Keywords: exergy

The Exergy Analysis of the Heating Mode of a Trigeneration Energy Complex Based on a New Heat Transformer

https://doi.org/10.58224/2618-7183-2023-6-4-58-68
Abstract
The article analyzes from energy and exergy positions the trigeneration power complex, developed by the authors and consisting of two main units: a heat engine and a new heat transformer, additionally having a generator for generating electricity for own needs. The main advantage of this energy complex is the reduction of fuel consumption in the heating mode. The emphasis is on the thermal efficiency of the installation and its thermodynamic parameters.
The energy complex under study operates on organic fuel as well as using renewable energy sources (heat pump on organic fuel) and allows obtaining the value of the coefficient of energy effi-ciency from one and a half to more than three in the heating mode. Based on the analysis of energy efficiency calculated by the method of thermal balances, the authors conducted an exergetic analysis. Different variants of inclusion of mechanical and heat compressors of steam-compression and absorp-tion pumps, such as serial, parallel and mixed, were considered. For each variation, there will be dif-ferent working conditions, efficiency and different use of a source of heat and mechanical energy
As a result of the calculation analysis it was concluded that at a sufficiently high coefficient of en-ergy efficiency in the heating mode, the energy complex also has a large potential for its additional increase. In addition, the energy complex produces cold in the warm season and does not need to be connected to the power supply networks. And insufficiently high values of exergy efficiency indicate the imperfection of the thermodynamic system and its potential for further improvement and increase of the energy efficiency coefficient.
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EXERGETIC ANALYSIS OF A BUILDING AS A KEY ELEMENT OF A HEAT SUPPLY SYSTEM

https://doi.org/10.34031/2618-7183-2021-4-3-23-40
Abstract
The study of the complex influence of weather and climatic factors and their variability on the needs of energy and exergy when creating thermal comfort in a house with various engineering and architectural characteristics is carried out. It is confirmed that even for houses with relatively low thermal characteristics built in accordance with regulatory documents, the role of solar radiation in the formation of the heat balance, especially at the beginning and end of the heating season, is important. Studies showed that due to the combined influence of external meteorological factors, with the improvement of the thermal characteristics of houses, the correlation between the energy demand for creating a favorable microclimate and the outdoor air temperature significantly worsens. It is determined that in this case, the value of the approximation reliability decreases from 1 (with a linear dependence) to 0.55 and lower (with the maximum possible improved thermal characteristics of the house today). This position significantly corrects the operating modes and characteristics of the ST. In particular, this makes it necessary to improve the automatic control system of ST. And this, in turn, increases the investment component of the system. A method was developed for calculating exergy needs to create thermal comfort inside the house by taking into account, using the probability theory, the influence of the random nature of meteorological factors within the heating period, on the basis of which, in the conditions of the region, it is shown and calculated that when de-termining the seasonal exergy needs for the heat supply of the house, the use of a stationary approach leads to an underestimation of the results by 12...28% compared to the dynamic approach.
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