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Energy Inputs on the Production of Plastic Products

Marczak Halina

Journal of Ecological Engineering

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2022

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Vol. 23, nr 9

146--156

EN

The paper considers plastic products in terms of energy consumption at two stages of their life cycle, i.e. at the stage of production of virgin polymers and at the stage of processing polymers into a finished product. Energy intake places were indicated and energy needs related to the production of polymer products were assessed. This allowed to indicate which polymer production and processing processes into finished products are particularly energy-intensive. The research shows that the greater the amount of energy accumulated in the plastic during its production, the greater the importance of this plastic in the post-consumer phase as a recyclable material. Recycling of waste plastics allows the use of this energy and reduces the consumption of virgin raw materials. Primary polymers were compared in terms of the energy efficiency index of their production process. This indicator is the quotient of the calorific value of the polymer and the energy consumption in its production. It shows how much of the energy input during the production of primary plastic can be recovered from the thermal processing of the waste plastic. The highest indicator value was obtained for polyethylene and polypropylene. It was found shown that the total energy consumption (converted to primary energy) of the PET virgin polymer production process and its processing into packaging reaches the value of 109.2–115.2 MJ/kg. This is almost five times the calorific value of this polymer.

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Analysis of Pollutants Emission into the Air at the Stage of an Electric Vehicle Operation

Marczak Halina, Droździel Paweł

Journal of Ecological Engineering

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2021

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Vol. 22, nr 8

182--188

EN

The article discusses the research on CO2 emissions at the stage of electric engine vehicle operation. The operation stage includes, among others use of the vehicle as well as maintenance and charging for the vehicle’s propulsion. The origin of the electricity consumed during charging has an impact on the vehicle’s emissions balance. The scope of considerations concerns coal as the main energy carrier in Poland. The obtained results can be a benchmark for comparing other primary energy sources used for electricity production. Based on the collected technical data of electric cars, the values of CO2 emission factors from electricity production in thermal power plants and data on the state and structure of electricity production in Poland, an analysis of CO2 emissions from electric vehicles in the operational stage was performed. The vehicle’s electricity consumption of 0.14–0.16 kWh/km is accompanied by CO2 emissions of 100.94–115.36 g/km. The calculated CO2 exceeds the EU limit value from 01/01/2020 (95 g/km) for average CO2 emissions from new passenger vehicles. The main message of the work is the statement that increasing the efficiency of the electricity generation process in commercial thermal power plants in Poland will translate into a reduction in the emission of electric cars consuming this energy for propulsion. The research shows that the change in the efficiency of energy transformations in a thermal power plant from 38% to 46% leads to a reduction in the emission of an electric vehicle by over 17%. The emission of CO2 from a passenger car with a compression-ignition engine is discussed. The considerations include the stage of the use of the vehicle and the stage of production of diesel oil, which is consumed during the use of the vehicle.

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Analysis of Energy Consumption in the Production Chain of Heat from Pellet

Marczak Halina

Advances in Science and Technology. Research Journal

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2020

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Vol. 14, no 2

206--214

EN

Wood pellets, as a renewable energy source, are an alternative to fossil fuels. Their use contributes to the quantitative protection of the traditional energy resources which are non-renewable and single use. The combustion of pellets has a neutral effect on increasing the concentration of carbon dioxide in the atmosphere. An important environmental aspect of the Life Cycle Assessment of pellets is the energy consumption over its life cycle. The results of this assessment can be helpful in improving the environmental management in the companies related to the pellet life cycle. They can also be used in the comparative assessment of pellets and other energy carriers in terms of the environmental load resulting from the energy consumption over the entire life cycle of the analyzed fuels. The work aimed at analyzing and assessing the energy efficiency of using wood pellet taking into account its life cycle. In order to achieve the purpose of the work, the energy efficiency index, calculated as the quotient of energy benefits and energy expenditure incurred at individual stages of the pellet life cycle, was used. The results of the analysis indicate that among the studied stages of the pellet life cycle, the highest energy consumption occurs in the pellet use and production phases. Research shows that the energy benefits expressed in the amount of energy emitted in the form of heat in the pellet combustion process outweigh the energy expenditure being the sum of energy spent in subsequent stages of the pellet life cycle. The obtained results indicate a positive energy balance. The use of pellets for heating purposes allows for the recovery of energy spent throughout its entire life cycle.

4

Analysis of the Energetic Use of Fuel Fractions Made of Plastic Waste

Marczak Halina

Journal of Ecological Engineering

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2019

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Vol. 20, nr 8

100--106

EN

The overriding principle of waste management (already produced) is their reuse or use as secondary materials. It is consistent with the concept of a circular economy. Recycling materials and raw materials have the highest rank in the field of waste processing. For non-recyclable waste, other recovery processes also play a role. In the case of plastic waste, economically and ecologically justified processes of thermal transformation and catalytic depolymerisation leading to the formation of fuel fractions destined for energetic use may be useful. This direction of polymer waste processing is justified by the high calorific value of plastics. In the objective evaluation of waste treatment technologies, from the point of view of economics and environmental protection, it may be helpful to analyse the energy balance. The aim of the article is to analyse and evaluate the energy efficiency of using a mixture of hydrocarbons obtained in the process of catalytic depolymerisation of plastic waste based on the energy efficiency index for energy purposes. The efficiency index is calculated as the quotient of energy benefits and energy inputs for the use of depolymerisation products. Energy expenditure includes expenditures incurred in individual stages of the life cycle of a liquid product made of plastic waste. The conducted analysis showed that the energy use in the post-use phase of polymer products allows for the recovery of nearly 40% of the energy required for the production of products and processes enabling the use of waste from these products. Despite the low efficiency index, energy recovery from non-recyclable plastic waste should be considered as a positive action. Plastic packaging waste subjected to catalytic cracking can be included in the settlement of the obligation to achieve the required level of recovery if the cracking products are used for energy purposes.

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Modeling of Post-Failure Behavior of the Rock Mass and its Effect on the Stress-Deformation State in the Vicinity of a Mining Excavation

Marczak Halina

Advances in Science and Technology. Research Journal

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2019

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Vol. 13, no 2

130--140

EN

The study investigated the impact of post-failure properties of the rock mass on the stress-deformation state in the vicinity of the underground excavation and the pressure exerted on the support. An analytical solution to the problem was presented, including the creation of inelastic zones in the vicinity of the excavation: ideal-plastic zone with residual strength and plastic zone with mild decrease of rock medium strength and taking into account the dilatancy. The analysis of the obtained dependencies was carried out using geotechnical parameters characterizing the Carboniferous rock mass of a hard coal mine. The influence of the plastic zone was determined with a mild decrease in strength to the state of stress, deformation and pressure on the rock mass support. The results of the considerations were compared with the solution, which omitted the softening of the rock mass and the solution based on the model of the elastic-plastic-brittle medium. The results of the analysis broaden the knowledge on the behavior of the rock medium in the vicinity of the excavation. The obtained solution can be further developed in order to enable its practical application, especially under the conditions in which the behavior of the rock medium in the vicinity of the excavation well reflects the elastic-plastic model with a gentle drop in the strength of the rock material.

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Application of the elastic-plastic model in the analysis of the displacement in a rock mass

Marczak Halina

Advances in Science and Technology. Research Journal

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2018

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Vol. 12, no 2

188--196

EN

The concern of this article is the analysis of the impact of increased volume (dilation) and decreased strength of the rock material in the plastic zone on the displacement field in the vicinity of the roadway. Elastic-plastic model of the behaviour of the rock material and the strength criterion of Coulomb-Mohr were assumed. The volume change of the rock material is controlled by the angle of dilation ψ, which determines dilation parameter β that is taken into account in the analysis. The influence of parameter β and the strength of the rock material, after crossing the border state of stress, in the field of displacements in the vicinity of the excavation and rock pressure on the elastic support of the excavation was proved. The relationships determining displacement fields in the plastic zone which were obtained with consideration to in this zone of both the elastic and plastic displacement, as well as the relationships which were obtained without elastic deformations was discussed. The exact form of the equation for the displacement field in the plastic zone depends on how the elastic deformation in the plastic zone is defined. There are three ways of describing these deformations. In the first method it is assumed that in plastic deformation area the elastic deformation constants are equal to the deformation constants at the plastic and elastic border. The second method of description is based on the assumption that the plastic zone is a thick-walled ring whose edges: internal and external have been appropriately debited. In the third method, elastic deformations in the plastic zone were made dependent on the state of stress in the zone. The results are illustrated in a form of response curves of the rock mass.