Solar-biomass hybrid dryer enhanced by the Co-Gen technique

Solar-biomass hybrid dryer systems use biomass burners as the backup source of heat to warm the air prior to charging it in the drying chamber. The flue gas produced from biomass combustion has a considerable amount of heat and is exhausted into the ambient. This article presents a new approach that uses the cogeneration (Co-Gen) technique in utilizing the flue gas exhausts from the burner. This approach enhances the circulation of warm air in the drying chamber and eliminates the need for an extraction fan. The exhaust flue is simply injected inside the chimney at the upper part to increase the natural stack effect caused by the rise in temperature and reduction in pressure. This technique is investigated experimentally; the dryer is tested with and without Co-Gen by drying red chili. The system efficiency of the biomass mode using Co-Gen is enhanced by 6%. In addition to enhanced efficiency, the main advantage of this approach is the elimination of electricity, given that the Co-Gen replaces the electrical extractor. This advantage renders the hybrid solar drying applicable in rural areas.