每次過節，回國前總是為禮品發愁。這回俺發現了理想禮物。
有點兒空兒的時候，理工男喜歡自己動手給自己造玩具 （見 【1】和 【2】）。但這個東東：Burnout 恒溫咖啡/茶/熱水杯（是的，不僅保溫： 是恒溫！） 是俺從網上買的。
大概是這一兩年剛出的最新產品，“魔杯”讓俺喜愛上癮，辦公室家中各有一個，現在很少離手：100度 （C） 的水倒入，1-2 分鍾內降至最宜喝的 60C，並恒溫在此五六個鍾頭。一杯在手，I can have a sip of coffee, tea, or hot water of perfect temperature, whenever and wherever I wish. 真的會上癮的。
Amazan 上有賣。查 ”Burnout mug“ 就能找的。
俺找了個包，出門到處都帶著。還送給幾個給朋友和同事做禮物，用過的都很喜愛 。我2018年底送了秘書一個，結果聖誕時她給她的老爹老媽老弟一人買了一個。Amazon 的 Customer Review 也很好：
杯子的密秘是用了變相材料層吸溫恒溫。他們的網站上有解釋 （Amazon上還有另一品牌的，好象具相同功能，但那個要價149刀，還需要電池電源來保溫恒溫。這個Burnout什麽都不用）。理工男覺得Burnout的工作原理應是如下：
From their website, it is clear that a Burnout mug is firstly a normal thermos mug, but with an added layer filled with phase-changing material (PCM). Therefore, so far as keeping the heat in, it functions exactly like a normal thermos mug.
However the added PCM layer will firstly absorb the excessive heat quickly to cool the beverage down to optimal drinking temperature, and then keep this amount of heat within it through changing its state (or change of phase, like when water boils to absorb heat to become steam).
Acorrding to thermodynamics, this amount of heat cannot just disappear, so it keeps the beverage at the constant temperature by gradualy releasing the heat back to the beverage - kind like having a built-in heater - untill all heat is used up and the PCM then goes back to its original state.
Scientifically, therefore, a Burnout mug firstly cools the drink down quickly to the optimal drinking temperature, and then keeps the beverage at this temperature for hours, all done "naturally" without having to use batteries, power-supplies, and APPs to regulate the temperature.
Economically, it helps reduce costs of beverage by eliminating waste due to thrown-away cold coffee/tea.
Environmental, in the long run it should help reducing food waste which is a significant issue global-wise.
Finally rom an engineering point of view: simple, elegant, and very clever!
