Classification of Local Exergetic Losses in Heat Recovery Systems of Different Types

Abstract

The results of classification and analysis of local exergy losses in heat recovery systems of various types are presented. The combined heat recovery system of a boiler plant, designed for heating water and blast air, as well as heat recovery systems with anti-corrosion methods for protecting gas exhaust tracts, are considered. On the examples of these systems, a classification of local exergy losses was carried out and their type and place in heat recovery systems were established. For research, a complex methodology was used, combining structural-variant methods of exergy analysis with methods for presenting exergy balances in matrix form. Structural diagrams of heat recovery systems are presented and exergy equations are obtained for calculating exergy losses in places of localization. For a combined heat recovery system, a comparative analysis of local exergy losses was carried out. It has been established that the smallest exergy losses are observed in the hot air heat exchanger and in the gas heater. The total contribution to the total exergy losses of the pumping system and the piping system is quite significant for all boiler power values. With an increase in boiler power from 30 to 70% of the installed power, there is a slight increase in exergy losses in the heat recovery system and in the hot water heat recovery unit. In this section, the main exergy losses are in the pumping system and in the pipeline system. With a further increase in the power of the boiler, the exergy losses in the heat recovery system and in the hot water heat recovery unit begin to increase more significantly. In this case, the main exergy losses fall on the hot water heat exchanger. It is concluded that the optimal mode of operation of the installation is carried out at the boiler power, which is 50 ... 60% of its installed power.