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Aerosols in the atmosphere affect our health and quality of life. The most commonly measured property is their mass concentration. In this work was measured the mass concentration of aerosols by optical particle sizer in the range from 0.3 μm to 10 μm. It was realized in the laboratory with an automatic heat source for pellet combustion. Aerosols were firstly measured before the combustion process, then during combustion of three types of samples: pellets from pure sawdust, pellets from 5 % of disintegrated face masks FFP2 blended with spruce sawdust and from10 % of disintegrated face masks FFP2 blended with spruce sawdust. The lowest total mass concentration was measured during the combustion of pellets from pure spruce sawdust. However, results indicate that the combustion process does not have an impact on aerosol mass concentration in the laboratory space for the particle range 0.3-10 μm when an automatic heat source for pellets is used.

The use of refrigerants requires to meet ecology and legislation requirements. The aim of the legislation is also to reduce the global warming potential (GWP). Natural refrigerants such as carbon dioxide, ammonia, and hydrocarbons such as propane, isobutene, and propylene are used mainly because of their environmental benefits compared to synthetic refrigerants. This work compares two natural refrigerants: R-744 and R-290 and two synthetic refrigerants: R-134a and R-32. All these refrigerants are used mainly in heat pumps. In this work were calculated and compared the following performance parameters: heat rejected in the condenser, cooling power, compressor power, and the coefficient of performance (COP). The most important parameter is the coefficient of performance because when it decreases, electric energy consumption increases. It requires reaching a high value of COP. Further, this work deals with the economic analyses of selected refrigerants. The last aim of this article is their ecologic analysis based on the GWP factor.

Solid fuel combustion accompanies particulate matter production. These particles negatively affect human health, so ways of capturing them are being sought. Local heat sources are a major producer, with this article focusing on the flue gas tract of this heat source. A baffle has been placed in the flue gas tract, the position of which is changing. It is observed the impact of particulate matter flowing through this baffle with a focus on the settling areas. Particles are trapped in the settling areas and do not flow further through the flue gas tract. Particulate matter flowing was investigated by the visualization method called Particle image velocimetry (PIV). Visualizing the flow allows to get a figure of the flow and a dynamic record of the state of the object. The result of the visualization is the assessment of the monitored flow, the determination of its trajectory and streamlines.

The demand for energy is growing in the world, and therefore attention has been focused on the use of possible alternative energy sources. For countries with limited access to common hydrocarbon gases, methane hydrates appear to be a potential source of energy. Under certain pressure and temperature conditions, it is also possible to produce hydrates of hydrocarbon gases under laboratory conditions. However, we are currently at a very early stage in the development of methane hydrates. The transition from scientific theory to practical extraction is currently underway. This article describes the influence of selected physical parameters on the nucleation rate of hydrocarbon gas hydrates.

The standard detection of the emission and power parameters of the combustion process can be time and money consuming due to the performance of experimental measurements with the necessary measuring instruments. Alternatives to describe the combustion process are mathematical models. Their variability is high and therefore, depending on the need for use, an analytical mathematical model was chosen. Among the computationally faster and less time-consuming models is the analytical model, which can not only describe some parameters of the combustion process (power, emissions and others) but also predict the parameters of the combustion process according to the selected input values. This work is focused on the prediction of selected emission parameters through an analytical model for 100 % straw and 100 % wood pellets.

The COVID-19 pandemic brought a period of high consumption of protective masks and an increase in their waste. Therefore, it was necessary to look at possibilities for their disposal. This article is focused on the disposal of FFP2 masks in the form of pellets blended with sawdust. Further, their ash melting behavior was observed. The method of ash preparation can impact the resulting values of melting temperatures. Therefore, this article investigates the resulting values of ash melting temperatures determined during different ash preparations, such as temperatures (550 °C and 815 °C) and ash size (non-sifted, smaller than 50 µm and 100 µm). All measured deformation temperatures were higher than 1100 °C and even higher than 1200 °C for some samples. Moreover, the presence of FFP2 masks in pellets only insignificantly affected the values of melting temperatures compared to pure wood pellets. The measured values also showed that increasing the temperature of ash preparation from 550 to 815 °C can increase the resulting values of melting temperature. The most significant proportion of the fraction size on the resulting melting temperatures was observed for beech with 5% and 10% of masks at an ash temperature of 550 °C and for spruce with 10% of masks at an ash temperature of 815 °C. [ABSTRACT FROM AUTHOR]

Agricultural and other residues are promising renewable energy sources. However, they can cause problems in combustion processes. One of these problems is also low ash melting temperatures. Except, the ash melting behavior can be impacted by many factors, such as ash preparation or used atmosphere. This article deals with comparing different atmosphere conditions during measurements of ash melting temperatures of three agricultural pellets: alfalfa, straw, and hay. The first one was oxidizing with compressed air and nitrogen. The second atmosphere was reduced with the air purge, and the last was only reduced, consisting of 60% carbon monoxide and 40% carbon dioxide. Differences between individual atmospheres were none, up to 9.8%. The most significant differences have appeared between oxidizing and reducing atmospheres. In general, the oxidizing atmosphere presents a less expensive way. More attention should be paid to the use of oxidizing atmosphere for applications in heat sources mainly due to its similarity to the combustion process. However, it would be suitable to realize more comprehensive research regarding ash preparation in different ways and with using of different types of fuel. [ABSTRACT FROM AUTHOR]

Biomass has been still on the rise in recent years in the world. But combustion of biomass led to the increase of emissions in the atmosphere. Mainly in winter time is formed a large amount of particulate matter. They have adverse impact on our health when human breathes them. This is a reason why is important to produce low level of these emissions. However, several aspects impact on their formation. This article examines impact of type of fuel and operation of heat source on PM formation. It compares particulate matter from combustion of wood chips and sawdust at nominal and reduced output.

It is very important to separate particulate matter before their leaving into the air because of their harmful impact on human health. It exists a lot of devices, which can separate these particles. But their implementation and operation in small heat source can be considerably difficult on finances, and often have complex maintenance. Therefore, it is important to look for solutions of reduction the producing of particulate matter with easier maintenance and also less financial difficulty. This article deals with flow modelling of particulate matter by using baffles placed in the flue tract of wood stove. Influence of baffles is observed by using CFD simulations.

Bio-waste is a source of energy-rich material. Therefore, it can be used in further processes and efficiently utilized. Further processes of waste utilization include compressing them to pellets. However, this type of pellet often has a low bulk density, high ash content, low ash melting temperature, and low calorific value. This research dealt with the energy properties of peanut and pistachio nut shells that were pure or mixed with spruce sawdust in half proportion and compressed into pellets. As a continuation of previous research, the properties of these pellets prepared were measured and compared with pure spruce pellets and with pellets from walnut shells. The tested shell pellets had calorific values similar to wood pellets from spruce. However, mixing nut shells with spruce solved the problems of high ash content and low ash melting temperatures. The amount of wood present in the pellets resulted in increased ash melting temperatures and decreased the ash content. [ABSTRACT FROM AUTHOR]

Several factors affect how particulate matter and gaseous emissions are formed during the combustion processes of biomass. The amount of combustion air, as well as its redistribution, is one of these factors. This article deals with the performance and emission parameters determined using different distributions of the amount of combustion air of the wood stove with beech wood as a fuel. Eighteen different settings of primary, secondary and tertiary air supplies were realized, while heat output, efficiency, particulate matter, carbon monoxide and nitrogen oxides were measured or determined. The aim of this article is to identify the optimal air distribution between primary, secondary, and tertiary air supplies focused on the mentioned parameters. Based on the results, two settings (25/50/25 and 0/100/0) could be the optimal variant. However, the concentration of particulate matter reached a higher value during the setting with a ratio of 25/50/25, similar to a ratio of 50/25/25. The measurement during the setting with a ratio of 0/100/0 could be influenced by the existing embers on the grid before the start of the measurement. However, it is important to supply all three types of combustion air with the main emphasis on the secondary air supply due to the completely use of the combustible gases. [ABSTRACT FROM AUTHOR]

At present, we are still feeling the effects of the COVID-19 pandemic in connection with the huge amount of waste generated. However, the reuse of the produced waste in other processes requires energy consumption. This article deals with the reuse of face masks FFP2, which were added as an admixture to spruce or beech sawdust and then processed into pellets. During the production process of the pellets, energy consumption was measured and further converted to one ton of pellets, and also the consumption was reflected in the price of electricity. After storage, the mechanical durability and dimensions of the individual pellets were measured, and their density was calculated. Based on the results, it can be concluded that spruce pellets with 10% face masks FFP2 (consumption 747.41 kWh; durability 97.53%) and beech pellets with 5% face masks FFP2 (consumption 721.27 kWh; durability 97.38%) achieved higher values of mechanical durability and also consumed more energy than the remaining samples with lower values of durability without considering the sample with spruce sawdust and 5% FFP2 face masks (consumption 872.63 kWh; durability 91.68%). The production of spruce pellets with 5% FFP2 face masks was affected mainly by cold outside weather. [ABSTRACT FROM AUTHOR]

A lot of residual biomass has energy value and can be used for further applications through suitable treatments, such as pelletization. This treatment can improve properties, mainly energy density, but can also lead to problems due to their low ash melting temperatures, high ash content, and the formation of harmful compounds during combustion. This article deals with the energy potential of pellets produced from spruce sawdust, spruce bark, and pine cones in different proportions. The impact of cone and bark contents on pellet properties was also observed. The energy properties of the produced pellets were measured, such as the contents of carbon, hydrogen, nitrogen, moisture, volatile, fixed carbon, and ash, as well as calorific values and ash melting temperatures. Based on the results, it can be concluded that the addition of pine cones and spruce bark to spruce sawdust mainly affected the contents of nitrogen and ash and melting temperatures. Despite this, all produced pellets met the standard EN ISO 17225-2 for the content of nitrogen, ash, and also lower calorific value at least B quality. However, only three pellet samples of five met this standard for A2 and B quality for ash melting behavior. Therefore, they present an alternative fuel with interesting energy potential. [ABSTRACT FROM AUTHOR]

Micro-cogeneration is cogeneration with small performance, with maximal electric power up to 50 kWe. On the present, there are available small micro-cogeneration units with small electric performance, about 1 kWe, which are usable also in single family houses or flats. These micro-cogeneration units operate on principle of conventional combustion engine, Stirling engine, steam engine or fuel cell. Micro-cogeneration units with fuel cells are new progressive developing type of units for single family houses. Fuel cell is electrochemical device which by oxidation-reduction reaction turn directly chemical energy of fuel to electric power, secondary products are pure water and thermal energy. The aim of paper is measuring and evaluation of operation parameters of micro-cogeneration unit with fuel cell which uses natural gas as a fuel.

Various waste materials have energy potential. It is important to make use of this potential and prepare the product for further use by treating the waste. Treatments such as compressing waste into pellets leads to increasing the energy density of this fuel, which benefits transport and storage costs. However, low bulk density, high ash content, low-ash melting temperatures, and low calorific values of non-woody pellets can cause problems during their combustion. This article deals with the energy usage of walnut shells, which were blended with spruce sawdust in various amounts and compressed into pellets. The mechanical and energy properties of these were measured and compared with recommended or standardized values. The formed pellets met the quality limit for bulk density, ash content, moisture content, the content of nitrogen and sulfur, and net calorific value according to ISO 17225. However, low ash melting temperatures were noticed for pellets from pure walnut shells, and also lower mechanical durability for produced pellets with walnut shells contents higher than 10% were detected. [ABSTRACT FROM AUTHOR]

With the combustion of solid fuels, emissions such as particulate matter are also formed, which have a negative impact on human health. Reducing their amount in the air can be achieved by optimizing the combustion process as well as the flue gas flow. This article aims to optimize the flue gas tract using separation baffles. This design can make it possible to capture particulate matter by using three baffles and prevent it from escaping into the air in the flue gas. The geometric parameters of the first baffle were changed twice more. The dependence of the flue gas flow on the baffles was first observed by computational fluid dynamics (CFD) simulations and subsequently verified by the particle imaging velocimetry (PIV) method. Based on the CFD results, the most effective is setting 1 with the same boundary conditions as those during experimental PIV measurements. Setting 2 can capture 1.8% less particles and setting 3 can capture 0.6% less particles than setting 1. Based on the stoichiometric calculations, it would be possible to capture up to 62.3% of the particles in setting 1. The velocities comparison obtained from CFD and PIV confirmed the supposed character of the turbulent flow with vortexes appearing in the flue gas tract, despite some inaccuracies. [ABSTRACT FROM AUTHOR]

The combustion of biomass is accompanied by the formation of particulate matter, the presence of which in the atmosphere harms human health. It is important to show the issues of reducing these pollutants and their impact on human health. This article focuses on the process of biomass combustion. The used model consists of two parts: the combustion chamber and the flue gas tract. The article shows four types of modification of the flue gas tract designed to reduce the amount of particulate matter in the atmosphere. Baffles are located in the flue gas tract, which is designed to capture the particulate matter. The final model is simulated by turbulent–viscosity models, k-ε realizable model, and then k-ω shear stress transport model. The interaction between turbulence and chemical reactions is expressed by using the Eddy Dissipation Concept model. The results then show different profiles of temperature, velocity, and particle distribution. Based on the evaluated data from two different calculations, it can be concluded that the baffles have a significant effect on the reduction of particulate matter in the atmosphere. The used baffles are able to capture mainly particles with a diameter greater than 100 µm. A significant number of particles with a diameter lower than 100 µm flows from the flue gas tract to the surrounding environment. [ABSTRACT FROM AUTHOR]

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The combustion leads to pollution with particulate matters (PM). These emissions are considered to cause the greatest harm to human health. Particulate pollutants consist of the following substances: carbon, ammonium, metals, organic materials, nitrates and sulfates. This article deals with analysis of the particulate matters samples from wood biomass and brown coal. The analyses were carried out by elemental determinator and thermogravimetric analyzer. Thermogravimetric analyzer determines the composition of organic, inorganic, and synthetic materials. The elemental determinator is used to determine carbon, hydrogen, nitrogen and sulfur in organic matrices. Further analysis compares the size distribution of these samples. Size distribution was determined by using of vibratory sieve shaker machine. The shape of particles was observed by stereo microscope and density was also determined such as a ratio of their weight and volume. It is important to analyze chemical and physical properties of PM in order to decrease their concentration during combustion process. [ABSTRACT FROM AUTHOR]

Heat pipes, as passive elements show a high level of reliability when taking heat away and they can take away heat flows having a significantly higher density than systems with forced convection. A heat pipe is a hermetically closed duct, filled with working fluid. Transport of heat in heat pipes is procured by the change of state of the working fluid from liquid state to steam and vice versa and depends on the hydrodynamic and heat processes in the pipe. This study have been focused on observing the impact these processes have on the heat process, the transport of heat within the heat pipe with the help of thermovision. The experiment is oriented at scanning the changes in the surface temperatures of the basic structural types of capillary heat pipes in vertical position. [ABSTRACT FROM AUTHOR]

Presence of particulate matter (PM) in the atmosphere is a problem mainly in the winter time. PM are getting into atmosphere from combustion of solid fuels in heat sources. Their impact on people health is harmful, when we breathe them. Therefore, it is necessary for reduction these emissions in the atmosphere. This article investigates downfall velocities of particulate matter based on calculations and then it observes velocity simulation of particulate matter flowing through baffles placed in the flue tract of local heat source by using program Ansys. These baffles are usable for separation of particulate matter in the flue tract. When particles reach downfall velocity, forces which acting on them are in equilibrium and they would not get into atmosphere from the flue tract of heat source. CFD simulation in program Ansys allows us to observe velocity distribution in flue tract and compare it with calculated downfall velocity of these particles. [ABSTRACT FROM AUTHOR]