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Abstract Air pollution with dust is particularly noticeable in winter. This problem is visible especially in those living areas in which furnaces fed by low-quality fuels are used for heating houses and flats. One of the possible ways of limiting the number of used furnaces may be heating and powering of the housing estates and villages by specially designed combined heat and power (CHP) steam (or vapor) power plants. To be competitive to other heating technologies these systems should be cheap, reliable and easy to operate. Therefore, their design should be as simple as possible. Steam or organic Rankine cycle (ORC) energy conversion systems utilizing simple volumetric expanders, which can be applied for distributed power generation are meeting these conditions. The article presents literature review as well as selected thermodynamic and design issues concerning these systems. Literature review gave an outlook on the modeling, experiments, operating conditions and possible configurations of steam and ORC CHP systems. Then, model of the CHP system was implemented in computer software. Thanks to the positive technical features and ability to operate with wet gas the screw machine was selected as the system’s expander. Selected experimental data obtained from the literature review were used for system modeling. Especially the operating conditions of the selected expander (i.e., maximum mechanical power, maximum inlet pressure, expansion ratio and internal efficiency) were assumed based on the experimental results, technical data and information reported in different papers. Expander’s operating conditions and technical data (in particular the value of maximum working fluid pressure allowable at the inlet to the expander) were the basis for pre-selection of working fluids which are possible to apply in the modelled system and selection of the heat source thermal parameters. Modeling was proceeded for different conditions and the results show that depending on the operating conditions and applied working fluid electric power output of the CHP system ranges between 1570 and 2511 kWe (for heat source temperature of 200 °C) and between 1583 and 2631 kWe (for heat source temperature of 150 °C). However, not only maximum power output should be considered as the selection criteria of the system design and working fluid choice. The other important criteria are related to maximization of the obtained electric power, minimization of the vapor pressure at the outlet of the vapor generator and at the inlet to the expander, minimization of the working fluid flow, minimization of fuel consumption and maximization of the temperature of the working fluid at the outlet of the expander. The modeling results show that from all cases studied the ORC CHP power plant utilizing screw expander, using MD2M as working fluid and featuring the electric power of 1570 kWe fed by rapeseed oil is the best possible solution if technical assessment criteria are taken into consideration. Such a system can cover the heating demands of ca. 9615 flats.

Abstract Air pollution with dust is particularly noticeable in winter. This problem is visible especially in those living areas in which furnaces fed by low-quality fuels are used for heating houses and flats. One of the possible ways of limiting the number of used furnaces may be heating and powering of the housing estates and villages by specially designed combined heat and power (CHP) steam (or vapor) power plants. To be competitive to other heating technologies these systems should be cheap, reliable and easy to operate. Therefore, their design should be as simple as possible. Steam or organic Rankine cycle (ORC) energy conversion systems utilizing simple volumetric expanders, which can be applied for distributed power generation are meeting these conditions. The article presents literature review as well as selected thermodynamic and design issues concerning these systems. Literature review gave an outlook on the modeling, experiments, operating conditions and possible configurations of steam and ORC CHP systems. Then, model of the CHP system was implemented in computer software. Thanks to the positive technical features and ability to operate with wet gas the screw machine was selected as the system’s expander. Selected experimental data obtained from the literature review were used for system modeling. Especially the operating conditions of the selected expander (i.e., maximum mechanical power, maximum inlet pressure, expansion ratio and internal efficiency) were assumed based on the experimental results, technical data and information reported in different papers. Expander’s operating conditions and technical data (in particular the value of maximum working fluid pressure allowable at the inlet to the expander) were the basis for pre-selection of working fluids which are possible to apply in the modelled system and selection of the heat source thermal parameters. Modeling was proceeded for different conditions and the results show that depending on the operating conditions and applied working fluid electric power output of the CHP system ranges between 1570 and 2511 kWe (for heat source temperature of 200 °C) and between 1583 and 2631 kWe (for heat source temperature of 150 °C). However, not only maximum power output should be considered as the selection criteria of the system design and working fluid choice. The other important criteria are related to maximization of the obtained electric power, minimization of the vapor pressure at the outlet of the vapor generator and at the inlet to the expander, minimization of the working fluid flow, minimization of fuel consumption and maximization of the temperature of the working fluid at the outlet of the expander. The modeling results show that from all cases studied the ORC CHP power plant utilizing screw expander, using MD2M as working fluid and featuring the electric power of 1570 kWe fed by rapeseed oil is the best possible solution if technical assessment criteria are taken into consideration. Such a system can cover the heating demands of ca. 9615 flats.

Baking ovens are necessary to be installed in a paint shop of assembly automotive manufacturers for drying the paint of automotive bodies (i.e., in the coating process). In this process, a large amount of heat is provided by burning the natural gas in the gas burner. Practically, the design of the heat confinement in the oven is often poor, which results in considerable heat losses (i.e., waste heat) which are released during the drying process and significantly raise the temperature of a working environment thereby lowering the thermal comfort of the factory staff. To address this issue and limit the waste heat transfer to the surroundings, the application of a waste heat recovery system of a specific design employing the organic Rankine cycle (ORC) may be a viable alternative solution. A combined design of such a system utilizing an evaporator and thermal energy storage (TES) device in a simple ORC layout will be discussed in this article. The obtained simulation result was computed using MATLAB coupled with thermophysical properties libraries, i.e., CoolProp. The obtained results indicate that the sustainability of the studied system scheme appears to be favorably implemented in the selected paint shop and may benefit to lower the temperature of the working area, improve the thermal comfort of factory staff and at the same time produce electricity since some car/automotive manufacturers likely run the production for over 20 hours per day.

Baking ovens are necessary to be installed in a paint shop of assembly automotive manufacturers for drying the paint of automotive bodies (i.e., in the coating process). In this process, a large amount of heat is provided by burning the natural gas in the gas burner. Practically, the design of the heat confinement in the oven is often poor, which results in considerable heat losses (i.e., waste heat) which are released during the drying process and significantly raise the temperature of a working environment thereby lowering the thermal comfort of the factory staff. To address this issue and limit the waste heat transfer to the surroundings, the application of a waste heat recovery system of a specific design employing the organic Rankine cycle (ORC) may be a viable alternative solution. A combined design of such a system utilizing an evaporator and thermal energy storage (TES) device in a simple ORC layout will be discussed in this article. The obtained simulation result was computed using MATLAB coupled with thermophysical properties libraries, i.e., CoolProp. The obtained results indicate that the sustainability of the studied system scheme appears to be favorably implemented in the selected paint shop and may benefit to lower the temperature of the working area, improve the thermal comfort of factory staff and at the same time produce electricity since some car/automotive manufacturers likely run the production for over 20 hours per day.

Abstract Emerging and promising ways of utilizing any heat sources from geothermal, solar, combustion, and industrial waste heat may be the application of power plants that are operating according to conventional Rankine cycle (RC), organic Rankine cycle (ORC), trilateral flash cycle (TFC) employing different types of expansion (i.e., volumetric expanders or turbine). In this paper, the studies about partially evaporated ORC (PE-ORC) was carried out; furthermore, it reports on novel results related to the comparison of thermodynamic efficiency of TFC, ORC and PE-ORC. These results were obtained by modelling the system operations computed with MATLAB and the thermal properties library taken from CoolProp and REFPROP. The calculation was based on selected different types of working fluid classified by A, C, Z, M, N points (conventionally categorized by dry, wet, and isentropic working fluids) and the upper-lower operating temperature. The obtained results explain a new point of view on the efficiency of TFC, ORC and PE-ORC plants, that in some of the conditions (i.e., one can find certain combinations of working fluid quality, maximal and minimal cycle temperature), the efficiency of PE-ORCs outperforms TFC and ORC. It means that at certain temperature ranges and conditions when starting the expansion step from a partially evaporated state, it may be recommended to improve the performance of the cycle. It seems that obtained results offer new insight to scientists and engineers in designing the thermal power plant working under a subcritical cycle with high-temperature heat sources or a low-temperature heat sinks employing the selection of working fluids and different types of expanders.

Abstract Emerging and promising ways of utilizing any heat sources from geothermal, solar, combustion, and industrial waste heat may be the application of power plants that are operating according to conventional Rankine cycle (RC), organic Rankine cycle (ORC), trilateral flash cycle (TFC) employing different types of expansion (i.e., volumetric expanders or turbine). In this paper, the studies about partially evaporated ORC (PE-ORC) was carried out; furthermore, it reports on novel results related to the comparison of thermodynamic efficiency of TFC, ORC and PE-ORC. These results were obtained by modelling the system operations computed with MATLAB and the thermal properties library taken from CoolProp and REFPROP. The calculation was based on selected different types of working fluid classified by A, C, Z, M, N points (conventionally categorized by dry, wet, and isentropic working fluids) and the upper-lower operating temperature. The obtained results explain a new point of view on the efficiency of TFC, ORC and PE-ORC plants, that in some of the conditions (i.e., one can find certain combinations of working fluid quality, maximal and minimal cycle temperature), the efficiency of PE-ORCs outperforms TFC and ORC. It means that at certain temperature ranges and conditions when starting the expansion step from a partially evaporated state, it may be recommended to improve the performance of the cycle. It seems that obtained results offer new insight to scientists and engineers in designing the thermal power plant working under a subcritical cycle with high-temperature heat sources or a low-temperature heat sinks employing the selection of working fluids and different types of expanders.

The scientific and technical issues related to energy harvesting and conversion are inseparably bound to the issues of environmental protection. Energy conversion systems and devices that are applied for converting the chemical energy contained in different fuels into heat, electricity, and cold in industry and housing are sources of different gases and solid particle emissions. Thus, the development of different technologies for energy conversion and environmental protection that can be jointly applied to cover growing energy needs has become a crucial challenge for scientists and engineers around the world. Progress in the precise description, modeling, and optimization of physical and chemical phenomena related to these energy conversion systems is a key research and development field for the economy. Legal and social issues that are affecting key aspects and problems related to the energy conversion and power sector are also significant and worth investigating. The aim of Energy Processes, Systems and Equipment Special Issue is to publish selected high-quality papers from the XV Scientific Conference POL-EMIS 2020: Current Trends in Air and Climate Protection—Control Monitoring, Forecasting, and Reduction of Emissions (29–31 March 2021, Wrocław) and other papers related to the field of energy conversion.

The scientific and technical issues related to energy harvesting and conversion are inseparably bound to the issues of environmental protection. Energy conversion systems and devices that are applied for converting the chemical energy contained in different fuels into heat, electricity, and cold in industry and housing are sources of different gases and solid particle emissions. Thus, the development of different technologies for energy conversion and environmental protection that can be jointly applied to cover growing energy needs has become a crucial challenge for scientists and engineers around the world. Progress in the precise description, modeling, and optimization of physical and chemical phenomena related to these energy conversion systems is a key research and development field for the economy. Legal and social issues that are affecting key aspects and problems related to the energy conversion and power sector are also significant and worth investigating. The aim of Energy Processes, Systems and Equipment Special Issue is to publish selected high-quality papers from the XV Scientific Conference POL-EMIS 2020: Current Trends in Air and Climate Protection—Control Monitoring, Forecasting, and Reduction of Emissions (29–31 March 2021, Wrocław) and other papers related to the field of energy conversion.

Environmental issues are nowadays of great importance. In particular air and water quality should be kept at as high levels as possible. Energy conversion systems and devices which are applied for converting the chemical energy contained in different fuels into heat, electricity and cold in the industry and housing are sources of different gases and solid particle emissions. Medical data show PM2.5 dust in particular is highly dangerous for human health. Therefore, limiting the number of low-quality fuel combustion processes is a key issue of modern energy policy. Statistical data show that domestic heating systems account for a large share of the total emissions of PM2.5 and PM10 dust. For example in Poland in 2017, the share of households in the total annual emissions of PM2.5 dust was equal to ca. 35.8%, while the share of PM2.5 emission in industry (i.e., power generating plants, industrial power plants and technologies) was equal to only 23.6%. A possible way of solving this problem is by the successful replacement of old domestic furnaces by combined heat and power (CHP) or multigeneration boilers which can be used for heating the rooms and sanitary water and generating electricity and cold. Such systems can possibly contribute in the future to significant reductions of dust emissions and air pollution in urban and rural areas by limiting the number of low-quality fuel combustion processes. This article presents design considerations and experimental results related to a domestic micro-CHP unit which is based on organic Rankine cycle (ORC) technology. The main aim of the design works and experiments was therefore the analysis of the possibility of integrating the ORC system with a standard domestic central heating gas-fired boiler. The specially designed micro-ORC system was implemented in the laboratory and experiments were performed using this test stand. The main design aims of the test-stand were: low operating pressure, small working fluid flow, low price and compact dimensions. To meet these aims, volumetric machines were chosen as the expander and working fluid pump. The experimental results were positive and show that it is possible to integrate an ORC system with a standard domestic central heating gas boiler. For different heat source temperatures, the obtained expander power ranged from 109 W to 241 W and the thermodynamic cycle efficiency ranged from 4.3% to 8.8%. These positive research results were achieved partly thanks to the positive features of the different system subassemblies.