Modeling of granular heat transfer in cryogenic grinding system: Black pepper seeds

Abstract

In the case of grinding of spices, the cryogenic counterpart is commonly used for obtaining a high-quality spice powder retaining the maximum thermo-sensitive flavoring compounds; however, the operational cost restricts its industrial application. Therefore, in a cryogenic grinding system, an insight into the micro-mechanical behavior and heat transfer phenomena of the granules is obligatory in improving the design aspects. The present study aims to represent the three-dimensional thermal transport process for black pepper seeds in a cryogenic grinding system (precooler and mill). The explicit numerical method based on microstructural approaches such as Discrete Element Method (DEM): utilizing a Hertz–Mindlin with conduction contact model was used to corroborate the granular flow and thermal profile of the seeds. The adequacy of the proposed granular heat transfer model was validated by the experimental data such as granular temperature as well as the flow pattern. Concurrently, it confirms the applicability of DEM as a capable tool to model the heat transfer along with a better understanding of particle mechanics in the cryogenic grinding system.