• Energy Research

We have devised a scheme for the energy-generating unit based on the internal combustion engine 1Ch 6.8/5.4 with a spark ignition and a two-stage system for the recovery of heat from the exhaust gases. The basic elements for the first and second stages of the heat recovery system have been selected. A first stage involves a rotary piston expansion machine while a second stage employs the fuel conversion.We have studied effective parameters for the engine 1Ch 6.8/5.4 with a system of the deep two-stage recovery of heat from exhaust gases under different modes of operation. The dependences were established for change in the specific effective fuel consumption on the power of the energy-generating installation using only the conversion of fuel and in a combination with the expansion machine.The dependences have been derived for the operational parameters of a rotary piston engine on consumption of a working body. We have determined temperatures of the working bodies in a reactor and the heat capacity of exhaust gases depending on the load on the engine, as well as the necessary amount of energy to convert ethanol into synthesis gas. The dependences have been obtained of the degree of ethanol conversion on the reaction temperature and the mass flow rate through the reactor. We have established the dependence of specific heat of the chemical reaction on the degree of conversion.It was established that when reaching full conversion in line with the reaction of decomposition the entire liquid ethanol is completely converted into combustible synthesis gas, whose main components are hydrogen, carbon monoxide, and methane. The estimated specific lower combustion heat of the synthesis gas is 28.79 MJ/kg. Obtaining 1 kg of synthesis gas requires 4.0 MJ of thermal energy.It was determined that under condition of applying the conversion of fuel and, accordingly, the addition of synthesis gas, the specific effective ethanol flow rate, depending on the mode of engine operation, decreases by up to 12 %. The amount of energy that needs to be used in the reactor for obtaining synthesis gas is 50…65 % of the heat released with the exhaust gases under a given mode of operation.It has been established that the application of a rotary-piston expansion machine that acts as the first stage in the recovery of heat from exhaust gases has made it possible to gain an increase in the capacity of the energy-generating unit of 27 %.It has been found that the use of two stages of heat recovery leads to a decrease in the specific effective fuel consumption by 29 %

A schematic diagram of a transport hybrid power plant using a new design RPE-4.4/1.75 rotary piston air engine is proposed. Its external speed characteristic is determined, according to which the maximum engine power is 8.75 kW at 850 rpm and the maximum torque is 127.54 N∙m at 400 rpm. For various gears and speeds, all the components of the power balance were determined and the dynamic characteristic of the hybrid car was obtained when operated on an air engine. According to the dependences of the power balance, the total traction force from the rotary piston air engine on the driving wheels is 5 kN. The performance of acceleration of a hybrid car while working on an air engine is estimated, namely, the dependences of acceleration, time,and acceleration path are obtained. In urban traffic, the required time to accelerate the car to a speed of 60 km/h is 15.2 s and the path is 173 m. The possible drive range of the hybrid car on compressed air without additional recharging is analyzed. On one cylinder with compressed air with a volume of 100 liters, an initial pressure of 35 MPa, and a final pressure of 2 MPa, the hybrid car can travel about 26 km.

This article describes a rotary piston pneumatic engine with a gas exchange system design that minimizes the value of the relative dead volume, as well as ensures the minimum dimensions and weight of the engine. The main purpose of the study is to evaluate the conversion efficiency of compressed air energy in the working cylinder of the rotary piston pneumatic engines using the exergy method of thermodynamic analysis. To achieve the set goal of the study, physical modeling of various operation modes has been performed. The most significant result is that, based on the physical and mathematical modeling, a thermodynamic assessment of the efficiency of the compressed air energy conversion has been performed. The significance of the results obtained lies in the fact that the effect of the main operational parameters of the pneumatic engine on the efficiency of energy conversion is established. The basic equations of the exergy method of the thermodynamic analysis are presented. The results of physical and mathematical modeling of various operation modes are presented. The main reasons for the decrease in the energy conversion efficiency at low and rated loads are emphasized. The amount of exergy supplied with the air flow was established, which, depending on the operation mode, amounted to 2.2…11.4 kW. According to the presented results, the most optimal speed range, based on the achievement of the maximum values of the specific efficient work and exergy efficiency, is 55…70% of the nominal value. It was found that an increase in the operation pressure decreases slightly the exergy efficiency. A twofold increase in the operation pressure of the pneumatic engine increases the efficient power by 46 % at a simultaneous decrease in the exergy efficiency by 8.2 %.

This paper reports the results of an experimental study of the prototype rotary-piston air motor RPD-4,4/1,75 in the form of speed characteristics. The maxima of the air motor's performance effective indicators have been determined, as well as the rotation change ranges that correspond to them. It has been established that for the intake receiver's air pressure change range within 0.4...0.8 MPa the maximum value of effective power is 1.7...2.5 kW. In this case, the maximum value of the torque and mean effective pressure for a given pressure range in the intake receiver is 17.0...18.2 N∙m and 0.13...0.18 MPa, respectively. The dependence has been derived of the hourly air consumption on the rotations and pressure in the intake receiver. Depending on the test mode, the hourly air consumption is within 25…226 kg/hour. It has been established that the minimum values of the specific effective air consumption correspond to 800...1,000 rpm. Thus, for a maximum value of air pressure in the intake receiver of 0.8 MPa, the specific effective consumption is 60.8...93.2 kg/(kW∙h), for the minimum value of 0.4 MPa – 49.7...81.3 kg/(kW∙h). The potential of the adiabatic expansion capacity has been determined, brought to the air motor, as well as the effective adiabatic efficiency. The maximum efficiency of the air motor corresponds to 800...1,000 rpm. In this case, the maximum efficiency value was achieved at a pressure in the intake receiver of 0.4 MPa; it is 0.41. The dependences have been derived of the change in the pressure of spent air in the exhaust receiver, the maximum value of which does not exceed 0.075 MPa

This paper explores the possibility of using a solid oxide fuel cell as part of an energy system with an internal combustion engine running on bioethanol, incorporating thermochemical waste gas heat recovery. The main goal of the research is to determine the efficiency of energy con-version in energy systems with deep waste gas heat recovery. To achieve this goal, the following tasks were set: based on experimental studies of a spark-ignition engine running on bioethanol, determine the parameters of the process for synthesizing gas through thermochemical conver-sion; theoretically investigate the efficiency of using a solid oxide fuel cell in combination with a bioethanol thermochemical conversion reactor. The most significant result is the determination of the volt-ampere characteristic of the solid oxide fuel cell and the identification of the poten-tial heat recovery capacity of the internal combustion engine exhaust gases through deep heat recovery. The significance of the obtained results lies in the theoretical and experimental valida-tion of efficient energy conversion of synthesis gas in a solid oxide fuel cell, achieving a high thermodynamic efficiency of the cell (0.95–0.75). The proposed energy system configuration, based on an internal combustion engine running on bioethanol with thermochemical waste heat recovery, allows for a 6.5% increase in the overall system power output. This contributes to re-duced fuel consumption and improved environmental performance. The research findings can be applied in the design and development of highly efficient energy systems with internal com-bustion engines for various applications.

The article examines the features of the combustion process of hydrogen-containing gas (syngas) in the working cylinder of a spark-ignition internal combustion engine. The main objective of the study is to evaluate the heat release parameters of syngas. To achieve this goal, an experimental investigation was conducted to assess the nature of syngas combustion and establish its regularity. The most significant result is the derivation of dependencies for determining the current value of the combustion characteristic index m and the combustion duration φz in Professor I.I.Vibe's heat release model for spark-ignition engines operating on syngas, with an air excess ratio α ranging from 1.0 to 2.2 and hydrogen content in the fuel composition varying between 30% and 100% by volume. The significance of the obtained results lies in the establishment of the variability of the combustion index m (ranging from 1.6 to 5.5) in Professor I.I.Vibe's semi-empirical heat release model, which more closely corresponds to the actual heat release law observed in experimental studies. The proposed dependencies for determining m and φz allow for accounting the specific features of the syngas combustion process in spark-ignition engines, thereby significantly improving the accuracy of determining the indicated pressure in the working cylinder (the relative root-mean-square error does not exceed 4.5%), which, in turn, enhances the accuracy of assessing the engine's energy and economic parameters. The results of this study can be applied in the design and construction of new spark-ignition engines running on alternative fuel.

This article is devoted to the methods for enhancing the power plants’ efficiency in accumulation of a surplus electrical energy obtained using the renewable energy sources. The study is aimed at analyzing the efficiency of perspective power plants for accumulation of the surplus electricity in the form of compressed air based on rotary piston engines. To achieve the goal a comparative analysis of efficiency of diabatiс and adiabatic schemes of the electric energy storage was performed. The analysis was found to reveal the major advantages and disadvantages, along with the design features of each type of schemes. The main ways to increase the efficiency of the compressed air storage units, using the rotary piston engines as the electrical energy generators, were established. The experimental operational characteristics of the rotary piston engines showed that they are relevant to the parameters of the power units of air accumulation. The most significant results reveal that the methods for the analysis and of generalization have been used to develop the principal schemes of diabatic and adiabatic power plants for the accumulation of the surplus electrical energy in the form of compressed air using rotary piston engines, which require no additional air heating prior to expansion. The significance of the results obtained is that the use of the rotary piston engines being a part of the diabatic accumulation unit, allowed a complete exclusion of CO2 emission into the atmosphere.