Nearly a billion kilowatt hours of energy are expended annually by the food industry in Germany for drying and roasting coffee beans, nuts, and fruits. Finding the optimum temperature and process time is the key to major potential energy savings. Now, the German National Metrology Institute (PTB), using a compact temperature sensor from HBM, has developed a new process for measuringthe thermal conductivity and thermal diffusivity of small objects such as coffee beans.
Until now, the thermal capacity of coffee beanscould only be determined using pressed ground coffee. The structure of the material plays no role for this material constant. Thermal transport properties, on the other hand, are structure-dependent. Therefore, they can only be measured with sufficient accuracy using whole coffee beans. Since coffee beans are too small for previous measurement technology, thermal conductivity and thermal diffusivity could only be roughly estimated.