Te Whakawhiti Wera Whakawhiti i roto i ngā Pūnaha Whakamatao Mīhini
Ko te pūnaha whakamatao miihini tētahi o ngā pūnaha iti tino nui hei pupuri i te mahi miihini, te whai huatanga, me te roa o te ora—ahakoa i roto i ngā waka motuka, i ngā whakaputa hiko, i ngā mīhini ahumahi, i ētahi atu mīhini rānei e whakaputa ana i te wera nui. I te wā e mahi ana te miihini, ka puta he wera nui nā te tahunga wahie me te waku i waenga i ngā wāhanga o roto. Ki te kore e whakahaerea tēnei wera, ka piki ake te pāmahana o te miihini ki tua atu i ngā rohe haumaru, ka heke te mahi, ka pakaru te hinu whakahinuhinu, ka rerekē te āhua o te wāhanga, tae noa ki te rahunga o te miihini. Koinei te wāhi e whai wāhi nui ai te whakawhiti wera, inā koa ko te convection.
Ngā Ariā Taketake o te Whakawhiti Wera
I te nuinga o te wā, e toru ngā tikanga e puta ai te whakawhiti wera: te kawe hiko, te whakawhiti wera, me te irahiko. I roto i ngā pūnaha whakamatao miihini, ka puta ngātahi ēnei e toru, engari ko te whakawhiti wera te "kaitākaro matua" nā te mea e uru ana te rere o ngā wai (ngā wai, ngā hau rānei) e kawe ana i te wera mai i tētahi wāhi ki tētahi atu.
– Te kawe wera: te whakawhiti wera mā roto i ngā rauemi totoka, hei tauira, mai i te pakitara rango ki te wai uhi.
– Te whakawhiti wera: te whakawhiti wera i waenga i te mata totoka me te wai e neke ana, hei tauira, mai i te pakitara miihini ki te wai whakamatao, mai i ngā tara o te radiator ki te hau rānei.
– Te irahiko: te tukunga o te pūngao wera mā roto i ngā ngaru hikohiko, hei tauira, mai i te mata o te mīhini wera ki te taiao e karapoti ana.
Ahakoa ka honoa te wera mai i roto i te miihini e te ara iahiko ki ngā mata e pā ana ki te wai, ko te ara iahiko te mea e whakatau ana i te whai huatanga o te kawe me te tango atu i taua wera.
Te Whakamāramatanga me te Tikanga o te Whakawhitiwhiti
Ko te whakawhiti wera ko te whakawhiti wera e puta mai ana i te huinga o ngā tukanga e rua: (1) te horapa wera (te kawe) i roto i te paparanga wai e tata ana ki te mata, me (2) te whakawhiti papatipu o te wai tonu (te whakawhiti) e kawe ana i te pūngao wera. Ka taea te wehewehe i te whakawhiti wera ki:
1. Te kawe ā-taiao
Ka puta tēnei nā te rerekētanga o te mātotoru nā te rerekētanga o te pāmahana. Ka māmā ake, ka piki ake ngā wai wera, ko ngā wai matao ia ka totohu. Hei tauira, ko te hau e neke haere ana i te mīhini wera ahakoa kāore he pā.
2. Te whakawhiti ā-pūngao
Ka puta tēnei ina nekehia te wai e tētahi taputapu o waho pērā i te papu, i te pā hau rānei. I roto i ngā pūnaha whakamatao mīhini hou, ko te konukōkiri kaha te mea nui: ka papuhia te wai whakamatao huri noa i te poraka mīhini, ā, ka akiakihia te hau mā roto i te pūwhakamahana e te pā hau me te rere i puta mai i te nekehanga o te waka.
I roto i te pāngarau, ko te tere o te whakawhiti wera āwhata ka whakaatuhia mā te whārite māmā:
\[
Q = hA(T_s – T_infty)
\]
ko Q te tere wera (W), ko h te tauwehenga whakawhiti wera kawe (W/m²K), ko A te horahanga mata pa (m²), ko T te pāmahana mata, ā, ko T te pāmahana wai i tawhiti atu i te mata.
He mea nui te uara h nā te mea e whakaahua ana i te kaha o te pūnaha ki te whakawhiti wera mā te whakawhiti wera. Ka pāngia tēnei uara e te tere o te rere o te wai, te momo wai, ngā āhuatanga ā-tinana (te matotoru, te kawe wera), me ngā āhuatanga rere (te whakarewa, te turbulent rānei).
Te Tūranga o te Whakawhitiwhiti i roto i ngā Pūnaha Whakamatao Wai
I roto i te maha o ngā miihini, ka whakatutukihia te whakamatao mā te wai whakamatao (he ranunga wai me te ārai huka) e rere ana i roto i ngā awa huri noa i ngā rango me ngā pane rango. Ka taea te whakaahua i te tukanga hei raupapa o ngā tukanga whakawhiti wera:
1. Ka tukuna te wera mai i te rūma mura me ngā pakitara rango mā te ara iahiko ki te mata o te pakitara e pā ana ki te wai whakamatao.
2. Ka puta te whakawhiti wai mai i ngā pakitara o te miihini ki te wai whakamatao ina rere te wai whakamatao mā roto i te uhi wai. Ka tere ake, ka pōrearea ake te rere, ka teitei ake te tauwehenga whakawhiti wai.
3. Ka rere te wai whakamatao wera ki te pūwhakamahana, ka tukuna te wera ki te rangi.
I tēnei wāhanga tuarua ka mahi te convection hei tikanga "kawe" matua. He maha ngā wā ka hangaia ngā awa whakamatao i roto i te poraka miihini kia mau tonu te tere rere taurite. Ka taea e te aueue whakahaere te whakarei ake i te whakawhiti wera, ahakoa ka taea e te aueue nui te whakanui ake i ngā ngaronga pehanga me te taumahatanga o te papu.
Te Whakawhitiwhiti i roto i ngā Pāreti: Mai i te Whakamatao ki te Hau
He whakawhiti wera te mahi a te pūwhakamahana i waenga i te wai whakamatao me te hau o waho. Kei roto i te pūwhakamahana he paipa iti me ngā tara hei whakanui ake i te horahanga o te mata. Ko te tukanga:
– Ka rere te wai whakamatao wera i roto i ngā paipa o te pūwhakamahana; ka whakawhitia te wera mai i te wai whakamatao ki ngā pakitara o te paipa mā te kawe wera ā-roto.
– Ka uru te wera ki roto i ngā pakitara o ngā paipa (te ara iahiko).
– Ka whakawhitia te wera mai i te mata o waho o ngā paipa me ngā tara ki te hau e karapoti ana mā te whakawhiti wera o waho.
Ka piki ake te whakawhiti wera mēnā:
– He whānui te horahanga mata whai hua (he tara matotoru me te hoahoa tino pai),
– Te rere nui o te hau (te neke o te waka, te oma rānei o te pā hau o te radiator),
– Horoia te mata (ka ārai pea te paru, te puehu, ngā pepeke rānei i te rere o te wai, ā, ka whakaiti i te whai huatanga).
He iti ake te tauwehenga whakawhiti wera o te hau-ki-te-hau i te hau-ki-te-hau i te wai-ki-te-hau nā te mea he iti te kawe wera o te hau. Nō reira, me whai tara me te rere o te hau kaha ngā whakamahana hei tuku wera.
Ngā Take e Pā Ana ki te Whai Huatanga o te Whakawhitiwhiti
Ko ētahi o ngā āhuatanga matua e whakatau ana i te whai huatanga o te convection i roto i te pūnaha whakamatao miihini ko:
1. Te tere rere o te wai
Mā te whakanui ake i te tere rere ka piki ake te tauwehenga whakawhiti (h). I roto i te wai whakamatao, ka whakarite te papu wai kia rere tonu. I roto i te hau, ko te hauhautanga me te tere o te waka te mea e whakatau ana i te tere rere i roto i te radiator.
2. Ngā āhuatanga o te wai whakamatao
Ehara i te wai anake te wai whakamatao; he maha ngā wā ka tāpirihia ki te ethylene glycol, ki te propylene glycol rānei hei whakanui ake i te pāmahana koropupū, hei whakaiti i te pāmahana tio, hei ārai hoki i te waikura. Heoi, ki te nui rawa te glycol, ka taea te whakaiti i te kaha wera motuhake me te whakanui ake i te matotoru, ka pā ki te whakawhiti wera me te mahi a te papu.
3. Te tikanga rere (te rere o te wai, te rere o te hau, me te rere o te hau)
Ka whakanui ake te rere o te pōrearea i te whakaranu, ka angiangi te paparanga rohe wera, ka whakanui ake hoki i te whakawhiti wera. He maha ngā hoahoa paipa me te whakamahana e whakamahi haumaru ana i tēnei āhuatanga.
4. Ngā āhuatanga o te mata me te paru
Ka taea e te unahi, te waikura, ngā putunga rānei i roto i ngā raina whakamatao me te whakamahana te mahi hei ārai wera, hei whakaiti hoki i te whakawhiti wera. I te taha hau, ka whakaitihia e ngā tara kua purua te rere o te hau, ā, ka whakararu i te kawe wera.
5. Te rerekētanga pāmahana (te kaha akiaki)
Ko te nui ake o te rerekētanga pāmahana i waenga i te mata wera me te wai, ko te nui ake o te kaha mō te whakawhiti wera. Nō reira, he mahi tā te thermostat ki te pupuri i te pāmahana mahi tino pai o te miihini: he wera rawa mō te tahunga pai, engari kaua e tino wera rawa kia wera rawa.
Te Whakawhitiwhiti i roto i ngā Pūnaha Whakamatao Hau
Ka whakamahia e ētahi miihini te whakamatao hau, inā koa ngā miihini iti, ngā miihini rānei he hoahoa māmā noa iho. I roto i tēnei pūnaha, ka tangohia te wera mai i te mata o te miihini mā roto i ngā tara e whakawhanui ana i te horahanga o te mata. Ka puta te whakawhiti wera mai i ngā tara ki te hau, mā te taiao, mā te akiaki rānei mā te pupuhi, mā te hau rānei.
Ko te angitu o te whakamatao hau e whakawhirinaki ana ki:
– te hoahoa o te tara (te matotoru, te tawhiti, me te horahanga o te mata),
– te ahunga me te tere o te rere o te hau,
– te ma o te mata o te tara.
Nā te mea he iti ake te kaha o te hau ki te kawe wera i tērā i te wai, he pai te whakamatao hau mō ngā kawenga wera iti ake, ngā tono rānei kāore e hiahiatia he whakahaere pāmahana tika pērā i te whakamatao wai.
Te Hiranga o te Whakawhitiwhiti mō te Pono o te Mīhini
Mā te whakawhiti hiko whai hua ka noho te pāmahana o te mīhini ki roto i te awhe haumaru. Ka taea e ngā pāmahana tino tiketike te hua:
– te patuki me te heke o te whai huatanga,
– te pakaru o te hinu whakahinuhinu,
– te kino o ngā gaskets me ngā hiri,
– ngā pakaru i roto i te pane o te rango,
– te pikinga o te kakahu o ngā wāhanga.
I tētahi atu taha, ehara hoki i te mea pai te mīhini makariri rawa, nā te mea ka iti ake te pai o te tahunga, ka nui ake te whakapaunga wahie, ka nui ake hoki ngā tukunga. Nō reira, me taea e te pūnaha whakamatao te whakahaere i te whakawhiti hiko kia rite ki ngā āhuatanga whakahaere.
Te Katinga
Ko te whakawhiti wera whakawhiti te kaupapa matua o te mahi a te pūnaha whakamatao o te miihini. Mai i te uhi wai i roto i te poraka miihini ki te radiator e tohatoha ana i te wera ki te hau, ka whakatauhia e te whakawhiti te tere o te kawe me te whakakorenga o te wera. Ko tōna whai huatanga ka pāngia e te tere rere o te wai, ngā āhuatanga o te whakamatao, te hoahoa o te awa me te hiku, me te ma o te pūnaha. Mā te mārama ki te ariā o te whakawhiti me ngā āhuatanga e pā ana ki a ia, ka taea e ngā kaihoahoa miihini te whakapai ake i te mahi whakamatao, ā, ka taea e ngā kaiwhakamahi te mahi tika i te tiaki kia mau ai te mahi miihini, kia pai ai, kia roa ai hoki.
Ki te hiahia koe, ka taea hoki e au te tāpiri i tētahi whakaahua o te tukanga mahi o te pūnaha whakamatao, he tauira tatau māmā mā te whakamahi i te whārite whakawhiti hau, te whakatairite rānei i te mahi a te radiator i runga i ngā rerekētanga o te tere o te pā me te horahanga o te hiku.
