Principle of three heat conduction modes of coffee roaster which brand of coffee roaster should be disassembled?

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Three heat conduction modes of roaster

Direct fire:

The biggest feature is that the drum has a small hole, the fire can directly burn the bean table, it is easy to appear scorched black spots, or scorched beans, the heat is not easy to control. Often scorched the bean table, cut open the beans, but the bean stamens are not fully ripe. At present, direct-fire roasters are rarely seen, but if used properly, the aroma is thick.

Semi-direct fire:

That is, the semi-hot air baking machine, the contact surface between the drum and the flame has no hole, and it looks like a closed drum, but in fact, there is a small hole in the innermost side of the drum, which can guide the hot air into the furnace and assist the metal heat conduction of the drum to make the beans bake more evenly. Semi-direct fire is the most commonly used roaster for fine coffee in China and the United States. Bobart in Germany is best at making semi-hot air roasters, ranging from a minimum of 1.2 kg to a maximum of 120 kg. In addition, there are infrared heating tubes to bake beans, the United States is the best at this, but the baking time is slightly longer. The semi-direct firing roaster can be as small as 500 grams per furnace, but the maximum production capacity of each furnace rarely exceeds 120 kg. The semi-direct firing type is more common in 2 kg, 5 kg, 6 kg, 12 kg, 15 kg and 20 kg per furnace.

Hot air flow:

Michael, the American coffee roaster. Siviz strongly advocated the hot gas baking machine in the 1970s, using strong high temperature hot air to blow the beans in the oven to make the beans fly, the heat conduction effect is the best, it is the most time-saving baking method and the baking speed is fast. Siviz has spared no effort for decades to criticize that drum roasters are easy to scorch beans and often smell of dirty smoke. Metal flavor, drum roaster is the most popular machine at present. It depends on whether the furnace operator controls the heat correctly. Hot air flow has the advantages of fast and time-saving, clean and bright coffee flavor, but semi-direct fire style has the advantages of thick finish and sweetness. The semi-direct fire type requires professional roasters to operate with so many time-consuming and labor-consuming shortcomings. For beginners, I do not know how long it will take to get out of the roast. if you use a hot-air roaster, it will be much easier to operate and will not change the baking degree according to different people.

The biggest advantage of the hot air flow roaster is that the weight loss ratio of cooked beans is less than 1-2% of the semi-direct fire type, which is very important for large roasters, and shortens the working hours, so the general large coffee roasters almost all use the hot air flow roaster, which can be called a giant roaster with hundreds or thousands of kilograms per furnace, but the model can also be as small as a household popcorn machine, about 100 grams per furnace. The size is very flexible, which makes the hot air machine has the most development potential.