Nkhani yokhudza kusamutsa kutentha ndi convection
Kodi munapitako m'mphepete mwa nyanja pamene dzuwa linali litalowa? Pa tsiku loyera, pagombe, nthawi zonse pamakhala mphepo yochokera kunyanja. N’chifukwa chiyani nthawi zonse pamakhala mphepo pagombe, ndipo n’chifukwa chiyani mphepo ya m’nyanja (mphepo yochokera kunyanja kupita kumtunda) imachitika masana, mphepo ya kumtunda (mphepo yochokera kumtunda kupita kunyanja) imachitika usiku? N’chifukwa chiyani mitambo ingatsike m’nyengo yamvula? N’chifukwa chiyani mphepo imamveka yozizira? Mayankho a mafunso awa akukhudzana ndi kutentha kwa dziko lapansi ndi nyanja, kukula, kuchulukana kwa madzi, ndi kusamutsa kutentha kudzera mu convection!
Mukamvetsetsa bwino komanso molondola nkhaniyo, mutha kuyankha mafunso omwe ali pamwambapa ndi mafunso ena omwe mungawafunse mtsogolo.
Kusamutsa kutentha kudzera mu conduction nthawi zambiri kumachitika m'zinthu zolimba kapena kuchokera ku zinthu zolimba kupita ku zinthu zamadzimadzi (ndi kuchokera ku zinthu zamadzimadzi kupita ku zinthu zolimba) kapena kuchokera ku zinthu zolimba kupita ku zinthu za mpweya (ndi kuchokera ku zinthu za mpweya kupita ku zinthu zolimba). Ngakhale kusamutsa kutentha kudzera mu convection nthawi zambiri kumachitika m'zinthu zamadzimadzi (monga madzi) ndi zinthu za mpweya (monga madzi). Kusamutsa kutentha kudzera mu convection ndi kusamutsa kutentha komwe kumatsagana ndi kusamutsa kwa zinthu. Kuti mumvetse bwino kusamutsa kutentha kudzera mu convection, onani bokosi, mwachitsanzo, madzi otentha pogwiritsa ntchito moto. Madzi omwe ali mu chidebe akatenthedwa ndi moto, kutentha kumasuntha kuchokera pamoto (kutentha kwakukulu) kupita ku chidebe (kutentha kochepa) pogwiritsa ntchito conduction ndi radiation. Kenako, kutentha kumasuntha kuchokera ku chidebe (kutentha kwakukulu) kupita ku madzi pafupi ndi chidebe (kutentha kotsika) pogwiritsa ntchito conduction. Kutentha kowonjezera kumapangitsa kutentha kwa madzi pafupi ndi chidebe kukwera.
Kukwera kwa kutentha kwa madzi kumapangitsa kuti madzi achuluke kapena kuchuluka kwa madzi kumawonjezeka. Chifukwa pamene kuchuluka kwa madzi kukuwonjezeka, kuchuluka kwa madzi kumachepa. Madzi omwe ali pafupi ndi pansi pa chidebecho amakhala ndi kutentha kwakukulu kuposa madzi omwe ali pafupi nacho. Mwanjira ina, madzi omwe ali pafupi ndi pansi pa chidebecho amakhala ndi kuchuluka kwakukulu komanso kochepa, pomwe madzi omwe ali pamwamba pake amakhala ndi kuchuluka kochepa komanso kuchuluka kwakukulu. Kusiyana kwa kuchuluka kwa madzi kumapangitsa kuti pamwamba pa chidebecho, chomwe chili ndi kuchuluka kwakukulu, chisunthe pansi ndipo madzi omwe ali pafupi ndi pansi pa chidebecho, chomwe chili ndi kuchuluka kochepa, asunthe mmwamba. Izi zimachitika mosalekeza mpaka madzi onse omwe ali mkati mwake akhale ndi kutentha komweko (Ngati mpweya uli ndi mpweya umodzi, ndiye kuti madzi omwe ali mu chidebecho akutuluka kapena kuwira pa 100 o C).
Kubwera kwa mphepo zapamtunda ndi mphepo zapanyanja kumakhudzanso kusamutsa kutentha kudzera mu conduction ndi convection. Kutentha kwapadziko lapansi kumakhala kochepa kuposa kutentha kwa madzi a m'nyanja. Chifukwa chake, nthaka imakhala yotentha kwambiri ikakumana ndi dzuwa komanso kuzizira usiku ukafika. Kutentha kwapadziko lapansi kumatenthetsa mpweya womwe uli pamwamba (kutentha kumasuntha kuchokera kumtunda kupita kumlengalenga kudzera mu conduction). Kutentha kwa mpweya kumawonjezeka ndipo mpweya umakula. Zotsatira zake, kuchuluka kwa mpweya kumachepa. M'malo mwake, kutentha kwa madzi a m'nyanja kumakhala kozizira kwambiri kotero kuti mpweya womwe uli pamwamba pa nyanja nawonso umakhala wozizira kuposa mpweya womwe uli pamwamba pa nthaka.
Mpweya womwe uli pamwamba pa nyanja ndi wozizira kwambiri kotero kuti kuchulukana kumakhala kwakukulu. Kusiyana kwa kuchulukana kwa mpweya kumapangitsa kuti mpweya womwe uli pamwamba pa nyanja upite kumtunda, pomwe mpweya womwe uli pansi umakwera mmwamba. Pamene mpweya ukutalikirana ndi dziko lapansi, kuchuluka kwa mpweya kumachepa chifukwa mphamvu yokoka ya dziko lapansi imachepa. Chifukwa chakuti kuchuluka kwa mpweya kumachepa, kuthamanga kwa mpweya kukuchepanso.
Mpweya wotentha womwe umakwera mmwamba wazizira chifukwa uli kutali ndi pamwamba pa dziko lapansi, mphamvu ya mpweya imachepa. Mpweya wozizira umatsika, osati pamwamba pa dziko lapansi koma pamwamba pa nyanja, yomwe imakhala ndi kutentha kozizira kwambiri. Izi zimachitika mosalekeza kotero kuti pakhale kuyenda kwa mpweya kuchokera kunyanja kupita kumtunda. Mwachidule, mpweya womwe uli pafupi ndi pamwamba pa nyanja umapita pansi, mpweya womwe uli pafupi ndi pamwamba pa dziko lapansi umapita mmwamba, mpweya womwe uli pamwamba umapita pamwamba pa nyanja.
N’chifukwa chiyani utsi nthawi zonse umakwera mmwamba? Utsi umakwera mmwamba chifukwa kutentha kwake kuli kokwera kuposa kutentha kwa mpweya wozungulira. Chifukwa kutentha kwa utsi kumakhala kokwera, voliyumu yake imawonjezeka ndipo kuchuluka kwake kumachepa. Utsi wochepa umayambitsa kupanikizika kochepa, poyerekeza ndi mpweya wozungulira. Mpweya wozungulira utsiwo umakankhira utsiwo mmwamba.
N’chifukwa chiyani nthawi yamvula mitambo imatsika? Nthawi yamvula, mitambo imakhala ndi nthunzi yambiri yamadzi kotero kuti kuchuluka kwa mitambo kumawonjezeka. Mitambo yomwe imakhala ndi nthunzi yambiri yamadzi ndipo imakhala ndi kuchuluka kwakukulu, imapita pansi kupita kumalo komwe mpweya wozungulira derali uli ndi kuchuluka komweko ndi kuchuluka kwa mitambo. Mutha kufunsa ndikuyankha zinthu zambiri zokhudzana ndi nkhaniyi ngati mwamvetsa bwino komanso molondola kufotokozera pamwambapa.
