Enhancement of heat generator of a rotary baking oven based on mathematical modeling

Source abstract

Currently, only 20–30 % of bread-baking enterprises in the food industry are equipped with the latest technology, while the rest use worn-out fixed assets. Rotary baking ovens are widely used in industrial facilities. They have certain advantages: high productivity, uniform baking, the ability to bake multiple types of products in a single cycle and to bake using frozen dough. The thermal operation of rotary furnaces fired by gaseous and liquid fuels is carried out using a heat generator, consisting of a combination of a two-way tubular heat exchanger and a cylindrical combustion chamber (flame tube). The energy cost of a process largely depends on the efficiency of its operation. Therefore, the requirements for the main performance indicators of the heat generator, such as reliability, productivity, and energy efficiency are increasing. In this regard, there is a need to improve and replace outdated furnace designs and their elements with new ones that ensure high-quality products while reducing fuel, steam and electricity consumption. The heat generator of a rotary baking oven has been used as the object of study and for the improvement of the heat generator's design configuration. The study is based on a numerical experiment using mathematical modeling methods. As a result of the simulation, it has been found that the presence of a heat generator casing enhances heat transfer. The greatest heat transfer occurs when the heat generator is subjected to airflow along the tube bundle, starting from the flame pipe and extending to the second stroke of the tube bundle. The results of numerical studies indicate that the installation of deflectors makes it possible to increase the temperature of the cold coolant at the outlet of the heat exchange part of the heat generator. At the same time the deflectors should be short and occupy 50–55 % of the area in the peripheral zone and be located at a distance of 5 to 7 cm from the heat generator tubes. It helps to reduce the time required for the oven to reach operating mode, to reduce fuel consumption and increase the efficiency of the baking oven. Based on the results of numerical modeling, a heat generator design for a rotary baking oven has been developed and patented. The research findings are of both theoretical and practical significance and can serve as a basis to develop an engineering methodology for the thermal and structural design of heat generators applicable to both the design of new equipment and the modernization of existing oven systems in the domestic baking industry. The developed heat generator design is suitable for industrial implementation.