Heat exchangers of increased thermal efficiency for power and technological machines: development and research

Togliatti State University, Institute of Mechanical Engineering, 445020, Belorusskaya str., 14, Togliatti, Russia

^* Corresponding author: ns-chernov@mail.ru

Abstract

The paper reviews the development and application of new technologies and designs of heat exchangers, as well as the ways to increase the efficiency of heat exchange, with the aim to improve the thermal engineering parameters and performance characteristics of power and process machines and to reduce toxic emissions during their manufacture. Theoretical and practical foundations for increasing the heat exchange efficiency of heat exchangers are also reviewed. The increase in heat exchange efficiency of heat exchangers is achieved by increasing the area of heat exchange surfaces in contact with heat carriers by forming a macrorelief having optimal geometric parameters by finning. A high-efficiency method of machining, deforming cutting (DC), which is based on cutting and bending of the layers of the surface layer of the workpiece metal, providing a wide range of the resulting macrorelief, is chosen for finning the heat exchange surfaces. The paper provides optimal geometric parameters of finning: the fin height (H), the fin pitch (S) and the thickness of the rib (a). The efficiency of the selected geometric parameters is researched and experimentally tested. It has been experimentally established that the finest finning parameters are the minimum fin pitch and the maximum possible fin height. The interrelation is established, and the geometrical parameters of the heat exchange surface processed by the DC method are determined with the operational characteristics of heat exchangers. The greatest thermal efficiency was achieved with a fin pitch of S=1.5 mm, a fin height of h=3 mm, and a thickness of a=0.75 mm. We consider the TA (water oil) design developed by the author to enhance the efficiency of heat exchange. The research results on increasing the efficiency of heat transfer are presented in the paper. The application of the finned coiled tubing heat exchanger developed on the basis of the research results makes it possible to significantly improve the efficiency, reliability, and service life of power and process machines.