0000000000121373

AUTHOR

Raimonds Valdmanis

showing 13 related works from this author

Improvement of Biomass Gasification/Combustion Characteristics by Microwave Pretreatment of Biomass Pellets

2021

Pre treatmentBiomass combustionGeneral Chemical EngineeringThermal decompositionPelletsEnvironmental scienceBiomassGeneral ChemistryBiomass gasificationPulp and paper industryCombustionIndustrial and Manufacturing EngineeringMicrowaveChemical Engineering & Technology
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Mathematical modelling and experimental study of straw co-firing with gas using electric field control of combustion characteristics

2020

Nuclear engineeringElectric fieldEnvironmental scienceStrawCombustion19th International Scientific Conference Engineering for Rural Development Proceedings
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Electric Field Effect on the Thermal Decomposition and Co-combustion of Straw with Solid Fuel Pellets

2019

The aim of this study was to provide more effective use of straw for energy production by co-firing wheat straw pellets with solid fuels (wood, peat pellets) under additional electric control of the combustion characteristics at thermo-chemical conversion of fuel mixtures. Effects of the DC electric field on the main combustion characteristics were studied experimentally using a fixed-bed experimental setup with a heat output up to 4 kW. An axisymmetric electric field was applied to the flame base between the positively charged electrode and the grounded wall of the combustion chamber. The experimental study includes local measurements of the composition of the gasification gas, flame tempe…

Flue gasControl and OptimizationMaterials science020209 energyPelletsEnergy Engineering and Power TechnologyDC electric field02 engineering and technology010501 environmental sciencesCombustion01 natural scienceslcsh:TechnologyMass transferElectric field0202 electrical engineering electronic engineering information engineeringElectrical and Electronic EngineeringComposite materialco-firingEngineering (miscellaneous)thermal decomposition0105 earth and related environmental scienceswheat strawRenewable Energy Sustainability and the Environmentlcsh:Tbog peatSolid fuelpelletsAdiabatic flame temperaturesoftwoodCombustion chamberEnergy (miscellaneous)combustionEnergies
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Thermo-Chemical Conversion of Microwave Activated Biomass Mixtures

2018

Materials science020401 chemical engineeringChemical engineering020209 energyThermo chemical0202 electrical engineering electronic engineering information engineeringBiomass02 engineering and technology0204 chemical engineeringMicrowaveIOP Conference Series: Materials Science and Engineering
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Magnetic Field Control of Combustion Dynamics

2016

Abstract Experimental studies and mathematical modelling of the effects of magnetic field on combustion dynamics at thermo-chemical conversion of biomass are carried out with the aim of providing control of the processes developing in the reaction zone of swirling flame. The joint research of the magnetic field effect on the combustion dynamics includes the estimation of this effect on the formation of the swirling flame dynamics, flame temperature and composition, providing analysis of the magnetic field effects on the flame characteristics. The results of experiments have shown that the magnetic field exerts the influence on the flow velocity components by enhancing a swirl motion in the …

magnetic field forcesswirling flow dynamicsMaterials science010102 general mathematicsDynamics (mechanics)General EngineeringGeneral Physics and Astronomymixing of reactantsflame compositionMechanicsCombustion01 natural scienceslcsh:QC1-999010305 fluids & plasmasMagnetic fieldPhysics::Fluid Dynamics0103 physical sciencescombustion of volatilesPhysics::Chemical Physics0101 mathematicslcsh:PhysicsLatvian Journal of Physics and Technical Sciences
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Influence of mw pretreatment on main gasification/combustion characteristics of different types of biomass

2020

Environmental scienceBiomassCombustionPulp and paper industry19th International Scientific Conference Engineering for Rural Development Proceedings
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Thermal Decomposition and Combustion of Microwave Pre-Treated Biomass Pellets

2021

The objective of the study was to investigate a more effective use of commercially available biomass pellets (wheat straw, wood, peat) using microwave pretreatment to improve heat production. Pellets were pretreated using the originally designed microwave torrefaction device. The effects of microwave (mw) pretreatment were quantified, providing measurements of the weight loss and elemental composition of pellets and estimating the effect of mw pretreatment on their porosity, surface area and calorific values at pretreatment temperatures of T = 448–553 K. Obtained results show that the highest structural variations and elemental composition during mw pretreatment were obtained for wheat stra…

Materials science0211 other engineering and technologiesPelletsBioengineering02 engineering and technology010501 environmental sciencesCombustionlcsh:Chemical technology01 natural scienceslcsh:ChemistryChemical Engineering (miscellaneous)lcsh:TP1-1185021108 energythermal decomposition0105 earth and related environmental sciencesheating valuewheat strawProcess Chemistry and TechnologyThermal decompositionfood and beveragesStrawTorrefactionPulp and paper industrypelletsAdiabatic flame temperaturereactivitylcsh:QD1-999peatHeat of combustionMass fractionmicrowave pretreatmentwoodcombustionProcesses
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The Effect of Electric Field Configuration on the Thermo-Chemical Conversion of Straw Pellets

2020

Abstract With the aim to control and improve the thermo-chemical conversion of straw pellets, the experimental investigations of the DC electric field effect on the combustion dynamics and heat energy production were made. The electric field effect on the gasification/combustion characteristics was studied using three different positions of the positively charged electrode in flame. First, the electrode was positioned coaxially downstream the flame flow. Next, the electrode was positioned coaxially upstream the flame flow and, finally, the electrode was positioned across the downstream flow. The bias voltage of the electrode varied in the range from 0.6 up to 1.8 kV, while the ion current i…

heat energy020209 energyHeat energyPhysicsQC1-999composition emissionsGeneral EngineeringPelletsGeneral Physics and Astronomy02 engineering and technologyStrawthermochemical conversionelectric field020401 chemical engineeringElectric fieldThermo chemical0202 electrical engineering electronic engineering information engineering0204 chemical engineeringComposite materialstraw pelletsLatvian Journal of Physics and Technical Sciences
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Control of the Development of Swirling Airflow Dynamics and Its Impact on Biomass Combustion Characteristics

2017

Abstract The development of the swirling flame flow field and gasification/ combustion dynamics at thermo-chemical conversion of biomass pellets has experimentally been studied using a pilot device, which combines a biomass gasifier and combustor by varying the inlet conditions of the fuel-air mixture into the combustor. Experimental modelling of the formation of the cold nonreacting swirling airflow field above the inlet nozzle of the combustor and the upstream flow formation below the inlet nozzle has been carried out to assess the influence of the inlet nozzle diameter, as well primary and secondary air supply rates on the upstream flow formation and air swirl intensity, which is highly …

swirling flow dynamicsWaste managementPhysicsQC1-999020209 energyAirflowGeneral EngineeringEnvironmental engineeringHeat outputGeneral Physics and Astronomymixing of reactantsflame composition02 engineering and technologyheat outputBiomass combustioncombustion of volatiles0202 electrical engineering electronic engineering information engineeringLatvian Journal of Physics and Technical Sciences
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Electrodynamic Control of the Combustion Characteristics and Heat Energy Production

2015

ABSTRACTElectric field effects (EFE) on combustion characteristics, heat energy production, and composition of polluting emissions have been investigated experimentally for different types of fuels (natural gas, biomass) providing experimental study of the EFE in a district heating boiler and complex modeling experiments in a small-scale pilot device. The DC field-induced variations of the produced heat energy, efficiency of heat energy production, flame characteristics, and the composition of polluting emissions have been studied for a positively biased axially inserted electrode and negatively biased (grounded) heat surfaces by varying the applied DC voltage, net current, and consumed ele…

business.industryChemistry020209 energyGeneral Chemical EngineeringHeat energyAnalytical chemistryBoiler (power generation)General Physics and AstronomyEnergy Engineering and Power Technology02 engineering and technologyGeneral ChemistryMechanicsCombustionFuel TechnologyNatural gasElectric fieldElectrode0202 electrical engineering electronic engineering information engineeringbusinessAxial symmetryVoltageCombustion Science and Technology
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Electrodynamic control of straw co-firing with propane

2019

chemistry.chemical_compoundMaterials scienceChemical engineeringHydrogenchemistryPropanePelletschemistry.chemical_elementStrawCombustionEngineering for Rural Development
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The effects of biomass co-gasification and co-firing on the development of combustion dynamics

2018

Abstract Effects of wheat straw co-firing with gas (propane flame) and co-gasification/co-combustion with wood pellets on the development of thermo-chemical conversion of biomass pellets and on heat energy production were experimentally studied and analyzed with the aim to improve the gasification/combustion characteristics and the applicability of wheat straw as an alternative energy source for cleaner heat energy production. The results suggest that the wheat straw co-firing with propane provides an enhanced thermal decomposition of pellets with more complete combustion of volatiles increasing thus the heat output at thermo-chemical conversion of wheat straw and the produced heat energy p…

animal structuresMaterials science020209 energyPelletsBiomass02 engineering and technologyCombustionIndustrial and Manufacturing Engineeringlaw.inventionchemistry.chemical_compound020401 chemical engineeringlawBioenergyPropane0202 electrical engineering electronic engineering information engineering0204 chemical engineeringElectrical and Electronic EngineeringCivil and Structural EngineeringWaste managementbusiness.industryMechanical EngineeringFossil fuelfood and beveragesBuilding and ConstructionStrawPollutionIgnition systemGeneral EnergychemistrybusinessEnergy
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Mathematical modelling and experimental study of straw co-firing with gas

2019

The main goal of the present study is to promote a more effective use of agriculture residues (straw) as an alternative renewable fuel for cleaner energy production with reduced greenhouse gas emissions. With the aim to improve the main combustion characteristics at thermo-chemical conversion of wheat straw, complex experimental study and mathematical modelling of the processes developing when co-firing wheat straw pellets with a gaseous fuel were carried out. The effect of co-firing on the main gasification and combustion characteristics was studied experimentally by varying the propane supply and additional heat input into the pilot device, along with the estimation of the effect of co-firing on…

Materials science0211 other engineering and technologiesArrhenius kinetics02 engineering and technologyStrawaxisymmetric swirling flowPulp and paper industryModeling and Simulation021105 building & constructionPDE systemQA1-939021108 energyreaction-diffusion equationsMathematicsAnalysisMathematical Modelling and Analysis
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