Improving the thermal, productive, and environmental performance of a non-centrifugal cane sugar production module using a heat recovery system

Non-centrifugal cane sugar (NCS) is an unrefined sweetening product that has garnered growing interest in its commercialization for its nutritional attributes. However, NCS production modules present with thermal efficiency problems that may compromise the environmental and economic sustainability of the production process. Therefore, the objective of this study was to develop and implement a heat recovery system (HRS) within a traditional NCS production module to increase the production capacity and the overall thermal efficiency. A conceptual design of the system was carried out to recover residual heat from combustion gases. Later, a mathematical model was developed to predict the thermal performance of the HRS, and a techno-economic analysis was carried out as well. Finally, construction and experimental validation were carried out on an experimental NCS production module. The HRS consisted of a tube bank with staggered configuration and two coils located in the open exchangers (OEs) of the clarification and evaporation stages. The values predicted by the model, which represented average approximations of the experimental values, presented with a correlation coefficient of R-2 = 0.7378 and a mean relative error <= 8.13%. The implementation of the HRS achieved an increase in the capacity and overall thermal efficiency of the production module by 70% and 39%, respectively. Likewise, the emission rates of CO2 and CO per unit of mass produced by NCS decreased by 28.23% and 29.14%, respectively. The economic analysis indicated that the internal rate of return on investment does not differ significantly between the traditional system and the HRS, which allowed the financial cost to be corrected in a period of time less than or similar to that required by the traditional system.