DESAIN, ANALISIS SUHU, DAN KERATAAN BIJI PADA MESIN SANGRAI KOPI

Indonesia is a country with abundant wealth especially in plantation areas, one of Indonesia's plantation products is coffee. The seeds of the coffee plant are used to be processed into coffee drinks. Good quality coffee is obtained from a proper roasting process, the roasting process is a process that reducing the moisture content to give out the distinctive aroma and taste. If the roasting process is not done properly, it will cause an overroast of the coffee beans, this happened because coffee beans are not stirred properly during the roasting process or the temperature indicates was not accurate. Therefore research of temperature and evenness analysis of coffee beans are carried out by designing a 1 kg roaster machine. In this research, a coffee roaster with 1 kg capacity has a tube with 224 mm diameter, 230 mm height, and 4 mm thickness. Thus tube was analyzed using Computational Fluid Dynamics (CFD) software to determine the temperature inside the roaster tube with variations material like SS 304 and iron cast with 4 mm and 6 mm of thickness, and analysis the evenness of coffee beans when stirred using Discrete Element Method (DEM) software by comparing two types of stirrers. Based on the results of the research, it was found that iron cast material can reach high temperature faster than SS 304, with an average of air temperature 466 0C for SS 304 4 mm, 266 0C for SS 304 6 mm, 524 0C for iron cast 4 mm, dan 460 0C for iron cast 6 mm. Roaster drum thickness is very important therefore, material SS 304 should be used 4 mm thickness to reduce heating time and existing heat spots, while iron cast should be used 6 mm thickness, this is because the iron cast will be got cracks if the thickness not thick enough. The shape of the second stirrer with 6 blades got 118,59% better evenness compare to the first stirrer which only 4 stirrers on edge of the wall tube