烘豆機保溫

 討論到烘豆機保溫。

烘豆機通常會有一層保溫，從內到外分別是烘焙桶→內隔板→保溫棉→外飾板。 保溫層有厚有薄，影響的是烘焙時散熱的速度，越厚散熱越慢。 外飾板的溫度來自於烘豆機前後面板的傳導熱，所以前後面板的厚度影響烘豆時的保溫，尤其是正面板，正面板越厚，保溫越好。 進入烘焙室的空氣被燃燒器加熱的越完整，烘焙室內的溫度越穩定。所以強調的是烘焙室的密閉效果，讓空氣只能通過燃燒器才進入烘焙室。 環境氣溫影響機體散熱的效率，濕度影響火焰燃燒的熱值。 單層鍋、雙層鍋兩者的差異更多是連續烘焙時的穩定度。

大多數人對於烘豆機保溫多注重烘焙桶的厚薄與材質等等，有趣的是，烘焙桶的厚薄與豆量比較有關聯，1kg的烘焙桶對於600g的生豆，保溫的效果比起3kg烘焙桶對於1.8kg還要高。 烘焙桶保溫其實來自於烘焙桶本身的材質，材質密度越高，保溫效果越好，但保溫仍然有其極限，因為烘焙桶本身的重量是固定的，吸熱也是固定；以入豆溫180度C，固定的熱能提供給50%烘焙量或80%烘焙量，生豆能吸收到的熱能是不同的。 有趣的部分在於半熱風烘豆機的烘焙過程中，130度C前來自鍋體的熱能，而進入一爆前的鍋體溫度並非跟生豆溫度一致，許多的操作手法都是試著維持鍋體的溫度，在烘焙過程中穩定烘焙桶的溫度通常是穩定烘焙的主要目的。

Probat的設計為主軸的烘豆機，保溫層都有一定的厚度，Probatino 1.2的保溫層約40mm。 重點在於進入烘焙室的氣流，被限制成完全經過火排加熱才能進入烘焙室，於是烘焙室的基本溫度通常不會太低，火焰距離烘焙桶較遠，大火都不會接觸到鍋體。 雖說鍋體還是有一定的高溫，這裡卻採用了密閉雙層鍋的設計，強調熱風比例較高。 但為了維持火焰二次燃燒的穩定，還有穩定的熱風比例，固定抽風是必需的；所以形成：固定強抽風→足夠的空氣→穩定的火焰→高熱風比。 而連續烘焙時，即使雙層鍋體仍會累積上一鍋的蓄熱，雙層鍋的空氣層溫度也會逐漸提高，如何穩定內鍋的溫度避免過高，這就是設計上的細節。 相較於可變風門的單層半熱風烘豆機的特徵：利用風門微調傳導熱與對流熱之間的比例來調整烘焙的節奏；雙層鍋的設計導致烘焙上能調整的範圍就侷促了許多，而這種侷促也能算是一種穩定。 有點「萬物皆可蒸，致於蒸了好不好吃，至少是食物的原味。」的作法。 利用固定的烘焙模式去挑選適合的生豆。 而可調風門的半熱風烘豆機，大概是：「每種食物都有其最美味的作法，只是需要被發現。」 了解生豆的品質去抓出對應的烘焙模式，表現該生豆獨有的風味。

### Discussion on Roaster Insulation

Roasters usually have an insulation layer, structured from inside to outside as: roasting drum → inner partition → insulation cotton → outer panel.

The thickness of the insulation affects the rate of heat dissipation during roasting—the thicker it is, the slower the heat is lost.

The temperature of the outer panel comes from the conductive heat of the front and rear panels, so their thickness influences insulation during roasting, especially the front panel. The thicker the front panel, the better the insulation.

The more thoroughly the air entering the roasting chamber is heated by the burner, the more stable the chamber temperature becomes. Therefore, the emphasis is on sealing the roasting chamber so that air can only pass through the burner before entering.

Ambient temperature affects how efficiently the machine dissipates heat, while humidity affects the calorific value of the flame.

The difference between single-wall and double-wall drums lies mainly in temperature stability during continuous roasting.

Most people focus on the thickness and material of the roasting drum for insulation. Interestingly, drum thickness is more closely related to batch size. For example, a 1 kg drum roasting 600 g of green coffee has better insulation than a 3 kg drum roasting 1.8 kg.

Drum insulation actually comes from the drum material itself: the denser the material, the better the insulation. However, insulation has its limits because the drum’s weight is fixed, and so is its heat absorption. With a charge temperature of 180 °C, the same fixed amount of heat is shared between a 50% batch size and an 80% batch size, but the amount of heat absorbed by the beans differs.

An interesting point in semi-hot-air roasters is that before 130 °C, most heat comes from the drum body. The drum temperature approaching first crack does not necessarily match the bean temperature. Many operating techniques aim to maintain drum temperature, as stabilizing the drum temperature during roasting is usually the key to stable results.

Probat’s drum roasters are designed with a fixed insulation thickness—for example, the Probatino 1.2 has about 40 mm of insulation.

The focus is that airflow entering the roasting chamber is restricted so it must pass through the burner first, ensuring the chamber temperature never drops too low. The flame is kept at a distance from the drum, so even with high fire, the drum is not directly exposed.

Although the drum still maintains a high temperature, a sealed double-wall drum design is used, emphasizing a higher proportion of hot air.

To stabilize secondary combustion of the flame and maintain a consistent hot-air ratio, constant exhaust is necessary. This creates the sequence: fixed strong exhaust → sufficient air supply → stable flame → high hot-air ratio.

During continuous roasting, even with a double-wall drum, residual heat from the previous batch accumulates, and the air layer between the drums gradually rises in temperature. Managing the inner drum temperature to prevent overheating becomes a design detail.

Compared to single-wall semi-hot-air roasters with adjustable dampers—which allow fine-tuning of the ratio between conductive and convective heat to control roasting dynamics—the double-wall design limits the range of adjustments. Yet this limitation can also be seen as a form of stability.

It is somewhat like saying: “Everything can be steamed; whether it tastes good or not, at least it preserves the food’s original flavor.”

The fixed roasting mode is then used to select beans that are well-suited to it.

On the other hand, semi-hot-air roasters with adjustable dampers reflect the philosophy: “Every food has its most delicious preparation—it just needs to be discovered.”

Here, understanding the quality of the green coffee allows roasters to find the matching roast profile that best expresses each bean’s unique flavor.