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Woody and agricultural wastes are important fuels in many countries, and have the potential of being even more important in the future. The main problems of plant biomass combustion are low ash melting temperatures and increased emissions. The most widely used treatment to solve the problem of low ash melting point is blending a fuel with an additive. In this work, pellets were produced from wheat straw containing wood sawdust and paper sludge in the following proportions 40:40:20 and 45:45:10 (straw/sawdust/paper sludge). The purpose of this work was to study the influence of sludge and dendromass on the straw pellet parameters and combustion process. The highest calorific value of 15.71 MJ kg&minus, 1 was registered for a sample with a 10% paper sludge concentration. The effectiveness of paper sludge was proved, and the ash melting temperature was increased from 1025 to 1328 &deg, C for the same sample.

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.

Hydrogen was established as one of the main pillars of energy stability in the Europe Union. One of the ways how to achieve this goal is natural gas enriched with hydrogen. Due to this is very important to know the properties of this fuel and its behaviour during combustion. The main scope of the research is to provide a better understanding of the emissions, efficiency, and performance of the heat source when combusting hydrogen and gas fuel mixture. In this paper is described hydrogen characteristics, hydrogen fuel preparation, an overview of gas fuel combustion in gas appliances with the hydrogen additive, a mathematical model for the combustion process estimation. In the conclusion, multiple predictive models were compared. We can state that, based on calculations of a numerical predictive model, as hydrogen concentration raised emissions, as nitrogen, carbon dioxide, wet exhaust, and water, are decreasing.

Exhaust gases from combustion plants contain complex mixtures of air pollutants, of which many are harmful to human health. From all of these pollutants, particulate matter has the greatest negative effect on health. Small heat sources with biomass combustion are associated with high concentrations of particulate matter. It is crucial to reduce the quantities of solid particles getting into the atmosphere in every region of their formation in order to decrease environmental pollution and to improve the air quality. The main subject of this paper is the optimisation of the geometrical parameters of fireplace with the focus on exhaust gas path. A numerical model of tunnel labyrinth was created in order to investigate the behaviour of PM emitted into the ambient air from combustion process in the small heat sources. The results indicate that the modification of geometrical parameters has an impact on PM concentration in flue gas and on its separation.

Wood pellets as biofuel are more and more used in small heat sources in Europe. Standard wood pellets are produced from wood sawdust without bark. The paper deals about the impact of bark in wood pellets on their properties and combustion process. Special attention in this work is paid to production of particulate matter during combustion of wood pellets depending on bark content. There were experimentally produced spruce wood pellet samples with 0, 1, 2, 5, 10, and 20% content of bark. The density, moisture content, calorific value, ash content, and ash fusion temperature were detected on produced samples. Then, the combustion took place in a small heat source which was tested on an experimental device designed for the measuring of heat output and emission production. Based on the achieved results, we can conclude that bark content in pellets has a significant impact not only on wood pellet properties but also on performance and environmental characteristics of pellets. The results showed that growing bark content has negative impact on wood pellet properties, mainly decrease calorific value and ash fusion temperature, and increase ash content. Growing bark content in wood pellets also decreased heat output of heat source and increased gas emissions and particulate matter production.

The pulp and paper industry in Europe produces over 11 million tons of waste per year. Given high landfill operational costs, thermal co-processing with biomass may be a viable management and valorisation option for such wastes. In this work, the analysis of biomass (wood sawdust), mixture of primary and secondary pulp mill sludge and their respective blends (50 wt.%, 60 wt.%, 70 wt.% of sludge) was assessed by thermogravimetric analysis. One of the possibilities to ensure valorisation of paper pulp mill sludge is its combustion in the form of pellets containing a different amount of sludge. Production of pellets samples was realised on laboratory experimental device. The measurements showed that increasing the content of paper sludge in the produced pellets reduced the calorific value and increased the ash content. This research deals also with the effect of paper sludge on the ash melting temperatures. The results indicated that a higher content of paper sludge in the pellets increased the ash melting temperatures. This advantage of paper sludge can be utilized in co-combustion of biomass with a low ash melting temperature.

Constant effort to reduce heating costs leads to production of not only high-quality pellets from pure wood but also cheaper vegetable pellets of inferior quality in terms of energy properties.1,2 The combustion of alternative pellets in small boilers causes many problems, mainly ash sintering, as a result of their low melting temperature.3,4 The paper focuses on experimental determination of bed temperatures in the burning layer during wood pellet combustion. The bed temperatures are important for prediction of combustion phases and better localization and description of sites that are critical for the sintering of ash particles as temperatures are close to the ash melting points. This experiment describes a method for measurement of the temperature field in the symmetry plane of the burner during wood pellet combustion in the retort burner. The measurement of temperature profiles at different locations in the burner shows that the combustion process in the retort burner is rather more horizontally strat...

One of the important fuel properties is ash melting. Fuel with high ash sintering is not applicable for most of the boilers. Sintering is the process that can occur in the burner and block air flow to the base fuel layer. One of the materials, which can participate on this process, is wood bark. The ash melting from combustion of wood bark has negative impact and lowers the temperature in the process. The melting temperature depends on the chemical composition of ash. Ash melting takes place in several stages: first sign of deformation is gradually melting until complete reflow. In order to analyze the melting process, the various stages are recorded with characteristic temperatures. These temperatures are defined as follow: deformation temperature “DT”, the sphere temperature “HT”, hemispherical temperature “HT” and the flow temperature “FT”. For reliable operation of boilers is important to know melting temperature of ash. Melting temperature for low meltable ashes is from 1000 to 1200 °C, for medium meltable ashes from 1200 to 1450 °C and for heavy meltable ashes over 1450 °C. During the combustion of wood biomass the temperature should not exceed 1100 °C. This article deals with ash content from combustion of wood bark and its ash melting.

The fireplace combustion of wood is a significant and largely unregulated source of emission pollution. Therefore article deals about experimental measurements of emission parameters from combustion of biomass in small heat sources. The objectives of the present work are to analyse basic pollutants arising from the combustion process and to define measurement technique applied to characterise particle emissions from biomass combustion. Gravimetric methods are among the most accurate and precise methods of quantitative analysis and therefore was selected for measurement of solid emissions. Conclusion of work focus on evaluation of the tests results, especially concentration of particulate matter (PM) from the combustion of briquettes made from different kinds of biomass. During the combustion of certain briquettes was recorded a high amount of particulate matter and analyser switched to “stand by” mode in several cases. The results indicate that higher concentration of PM was determined in the case of briquettes made from phytomass in comparison to briquettes made of woody biomass.

This article deals with the performance of heat pipes, depending on the operating temperature and positions (operation angle). There is described the essential function of the heat pipe manufacturing process. Measurements were carried at an operating temperature of 40 °C to 90 °C. Stainless heat pipes were made of three kinds of materials AISI 304, AISI 310, AISI 316 and filled with a distilled water, up to 20% of the heat pipe inner volume. For each material was selected heat pipe with the best results. The heat pipes were measured at various angles of vertical inclination (0 ° - 90 °), at the working temperature 90 ° C. The performance was measured on the experimental device. Presented results show the progress of individual measurements and the effect of operating parameters on the performance of heat pipes.

Biomass as fuel is used for many years. At present it is important to effectively use energy sources because price of energy is more and more expensive. This is the main reason for building of modern low-energy houses. The projected thermal performance of these buildings rarely exceeds 4-6 kW. During most days of heating season these buildings need only 2-4 kW of heat but almost all produced heat sources have nominal thermal power higher than 10-15 kW. Because of this the thermal power of majority heat sources is oversized and using of them could be complicated. One of the solutions of this problem should be heat storage in accumulation vessels. The paper deals about using of local heat source with warm-water heat exchanger for combustion of wood biomass. There were tested thermal and emissions parameters of wood stoves. There was measured thermal power to air and to the accumulation vessels, production of carbon monoxide (CO), production of nitrogen oxides (NOx) and production of particulate matters (PM). The results shows that local heat sources with warm-water heat exchanger for combustion of wood biomass could be used for heating of new low-energy buildings.

Global energy consumption is increasing every year, and, despite their many negative impacts, fossil fuels are a major source of energy, but their reserves are gradually depleting. One of the promising but underutilized resources is plant biomass (phytomass). The main problem of plant biomass combustion is the low melting temperature of ash, but there are also problems with corrosion of heat exchangers and clogging of heat-exchanging surfaces. This work is concerned with the production of straw pellets in order to increase the melting temperature of ash by adding an additive. The paper sludge contains substances that can increase the melting point of ash and was therefore added to the pellet samples. This additive was mixed with straw in ratios from 90:10, 80:20 and 70:30 (straw/paper sludge). The use of paper sludge showed positive effects on increasing the melting temperature of the ash samples. The deformation temperature of the ash has already risen from 1020 to 1260 &deg, C after the addition of 10% sludge, which is comparable to wood pellets.

Nowadays it is important to limit the use and combustion of fossil fuels such as oil and coal. There is a need to create environmentally acceptable projects that can reduce or even stop greenhouse gas emissions. In this article, we dealt with the objectives of energy policy with regard to environmental protection, waste utilization, and conservation of natural resources. The main objective of the research was to assess the possibility of the use of spent coffee grounds (SCG) as fuel. As a part of the solution, the processing of coffee waste in the form of pellets, analysis of calorific value and combustion in the boiler were proposed. The experiments were done with four samples of pellets. These samples were made from a mixture of wood sawdust and spent coffee grounds with ratio 30:70 (wood sawdust: spent coffee grounds), 40:60, 50:50 and 100% of spent coffee grounds. The calorific values were compared with wood sawdust pellets (17.15 MJ.kg(-1)) and the best lower calorific value of 21.08 MJ.kg(-1) was measured for 100% of spent coffee grounds. This sample did not achieve the desired performance during the combustion in the boiler due to the low strength of the sample. Web of Science 13 5 art. no. 1235

You Heat pipe is a high efficiency heat transfer element, depends on the evaporation, condensation and circulation of inside working fluid. The working fluid of a high temperature pulsating heat pipe is generally alkali metals, and sodium heat pipe can operate in range of 500-1100°C. In order to investigate terminal velocity of working fluid, the glass pulsating heat pipe was produced for experimental purposes. The experiment was carried out, in order to simulate real operating conditions in range of 500-1100°C. Sudden boiling of liquid sodium (b.p. = 883°C at 1 atm) inside the all quartz-made heat pipe results in high-temperature reaction of sodium vapour with the inner wall surface. The reaction became more aggressive with increasing vapour temperature and resulted in heat pipe explosion. The evaluation of damage character is analysed in this paper.

Particulate matter (PM) belongs to significant pollutants threatening human health. Therefore, it is important to pay attention on these solid emissions. Several factors, such as type of fuel, quantity and temperature of the combustion air, operation conditions and design of heat source etc., influence on their formation. The aim of this work is investigation of fuel type and various inlet air temperatures on PM formation. The above mentioned parameters were measured in wood stove. In the first stage of the research, there were measured following fuels: beech, spruce wood, birch with bark and birch without bark. The results show that higher PM concentrations were measured during the combustion of birch with bark. The outcome of these analyses is the negative effect of bark on PM formation. In the second stage, there was investigated the effect of different combustion air temperatures on PM formation. Based on the measured results, it can be concluded, that temperature of combustion air has not influence on PM concentration, but it has influence on heat power.

During the aluminium production, 50% of the supplied energy is consumed by the chemical process, and 50% of the supplied energy is lost in form of heat. Heat losses are necessary to maintain a frozen side ledge to protect the side walls, so extra heat has to be wasted. In order to increase the energy efficiency of the process, it is necessary to significantly lower the heat losses dissipated by the furnace’s external surface. Goodtech Recovery Technology (GRT) has developed a technology based on the use of heat pipes for utilization energy from the waste heat produced in the electrolytic process. Construction of condenser plays important role for efficient operation of energy systems. The condensation part of the heat pipe is situated on top of the heating zone. The thermal oil is used as cooling medium in the condenser. This paper analyses the effect of different operation condition of thermal oil to thermal performance. From the collected results it is obvious that the larger mass flow and higher temper...

Performance heat pipes depends on several parameters. This article deals with the performance of heat pipes, depending on the working fluid and operating temperature. There is described the essential function of the heat pipe manufacturing process. Stainless heat pipes were made of material AISI 304 and filled with a distilled water and solution of distilled water with silver nitrate, up to 20% of the heat pipe inner volume. Measurements were carried at an operating temperature of 40 °C to 90 °C. The performance was measured on the experimental device. Presented results show the progress of individual measurements and the effect of operating parameters and working fluid on the performance of heat pipes.

This work is concerned with domestic boilers burning solid fuels. Time-dependent coal combustion in the counter-current fixed-bed has been investigated using both measurements and mathematical modeling. Three-dimensional, time- dependent model of the fixed-bed has been developed as a submodel to a computational fluid dynamics (CFD)-based model of the whole boiler. The overall 0.0177 kg/(m 2 s) and 0.0266 kg/(m 2 s) coal combustion rates have been observed for air velocities of 0.17 m/s and 0.26 m/s, respectively. Two temperature peaks have been observed: one propagating downward the bed and the other one moving upward from the bed bottom. The developed three-dimensional model has demonstrated good agreement with the measured data. The char oxidation rate is paramount in predicting the temperature−time history of the bed. A 20% increase in its rate has resulted in a 20% increase in the overall combustion rate. A 20% increase in the fuel density has slowed down the combustion rate by around 5%. A 20% increase in the effective thermal conductivity of the fixed-bed has resulted in minor changes.

Heat pipes are one of the most efficient ways to transfer thermal energy hundred times more efficiently than copper. In this work, we present the investigation of sodium terminal velocity inside a glass pulsating heat pipe. Velocity measurements were conducted under operating conditions within the range of 500 – 1 100 °C. Since sodium is generally able to etch glass and ceramic materials, its presence resulted in glass reduction and sodium oxidation. From the XPS analysis of specimens extracted from a glass pipe after sodium explosion, it can be concluded that the reaction products are sodium oxide Na2O and a thin layer of carbon, which is localized on the SiO2 glass. The character of damage induced by chemical reactions is analysed in this manuscript.

Air quality inside the building is an important measure of comfort for people living and working in it. Achieving optimal air quality requires a regulated indoor air control system, often in combination with thermal regeneration. Typical short ventilation, irregular window and door ventilation are rarely adequate. From the point of view of the thermal comfort of the environment, it is necessary to predict the development and selection of suitable systems for the thermal comfort of the environment to predict how many thermal factors will affect the population, room temperature uniformity, asymmetry of the radiation temperature, and turbulence intensity of the flowing air. People are capable of detecting heat, temperature changes can feel not only globally, but also as local heat loss on the parts of the body. Thermal comfort is given by the air temperature and radiant heat, air velocity and relative humidity in the room. The main impact of these factors on the comfort level of individuals depends on the activity and type of clothing. The bad thermal comfort is detrimental to workers' health, increasing the risk of accidents and affects adverse effects on the psyche. The assessment of impact of the working environment to human form comparing actual and optimal parameter values of the working environment.

Concentration of solid particles in ambient atmosphere is increasing in many countries nowadays. Particulate matter pollution in higher concentration has harmful impact on human and animal health. Source of particulate matter are not only industry and traffic. Small heat sources with biomass combustion, especially during winter heating season, are also significant producer of particulate matter emission. There is a huge importance to decrease quantities of solid particles which are getting into the atmosphere in every region of their production in order to decrease environmental pollution and improve air quality. The ability of flue gas emission elimination can influence future using of biomass combustion. Therefore effective and affordable solutions are searching for. The paper deals with the reduction of particulate matter in small heat source with biomass combustion by modification of geometric parameters in flue gas path.

The paper presents an analysis of the impact of fuel feed to power and emissions parameters of the automatic domestic boiler for combustion of wood pellets. For the analysis has been proposed an experimental methodology of boiler measuring. The investigated boiler is designed for operation in domestic heating system. It has heat power equal to 18 kW. Concentrations of flue gas species were registered at the exit the boiler and based on the measured parameters was carried out evaluation of the impact of the fuel feed to heat power and production of emissions.

The paper deals about the impact of the amount of combustion air and its allocation between primary, secondary and tertiary entrance to the combustion process. Concentration of emission and heat power of source can be affected by several factors. One of the important factors is the amount of combustion air and its allocation to primary and secondary combustion air. The paper includes a proposal of experimental equipment, where the effect of the amount of combustion air to formation emission was examined. The measurement methodology, measured results and analysis of the achievements are also described.

The aim of the work is to develop a method of simple characterization of solid fuels combustion in fixed bed, which would be useful for CFD modelling. In this work, the measurements were performed in a test rig, where a combustion front propagates against the airflow. Concentrations of flue gas species were registered at the exit of a fixed bed reactor and the temperature of burning coal was measured in selected points of the reactor as functions of time.