Optimisation of air exchange and heat transfer using coaxial air ducts

In modern industrial premises, it is important to ensure effective air exchange with minimal energy consumption, which necessitates the optimisation of ventilation systems, particularly through the development of new air duct designs. The aim of this article was to develop a combined exhaust-supply air duct structure to improve the efficiency of air exchange in industrial spaces and reduce energy consumption for air heating. A comprehensive analysis was conducted of current scientific sources published in various countries, covering advanced technologies in air exchange, ventilation, and microclimate regulation. Theoretical justification of the design and mathematical modelling of heat transfer processes between the exhaust and supply air ducts were applied. Methods of heat conduction, convection, and radiation were also used to analyse the physical processes. As a result, a coaxial air duct structure was developed, consisting of an inner exhaust and an outer supply pipeline, with their diameter ratio optimised by the formula D = 1.4 · d. Calculations confirmed the equality of exhaust and supply air volumes, ensuring stable air exchange. Modelling showed that the system effectively ensures uniform air distribution in the working zone, improving the overall performance of the ventilation system. A reduction in energy consumption was achieved by using the heat from the exhaust air to preheat the supply air. The calculations and modelling confirmed the effectiveness of the proposed design, which allows for a reduction in energy consumption for air heating and an improvement in air exchange in industrial spaces, contributing to the creation of comfortable working conditions. Overall, the developed ventilation system design is aimed at optimising air exchange processes in industrial premises and offers several advantages: energy efficiency – through the use of secondary heat resources; compactness – as the structure allows a reduction in the volume of ventilation equipment; versatility – since the system can be implemented across various industrial enterprises, including workshops with high levels of air pollution; improved occupational safety – as the new system contributes to the creation of comfortable conditions in the working area