentha (U = 3/2 n RT), chifukwa chake ngati mphamvu mu dongosolo ikuwonjezeka ndiye kuti kutentha kwa dongosolo kumawonjezekanso. Mosiyana ndi zimenezi, ngati mphamvu mu dongosolo yachepa, ndiye kuti kutentha kwa dongosolo kumachepa.

Kusintha kwa kuthamanga kwa magazi ndi kuchuluka kwa magazi mu ndondomeko ya adiabatic kukuwonetsedwa ndi chithunzi chomwe chili pansipa:

Mzere wa adiabatic womwe uli mu graph iyi (ma curve 1-2) ndi wokwera kuposa mzere wa isothermal (ma curve 1-3). Kusiyana kumeneku kwa kutsetsereka kukuwonetsa kuti pakuwonjezeka komweko kwa voliyumu, kuthamanga kwa dongosolo kumachepetsedwa kwambiri mu ndondomeko ya adiabatic kuposa njira ya isothermal. Kuthamanga kwa dongosolo kumachepa kwambiri mu ndondomeko ya adiabatic chifukwa pamene adiabatic ikukula, kutentha kwa dongosolo kumachepanso. Kutentha kumakhala kofanana ndi kuthamanga, chifukwa chake ngati kutentha kwa dongosolo kumatsika, kuthamanga kwa dongosolo kumachepanso. Mosiyana ndi njira ya isothermal, kutentha kwa dongosolo nthawi zonse kumakhala kokhazikika. Chifukwa chake, mu ndondomeko ya isothermal, kutentha sikukhudza kutsika kwa kuthamanga.

Chitsanzo chimodzi cha njira ya adiabatically imachitika mu injini yoyaka mkati, monga injini ya dizilo ndi injini ya petulo. Mu injini ya dizilo, mpweya umalowetsedwa mu silinda, ndipo mpweya mkati mwa silinda umakanikizidwa mwachangu pogwiritsa ntchito pistoni (ntchito imachitika mumlengalenga). Njira yochepetsera adiabatic (kuchepetsa voliyumu ya dongosolo) ikuwonetsedwa ndi curve 2-1. Chifukwa cha kuthamanga kwa adiabatic mwachangu, kutentha kumakwera mofulumira. Nthawi yomweyo, dizilo imapopera mu silinda kudzera mu injector, ndipo chisakanizocho chimayatsidwa nthawi yomweyo. Mu injini ya petulo, chisakanizo cha mpweya ndi petulo chimalowetsedwa mu silinda kenako chimakanikizidwa mwachangu pogwiritsa ntchito pistoni. Chifukwa chakuti imakankhidwira mwachangu adiabatic, kutentha kumakwera mofulumira. Nthawi yomweyo, ma spark plugs amayaka kuti njira yoyaka ichitike.

Njira ya Isochoric (voliyumu yokhazikika)

Mu ndondomeko ya Isochoric, voliyumu ya dongosolo imakhala yofanana. Popeza voliyumu ya dongosolo nthawi zonse imakhala yofanana, dongosolo silingagwire ntchito pa chilengedwe. Chilengedwe sichingagwirenso ntchito pa dongosolo. Ngati chikugwiritsidwa ntchito pa ndondomeko ya isochoric, lamulo loyamba la thermodynamic equation limasintha kukhala:

Δ U = Q – W

Dongosolo siligwira ntchito pa chilengedwe, kotero W = 0

Δ U = Q – 0

Δ U = Q

Kuchokera pa zotsatirazi, tingathe kunena kuti mu njira ya isochoric (voliyumu yokhazikika), kutentha (Q) komwe kumawonjezeredwa ku dongosolo kumagwiritsidwa ntchito kuwonjezera mphamvu mu dongosolo. Kusintha kwa kuthamanga kwa dongosolo ndi voliyumu mu njira ya isochoric kukuwonetsedwa ndi graph ili pansipa:

Poyamba, kuthamanga kwa dongosolo = p ₁ (kuthamanga pang'ono). Kutentha kowonjezera kwa dongosolo kumapangitsa kuti mphamvu mu dongosolo iwonjezereke. Pamene mphamvu mu dongosolo ikukwera, kutentha kwa dongosolo (mpweya woyenera) kumawonjezeka (U = 3/2 n RT). Kutentha kumakhala kofanana ndi kuthamanga. Chifukwa chake, ngati kutentha kwa dongosolo kukukwera, ndiye kuti kuthamanga kwa dongosolo kumawonjezeka (p ₂ ). Chifukwa cha kuchuluka kwa dongosolo kosasintha, palibe ntchito yomwe yachitika (palibe malo okhala ndi mthunzi).

Mu njira ya isochoric, dongosolo silingagwire ntchito pa chilengedwe. Momwemonso, chilengedwe sichingagwire ntchito pa dongosolo. Izi zili choncho chifukwa, mu njira ya isochoric, voliyumu ya dongosolo nthawi zonse imakhala yofanana. Pali mitundu ina ya ntchito yomwe sikutanthauza kusintha kwa voliyumu. Chifukwa chake ngakhale voliyumu ya dongosolo siisintha, ntchito ikhoza kuchitika pa dongosolo. Mwachitsanzo, pali fan + batri mu chidebe chotsekedwa. Fani imatha kuzungulira pogwiritsa ntchito mphamvu ndi batri. Pankhaniyi, mafani, mabatire, ndi mpweya mkati mwa chidebecho zimaonedwa ngati machitidwe.

Fani ikazungulira, fan imagwira ntchito, ikusewera mu chidebecho. Nthawi yomweyo, mphamvu ya kinetic ya fan imasanduka mphamvu mumlengalenga. Mphamvu zamagetsi mu batire, ndithudi, zimachepa chifukwa chasintha mawonekedwe kukhala mphamvu mumlengalenga. Chitsanzo ichi chikuwonetsa kuti mu njira ya isochoric (voliyumu nthawi zonse imakhala yokhazikika), ntchito ikhoza kuchitikabe pa system (ntchito yomwe sikutanthauza kusintha kwa voliyumu).

Njira ya Isobaric (kupanikizika kosalekeza)

Mu njira ya isobaric, kuthamanga kwa dongosolo kumakhala kosasintha. Popeza kuthamanga kumakhala kosasintha, kusintha kwa mphamvu yamkati ( Δ U), kutentha (Q) ndi ntchito (W) mu njira ya isobaric si zero. Chifukwa chake, njira yoyamba ya thermodynamics sinasinthe.

ΔU = Q − W

Kusintha kwa kuthamanga ndi kuchuluka kwa mpweya mu njira ya isobaric kukuwonetsedwa ndi graph ili pansipa:

Choyamba, voliyumu ya dongosolo = V₁ (voliyumu yaying'ono). Chifukwa chakuti kupanikizika kumakhala kosalekeza, kotero kutentha kukawonjezedwa ku dongosolo, dongosolo limakula ndikugwira ntchito pa chilengedwe. Pambuyo pogwira ntchito pa chilengedwe, voliyumu ya dongosolo imasintha kukhala V₂ (kuwonjezeka kwa voliyumu ya dongosolo). Kuchuluka kwa ntchito (W) dongosolo lachitika = malo okhala ndi mthunzi.

Funso 1:

Ma curve 1-2 m'ma diagram awiri pansipa akuwonetsa kufalikira kwa mpweya (kuwonjezeka kwa kuchuluka kwa mpweya) komwe kumachitika pang'onopang'ono komanso mosasinthasintha. Ndi njira iti yomwe ntchito yochitidwa ndi mpweya imakhala yochepa?

Ntchito yomwe imachitidwa ndi mpweya mu ndondomeko ya adiabatic ndi yochepa kuposa ntchito yomwe imachitidwa ndi mpweya mu ndondomeko ya isothermal. Malo okhala ndi mthunzi = ntchito yomwe imachitidwa ndi mpweya panthawi yokulitsa (kuwonjezeka kwa voliyumu ya mpweya). Malo okhala ndi mthunzi mu ndondomeko ya adiabatic ndi ochepa kuposa malo okhala ndi mthunzi mu ndondomeko ya isothermal.

Funso 2:

Njira za Thermodynamic zikuwonetsedwa pachithunzi chili pansipa. Ma curves ab ndi dc = njira za isochoric (voliyumu yokhazikika). Ma curve bc ndi ad = njira ya isobaric (kupanikizika kokhazikika). Mu ab process, kutentha (Q) 600 Joules kumawonjezeredwa ku system. Mu bc process, kutentha (Q) 800 Joules kumawonjezeredwa ku system.

a) Kusintha kwa mphamvu mu njira ya ab

b) Kusintha kwa mphamvu mu njira ya abc

c) Kutentha konse kwawonjezeredwa ku ndondomeko ya ADC

P ₁ = 2 x 10 ⁵ Pa = 2 x 10 ⁵ N / m ²

P ₂ = 4 x 10 ⁵ Pa = 4 x 10 ⁵ N / m ²

V ₁ = malita awiri = 2 dm ³ = 2 x 10 ^-3 m ³

V ₂ = malita 4 = 2 dm ³ = 4 x 10 ^-3 m ³

Anakonza

a) Kusintha kwa mphamvu zamkati mu njira ya ab

Mu njira ya ab, kutentha kwa 600 J kumawonjezedwa ku dongosolo. Njira ab = njira ya isochoric (voliyumu yokhazikika). Mu njira ya isochoric, kuwonjezera kutentha mu dongosolo kumangowonjezera mphamvu mu dongosolo. Chifukwa chake, mphamvu zimasintha mu dongosolo mutalandira kutentha:

ΔU = Q

ΔU = 600 J

b) Kusintha kwa mphamvu mu njira ya abc

Njira ab = njira ya isochoric (voliyumu yokhazikika). Mu njira ya ab, kutentha kwa 600 J kumawonjezedwa ku dongosolo. Chifukwa cha voliyumu yokhazikika, palibe ntchito yomwe imachitika ndi dongosolo.

Njira bc = njira ya isobaric (kupanikizika kosalekeza). Mu njira ya bc, kutentha (Q) 800 Joules kumawonjezedwa ku dongosolo. Mu njira ya isobaric, dongosololi limatha kugwira ntchito. Kuchuluka kwa ntchito yomwe dongosololi lachita mu njira ya bc (njira ya isobaric) ndi:

W = P (V ₂ – V ₁ ) — kupanikizika kosalekeza

W = P ₂ (V ₂ – V ₁ )

W = 4 x 10 ⁵ N/m ² (4 x 10 ^-3 m ³ – 2 x 10 ^-3 m ³ )

W = 4 x 10 ⁵ N/m ² (2 x 10 ^-3 m ³ )

W = 8 x 10 ² Joule

W = 800 Joule

Kutentha konse komwe kwawonjezeredwa ku dongosolo mu ndondomeko ya abc ndi:

Chiwerengero chonse cha Q = Q ab + Q bc

Chiwerengero chonse cha Q = 600 J + 800 J

Chiwerengero chonse cha Q = 1400 Joules

Ntchito yonse yomwe yachitika ndi dongosololi mu ndondomeko ya abc ndi:

Chiwerengero chonse = W ab + W bc

Chiwerengero chonse cha W = 0 + W bc

Chiwerengero chonse cha W = 0 + 800 Joule

Chiwerengero chonse cha W = 800 Joule

Kusintha kwa mphamvu zamkati mu ndondomeko abc = 600 J

c) Kutentha konse kwawonjezeredwa ku ndondomeko ya ADC

Kutentha konse komwe kwawonjezeredwa ku dongosololi kungawerengedwe ndi equation pansipa:

ΔU = Q – W

Q = ΔU + W

Kutentha konse komwe kwawonjezeredwa ku process adc = kusintha kwa mphamvu yamkati mu adc + ntchito mu process adc.

Kutentha ndi ntchito zimakhudzidwa ndi kusamutsa mphamvu pakati pa machitidwe ndi chilengedwe, pomwe kusintha kwa mphamvu mkati ndi chifukwa cha kusamutsa mphamvu pakati pa machitidwe ndi chilengedwe. Chifukwa chake, kusintha kwa mphamvu sikudalira njira yosamutsira mphamvu. Kumbali ina, kutentha ndi ntchito zimadalira njira. Mu njira ya isochoric (dongosolo la voliyumu yokhazikika), kusamutsa mphamvu kumachitika mu mawonekedwe a kutentha kokha, pomwe ntchito siili. Mu njira ya isobaric (kupanikizika kokhazikika), kusamutsa mphamvu kumaphatikizapo kutentha ndi ntchito. Ngakhale sikudalira njira, mphamvu zimasintha kutengera momwe zinthu zilili poyamba komanso momwe zinthu zilili kumapeto kwa dongosolo. Ngati mikhalidwe yoyambirira ndi yomaliza ili yofanana, kusintha kwa mphamvu nthawi zonse kumakhala kofanana, ngakhale kuti njirayo ndi yosiyana.

Mikhalidwe yoyambirira ndi yomaliza ya njira ya abc mu graph pamwambapa = mikhalidwe yoyambirira ndi yomaliza ya njira ya adc. Motero, mphamvu yamkati imasintha mu njira ya adc = 600 J.

Ntchito yonse (W) yomwe yachitika pa adc = W process pa ad + W pa dc process.

Njira yotsatsira malonda ndi njira ya isobaric (kupanikizika kosalekeza), pomwe njira ya dc ndi njira ya isochoric (voliyumu yosalekeza). Chifukwa cha voliyumu yosalekeza, palibe ntchito yomwe imachitika pa ndondomeko ya dc. Choyamba, timawerengera ntchito yomwe yachitika pa ndondomeko yotsatsira malonda.

W ad = P (V ₂ - V ₁ )

W ad = P ₁ (V ₂ ‐ V ₁ )

Wad ad = 2 x 10 ⁵ N/m ² (4 x 10 ^‐3 m ³ ‐ 2 x 10 ^‐3 m ³ )

Wad ad = 2 x 10 ⁵ N/m ² (2 x 10 ^‐3 m ³ )

W ad = 4 x 10 ² Joule

W ad = 400 Joule

Chiwerengero cha W = W mu ndondomeko a-d + W mu ndondomeko d-c

Chiwerengero chonse cha W = 400 Joules + 0

Chiwerengero chonse cha W = 400 Joule

Chifukwa chake, kuchuluka kwa kutentha komwe kumawonjezedwa ku ndondomeko ya ADC ndi:

Q = ΔU + W

Q = 600 J + 400 J

Q = 1000 J

Funso 3:

Madzi lita imodzi amasanduka malita 1671 a nthunzi akaphikidwa pa mphamvu ya atm imodzi. Werengani kusintha kwa mphamvu yamkati ndi ntchito yomwe madzi amagwira akamasanduka nthunzi … (Kutentha kwa nthunzi ya madzi = L _V = 22.6 x 10 ⁵ J/Kg)

Anakonza

Kuchuluka kwa madzi = 1000 kg/ ^m3

Kutentha kwa nthunzi ya madzi (L _V ) = 22.6 x 10 ⁵ J / Kg

P = 1 atm = 1.013 x 10 ⁵ Pa = 1.013 x 10 ⁵ N/m ²

V ₁ = lita imodzi = 1 dm ³ = 1 x 10 ^-3 m ³ (Kuchuluka kwa madzi)

V ₂ = 1671 malita = 1671 dm ³ = 1671 x 10 ^-3 m ³ (Kuchuluka kwa nthunzi)

a) Kusintha kwa mphamvu zamkati

Kusintha kwa mphamvu yamkati = Kutentha kumawonjezeredwa kumadzi kupatula Ntchito yomwe imachitidwa ndi madzi akasungunuka. Kuwerengera koyamba Kutentha (Q) kumawonjezeredwa kumadzi …

Q = m L _V

Kuchuluka kwa madzi = kuchuluka kwa madzi / kuchuluka kwa madzi

Kulemera kwa madzi (m) = kuchuluka kwa madzi x kuchuluka kwa madzi

Kulemera kwa madzi (m) = (1000 kg/m3 ⁾ ( 1 x 10 ^-3 m3 ⁾

Kulemera kwa madzi (m) = (1000 kg/m3 ⁾ (0.001 ^m3 )

Kulemera kwa madzi (m) = 1 kg

Q = (1 kg) (22.6 x 10 ⁵ J / kg)

Q = 22.6 x 10 ⁵ J

Werengerani ntchito (W) yochitidwa ndi madzi akaphwanyika. Kuwira kwa madzi kumachitika pa mphamvu yosalekeza (njira ya isobaric).

W = p (V ₂ – V ₁ )

W = 1.013 x 10 ⁵ N/m ² (1671 x 10 ^-3 m ³ – 1 x 10 ^-3 m ³ )

W = 1.013 x 10 ⁵ N/m ² (1670 x 10 ^-3 m ³ )

W = 1691.71 x ¹⁰⁵ Joules

W = 1.7 x ¹⁰⁵ Joules

Kusintha kwa mphamvu yamkati mwa madzi:

ΔU = Q – W

ΔU = 22.6 x 10 ⁵ J – 1.7 x 10 ⁵ J

ΔU = 20.9 x 10 ⁵ J

ΔU = 21 x 10 ⁵ J

Kutentha kwa ma Joule 21 x 10 ⁵ komwe kumawonjezeredwa m'madzi kumagwiritsidwa ntchito kuwonjezera mphamvu zamkati (kugonjetsa mphamvu zomangika pakati pa mamolekyu omwe amasunga madzi m'madzi). Mwanjira ina, 21 x 10 ⁵ J imagwiritsidwa ntchito kusintha madzi kukhala nthunzi. Madzi akakhala nthunzi, 1.7 x 105 J yotsalayo imagwiritsidwa ntchito kugwira ntchito.

Funso 4:

Mole imodzi ya mpweya mu silinda imakula mofulumira kwambiri. Poyamba, kutentha kwa mpweya = 1000 K. Pambuyo pokulitsa, kutentha kwa mpweya kumachepa kufika pa 500 K. Dziwani ntchito yomwe mpweyawo wagwira ...

Anakonza

Kuchuluka kwa mpweya kumachitika pang'onopang'ono. Mu ndondomeko ya adiabatic, palibe kutentha komwe kumalowa kapena kutuluka mu dongosolo. Motero, ntchito yomwe imachitika mu mpweya = kusintha kwa mphamvu mu mpweya.

ΔU = Q – W kapena W = Q – Δ U → Q = 0

W = 0 – ΔU

W = – ΔU

Tikhoza kuwerengera kusintha kwa mphamvu mu mpweya pogwiritsa ntchito equation ya mphamvu mu mpweya woyenera:

ΔU = 3/2 (1 mol) (8.315 J / mol. K) (500 K – 1000 K)

ΔU = 3/2 (1 mol) (8.315 J / mol. K) (- 500 K)

ΔU = -6236.25 J

Choncho, kuchuluka kwa ntchito zomwe zimachitika ndi gasi ndi:

W = – ΔU

W = – (- 6236.25 J)

W = 6236.25 J