The main aim of this study is to estimate the kinetic and thermodynamic parameters of thermal decomposition of starches by the Coats–Redfern method. This procedure is a commonly used thermogravimetric analysis/difference thermal gravimetry/differental thermal analysis (TG/DTG-DTA) kinetic method for single rate form. The study also shows a proposed method for reactive hydroxyl groups content on the starch surface determination, and values were in range of 960.21–1078.76 mg OH per 1 g of starch. Thermal processing revealed the thermophysical properties of biomass for the kinetics of decomposition estimation. Activation energies reached the values in range of approximately 66.5–167 kJ·mol−1. This research also enables the determination of the temperature conditions required for becoming the desired form of material. Therefore, it is necessary to achieve the requested compact porous structure in an activation process, because in the native state, the polymer exhibits limited applications as a result of thermal decomposition, low shear stress, retrogradation, and syneresis, hence the low solubility in organic solvents. Thermodynamic parameters and reactive hydroxyl groups in this article review are innovative and have not yet been found in the literature.

The paper focuses on the determination of fuel consumption (CO 2 emission) and exhaust emissions such as CO, HC, NO x , and PM in the process of timber extraction and transport. A complex assessment of fuel consumption and exhaust emissions was performed for the entire, fully mechanized supply chain including, tree felling, delimbing, and bucking with a harvester, timber extraction with a forwarder and transport with a truck. The performed investigations determined unit exhaust emissions (referred to 1 m 3 of timber) for the entire technological process and its individual stages. The investigations of the exhaust emissions and fuel consumption were performed under actual conditions of typical forest operations and transport. State-of-the-art portable emissions measurement system equipment was used for the measurements. The fuel consumption was determined through the carbon balance method. The investigations were performed for the process of extraction and transport of pulpwood. The measurements were performed on location in the town of Bębnikąt near Poznań, in a pinewood forest, typical of this part of Europe. The analysis includes the transport of timber to the lumberyard on a distance of 31.4 km. The total fuel consumption for the entire mechanized supply chain was 2.10 dm 3 /m 3 . The total exhaust emissions, however, amounted to: CO-8.91 g/m 3 , HC-1.19 g/m 3 , NO x -45.32 g/m 3 , PM-4.04 g/m 3 .

The projected increase in the availability of gaseous fuels by growing popularity of household natural gas (NG) filling stations and the increase in the production of gaseous biogas-derived fuels is conducive to an increase in the use of NG fuel. Currently, natural gas in various forms (compressed natural gas (CNG), liquefied natural gas (LNG)) is popular in maritime, rail and road transport. A new direction of natural gas application may be non-road mobile machines powered by a small spark-ignition engine (SI). The use of these engines in the wood chippers can cause the reduction of machine costs and emissions of harmful exhaust gases. In addition, plant material chippers intended for composting in bio-gas plants can be driven by the gas they are used to produce. The biogas can be purified to bio-methane to meet natural gas quality standards. The article presents the design of the natural gas supply system, which is an upgrade of the Lifan GX 390 combustion engine spark ignition engine (Four-stroke, OHV (over head valve) with a maximum power of 9.56 kW), which is a common representative of small gasoline engines. The engine is mounted in a cylindrical chipper designed for shredding branches with a maximum diameter of up to 100 mm, which is a typical machine used for cleaning work in urban areas. The engine powered by CNG and traditionally gasoline has been tested in real working conditions, when shredding cherry plum (Prunus cerasifera Ehrh. Beitr. Naturk. 4:17. 1789 (Gartenkalender4:189–204. 1784)). Their diameter was ca. 80 mm, 3-metere-long, and humidity content ca. 25%. The systems were tested under the same actual operating conditions, the average power generated by the drives during shredding is about 0.69 kW. Based on the recorded results, it was found that the CNG-fuelled engine was characterized by nitrogen oxides (NOx) emissions higher by 45%. The other effects of CNG were a reduction in carbon dioxide (CO2), carbon monoxide (CO) and hydrocarbon (HC) emissions of about 81%, 26% and 57%, respectively. Additionally, the use of CNG reduced fuel consumption by 31% and hourly estimated machine operating costs resulting from fuel costs by 53% (for average fuel price in Poland: gasoline: 0.99 EUR/L and CNG: 0.71 EUR/m3 on 08 November 2020). The modernization performed by the authors ensured the work of the drive unit during shredding, closer to the value of stoichiometric mixtures. The average (AVG) value of the air fuel ratio (AFR) for CNG was enriched by 1.2% (AVG AFR was 17), while for the gasoline engine the mixture was more enriched by 4.8% (AVG AFR was 14). The operation of spark-ignition (SI) combustion engines is most advantageous when burning stoichiometric mixtures due to the cooperation with exhaust aftertreatment systems (e.g., three-function catalytic converter). A system powered by CNG may be beneficial in systems adapting to operating conditions, used in low-power shredding machines, whose problem is increased HC emissions, and CNG combustion may reduce them. The developed system does not exceed the emission standards applicable in the European Union. For CO emissions expressed in g/kWh, it was about 95% lower than the permissible value, and HC + NOx emissions were 85% lower. This suggests that the use of the fuel in question may contribute to tightening up the permissible emission regulations for non-road machinery.

This paper discusses the determination of fuel consumption and exhaust gas emissions when shredding branches in urban areas. It aimed to determine the hourly emission of exhaust gases to the atmosphere during such work and to identify the designs that can reduce it. The research was carried out with a cylinder woodchipper driven by a low-power (9.5 kW) combustion engine. There were three configurations of the tested drive unit: The factory setting (A) with a carburettor fuel supply system, modernized by us to include an electronic injection system (B). This system (B) was expanded with an adaptation system patented by the authors (P. 423369), thus creating the third configuration (C). The research was carried out when shredding cherry plum (Prunus cerasifera Ehrh. Beitr. Naturk. 4:17. 1789 (Gartenkalender 4:189-204. 1784)) branches with a diameter of 80 mm, which presented a large load for the machine. The machine was operated by one experienced operator. The average operating conditions during the tests were as follows: Branch delivery frequency of about 4 min−1 and mass flow rate of about 0.72 t h−1. During the tests with the use of PEMS (portable emissions measurement system, here Axion RS from Global MRV), we analyzed the emissions of compounds, such as CO, CO2, HC, and NOx, and determined the fuel consumption based on the carbon balance. The research showed that the use of an injection system (B) reduced fuel consumption from 1.38 to 1.29 l h−1 (by 6.7%) when compared to the carburettor system (A). Modernization of the injection system (B) with an adaptive system (C) reduced fuel consumption from 1.38 to 0.91 l h−1 (by 34%) when compared to the carburettor system (A). An hour of shredding with a cylinder chopper emits the following amounts of flue gases: design A (HC 0.013 kg h−1; CO 0.24 kg h−1; CO2 2.91 kg h−1; NOx 0.0036 kg h−1), design B (HC 0.0061 kg h−1; CO 0.20 kg h−1; CO2 2.77 kg h−1; NOx 0.0038 kg h−1), and design C (HC 0.017 kg h−1; CO 0.22 kg h−1; CO2 1.79 kg h−1; NOx 0.0030 kg h−1). The adaptive system entails significant reductions in non-HC emissions, which indicates that the system needs to be improved with respect to fuel-air mixture control for its enrichment of the low-to-high-speed change. The admissible emission limits for harmful compounds in exhaust gas for the tested group of propulsion units are in accordance with the provisions in force in the European Union from 2019 for the tested propulsion units during operation, with a full CO load about 6100 g h−1 and HC + NOx about 80 g h−1. The tested propulsion units emitted significantly less pollution under real operating conditions (because they did not work under full load throughout the entire test sample).

Abstract. The paper presents the results of investigations on the exhaust emissions carried out under real operating conditions of gasoline engines operating in a power generator and a chainsaw. During the operation of these devices the authors measured the following exhaust emissions: CO, HC, NO x and CO 2 . For the measurements the authors used a portable exhaust emission analyzer SEMTECH DS by SENSORS. This analyzer measures the concentrations of the exhaust gas components in an on-line mode while the engine is running under real operating conditions (road, field etc.). The exhaust emissions tests of non-road engine applications are performed on engine test beds in the NRSC (ISO 8178) and NRTC tests. The presented method is a new solution in determining of the exhaust emissions from such engines. The obtained results were compared with the applicable emission requirements. Besides, based on the performed investigations, the authors attempted an evaluation of the possibilities of the use of the measurement method for development works related to the reduction of the emission from small gasoline engines.