Rancang Bangun ROKOTALI (Roaster Kopi Tanpa Listrik) Dengan Evacuated Tube Solar Collectors

Abstract

The growth of the coffee industry and the high current price of coffee shows that coffee farming can contribute greatly to the income of coffee farming households in Indonesia. But in reality, the impact of such growth can’t be felt by coffee farmers who have limitation in technology, especially in roasting process that is still using the wok media and firewood stove. Uneven distribution of heat and unknown temperature in the process of roasting coffee beans have traditionally caused roasted roasted coffee beans so that coffee beans can only be marketed in the form of raw beans (green beans). This will certainly affect the income earned by coffee farmers. Solar energy is energy that can be utilized to be the energy source that is implemented in coffee bean cultivator. ROKOTALI (Coffee Roaster Without Electricity) is a tool that applies the working principle of solar collector with type Evacuated Tube Solar Collectors. Where this type will be made in a vacuum state and capable of generating heat at temperatures up to ≥200o C, but the heat is wasted or heat losses are relatively low. This coffee bean tube apparatus will be designed to rotate on a shaft with pillow block bearing and will be mounted pressure gauge and thermometer so that during the process of roasting, coffee beans get evenly distributed heat to produce good roasted coffee beans. In this test will be tested the effect of vacuum space in improving and maintaining high temperature in the process of heat transfer with solar energy source that is useful to roast coffee beans to reach the level of light roast and testing the level of effectiveness of this tool when compared with traditional coffee beans or conventional grill . Based on the tests that have been done, obtained efficiency of 73.28% for the collector tube when the vacuum pressure and only 44.34% when not vacuum. The temperature rise during the vacuum state test is only 11.2°C while the tube under vacuum can reach up to 42° C with respect to ambient temperature. With this experiment the roasted coffee beans can be improved in quality, but with the advantages do not need to increase the burden of production costs.