台北時間3月17日，特斯來開啟了Model Y的交付，盡管由於新冠病毒的影響，全球各地商業營運或多或少都遭受影響，但是特斯拉缺開啟了Model Y的上市交付，此舉對於新能源市場來說無疑不是大的提振。
從目前透漏出來的資訊來看，Model Y相比於此前的Model S、Model X及Model 3來說提供了一些獨特的解決方案那就是熱泵系統的搭載。
那麽什麽是熱泵系統呢？
根據特斯拉的使用者手冊如圖1所示，熱泵系統能最大化效率，位於左前輪左側，且告知了使用者在低溫情況下當車輛進行加熱或者快充的時候空調壓縮機及前端風扇工作會產生噪音。
圖1：特斯拉使用者手冊介紹
從圖中我們只能看到空調壓縮機，具體的熱泵系統是怎樣的目前所知資訊甚少。據國外特斯拉的死忠粉youtube播主Andy Slye視訊介紹，詳細的科普了什麽是熱泵，以及熱泵系統的基本原理以及Tesla套用熱泵的原因。（原文如下，詳細的介紹了什麽是熱泵，以及熱泵的優劣，本人就不做轉譯）
「The SECRET Model Y Feature That No Other Tesla Has!
One of the biggest problems with Tesla vehicles up to this point may have just been fixed with this new feature on the Model Y that Tesla decided to hide from us until now. Driving a Tesla can be somewhat scary because of 「range anxiety」 which means you’re worried about running out of battery before reaching your destination.
In cold winter conditions an electric vehicle can lose up to 40% or more of its estimated range. In February I was on a road trip in my Model 3 and lost a lot of my estimated range while driving highway speeds when it was around 30 degrees F.
Electric vehicles lose range in cold temperatures because: colder air which means more drag, energy loss from heating the battery, and the energy used to warm up the vehicle’s cabin. All Tesla vehicles (prior to Model Y) warm the cabin through a resistive heating system where electricity is sent through a resistive heating element, which creates heat that’s blown out of the air vents. .
This means for an EV (like my Model 3) to warm up the cabin, energy from the battery must be used which of course decreases the estimated range. Electric resistance heating is considered 100% energy efficient in the sense that all the incoming electric energy is converted to heat.
Well it doesn’t get any better than 100% efficiency, right? Actually there is something better. It’s called a heat pump, and the Model Y is the first Tesla to have one. In the manual it says 「Model Y uses a heat pump to maximize efficiency; therefore, your air conditioning compressor and external fan may run and make noise even when the outside temperature is cold and your vehicle is heating or Supercharging"
A heat pump can be thought of as an air conditioner that has the ability to work in reverse. An air conditioner works by using refrigerant to trap the heat inside of an area, then move it outside. A heat pump works in exactly the same way, only it has a reversing valve which allows it to reverse the flow of the refrigerant and heat an area when it's cold out.
Heat pumps help efficiency because they move heat rather than generate it. The electricity is used by the compressor to send refrigerant around the system and capture the heat from outside, then bring it inside. It can do this because the refrigerant has an extremely low boiling point. And the best part is a heat pump can typically produce around 3kW of thermal energy for every 1kW of electrical energy resulting in an 「efficiency」 of 300%.
So this 「300% efficiency」 sounds awesome, right? Well, heat pumps are usually not effective below a certain temperature range and typically don't work well in extremely cold temperatures. However, heat pump technology has recently improved, and in some cases can be rated for outdoor temperatures as low as -4°F.
Why is the Model Y’s heat pump so important? A heat pump should be able to heat the cabin while using less energy which should lead to longer battery range when driving in cold temperatures compared to all the other Tesla models. This is a huge advantage!
Why didn't Tesla implement this before the Model Y? Most likely it was because a heat pump adds cost, complexity, and weight. But for a Tesla, which already has an air conditioner, a heat pump seems like a no-brainer because the added complexity would be pretty minimal.
The biggest questions now are: where does the heat come from in the Model Y heat pump and does the Model Y always use a heat pump or does it alternate between heat pump and resistance heating? From the Model Y manual it looks like it could be taking excess heat from the motor and battery, which would probably make it efficient even in extremely cold temperatures which would be nice. Teslas already have the ability to use the motors to heat the battery, and if the heat pump is powerful enough it can potentially heat both the battery and the cabin.
Either way, I can’t wait to see how the Model Y handles driving in the winter. It sounds like it will be the best Tesla for that task. 」
針對特斯拉的熱泵方案，我們可以進行幾個方面的猜測。
猜測一：直接式熱泵「三換」方案
如圖2所示，Tesla的Model 3 制冷如傳統車用空調系統，制熱采用了一個7Kw的風暖PTC，這樣的系統設計很簡潔，相對而言零部件數量少、復雜程度低。根據目前主流的熱泵方案我們大膽可以猜測，Model Y有可能采用圖3類似的熱泵系統，即其熱泵系統是由HVAC內增加一個室內冷凝器做為熱泵空調的熱源向乘員艙加熱。此種方案為目前主流方案NISSAN、比亞迪等都是類似這樣的方案。
圖2：Tesla空調系統HVAC
但是考慮到現行的熱泵系統受制冷劑的限值，在及低溫下加熱情況不太理想，可能還需要輔熱，結合現在特斯拉的設計可能輔一小功率的風PTC進行低溫環境下的輔熱。
圖3：典型的直接式「熱泵」三換系統
猜測二：四通閥熱泵方案
透過四通換向閥改變制冷劑的流動通道，改變制冷劑流向，直接將室內外換熱器功能進行切換，從而達到制冷及制熱的功能。三花作為此前特斯拉制冷劑閥的供應商，在閥體技術上的積累是深厚的，因此開發成熟的四通閥進行流向切換或授權以成熟套用，透過四通閥來實作熱泵的功能，減少了一個「三換」方案的室內冷凝器，相應的管路傳感器等都會減少，並且在系列車型上對於HVAC變動及相應開發減少了很多工作量。
如下圖所示為一種利用四通閥設計實作的熱泵空調系統：
圖4：一種四通閥設計的熱泵系統
猜測三：補氣增焓式熱泵方案
補氣增焓是指壓縮機采用兩級節流中間噴射技術，采用閃蒸器進行氣液分離，實作增焓效果。它透過中低壓時邊壓縮邊噴射混合冷卻，然後高壓時正常壓縮，提高壓縮機排氣量，達到低溫環境下提升制熱能力的目的。
補氣增焓技術的壓縮機多了一個吸氣口，透過產生蒸汽來冷卻主迴圈的制冷劑，蒸汽從第二個吸氣口進入壓縮機，其壓縮過程被補氣過程分割成兩段，變為準二級壓縮過程。補氣降低排氣溫度，同時降低其排氣過熱度，減少冷凝器的氣相換熱區的長度，增加兩相換熱面積，提高冷凝器的換熱效率，當蒸發溫度和冷凝溫度相差越大會產生越好的效果，所以在低溫環境下效果更明顯。
如下圖5所示，為豐田普銳斯的補氣增焓熱泵系統示意，此種系統制冷劑管路較為復雜，整車前艙布置繁雜
圖6：豐田補氣增焓熱泵系統
猜測四：間接式整合熱泵方案
與直接式不一樣的是，間接式熱泵空調系統將空調箱內部冷凝器拿掉，將其布置在機艙內，我們稱之為外部板式換熱器。最典型的例子就是BMW I3，如下圖所示
圖6：BMW間接式熱泵系統
如下圖5所示，為一種整合式的熱泵方案，在此種方案中去除了傳統的氣液換熱的散熱器冷凝器和蒸發器雞兒采用了「液液換熱」的板換代替，此種形式將極大的最佳化空調變冷劑系統的管理，更多是透過水管進行整車的熱量互動。
圖7：一種高度整合的間接式熱泵系統
考慮到Tesla在Model 3上套用的Supper Bottle專利技術，這一技術很有可能在Model Y上進行延續，根據Tesla對熱泵的描述，其熱泵系統可以對乘員艙及電池包進行加熱，進而套用高度整合式的熱泵系統將能有效的將電機液冷回路及電池液冷回路連線起來進行綜合管理。
近日，銀輪股份公告說，子公司上海銀輪熱交換系統有限公司與特斯拉、特斯拉（上海）有限公司簽訂了產品零件或服務通用條款合約。特斯拉將向公司采購汽車換熱模組產品。不知這其中是否涉及到」液液板換」（大家見到最多的當屬電池Chiller，此種即為制冷劑路和冷卻液路進行熱量交換）相關
綜上，本人認為第四種可能性較大，特斯拉作為新能源汽車的當之無愧技術前沿，其新的熱泵技術是否能帶來行業變革，我們拭目以待。
