Increase of energy efficiency of direct-flow heat exchangers

Abstract

The article is devoted to the development of a method for determining the minimum interaction surface in a system of heat exchangers. A comparative analysis of direct-flow and counter-current types of heat exchange is carried out in relation to the creation of systems for ensuring temperature conditions, for which weight and size characteristics are decisive. It is shown that the main characteristic of efficiency in the design and simulation of heat exchangers, based on the temperature representation, is not applicable for devices with a phase transition. The definition of efficiency as the energy characteristic of the energy exchange process of interacting flows is proposed. Comparison of the energy received by the heated stream from the heating stream made it possible to determine the energy potential in the heat exchanger. The introduction of energy efficiency made it possible to substantiate the relationship between the efficiency of once-through and counter-flow heat exchangers with access to structural and thermophysical requirements. The analysis of analytical relationships showed that in assessing the thermal stresses arising in the apparatus, the determination of average values over the surface of the temperature of the coolant plays a significant role. It is shown that the countercurrent heat exchanger represents the limiting case of minimizing the heat transfer area. The increase in the efficiency of once-through heat exchangers due to sectioning is analyzed and the possibility of increasing the efficiency of once-through heat exchangers is shown. The research results indicate not only the topological equivalence of the direct-flow apparatus system to one counter-current, but also the possibility of constructing a partitioned apparatus system with the serial connection of its elements with an efficiency equal to the efficiency of counter-current apparatuses. A recursive algorithm is proposed for constructing a partitioned system of direct-flow apparatus. The developed method can be used to create computer-aided design systems for heat exchangers of complex chemical plants.