Isihloko mayelana nokushisa okucashile kanye nomthamo wokushisa
Uma ufaka i-thermometer ye-mercury esitsheni esinengxube yamanzi abandayo neqhwa, uzobona ngemva kokuhamba uye phansi, ubuso be-mercury buyayeka ukuhamba. Ubuso be-Mercury buyayeka ukuhamba ngemva kokufinyelela izinga lokushisa lendawo yokubanda yamanzi (0 o C). Uma isitsha sivulekile, ukushisa kuphuma emoyeni onezinga lokushisa eliphezulu kuya engxubeni yeqhwa namanzi abandayo. Ukwengezwa kokushisa okuvela emoyeni kubangela ukuthi iqhwa lincibilike. Uma nje iqhwa lincibilika, ingabe izinga lokushisa lengxube yeqhwa namanzi abandayo liyashintsha? Uma nje iqhwa lincibilika, izinga lokushisa lengxube yamanzi neqhwa alishintshi.
Uma ingxube yeqhwa namanzi ifudunyezwa kusetshenziswa umlilo noma i-heater kagesi, isibonelo, lonke iqhwa liphenduka amanzi. Uma liqhubeka nokufudunyezwa, izinga lokushisa lamanzi lenyuka lifike ku-100 o C. Ku-100 o C, amanzi aqala ukuhwamuka. Uma amanzi eqhubeka nokufudunyezwa, amanzi aphenduka ngokushesha abe umusi, kuyilapho izinga lokushisa lamanzi lingashintshi noma lihlala liyi-100 o C. Leli izinga lokushisa lephuzu lokubila lamanzi, izinga lokushisa eliphakeme kakhulu elingafinyelelwa ngamanzi.
Igrafu yobudlelwano bokushisa nezinguquko zokushisa kanye nezinguquko esigabeni samanzi
AB = Ukushisa okwengeziwe kwandisa izinga lokushisa leqhwa libe ngu-0 o C
BC = Ukushisa okwengeziwe kuncibilikisa iqhwa emanzini
I-CD = Ukushisa okwengeziwe kwandisa izinga lokushisa kwamanzi kusuka ku-0 o C kuya ku-100 o C
DE = Ukushisa okwengeziwe kuhwamukisa amanzi
EF = Ukushisa okwengeziwe kwandisa izinga lokushisa lomusi
Igrafu engenhla ikhombisa inqubo yokushintsha kwezinga lokushisa kanye noshintsho esigabeni samanzi uma nje amanzi emunca ukushisa (ngengcindezi yomoya womoya owodwa). Uma amanzi ekhipha ukushisa, inqubo eyenzekayo iphambene nenqubo engenhla. Ukwengezwa kokushisa okuvela ku-BC akubangeli izinguquko ekushiseni kwamanzi, kodwa kuncibilikisa iqhwa libe ngamanzi kuphela.
Ukwengezwa kokushisa okuvela ku-DE akubangeli izinguquko ekushiseni kwamanzi, kodwa kuguqula amanzi abe umusi kuphela. Amanzi ayisibonelo esisodwa nje. Zonke izinto zizodlula enkambisweni yokushintsha kwesigaba kanye nokushintsha kwezinga lokushisa, njengoba kwenzeka emanzini uma into imunca ukushisa. Umehluko usekugcineni kokuqandisa kanye nokubila. Into ngayinye inephuzu lokuqandisa elihlukile kanye nokubila. Uma izinto zikhipha ukushisa, inqubo eyenzekayo iphambene nenqubo engenhla.
1. Ukushisa kokuhlanganiswa (L F )
Ukushisa kokuhlanganiswa inani lokushisa elimuncwa yi-1 kg yezinto ukushintsha isigaba sazo kusuka kokuqinile kuya kokumanzi, noma ukushisa okukhishwe yi-1 kg yezinto ukushintsha isigaba sazo kusuka kokumanzi kuya kokuqinile. Ifomula yokunquma inani lokushisa okumuncwayo (noma okukhishwe) ukushintsha isigaba sento kusuka kokuqinile kuya kokumanzi (noma okuketshezi kuya kokuqinile):
Q = m L F
Incazelo: Q = ukushisa okumuncwe noma okukhishwe, m = isisindo sento, L F = ukushisa kokuhlanganiswa
2. Ukushisa kokuhwamuka ( LV )
Ukushisa kokuhwamuka yinani lokushisa elimuncwa yi-1 kg yezinto ukushintsha isigaba salo kusuka kuketshezi lube yigesi, noma ukushisa okukhishwe yi-1 kg yezinto ukushintsha isigaba salo kusuka kugesi kuya kuketshezi. Ifomula yokunquma inani lokushisa elimuncwayo (noma elikhishwe) ukuguqula into kusuka kuketshezi ibe yigesi (noma igesi ibe uketshezi):
Q = m L V
Incazelo: Q = ukushisa okumuncwayo noma okukhishwe, m = isisindo sento, L V = ukushisa kokuhwamuka
Ukushisa kokuhlanganiswa kanye nokushisa kokuhwamuka kubizwa ngokuthi ukushisa okucashile.
Ukushisa okukhethekile (c)
Ukushisa okuqondile (c) = inani lokushisa (Q) elidingekayo ukuphakamisa izinga lokushisa (T) leyunithi eyodwa yobunzima (m) bezinto ngezinga elilodwa. Isibalo sokushisa okuqondile:
Iyunithi Yesistimu Yamazwe Ngamazwe yokushisa okuthile yi-J/Kg K.
Ukushisa okuthile kwento kuyashintsha ngokushisa. Uma ushintsho lokushisa lungelukhulu kakhulu, ukushisa kungabhekwa njengokungaguquguquki.
Okulandelayo ukushisa kwezinto eziningana ngokucindezela okungu-1 atm kanye nokushisa okungu-20 o C (okutholakale ngokuhlolwa).
Umthamo wokushisa (C)
Umthamo wokushisa (C) = inani lokushisa elidingekayo ukuphakamisa izinga lokushisa lazo zonke izinto ngedigri elilodwa. Isibalo somthamo wokushisa:
C = mc
Incazelo: C = umthamo wokushisa, m = isisindo, c = ukushisa okuthile kwento.
