Investigation of combined heat recovery systems: analysis of the influence of operating parameters and geometric characteristics on the efficiency of heat recovery

Purpose of research. The article provides a mathematical description of the heat transfer process during the combined utilization of low-potential waste heat and ventilation emissions in the channels of a multilayer plate heat exchanger. Methods. To carry out a comparative analysis of the Eulerian criteria based on the theory of similarity in a hot channel for various configurations of turbulators in combined low-potential heat recovery systems, to determine how high-speed modes of air flows affect the heat transfer coefficient, as well as thermal and electrical efficiency in the processes of recycling secondary and renewable energy resources with associated thermoelectric generation. Results. The advantage of the staggered configuration of cylindrical turbulators in the recuperator under study is established in comparison with the corridor and rib schemes of their arrangement, for which a comparative analysis of Euler criteria based on similarity theory was used. A mathematical model of thermal processes with a filling arrangement of cylindrical turbulators (checkerboard, corridor) in a plate heat exchanger in a quasi-stationary thermal regime has been created. A method for determining the coefficients of heat transfer and heat transfer of a complex multilayer plate heat exchanger with increased turbulence of heat carriers is proposed. Conclusion. The study showed that the staggered configuration of cylindrical turbulators significantly increases the efficiency of heat transfer compared to other schemes, which makes it preferable for use in hot channels of plate heat recuperators of combined low-potential heat recovery systems. The developed mathematical model makes it possible to predict and optimize thermal processes, taking into account the influence of turbulators. The method of determining heat transfer coefficients ensures high accuracy of calculations, and a comparative analysis of Euler criteria based on similarity theory has confirmed the advantage of the chess scheme. The areas of operating parameters and the influence of the geometric characteristics of the turbulators on the efficiency of the heat recovery process were also determined, which underlines the importance of their optimization.