Explore the vast range of titles available.

The heat release rate in internal combustion engines obtained from in-cylinder pressure data is a fundamental method to analyse the combustion characteristics of engines. As the measured in-cylinder pressure is lower than the pressure in the absence of heat loss to the walls, the methodology typically leads to the apparent rate of heat release as the heat loss to the cylinder walls cannot be segregated. Heat loss can then be inferred by reference to the chemical fuel energy expected to be released by the fuel. Typically, in engine thermodynamic analysis, the lower heating value is used to determine the energy released by the fuel. However, in this article, we argue that when detailed comparison with validated combustion modelling was done, it was concluded that the higher heating value is the more appropriate calorific value. In this research, the analysis of heat release rate and its determination using the first law of thermodynamics with constant ratio of specific heats γ and also varying γ is discussed. It was noted that the use of the “3rd term” (term due to the dγ/dϑ) in the heat release rate is advisable as it gives a more reasonable heat loss even in the compression stroke.

Due to the threat posed by the spread of invasive plant species, there is an urgent need to develop effective methods of eradicating and managing their biomass. The aim of the study was to examine selected invasive plants in terms of their use for energy purposes and to find out whether they can be a raw material for the production of second-generation biofuels. First, their chemical compositions were determined. The higher heating value (HHV) and lower heating value (LHV) were also calculated. High values of the higher heating value, ranging from 18.490 MJ∙kg−1 to 19.900 MJ∙kg−1, indicate the possibility of using the biomass of invasive plants for energy purposes (combustion). All investigated invasive plant species were also subjected to the process of obtaining ethanol. This included an alkaline pretreatment with 1% sodium hydroxide, followed by a simultaneous saccharification and fermentation (SSF) process. The highest ethanol yield per ha of plants was obtained at 2.6 m3∙ha−1 for the Reynoutria × bohemica biomass. The remaining species showed an ethanol yield below 2 m3∙ha−1. The conducted research allows for the conclusion that the studied invasive plants can be a promising raw material for the production of bioethanol.

Due to the need to diversify energy sources and transform the energy system and its decarbonization, new paths for obtaining raw materials are being sought. One of the potential options is to increase the use of grasses’ share in bioenergy production, which has a significant area potential. However, the diversified chemical composition of grasses and their anatomical heterogeneity mean that, between the various cultivars and species, the parameters determining their energetic usefulness may differ significantly, hence the key is to know the appropriate parameters at the variety level of a given species in order to effectively carry out the combustion process. In this experiment, a total of 23 varieties of seven grass species (Kentucky bluegrass (Poa pratensis L.), Red Fescue (Festuca rubra L.), Perennial Ryegrass (Lolium perenne L.), Meadow Fescue (Festuca pratensis Huds.), Timothy (Phleum pratense L.), Common Bent (Agrostis capillaris L.), Sheep Fescue (Festuca ovina L.), which had not yet been evaluated in terms of energy utilization, were tested. Proximate analysis showed the average ash content was in the range of 5.73–8.31%, the content of volatile matter in the range of 70.99–82.29% and the content of fixed carbon in the range of 5.96–17.19%. Higher heating value and lower heating value of grasses ranged from 16,548–18,616 kJ∙kg−1, 15,428–17,453 kJ∙kg−1, respectively. The Sheep Fescue turned out to be the most useful species for combustion. It has been shown that there may be statistically significant differences in the parameters determining their combustion suitability between the various varieties of a given species of grass. Therefore the major finding of this work shows that it is necessary to need to know theparameters of a given variety is necessary to optimize the combustion process and maintain the full energy efficiency of the system (especially lower heating value).

Scientists and policymakers are continuously making techno-economic efforts to close the loop in the agricultural value chain by utilizing and maximizing agricultural wastes and their products. The rising issues of agricultural waste management significantly impact the ecosystem and impede environmental sustainability. Untreated and wrongly disposed agricultural residues are a major threat to health (human and animal), the economy, and a significant contributor to greenhouse gas emissions. However, this review extrapolates a resource efficiency technology to address the energy deficit by converting these sustainable waste resource sources to sustainable energy through a sustainable energy system. The torrefaction technique is a more energy-efficient thermochemical process to upgrade the biomass fuel quality. Studies on readily available and commonly disposed agricultural wastes valorised with their energy values, energy density and physicochemical properties were reported in this study, and their performances were compared with fossil fuel (coal and sub-bituminous coal) properties. The assessment brings to the submission that many agricultural wastes can be upgraded to comparable quality in performance via the torrefaction process. It further discovers that the synergy of certain additives and the optimization of process conditions, such as residence time, temperature, pressure, and gas carrier, could better upgrade the biofuel quality without major compromise on product yield.

Biomass has become an increasingly important resource for energy generation. The influence of the chemical composition on the heating value of biomass has not been a thoroughly studied subject, as shown by a bibliometric analysis. It is well known that the heating value of lignin is significantly higher (23.26–25.58 MJ/kg) than that of polysaccharides (18.6 MJ/kg), while extractives often have HHVs over 30 MJ/kg, depending on their oxidation levels. Therefore, the proportions of the chemical components in biomass determine its HHV. Softwoods generally have higher HHVs than hardwoods due to their higher contents of lignin and lipophilic resin. Ashes are incombustible, and a high ash content leads to a lower HHV in biomass. Several models have been proposed to correlate the heating values and chemical compounds of biomass, but the most accurate models are based on the lignin from extracted samples, while good correlations between lignin and extractives have also been reported. No good correlations have been obtained with polysaccharide compounds.

Biomass gasification is one of the promising technologies to produce energy from the renewable energy sources, and the downdraft biomass gasifier is a widely used biomass energy conversion device. Among the various components of a gasifier, the position and the inclination of air nozzle have a vital role in the generation of producer gas. Therefore, a proper design is needed to fix the position and angle of the air nozzle. Keeping the above aspects, the present work focuses on the numerical simulation to predict the appropriate position and inclination of the air nozzle in a 50kWth imbert type downdraft gasifier by the species transport approach. The nozzle inclination varies from 0°, 20°, 30°, 45° and 60°, and the nozzle position is considered from 50mm, 100mm, 150mm and 200mm respectively. Experiments were also conducted to validate the numerical study. Both the studies show that the nozzle inclination at 45° and its position at 100mm above the reduction zone gives a reasonable composition of producer gas.

Waste residues produced by agricultural and forestry industries can generate energy and are regarded as a promising source of sustainable fuels. Pyrolysis, where waste biomass is heated under low-oxygen conditions, has recently attracted attention as a means to add value to these residues. The material is carbonized and yields a solid product known as biochar. In this study, eight types of biomass were evaluated for their suitability as raw material to produce biochar. Material was pyrolyzed at either 350 °C or 500 °C and changes in ash content, volatile solids, fixed carbon, higher heating value (HHV) and yield were assessed. For pyrolysis at 350 °C, significant correlations (p < 0.01) between the biochars’ ash and fixed carbon content and their HHVs were observed. Masson pine wood and Chinese fir wood biochars pyrolyzed at 350 °C and the bamboo sawdust biochar pyrolyzed at 500 °C were suitable for direct use in fuel applications, as reflected by their higher HHVs, higher energy density, greater fixed carbon and lower ash contents. Rice straw was a poor substrate as the resultant biochar contained less than 60% fixed carbon and a relatively low HHV. Of the suitable residues, carbonization via pyrolysis is a promising technology to add value to pecan shells and Miscanthus.

The utilization of lignocellulosic biomass is closely related to one of the renewable sources of energy. However, a few inherent properties of lignocellulosic biomass such as high moisture content, low density, high volume, and heterogeneous composition make it unfavorable for bulk transportation, storage, handling, and conversion. The pretreatment of biomass is found to resolve a few of the aforementioned limitations while increasing the conversion efficiency of lignocellulosic biomass into biofuels. This article reviews the opportunities, challenges, and state-of-art research on torrefaction as a widely used biomass upgrading technique for solid fuel production and thermochemical biomass conversion. Some notable applications of such pretreatments in high-value solid biofuel production, densification, combustion, co-firing, gasification, and metallurgy have been reviewed. The broad changes in physicochemical characteristics and structural chemistry of lignocellulosic biomass because of torrefaction have been thoroughly described. This review also comprehends the effects of different process parameters and operating conditions of torrefaction of lignocellulosic biomass to produce high-value solid fuel. This article attempts to highlight some recent advancements in biomass torrefaction technology concerning the fundamental characteristics of biomass and process operation and optimization as well as the evolution of physicochemical features of torrefied biomass. Lastly, the value-added industrial applications of torrefaction technology and torrefied biomass are also elucidated.

In this study, the quality of wood fuel pellets, commercially available in the Greek market, was evaluated using the ISO 17225 Standard Requirement Thresholds as a benchmark. The examined quality criteria were calorific value, ash content, mechanical durability, bulk density and moisture content. The reliability of the information on packages was evaluated. Meanwhile, the potential correlation between the most crucial qualitative properties of pellets was investigated to elucidate their potential contribution to pellets’ quality estimation. Most of the pellet brands showed low moisture and ash content and acceptable calorific values for residential use—although the quality of half of the pellet brands was found to be lower than that reported, mainly with regard to the mechanical durability and bulk density. The application of two different collection periods highlighted a stability in quality over time. Higher calorific value seemed to be provided by pellets which had low ash and low moisture content and were mechanically durable. As regards the specific samples, a dark colour and high roughness were correlated with lower fuel quality (impact of 56.2% and 43.6%, respectively).