Txhua tus menyuam kawm ntawv los hla lub tswvyim xws li "kev muaj peev xwm kub tshwj xeeb" hauv cov lus qhia physics. Feem ntau, tib neeg tsis nco qab lub tsev kawm ntawv txhais lus, thiab feem ntau tsis to taub lub ntsiab lus ntawm lo lus no txhua. Hauv cov tsev kawm txuj ci, feem ntau cov tub ntxhais kawm yuav sai lossis tom qab ntsib qhov kub tshwj xeeb. Tej zaum, raws li ib feem ntawm kev kawm ntawm physics, los yog tej zaum ib tug neeg yuav muaj xws li kev qhuab qhia xws li "kub engineering" los yog "technical thermodynamics". Hauv qhov no, koj yuav tsum nco ntsoov lub tsev kawm ntawv cov ntaub ntawv kawm. Yog li, hauv qab no yog cov ntsiab lus, piv txwv, lub ntsiab lus rau qee yam khoom.
Definition
Lub peev xwm kub tshwj xeeb yog lub cev muaj zog uas qhia tias yuav tsum muaj cua sov ntau npaum li cas rau ib chav tsev ntawm cov khoom lossis tshem tawm ntawm chav tsev ntawm cov khoom kom nws qhov kub thiab txias hloov ntawm ib qib. Nws yog ib qho tseem ceeb uas yuav tsum tau tshem tawm tias nws tsis muaj teeb meem yog tias Celsius, Kelvin lossis Fahrenheit, qhov tseem ceeb yog qhov hloov pauv ntawm qhov kub ntawm ib chav tsev.
Cov peev txheej kub tshwj xeeb muaj nws tus kheej ntsuas ntsuas - hauv cov txheej txheem thoob ntiaj teb ntawm chav nyob (SI) - Joule faib los ntawm cov khoomkilograms thiab degrees Kelvin, J / (kg K); chav tsev off-system yog qhov sib piv ntawm calorie rau cov khoom ntawm ib kilogram thiab degree Celsius, cal / (kg ° C). Tus nqi no feem ntau qhia los ntawm tsab ntawv c lossis C, qee zaum siv cov ntsuas. Piv txwv li, yog hais tias lub siab tsis tu ncua, ces qhov Performance index yog p, thiab yog hais tias lub ntim yog tas li, ces v.
Definition variations
Ntau cov qauv ntawm cov ntsiab lus ntawm lub cev sib tham tau ua tau. Ntxiv rau qhov saum toj no, lub ntsiab lus suav hais tias yog qhov tsim nyog, uas hais tias qhov tshwj xeeb cua sov yog qhov piv ntawm qhov muaj peev xwm kub ntawm cov khoom rau nws qhov loj. Nyob rau hauv cov ntaub ntawv no, nws yog ib qhov tsim nyog yuav tsum tau kom meej meej to taub dab tsi "heat peev" yog dab tsi. Yog li, lub peev xwm kub yog hu ua lub cev kom muaj nuj nqis uas qhia tias yuav tsum muaj cua sov ntau npaum li cas rau lub cev (cov khoom siv) lossis tshem tawm txhawm rau txhawm rau hloov tus nqi ntawm nws qhov kub ntawm ib qho. Qhov tshwj xeeb kub muaj peev xwm ntawm ib pawg ntawm cov khoom ntau dua li ib kilogram yog txiav txim siab tib yam li rau ib tus nqi.
Qee yam piv txwv thiab lub ntsiab lus rau ntau yam khoom
Nws tau sim pom tias tus nqi no txawv ntawm cov khoom sib txawv. Piv txwv li, lub peev xwm kub ntawm dej yog 4.187 kJ / (kg K). Qhov loj tshaj tus nqi ntawm lub cev muaj nuj nqis rau hydrogen yog 14.300 kJ / (kg·K), qhov tsawg tshaj plaws tus nqi rau kub yog 0.129 kJ / (kg·K). Yog tias koj xav tau tus nqi rau ib yam khoom tshwj xeeb, ces koj yuav tsum nqa phau ntawv siv thiab nrhiav cov rooj sib tham, thiab hauv lawv - qhov tseem ceeb ntawm koj nyiam. Txawm li cas los, niaj hnubtechnologies ua rau nws muaj peev xwm ua kom ceev cov txheej txheem tshawb fawb lub sij hawm - nws yog txaus rau txhua lub xov tooj uas muaj kev xaiv nkag mus rau lub Ntiaj Teb Wide Web, ntaus cov lus nug ntawm kev txaus siab nyob rau hauv lub tshawb nrhiav bar, pib tshawb nrhiav thiab nrhiav cov lus teb raws li. qhov tshwm sim. Feem ntau, koj yuav tsum nyem rau ntawm thawj qhov txuas. Txawm li cas los xij, qee zaum koj tsis tas yuav mus rau lwm qhov ntawm txhua qhov - cov lus teb rau cov lus nug yog pom hauv cov lus piav qhia luv luv ntawm cov ntaub ntawv.
Cov tshuaj nquag tshaj plaws uas lawv tab tom nrhiav kom muaj peev xwm ua kom sov, suav nrog cov cua sov tshwj xeeb, yog:
- air (dry) - 1,005 kJ/(kg K),
- aluminium - 0.930 kJ/(kg K),
- copper - 0.385 kJ/(kg K),
- ethanol - 2, 460 kJ / (kg K),
- iron - 0.444 kJ/(kg K),
- mercury - 0.139 kJ/(kg K),
- oxygen - 0.920 kJ/(kg K),
- wood - 1,700 kJ/(kg K),
- sand - 0.835 kJ/(kg K).
