Design and numerical investigation of heat transfer characteristics in annular cooking bowl using food graded heat transfer fluid for NCCS

Abstract

The design of non-centrifugal cane sugar (NCCS) preparation methods is paramount for jaggery production. A numerical analysis is performed on an Annular Cooking Bowl (ACB) in which food graded heat transfer fluid (FHTF) is used as heat transfer fluid. The effect of mass flow rates (10 lpm, 15lpm and 20 lpm) and inlet temperatures (403 K, 413 K, 423 K and 433 K) are studied. Transient numerical simulations are conducted to predict the temperature of inner ACB surface and sugar cane juice, heat transferred from FHTF to bowl for various inlet conditions. In addition to, thermal efficiency of ACB and its effectiveness is estimated. The present approach shows that it can replace the traditional sugar cane juice boiling methods with NCCS unit, which eliminates bagasse as fuel and reduces the carbon emissions. From the results, highest ACB’s thermal efficiency is seen with FHTF inlet temperature of 433 K at low mass flow rate. However, ACB’s thermal efficiency decreases drastically with increasing in mass flow rate due to uncontrolled heat losses to surroundings. It is concluded that ACB’s thermal efficiency is observed as 21 % when FHTF is suppled 10 lpm and 433 K. It is seen that at temperature of 433 K and mass flow rate, 15 lpm and 20 lpm ACB’s thermal efficiency is registered as 17 %, and 13 % respectively. Results reveal that higher heat transfer rates are seen with food graded heat transfer fluid, and relatively high convective losses are observed, which further reduces the bowl thermal efficiency.