Experimental investigation of a novel waste heat based food drying system

World Food Program reports that more than 821 million people are subjected to acute hunger despite sufficient amount of food being produced. One of the underlying reasons is the food wastage due to poor preservation techniques and the energy cost of the established processing methods. Drying techniques are an effective means for reducing post-harvest food loss. However, the existing industrial drying techniques consume 20-25% of the energy used in the food processing chain. A system that utilizes the waste heat recovered from a diesel engine exhaust flue gas is proposed and an initial prototype tested. The system requires no external energy to operate the drying process; hence no CO2 is generated as a result of this process. Furthermore, the entropy is reduced by 0.206 kJ/kg.K as the overall thermal efficiency increases by 8.46%. It is estimated that the payback period is in the range of 321 days. Drying experiments were conducted to assess the dried food quality of five different staple food products, i.e. potato, pumpkin, carrot, radish, and apple. The drying performance (moisture removal rate) and product quality (Color analysis and Vitamin C analysis) conformed to the current industry standard. The overall performance assessment suggests that the system has the potential to reduce current levels of emission in food drying process and could be a stepping stone towards the development of energy-efficient food preservation technique.