溫暖享受,節能生活🤗
今天我們就用影片方式讓你輕鬆理解的方式
SUPER VE超級真空保溫熱水瓶如何為生活帶來更便利的功能吧!
產品介紹:
http://www.zojirushi.com.tw/product/electric-water-boilers/cv-wff40
#全台最省電熱水瓶 #能源效率第一級
同時也有1部Youtube影片,追蹤數超過127萬的網紅Survival Skills Primitive,也在其Youtube影片中提到,Hi. This is the second episode when we were on a deserted island. In this video we find an important source of freshwater to sustain life on a deserte...
boilers 在 Lau Kin Lam - 林仔 Facebook 的最讚貼文
[世界冠軍教室]
我作為一個超頻玩家
我係成日拎HKEPC OC LAB嘅液態氮來玩洗手
TVB柒野多係常識吧
#無睇CCTVB好耐
[返屋企睇paper寫無聊野 orz]
液態氮會辣傷手?
[edit: 本身冇諗過咁多人會留意呢個status。而家既然有咁多人睇到,咁都要講返啲有關安全意識嘅野。雖然照劇情嚟講,Liquid Nitrogen濺到確實係唔會有大礙,但係亦都唔想令大家覺得處理Liquid Nitrogen係完全安全、毫無危險嘅事。Liquid Nitrogen處理不當,係真係會凍傷。另外,喺密閉空間使用,或大量Liquid Nitrogen氣化時,係有機會引至窒息。所以點都要謹慎小心。]
今日食飯睇到《親親我好媽》嘅呢一段,講到話Hayden(劇中角色)畀液態氮淋到,所以灼傷左。其實呢段本身係無關痛癢嘅劇情,不過我一睇就覺得好好笑(不過都唔怪佢嘅,哈哈),因為咁嘅情況基本上係唔會灼傷。
作為一個每日同一大枝Liquid Nitrogen共處一室嘅人(仲間唔中會拎嚟玩),我諗我或多或少都有啲權威去討論下 XD。
Liquid Nitrogen係真係好凍,我諗呢點好多人都知。佢嘅沸點係 −195.79 °C。 即係當溫度高過 −195.79 °C,氮就已經會變返做氣體。亦即係話,氮喺液態嘅狀態係低過−195.79 °C,絕對係難以想像嘅溫度。(對比一下,正常雪櫃冰格應該係大概-20°C)。
你可能會諗,我人體37°C; 手指表層皮膚雖然低啲,但係都有大概30-32°C到 [ref 1]。相對於Liquid Nitrogen,呢度有成200幾度嘅差異;我平時掂一掂滾水(100°C)都會辣傷啦,但係滾水同我體溫都係差60幾度,而家掂Liquid nitrogen 咪好傷?
我可以話你知,我一個月好多時都會有幾次直接伸手指落Liquid Nitrogen度拎啲野(當然都有戴手套嘅,不過係好薄嗰隻,掂到滾水會傷嗰種。)咁點解冇事呢?
呢個係因為有一個叫Leidenfrost effect嘅現象。嗱,個名就唔係因為關凍事,所以叫做Leiden-FROST,而只不過係發現呢個effect嘅人叫Leidenfrost,佢喺1756年嘅"A Tract About Some Qualities of Common Water"討論過呢個現象。
喺講呢個effect之前,想問下大家有冇見過一種情況:就係當你燒熱左隻鑊,然後你加一滴水落去,你會發覺粒水珠會跣嚟跣去,好似氣墊球咁,又唔會一下子就蒸發消失?
呢個就係因為有Leidenfrost effect。你可能會問:咁關Liquid Nitrogen咩事?等多陣就會知,因為佢都係關乎到Leidenfrost effect。當一滴水掂到高過100度嘅鑊(最好係再高啲,約160度以上),佢最下層嘅水會急速變成水蒸氣,呢個過程叫film boiling。而基於氣體係好差嘅傳熱媒介,所以就好似形成左一層保護膜咁,即使下面溫度好高,都唔能夠快速同直接影響到上面嘅水份子。十九世紀有人試過,當個放一滴水落加熱咗嘅鐵度,當嚿鐵嘅溫度係 168 °C,粒水滴可以維持到152秒[ref 2.]
咁呢個關Liquid Nitrogen 咩事呢?好簡單,你可以將啲液態氮睇成係水,你隻手就係熱辣辣嘅鑊。當液態氮一掂到你隻手,佢就好似掂到啲超熱嘅野,會即刻氣化。當佢氣化嘅時候,基於氣體傳熱能力差,佢就會喺你皮膚表層形成左一層保護膜。所以你係唔會直接掂到−195.79 °C(或以下)嘅嘢架。
不過雖然係咁講,Liquid Nitrogen都唔係啲應該亂掂嘅野,因為如果接觸時間稍為加長,又或者太大範圍咁接觸[ref 3],咁樣Leidenfrost effect都未必救到你,都真真真真係會好傷。所以,要處理Liquid Nitrogen,都係小心啲好[ref 4]。有潛在危險嘅嘢,小心駛得萬年船,輕視好多時都係意外嘅源頭。要特別提一樣嘢,雖然掂到Liquid nitrogen係有Leidenfrost effect幫你擋一擋;但係如果你係掂到一啲之前被Liquid nitrogen整凍咗嘅固體(例如裝住Liquid nitrogen嘅容器內側,又或者你用Liquid nitrogen雪住嘅嗰啲嘢),你就真係直接掂住−195.79 °C,而唔會有Leidenfrost effect,所以會好快凍傷,要好小心。
但係講返濺到Liquid Nitrogen落手呢,其實你只會覺得手背涼一涼(我成日都會試到),就係咁架咋。就算真係倒左Liquid Nitrogen落手,因為佢會好快跣離你隻手,所以個接觸時間都係好短。只要個量唔太多、冇持續掂住,其實都唔會有好大問題;就絕對唔洗好似劇入面要去包紮晒咁嘅。
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p.s. 唔信冇事?睇片啦!
How Fast Will Liquid Nitrogen Freeze Your Skin?
https://www.youtube.com/watch?v=jnsDdJwW-KU
(呢段片有試下可以掂幾耐,幾多資訊。)
Hand vs. Liquid Nitrogen and the Leidenfrost Effect
https://www.youtube.com/watch?v=gjsMV1MglA4
(好似係最多view嘅片,09年拍嘅)
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[ref 1]
"Seasonal differences in finger skin temperature and microvascular blood flow in healthy men and women are exaggerated in women with primary Raynaud's phenomenon"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2014513/
[ref 2] Two Lectures: The Construction of Boilers, and on Boiler Explosions, with the means of prevention, Pg 18
https://books.google.com.hk/books…
[ref 3] 如果個droplet太大,Leidenfrost effect 會變得unstable
http://www.annualreviews.org/…/…/annurev-fluid-011212-140709
[ref 4]
Section 7: Safe Handling of Cryogenic Liquids
http://ccehss.berkeley.edu/section7-cryogenic-liquids
boilers 在 Survival Skills Primitive Youtube 的最佳解答
Hi. This is the second episode when we were on a deserted island. In this video we find an important source of freshwater to sustain life on a deserted island. We caught fish to eat. We take fresh water from seawater by evaporation method. We use bamboo pipes and soil to make water boilers. We will continue to do the next episode on the deserted island. Everyone subscribe to the channel to follow the latest videos. Thank you.
Channel: https://www.youtube.com/channel/UChUP6B_3zcdFYZnOdMM21og?view_as=subscriber
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