Experimental Investigation of Greenhouse Coffee Beans Drying System Using Solar Air Heater Enhanced with Reverse Absorber Flat-Plate Collector and Nanofluid coated Absorber

Abstract

Coffee Bean Is One Of High Commodity From Ethiopia. The Drying Process Is An Important Step In Its Production. The Process Is To Determine The Moisture Level Of The Coffee Bean Which Also Affects The Quality Of The Coffee. However, This Process Takes A Long Time. The Drying Process Of Coffee Cherries By Sun Drying Needs Two To Three Weeks To Produce Dry Coffee Beans. To Facilitate The Drying Process Solar Thermal System Is Designed. The Main Aim Of This Study Is To Develop And Experimentally Test The Performance Of Solar Greenhouse Washed Coffee Dryer. The Dryer Is Designed Based On Requirements To Dry 5kg Of Washed Coffee Beans And The Study Set Up Consists Of Solar Collector And Greenhouse With Their Axillary Components. The Greenhouse Consists Six Equally Spaced Tray Having Dimensions Of 60 Cm X 60cm And To Enhance The Out Temperature Of Solar Collector Black Ink With 3% Concentrated Nano fluid Paint/Coat, Double Pass, And Reverse Back Reflector Are Used. Since Coffee Needs Continuous Drying Thermal Energy Storage Is Provided To Store Heat And Release When It Is Need. Tube And Shell Type Heat Exchanger Is Designed And Manufactured To Store 9 Kg Of Paraffin Wax. A Comparative Study Of The Performance Of A Greenhouse With And Without Enhanced Solar Collector With Reverse Absorber And Nanofluid Absorber Coat And Thermal Energy Storage Was Conducted, And The Result Shows That Integrating The Reverse Absorber And Nano fluid Coted Absorber Collector To Greenhouse Increases Change In Inlet Air Temperature, Thermal And Exergy Efficiency Of The Greenhouse By An Average Value Of 6 ???, 7% And 0.53%, Respectively. The Addition Of Thermal Energy Storage Reduces The Air Temperature Fluctuation In Afternoon. Washed Coffee Beans Was Dried Within 16 H And 24 H, Reducing The Moisture Content From An Initial Value Of 61% (Wet Basis) To A Final Value Of 11.6% (Wet Basis) And 12.1%( Wet Basis), In The Greenhouse Integrated With Enhanced Solar Collector And Solo Greenhouse, Respectively. The Computational Fluid Dynamics Analysis Was Performed And Their Model Validation Lies In Acceptable Range. Finally, An Economic Analysis Was Carried Out And The Pay-Back Period Of The Dryer Was Found To Be 2.04 Years