The schemes of a carbon dioxide trigeneration plant using secondary energy resources in the form of products of combustion or flue gases and a combined cycle gas turbine unit (CCGT) with a recovery boiler, which simultaneously produce electricity, heat and cold for centralized and decentralized supply of consumers, are presented. In addition, the production of liquid and gaseous carbon dioxide is possible. The main elements of the plants are a heating unit, a gas turbine unit with a recovery boiler, a turboexpander unit and a carbon dioxide unit for the production of cold, liquid and gaseous carbon dioxide. A thermodynamic calculation and a brief exergy analysis of the plants were carried out.

The article examines the possibility of increasing the efficiency of the turbo-expander cycles on low-boiling working fluids using those methods that are used for steam turbines, viz. increasing the parameters of the working fluid before the turbo-expander and using secondary overheating. Thus, four schemes of the turbo-expander cycle are considered: the one without overheating of the low-boiling working fluid, the one with single overheating of low-boiling fluid, the one with double overheating and the one with double overheating at supercritical parameters. All the studied cycles were considered with a heat exchanger at the outlet of the turbo expander, designed to heat the condensate of a low-boiling working fluid formed in the condenser of the turbo expander unit. Cycles in P–h coordinates were built for the studied schemes. The method of thermodynamic analysis of the studied cycles based on the exergetic efficiency has been developed. The results of the research are presented in the form of Grassman-Shargut diagrams, which show exergy losses in the elements of the studied cycles on a scale, and also show the positive effect of the operation of the turbo-expander cycle in the form of electrical power. The analysis of the obtained results showed that the main losses that have a significant impact on the exergy efficiency are the losses of exergy in the recovery boiler. The increase of parameters of low-boiling working body, and the use of intermediate superheating reduce losses in the waste heat boiler and, consequently, increases exergetic efficiency of turbo-expander cycle. The turbo-expander cycle with double overheating at supercritical parameters of the low-boiling fluid is of the largest exergetic efficiency out of the schemes that have been examined.

The influence of the initial parameters of a low-boiling working fluid on the thermodynamic efficiency for two turbo-expander cycles (with a heat exchanger at the outlet of the turbo-expander and without a heat exchanger) is considered. For each of the studied cycles, the dependences of the exergy efficiency on the temperature of the low-boiling working fluid before the turboexpander at a constant pressure and the dependence of the exergetic efficiency on the pressure of the low-boiling working fluid before the turbo-expander at a constant temperature were obtained. The dependences of exergy losses on the elements of the studied cycles on the parameters of a low-boiling working fluid are constructed and their analysis is carried out. For the considered schemes, the dependences of the exergy efficiency on pressure are constructed at various temperatures of the low-boiling working fluid in front of the turboexpander. An analysis of the results showed that at any temperature of a low-boiling working fluid, it is possible to determine the pressure at which the exergy efficiency of the investigated circuit will be maximum. Graphic dependencies are obtained that are characterized, from a thermodynamic point of view, by the optimal parameters of a low-boiling working fluid. Comparison of these dependences revealed that, over the entire range of studied temperatures (from 100 °C to 300 °C), a cycle with a heat exchanger at the outlet of the turboexpander has a large exergy efficiency. These graphical dependencies make it possible to determine the optimal parameters of the working fluid in the turboexpander cycle, as well as to predict the change in the exergy efficiency of the installation with changing parameters of the working fluid.

The object of research is the processes of heat and mass transfer during phase transitions of ozone-safe refrigerants and their oil-freon mixtures on smooth finned and capillary-porous heat-transfer surfaces of industrial heat exchange apparatuses. The purpose and objectives of the research was theoretical and experimental research of processes of heat transfer in developed bubble boiling of ozone friendly refrigerant and oil-refrigerant mixtures on smooth and developed surfaces of heat exchange by establishing relationships to determine the coeffi-cients of heat transfer and influence of the various factors that determine the intensity of heat transfer at phase transitions in devices of refrigeration, heat pump systems and air conditioning systems; the estab-lishment of the mechanism of heat transfer processes during evaporation of oil-refrigerant mixtures. De-velopment of practical recommendations for the calculation and design of high-efficiency heat exchange equipment, reducing the material consumption and weight and size indicators of heat exchangers. Development and implementation of improved performance vaporizers and condensers for refrigeration, heat pump installations and air conditioning systems. For the first time, experimental studies of heat exchange processes during the boiling of refriger-ants and their oil-freon mixtures on various surfaces in a wide range of thermal loads (2,9…100,8 kW / m2). Graphic dependences of the heat transfer intensity on the operating parameters of the boiling process and other characteristics are obtained. The results of the work are implemented in the technological process of VESA LLC and in the educational process of Sukhoi state technical University for lectures on the disciplines “heat and mass Transfer” and “Industrial heat and mass transfer processes and installations”. The results obtained can be used in the development and creation of highly efficient evaporative heat ex-changers.

A program that allows modeling, thermodynamically optimizing and performing exergetic analysis of more than a hundred different variations of the schemes of trigeneration turbine units based on low-boiling working fluids. With the aid of the program that had been developed, an exergetic analysis of six schemes of trigeneration turbine units on the organic Rankine cycle was performed, viz. on an overheated steam with a steam compression refrigeration unit; with an intermediate overheating of the working fluid and a steam compression refrigeration unit; on an overheated steam with a refrigeration unit with carbon dioxide production; with an intermediate overheating of the working fluid and a refrigeration unit with carbon dioxide production; on an overheated steam with a refrigeration unit with production carbon dioxide and cooling of the turbine condenser with liquid carbon dioxide; with intermediate overheating of the working fluid, a refrigeration unit with carbon dioxide production and cooling of the turbine unit condenser with liquid carbon dioxide. A gas turbine unit was used as an energy source for the above-mentioned schemes. The possibility of using the resulting liquid carbon dioxide to cool the condenser of a turbine unit on an organic Rankine cycle has been studied. A comparative analysis of two methods of obtaining cold (using a steam compression refrigeration unit and a refrigeration unit with carbon dioxide production) for use in trigeneration schemes has been carried out. The research was based on the method of exergetic analysis, the results of which are presented in the form of enlarged Grassmann – Shargut diagrams. A technical and economic analysis of the use of intermediate overheating in the organic Rankine cycle has been carried out, ozone-safe freon R245FA was used as the working fluid. Recommendations for the application of the studied trigeneration schemes on the organic Rankine cycle are formulated.