The energy efficiency concept and implementation prospects of the jet thermocompression principle in small heat energy

Abstract

The expediency of the implementation of the principle of steam thermal compression to improve the energy efficiency of sources of electricity and heat supply of small heat power engineering is substantiated. The results of thermodynamic analysis and numerical optimization of the parameters of the compressor steam-turbine cycle of a small cogeneration power plant are presented. A jet step-down thermotransformer has been tested - as an alternative to traditional boiler heating. On the basis of the conducted thermodynamic analysis, a new combined cycle of a step-down thermotransformer has been developed, which ensures efficient conversion of the supplied energy (mainly in the form of fuel heat) into the heat carrier flow of the heat supply system with the required temperature level 50 ... 90 °C). The fundamental difference between the considered thermal transformer and steam compressor heat pumps is the replacement of a mechanical compressor with a steam thermocompressor module (STC-unit). The working process in the STK-module is realized by using the liquid phase of the refrigerant, which boils up during expiration, subcooled to saturation, as an active medium of a jet compressor. Injection of steam from the evaporator is provided due to the fine-dispersed vapor-droplet structure formed in the outlet section of the active flow nozzle. A program for the numerical study of the working process of a step-down thermal transformer was prepared and tested, on the basis of which multivariate calculations were carried out. On the basis of computational studies, the area of achievable indicators of the proposed heat supply system has been established; the area of initial operating parameters corresponding to the maximum values of the conversion coefficient and exergy efficiency was determined; comparative indicators of the main parameters of the investigated thermal transformer on various working substances in the range of operating modes as a heat pump or a refrigerating machine were obtained. Key words: workflow, steam thermocompressor, step-down thermotransformer, energy efficiency, heat pump mode