Numerical Study on Flame Mesoscopic-Characteristics of Oxy-Coal Mild Combustion

2016 ◽  
Author(s):  
Ruochen Liu ◽  
Enke An ◽  
Kun Wu
Keyword(s):  
Flame Front ◽  
High Velocity ◽  
Numerical Study ◽  
Combustion Process ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Small Scale ◽  
Turbulent Regime ◽  
Mild Combustion ◽  
Global Regime

For achieving efficient oxy-coal combustion in a MILD (Moderate or Intense Low Oxygen Dilution) state, the optimum operating conditions with high-velocity jets in a lab-scale cylindrical furnace (Φ200mm×2000mm) was determined. The mesoscopic characteristics of turbulent and flame behavior under different jet design and jet spacing were simulated and compared. The results show that L=30∼60mm(O2 side) and L=60mm(O2 center) conditions are recommended as oxy-coal MILD combustion as well as IFRF furnace condition, the flame front locates in distributed regime, the global regime was depict as 1 < l/lF < 4, 60 < ReT < 150 and 50 < Ka < 500 ; for flaming conditions, the flame front locates in small-scale turbulent regime or thin reaction zone, the global regime was depicted as 0.5 < l/lF < 4, 40 < ReT < 110 and 30 < Ka < 900 ; with high-velocity oxygen jet technology, the combustion process is in slow chemistry regime (Da << 1), governed by chemical-kinetic mechanism; large spacing (L=75mm) is not favored for co-flow burners due to poor radial mixing as well as the restriction of wall.

Conduction Roaster for Accelerated Roasting of Peanut

2021 ◽  
Vol 58 (02) ◽  
pp. 112-123
Author(s):  
Rakesh Kumar Raigar ◽  
Hari Niwas Mishra
Keyword(s):  
Energy Consumption ◽  
Specific Energy ◽  
Rotational Speed ◽  
Specific Energy Consumption ◽  
Quality Parameters ◽  
Operating Conditions ◽  
Moisture Loss ◽  
Optimum Operating ◽  
Small Scale ◽  
Roasting Temperature

Roasting is one of the thermo-mechanical operation in cereals and oilseeds processing. Low-capacity machine for mechanisation of roasting is necessary for small-scale processing. A conduction-type motorised rotary roaster (8 kg per batch) was designed and developed for roasting of peanuts. Performance of the roaster was evaluated in terms of moisture loss, scorched kernels, and specific energy consumption for accelerated roasting of peanut. The effects of different roasting conditions were studied to determine the optimum operating conditions of the roaster. Quality indices of peanuts as moisture loss (kg.kg-1), scorched kernel (%), and specific energy consumption (kWh.kg-1) were dependent on the operating conditions. The optimum value of moisture loss (0.041± 0.003 kg.kg-1), scorched kernel (0.93± 0.0.004 % ), and specific energy consumption (0.185 ± 0.005 kWh.kg-1) were obtained at roasting temperature of 170°C, roasting time of 15 min, and rotational speed of 20 rpm for roasting peanut. The roasting characteristics of peanut decreased linearly with increase in the temperature and time; and decrease in the rotational speed. The inferior quality parameters were observed at higher temperatures, speed and medium time of roasting. The study indicated optimum roasting temperature of peanut to be 170°C, and further increase in the process temperature had undesirable effects on roasted peanut quality due to high loss of moisture.

scholarly journals The new design of the wood stove based on the numerical analysis and experimental research

2020 ◽  
Vol 154 ◽  
pp. 04001
Author(s):  
Przemysław Motyl ◽  
Marcin Wikło ◽  
Julita Bukalska ◽  
Bartosz Piechnik ◽  
Rafał Kalbarczyk
Keyword(s):  
Fluid Flow ◽  
Heat Exchange ◽  
Numerical Analysis ◽  
Heat Release ◽  
Experimental Research ◽  
Numerical Study ◽  
Combustion Process ◽  
Small Scale ◽  
Wood Stove ◽  
Wood Stoves

In Europe, especially in Poland, wood-fired stoves remain one of the most popular renewable household heating. The use of wood logs in small-scale units stoves are expected to increase substantially. The work proposes a comprehensive approach to modify the design of wood stoves with heating power up to 20 kW, including design works, simulations, and experimental research. The article also presents the numerical study of a combustion process including fluid flow, chemical combustion reaction, and heat exchange in the wood stove. The retrofit enhanced a more stable heat release from the wood stove, which increased efficiency and reduction of the harmful components of combustion.

Response Surface Based Optimization of Solar Collector Integrated With an Ammonia-Water Combined Power/Cooling Cycle Supported by Exergy Analysis

2015 ◽  
Author(s):  
Jesús M. García ◽  
Marco E. Sanjuan M. ◽  
Ricardo Vasquez Padilla
Keyword(s):  
Thermodynamic Properties ◽  
Response Surface ◽  
Ammonia Concentration ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Small Scale ◽  
Cooling Systems ◽  
Response Variable ◽  
Ammonia Water ◽  
Cooling Cycle

Finding optimal operating conditions of solar-based power and cooling systems is always a challenge. Performance of these systems is highly dependent on several important parameters, which not only impact the long-term efficiency but also its technical and economic feasibility. This paper studies the operation/configuration problem of an ammonia-water power and cooling cycle using an exergetic analysis. Thermodynamic performance of the combined cycle was addressed by using analysis of variance and multiple linear regression analysis. Modeling was done in Matlab®, using Refprop 9.0 to calculate the thermodynamic properties of the ammonia-water mixture. Convergence issues were observed on the thermodynamic properties estimation carried out by Refprop when the stream had high ammonia mass fraction. To solve this issue an averaging algorithm was implemented online to estimate such properties using pure ammonia data and high, but stable, ammonia concentration data. After this implementation, small differences between current and reference model were seen. Optimum operating conditions were obtained using response surface technique. The response variable used was the ratio between exergetic efficiency and exergy destruction. Results showed that the response variable is mainly influenced by the ammonia concentration, pressure ratio, turbine efficiency and temperature gradient in the heat exchanger. Finally integration of the power/cooling cycle with a solar field was performed using two types of concentrated solar collectors: Linear Fresnel Collector (LFC) and Parabolic Trough Collector (PTC). The analysis showed that LFC technology can be a viable alternative for small scale applications combined with power/cooling systems.

scholarly journals Modeling of pulverized coal combustion for in-furnace NOx reduction and flame control

2017 ◽  
Vol 21 (suppl. 3) ◽  
pp. 597-615 ◽  
Author(s):  
Srdjan Belosevic ◽  
Ivan Tomanovic ◽  
Nenad Crnomarkovic ◽  
Aleksandar Milicevic
Keyword(s):  
Coal Combustion ◽  
Numerical Study ◽  
Nox Reduction ◽  
Combustion Process ◽  
Pulverized Coal ◽  
Operating Conditions ◽  
Nox Emission ◽  
Differential Model ◽  
No Formation ◽  
Turbulent Reactive Flows

A cost-effective reduction of NOx emission from utility boilers firing pulverized coal can be achieved by means of combustion modifications in the furnace. It is also essential to provide the pulverized coal diffusion flame control. Mathematical modeling is regularly used for analysis and optimization of complex turbulent reactive flows and mutually dependent processes in coal combustion furnaces. In the numerical study, predictions were performed by an in-house developed comprehensive three-dimensional differential model of flow, combustion and heat/mass transfer with submodel of the fuel- and thermal-NO formation/ destruction reactions. Influence of various operating conditions in the case-study utility boiler tangentially fired furnace, such as distribution of both the fuel and the combustion air over the burners and tiers, fuel-bound nitrogen content and grinding fineness of coal were investigated individually and in combination. Mechanisms of NO formation and depletion were found to be strongly affected by flow, temperature and gas mixture components concentration fields. Proper modifications of combustion process can provide more than 30% of the NOx emission abatement, approaching the corresponding emission limits, with simultaneous control of the flame geometry and position within the furnace. This kind of complex numerical experiments provides conditions for improvements of the power plant furnaces exploitation, with respect to high efficiency, operation flexibility and low emission.

Design and CFD Simulation of a Micro Gas Turbine Combustor Fuelled With Low LHV Producer Gas

2020 ◽  
Author(s):  
Francesco F. Nicolosi ◽  
Massimiliano Renzi
Keyword(s):  
Natural Gas ◽  
Combustion Process ◽  
Operating Conditions ◽  
Inert Gases ◽  
Injection System ◽  
Small Scale ◽  
Producer Gas ◽  
Part Load ◽  
Average Temperature ◽  
Gasification Process

Abstract In this paper, the authors analyze the feasibility of fuelling a small-scale 3.2 kWe MGT, manufactured by the Dutch company MTT, with a low LHV fuel produced via a gasification process. In particular, a CFD analysis on the combustor of the MGT is carried out in order to assess the behaviour of the component when it is fuelled with a traditional fuel (natural gas) and with a producer gas coming from a gasification process. The operating conditions of the combustor, used as boundary conditions for the simulations, are obtained by analyzing the characteristic performance curves of the turbo-machines used in the MGT. The simulation of the combustion process with methane has been validated using the temperature output from experimental tests and the NOX emissions. A RANS simulation using the Non-Adiabatic Non-Premixed Combustion Model Approach has been adopted. NOX formation has been simulated by the adoption of the extended Zel’dovich mechanism. Both nominal and part load simulations have been performed. This simplified modelling strategy allows to assess the main issues and figures of the combustion process with a reasonable computational effort. The CFD simulations showed that the combustion with a low LHV fuel are feasible but some modifications of the present configuration of the combustor are required, with specific attention to the fuel injection system. Results showed that, with Natural Gas, the average temperature of the exhaust mass flow is 1297 K, the level of CO and NOX referred to the 15% of O2 are respectively less than 1 ppm and 30.365 ppm, respectively. With S the original design of the injector proved to be non-adequate for a proper air and fuel mixing; therefore, a modified design has been proposed with an increased injection section. In the novel design for syngas, a better temperature distribution and lower emissions have been found: an average temperature of the flue gas at the combustor discharge of 1249 K is obtained, and the level of CO and NOX are both less than 1 ppm. The lower operating temperature is determined by the higher fuel flow rate and, in particular, by the high share of inert gases in the fuel. Additional simulations have been run at part load operation to assess the viability of the proposed design also in off-design conditions.

Numerical Study of Nanofluid-Based Solar Collector for Humidification-Dehumidification (HDH) Desalination

2018 ◽  
Author(s):  
Kapil Garg ◽  
Vikrant Khullar ◽  
Sarit K. Das ◽  
Himanshu Tyagi
Keyword(s):  
Solar Collector ◽  
Numerical Study ◽  
Open Water ◽  
Operating Conditions ◽  
Small Scale ◽  
Outlet Temperature ◽  
Direct Absorption ◽  
Output Ratio ◽  
Direct Absorption Solar Collector ◽  
Desalination Technology

Humidification-dehumidification (HDH) desalination technology is one such technology (based on thermal desalination technology) which has been found to be ideal for small scale water productions (1–100 m3/day). It requires less maintenance and can be combined with renewable energy sources such as solar or geothermal due to lower temperature operation. In this paper, nanofluid-based direct absorption solar collector (DASC) has been coupled with the one of the versions of HDH desalination system (closed air open water - CAOW) with the help of a counter-flow heat exchanger. These collectors (DASCs) have high thermal efficiency (10% higher) as compared to conventional surface absorption based collectors. Numerical model is prepared for a closed air open water HDH system, working together with a direct absorption solar collector. The aim of the present study is to evaluate the thermal performance of the system in terms of gained output ratio (GOR) against the various influencing parameters related to the solar collector such as, height (H) and length (L) of the collector, nanoparticle volume fraction (fv), and incident solar radiation on the collector (q) and the effect of the aforementioned parameters on the collector outlet temperature (Tout) have also been analyzed in detail. Solar weighted absorptivity (Sab) for different nanofluids has also been calculated which helps in choosing the suitable nanoparticle material for preparing the nanofluid. The gained output ratio of the proposed system was found to be around 16% higher, compared to conventional CAOW-HDH desalination systems under certain operating conditions. Finally, the model proposed in this study has been validated with the data available in literature.

Performance of SI Engine to Improve the Combustion Characteristics by Using Methanol Blended Petrol

2015 ◽  
Vol 813-814 ◽  
pp. 857-861
Author(s):  
A.N. Basavaraju ◽  
Mallikappa ◽  
B. Yogesha
Keyword(s):  
Fuel Injection ◽  
Fuel Efficiency ◽  
Combustion Process ◽  
Injection Pressure ◽  
Operating Conditions ◽  
Injection System ◽  
Optimum Operating ◽  
Injection Timing ◽  
Si Engine ◽  
Single Cylinder

The present energy situation has stimulated active research interest in non-petroleum and non-polluting fuels, particularly for transportation, power generation, and agricultural sectors. This paper describes feasibility of utilization of Spark ignition (SI) engine in single fuel mode and to develop the optimum operating conditions in terms of fuel injection timing and fuel injection pressure. Many modifications were made for the developed direct fuel injection system to improve the performance of the 350 cc four stroke single cylinder petrol engine. The engine is tested to conduct performance, combustion emission characteristics with the aid of carburetor. As single cylinder small engines have low compression ratio (CR), and they run with slightly rich mixture, their power are low and emission values are high. In this study, methanol was used to increase performance and decrease emissions of a single-cylinder engine. Initially, the engine whose CR was 7.5/1 was tested with gasoline and methanol at full load and various speeds. This method is used for increasing the fuel efficiency of a vehicle by adding different percentage of methanol to the petrol and to decrease the pollutants produced during combustion process.

Numerical Study of a Small-Scale Micro Gas Turbine-ORC Power Plant Integrated With a Biomass Gasifier

2020 ◽  
Author(s):  
Fabrizio Reale ◽  
Raniero Sannino ◽  
Raffaela Calabria ◽  
Patrizio Massoli
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Numerical Study ◽  
Fluid Dynamic ◽  
Combustion Process ◽  
Combustion Stability ◽  
Small Scale ◽  
High Hydrogen ◽  
Micro Gas Turbine ◽  
Fuel Blends

Abstract The paper is focused on coupling a small-scale power plant, based on a micro gas turbine (mGT) and a bottoming Organic Rankine Cycle (ORC), with a biomass gasifier. The aim of this study is to define the optimal strategies to maximize the benefits related to distributed generation and to promote the organic solid waste gasification, in terms of energy efficiency and renewable sources exploitation. In particular, they were investigated the energetic performances of the system when the micro gas turbine was fed with several fuel blends, made by specific volume concentration of syngas and biogas. The low heating value of both considered fuels implies the necessity of operating the mGT in peculiar conditions as determined by the performance maps of compressor and turbine. Then, the thermodynamic analyses of the whole energy system have been carried out to evaluate the performance for each fuel. The high hydrogen content of syngas and the different thermodynamic properties of the studied fuel blends required a deeper investigation of the combustion process. In order to analyze the combustion stability and the fluid dynamic aspects, an accurate investigation of combustion chamber has been performed through a CFD solver. Finally, a comparison of the plant performances for each fuel blend have been reported, along with opportunities and critical aspects related to power plant integration.

Combustion Chamber for a Directly Wood Particle Fired Gas Turbine

2002 ◽  
Author(s):  
Mario Pelzmann ◽  
Hermann Haselbacher
Keyword(s):  
Gas Turbine ◽  
Combustion Process ◽  
Wood Particle ◽  
Operating Conditions ◽  
Total Carbon ◽  
Small Scale ◽  
Two Stage ◽  
Fuel Feed ◽  
Cyclone Combustor ◽  
Primary Zone

Most of the processes using wood fuels in gas turbine applications that are presently being studied are based on gasification of the wood fuel and operating the gas turbine with the product gas. An alternative is running the gas turbine with the hot gas from a wood combustor — the directly wood particle fired gas turbine. This technique offers the possibility to realise efficient and cost effective small scale power generation systems in the low power range (1–2 MWe). For realizing a directly wood particle fired gas turbine, the Institute of Thermal Turbomachines and Powerplants at the Vienna University of Technology developed a two stage combustor. Solid and liquid fuels require relatively long residence times and good mixing with the oxidant to be completely burned. This can be achieved in the primary stage designed as a cyclone combustor/gasifier. In the cyclone chamber, burning fuel particles are suspended, according to their size, caused by centrifugal and drag forces. This cyclone effect of the flow offers the possibility that big particles remain in the cyclone combustor until they have been completely burned. Using a two stage combustor, the combustion process can be divided into two zones: A primary zone for fuel-rich pyrolysed-gasified-combustion and a secondary zone where the gasification products from the primary zone are oxidized with excess air. Staged combustion has the potential to reduce NOx (NO, NO2 and N2O), CO and total hydrocarbons CnHm concentrations in the exhaust. A large series of test runs was carried out with 3 different fuels, numerous fuel feed rates and equivalence ratios in the cyclone combustor resulting in stable operating conditions and almost total carbon burn-out. The main purpose of the test runs was to investigate the effect of air staging and temperature on the emissions of CO, CnHm and NOx.

scholarly journals Pengembangan Mesin Pencacah Tandan Kosong Sawit (TKS) dengan Metode Pemotongan Crusher

2014 ◽  
Vol 9 (2) ◽  
pp. 42
Author(s):  
Junaidi - ◽  
Anwar Kasim ◽  
Aidil Zamri ◽  
Sir Anderson
Keyword(s):  
Large Scale ◽  
Elastic Fiber ◽  
Testing Machine ◽  
Operating Conditions ◽  
Raw Material ◽  
Optimum Operating ◽  
Design Parameters ◽  
Small Scale ◽  
Processing Unit ◽  
Engine Capacity

Palm empty fruit bunches (EFB) fiber content ± 70 % and can be used for elastic    fiber, matrix, mattresses, rugs and raw material fiber -based composite board products, but until now has not been utilized to the fullest . The problem is not the availability of processing unit generates EFB fiber in small scale . One of them is the processing unit thrasher EFB. EFB counter technology that exists today is a large scale that can only be owned by the oil palm industry with a capacity of ± 4,124 kg/hour. For small-scale fiber industry needs a minimum engine capacity of census enumerators ± 300 kg/hour, but this machine is not yet commercially available.In general, the purpose of this research is small scale EFB cutting machines with a capacity of 200-300 kg/hour, the design parameters and identify optimum operating conditions for each component with the technical test of the prototype. From the results obtained machine design an engine capacity of 300 kg/hour, with a few major components, namely counter unit, unit funnel in and out, frame and drive unit . From the results of design calculations obtained engine power 15 hp motor drive with 1450 RPM rotation with 3 phase. From the results of the testing machine in the first enumeration results obtained by the size of the pieces of shredded EFB ± 7 x 7 ( cm ), while the second enumeration stage shredded EFB size becoming smaller ± 3 x 3 ( cm ).

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