Determining the thermal mode of bio-based raw materials composting process in a rotary-type chamber

G e n n a d i i G o l u b Doctor of Technical Sciences, Professor Department of Tractors, Automobiles and Bioenergo Resources* I v a n G r a b a r Doctor of Technical Sciences, Professor Department of Processes, Machines and Equipment in Agroengineering** D m y t r o D e r e v y a n k o Doctor of Technical Sciences Department of Processes, Machines and Equipment in Agroengineering** A n n a Н o l u b e n k o Assistant Department of Electrification, Automation of Production and Engineering Ecology** Е-mail: anikagogobl@gmail.com O l e k s a n d r M e d v e d s k y i PhD Department of Processes, Machines and Equipment in Agroengineering** V i a c h e s l a v C h u b a PhD, Associate Professor Department of Tractors, Automobiles and Bioenergo Resources* O l e k s a n d r S o l a r o v PhD, Associate Professor*** T a m a r a B i l k o PhD, Associate Professor Department of Occupational Safety аnd Environmental Engineering* M a k s y m P a v l e n k o PhD, Senior Lecturer Department of Tractors, Automobiles and Bioenergo Resources* A n a t o l i i S a i e n k o Senior Lecturer*** *National University of Life and Environmental Sciences of Ukraine Heroyiv Oborony str. , 15, Kyiv, Ukraine, 03041 **Polissia National University Staryi blvd., 7, Zhytomyr, Ukraine, 10008 ***Department of Tractors, Agricultural Machines and Transportation Technologies Sumy National Agrarian University Herasyma Kondratieva str. , 160, Sumy, Ukraine, 40021 One of the promising methods to dispose of agricultural bio-based raw materials is to produce compost by aerobic fermentation in rotary chambers. High efficiency of the composting process is achieved when a proper temperature mode is maintained at each phase of the process. Changes in temperature are directly related to the effective transformation of organic substrates by microorganisms and are the reason for the low quality of produced compost in terms of its agrochemical and microbiological parameters. It was established that a high-temperature regime is achieved on the condition that the amount of heat released during the biodegradation of raw materials by microorganisms is greater than the heat loss associated with the substrate aeration and surface cooling. Therefore, the time during which the fermented mass remains warm depends entirely on the substrate’s physical-chemical characteristics, the parameters of the equipment, and the modes of its operation. To describe the established conditions, based on the equation of thermal balance, a mathematical model has been built. The model relates the thermal costs necessary to maintain the optimal temperature regime of the process to the substrate’s moisture content and specific active heat generation, as well as to such an important thermal physical parameter of the chamber as the coefficient of heat transfer of the wall material. A rotary chamber was manufactured to investigate the thermal mode of the bio-based raw materials composting process. It has been experimentally established that the chamber walls’ heat transfer coefficient of 1.6 W/(m2·°C), a value of the substrate’s specific active heat generation of 9.2 W/kg, and a moisture content of 58 % provide for the thermal needs for the process with the release of 140 MJ of excess heat. The reported study could be the basis for the modernized methodology of thermal calculations of the bio-based raw materials composting process in closed fermentation chambers