Abstract
The article presents the impact of sawdust conditioning from coniferous trees with a pulsed electric field (PEF) on the characteristics of the combustion heat. The study used four variants of electric field parameters, i.e., (I) 300 discharges with an electric field intensity of 25 kV·cm−1, (II) 150 discharges with an electric field intensity of 25 kV·cm−1, (III) 300 discharges with an electric field intensity of 30 kV·cm−1, (IV) 150 discharges with an electric field intensity of 30 kV·cm−1. It should be noted that the interval between successive discharges was 10 sec and it was constant for each variant of the experiment. A change in the characteristics of the heat of combustion was found under the influence of a pulsed electric field on sawdust from coniferous trees in each period of the measurement. The highest temperatures were achieved by the interaction of a pulsed electric field with a discharge pulse of 30 kV·cm−1 and the number of discharge cycles amounting to 300, whereas significantly lower temperature values were recorded with the discharge electric field intensity of 25 kV·cm−1. It was found that the longest times from the moment of ignition to reaching the maximum temperature were obtained for the material after the influence of PEF with an electric field intensity of 30 kV·cm−1 and the number of pulses 300 (IV combination), while the shortest time of the analyzed interval was stated for the first combination of the experiment (electric field intensity 25 kV·cm−1 and a number of pulses 150). The use of a pulsed electric field allows modeling the combustion time of a homogeneous material, which enables the improvement of the process control possibilities, and is also important information for the design of devices intended for biomass combustion.
Highlights
In many countries, the production of energy from biomass constitutes the largest share in the structure of the use of renewable energy, and biomass is believed to be most likely to increase the use of this fuel as a source of renewable energy [1,2,3,4].Statistically, biomass is one of the three most important sources of fuel used for generating electricity and thermal applications [2]
Analyzing the temperature characteristics during the combustion of biological material, which was a spruce tree previously subjected to stimulation with a pulsed electric field (Figure 10), it was found that the highest temperature was obtained in the case of PEF
Which was a spruce tree previously subjected to stimulation with a pulsed electric field (Figure 10), it was found that the highest temperature was obtained in the case of PEF
Summary
In many countries, the production of energy from biomass constitutes the largest share in the structure of the use of renewable energy, and biomass is believed to be most likely to increase the use of this fuel as a source of renewable energy [1,2,3,4].Statistically, biomass is one of the three most important sources of fuel used for generating electricity and thermal applications [2]. The most important parameters characterizing wood and other thermally transformed fuels in terms of their energy use are combustion heat and calorific value [11,12]. These parameters may differ significantly even within the same fuel, which is affected by many factors, and so, for example, pinewood in air-dry conditions may reach values from 18.6 MJ·kg−1 [13] to 20.54 MJ·kg−1 [14]. Measurement of the temperature of individual periods of the combustion process enables to determine the so-called corrected temperature rise needed to estimate the calorific value. The duration of individual periods is used to determine the so-called amount of heat exchange in the calorimeter, which allows defining the correction for heat exchange between the calorimeter and the thermostat [18]
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