Combustion Of Liquefied Petroleum Gas Research Articles

Improvement of Airflow Distribution in a Glutinous Rice Cracker Drying Cabinet

Fried glutinous rice cracker or Khaotan is one of the important traditional snacks for local Thai economy. When there is no sunlight, a dryer is usually employed in moisture removal process of Khaotan products. A traditional dryer is essentially a drying cabinet with multidirectional flow of hot flue gas from liquefied petroleum gas burner. In this work, an improved design using biomass energy with recirculation of unidirectional airflow inside the drying cabinet was developed. For this improved design of Khaotan dryer, airflow distribution was crucial in providing uniform drying condition and ensuring that all rice crackers were uniformly dried. Numerical simulation based on solving Navier-Stokes equations was carried out to predict airflows in the improved dryer. Swing panel was used to vary the direction of bulk air flow. Effects of swing angle (30, 45, and 60°) and air velocity (0.5, 1, 1.5 m/s) were investigated. Good airflow distributions without dead zone can be obtained from the simulation and implemented in experimental runs. Flow trajectories in the drying cabinet were found to give good agreement between prediction and experiments. With improved design and installation of swing panel, the times used to reduce the Khaotan moisture content to 10% dry basis and the operating cost in this process were reduced, hence, better energy efficiency.

Is MSW derived DME a viable clean cooking fuel in Kolkata, India?

Abstract An important energy poverty reduction initiative in India is aimed at replacing the use of solid cooking fuels with cleaner burning Liquefied Petroleum Gas (LPG). Projections suggest however that India will become increasingly dependent on LPG imports, the cost of which is strongly linked to the prevailing oil price and associated volatility. Dimethyl ether (DME) is a synthetic fuel which may be manufactured from domestically available carbonaceous feedstocks, and is compatible with blending with LPG. Very large quantities of Municipal Solid Waste (MSW) are generated in India's metropolitan cities, 90% of which is disposed of onto unsanitary landfills, creating major environmental and health concerns. This article investigates the techno-economic merits of reducing these impacts by using a portion of the MSW generated in Kolkata (in the form of a Refuse Derived Fuel (RDF)) to produce DME. Results suggest that the production of DME from a 50:50 blend of locally available coal and RDF (comprising 10% of the MSW placed at Kolkata's main landfill) will enable the supply of a clean cooking fuel to approximately 15% of Kolkata's population, and become cost competitive with imported LPG at an Indian basket oil price of $130 per barrel. Results also suggest that, at this blend ratio, the fossil fuel derived greenhouse gas emissions at the DME production plant will be more than offset by landfill methane emissions avoided using the RDF.

Producing a CO2-neutral clean cooking fuel in India – Where and at what cost?

Indoor air pollution, caused by solid cooking fuels, is the fourth largest global contributor to premature death, equivalent to unsanitary water, and greater than malaria. Therefore, the Indian government currently subsidises replacement of these fuels with cleaner burning Liquefied Petroleum Gas (LPG), but an import dependency makes this program vulnerable to oil price shocks and supply disruption. The blending of LPG with dimethyl ether (DME), produced from domestically available feedstocks, may be one means of reducing this vulnerability. In the context of pursuing a low carbon future, this study investigates the use of CO2 released during ethanol production, combined with hydrogen gained by water electrolysis from renewable electricity, for this purpose. More than 85% of India's ethanol is produced in five states, four of which are richly endowed with a renewable electricity generation potential. The estimated cost of DME produced in this manner is significantly above a historically high LPG price but may become viable in the EIA's “high oil price” scenario if future (US DOE) electrolysis performance targets are achieved, and at electricity costs below $45 per MWh.

Porous Radiant Burner for Domestic Cooking Purpose: A Review

For cooking, liquefied petroleum gas (LPG) is one of the most commonly used fuels in India and many other countries. LPG being a clean fuel burns with no soot and has high calorific value than kerosene and wood. In India, as the living standard of the people is improving the number of LPG consumers is also increasing. The total domestic consumption of LPG in India is almost comparable with other petroleum products used in industrial applications. The thermal efficiency of the current LPG cooking stoves available in the Indian market are in the range of (60-65) % and at the same time the CO and NOX emissions levels are above the world health organization standards. Considering the energy conservation, environment issues and increase in demand of LPG in the near future. The present review paper summarizes the recent modification in the design of free flame conventional LPG burner by using porous materials and highlights its potential.

Effect of central cone-shaped bluff body on performance of premixed LPG burner

Improvement of air entrainment rate for liquefied petroleum gas (LPG) premixed burner was achieved by placing a needle rod inside a circular fuel jet nozzle. To investigate the effect of needle rod on flow entrainment, selection of experimental results together with investigation on jet characteristics using CFD are presented. The predictive quality was achieved after performing grid refinement and validation of turbulent model against existing experimental results. Two modified standard k-ε turbulent models were employed for prediction of the jets. The results indicated that the annular port created narrower jet pattern with higher degree of penetration. The momentum decay rate was significantly lower with an average of 48% at z/D=30, for instance, corresponding to lower Reynolds shearing stress associated with jet shape upstream. This corresponded to the vorticity magnitude of the inner core that caused transport of jet momentum into the central region of the jet near the exit plane. In contrast, the circular one performed more expanded pattern together with faster decay rate. This expanded jet created limitation of air entrainment when issuing into a confined duct, while deeper penetration of the annular jet created greater entrainment. An averaged improvement of air entrainment was found at 25% for the range of firing rate between 1.8 and 4.4kW.

Effect of hydrogen addition on overall pollutant emissions of inverse diffusion flame

In this paper, the effect of hydrogen (H2) addition on the pollutant emissions of an IDF (inverse diffusion flame) burning LPG (liquefied petroleum gas) has been studied. Pollutant emission behavior was intensively investigated at fuel lean condition, and CO2, CO, HC, and NOx emitted from the flame were measured with their emission indices reported. HC and CO emissions are highly dependent on overall equivalence ratio, and both HC and CO are very high at fuel lean condition while reduce to nearly zero at equivalence ratio larger than 0.8 in LPG-H2 IDF. NOx emission follows the trend of HC due to N2O-intermediate and Fenimore mechanisms at fuel lean condition while NOx emission increases with equivalence ratio at fuel rich condition due to thermal NOx mechanism. Hydrogen addition is found to promote the conversion of CO and HC into CO2, and there exists a threshold fraction of hydrogen over which a significant reduction of CO and HC occurs. High air jet Reynolds number tends to induce poor combustion and thus increasing HC, CO and NOx emissions. Compared to LPG IDF, LPG-H2 IDF starts to generate noticeably CO and HC emissions earlier, and both CO and HC emissions are heavier.

Numerical and experimental analyses of LPG (liquefied petroleum gas) combustion in a domestic cooking stove with a porous radiant burner

This paper deals with numerical and experimental analyses of combustion of LPG (liquefied petroleum gas) (48% n-butane, 25% iso-butane, 23% propane, 4% ethane by mole fraction) in a domestic cooking stove with a two-layer porous radiant burner. The combustion zone consists of SiC matrix with 90% porosity, and the preheating zone is made of 3.0 mm diameter alumina balls. In the numerical study, for the 1-D planar geometry of the burner, the gas and the solid-phase energy equations, continuity equation, species conservation equation and ideal gas equation are simultaneously solved using the finite volume method. The volumetric radiation term appearing in the solid-phase energy equation is also computed using the finite volume method. Numerical results of temperature distributions, flammability limits and pollutant emissions for various equivalence ratios and thermal loads are found to have reasonably a good agreement with the experimental data. Towards improving the thermal performance of the cooking stove, effects of SiC matrix thickness, preheater thickness, solid-phase conductivity and scattering albedo on CO emissions and radiative flux are studied. In addition, following guidelines of the World Health Organization, the most effective burner on the basis of the minimum CO emission and the maximum thermal efficiency is proposed.

Analysis of combustion of liquefied petroleum gas in a porous radiant burner

This article deals with the combustion of liquefied petroleum gas (LPG) (40% C3H8+60% C4H10 by volume) in a planar silicon carbide porous radiant burner (PRB). With volumetric radiative source term needed in the solid-phase energy equation computed using the finite volume method, the gas- and the solid-phase energy equations, continuity equation, species conservation equation and ideal gas equation are simultaneously solved. The energy equations are solved using the finite volume method. The species conservation equation, and the species diffusion and the heat generation terms appearing in the gas-phase energy equation are computed using the solver Cantera. The chemical kinetics consists of 111 species and 784 reactions. Comparisons are made for the stability range of LPG with CH4 as well as with the combustion of LPG in the free-flame mode. For LPG combustion in the PRB, variations of species production rate, heat release rate, CO emissions, radiative heat flux and the total heat flux are analyzed. With LPG combustion in the PRB, the total heat flux is more than that of combustion of CH4 in the PRB, and also LPG combustion in the free-flame mode. The radiative heat flux with LPG in the PRB, is also more than that with CH4. CO emission with LPG combustion in the PRB is much lower than its combustion in the free-flame mode.

Design of LPG burner for hot air puffing machine

In puffing machines the hot air is produced either by burning liquefied petroleum gas (LPG) or electric heaters to develop puffed ready-to-eat (RTE) product. In puffing machine the product is puffed in LPG flue gas mixed hot air based on the whirling bed principle. Therefore, to produce hot air by burning LPG, three non-premixed diffusion type burner configurations were designed to produce a stable blue flame with minimum soot length. In Type I burner of 20 cm length two concentric galvanized iron pipes-inner gas pipe of 2.7 cm (OD) and outer air pipe of 5 cm (OD) were used. The gas was introduced in the inner pipe of burner through copper pipe of 1.3 cm (OD) from outside. It works and produces the flame with an obstruction plate of diameter equal to inner burner pipe which was positioned in front of inner pipe for stability of flame. In experimental tests it was observed that flame do not catches when blower was started and forms a single jet unstable luminous (soot) flame at high air velocity. In Type II burner two steam pipes of diameter 4.7 and 2.7 cm (OD) were used for fabrication. In order to protect the flame from high velocity air, a truncated conical metal (cast iron) shield of 4.7 cm diameter was welded to the rim of air pipe. The Type II burner produced characteristic long blue flame and less soot length but there was soot formation in flame at relatively low air flow rates. To overcome the problem of flame instability and soot formation a third burner configuration was used. Three concentric steam pipes were used for Type III burner. It was observed that the secondary air from central pipe results in proper combustion, complete blue flame formation at the burner tip and better flame stability under variable air flow rates. In Type II and Type III burner, the flue gases of temperature ranging from 90 o – 300 o can be produced at gas flow rates from 7 – 22 lpm.

LPG Burners for Weed Control

<abstract> <b><sc>Abstract. </sc></b>This article reports on the results of a study carried out on three prototypes of open flame burners for thermal weed control. Their performance is reported in terms of flame temperature and length, in order to ascertain the best ratio between primary and secondary air, and liquefied petroleum gas (LPG) consumption. To find the best ratio between primary and secondary air, the length and temperature of the flame were recorded for each of the three burners, examined by varying the inlet sections of the primary air and secondary air. The data on temperature and the flame length of each burner were processed using multiple regression analysis. The LPG consumption was determined with one of the burners using 10 different pressures in combination with three nozzles. The data obtained were subjected to non-linear regression using two gaseous outflow models. The various combinations of primary and secondary air inlet sections affected the values of the flame length and temperature. In general, the best combinations of primary and secondary air inlet for flame temperature did not correspond to those for flame length. However, this experiment showed that the inlet of secondary air is critical for the performance of this type of burner, in terms of flame temperature. The fuel consumption trial showed that the model proposed for the gaseous outflow is suitable for describing the values of LPG consumption collected during the trial.

Calibration of a Knock Prediction Model for the Combustion of Gasoline-LPG Mixtures in Spark Ignition Engines

Gaseous fuels, such as liquefied petroleum gas (LPG) and natural gas (NG), thanks to their good mixing capabilities, allow complete and cleaner combustion than gasoline in spark ignition (SI) engines, resulting in lower pollutant emissions and particulate matter. In a previous work the authors showed that the simultaneous combustion of gasoline and LPG improves an SI engine efficiency with respect to pure gasoline operation with any significant power loss. The addition of LPG to the gasoline-air mixture produces an increase in knock resistance that allows running the engine at full load with overall stoichiometric mixture and better spark advance. In order to predict both performance and efficiency of engines fed by LPG-gasoline mixtures, a specific combustion model and in particular a knock prediction sub-model is required. Due to the lack of literature works about this matter, the authors investigated the knock resistance of LPG-gasoline mixtures. As a result, a reliable knock prediction sub-model has been obtained. The model can be easily implemented in thermodynamic simulations for a knock-safe engine performance optimization. The authors recorded light knocking in-cylinder pressure cycles on a cooperative fuel research (CFR) engine fueled by LPG-gasoline mixtures in different proportions. The tests were performed varying the compression ratio, the spark advance, and the inlet mixture temperature. The collected data have been used to calibrate and then compare two classical knock-prediction models. The models have been calibrated with a heterogeneous set of experimental data in order to predict knock occurrence in SI engines of different kinds. The results show that the models predict the knock onset position with a maximum error of around 6 crank angle degrees (CAD).

An experimental investigation on char pattern and depth at postflashover compartments using medium‐density fibreboard (MDF)

SummaryTo determine the fire origins for postflashover compartments, the char pattern and depth are investigated. A set of experiments was carried out using large‐scale compartments made of medium‐density fibreboard. A liquefied petroleum gas burner was used as the ignition source to mimic the fire origin. The burner was set at different locations in different experiments. It is found that time to flashover, intermittent flame of gas burner and ventilation condition have effects on the char patterns. The ‘ventilation patterns’ are likely to confuse the fire investigators; therefore, it needs to be identified from the ‘flame patterns’. In general, the ventilation patterns at the floor would initiate directly from the compartment opening. CFD simulations is used to reflect the ventilation conditions during fires thus assisting the identification of ventilation patterns. For those cases with less distinguishable char patterns, the profiles of total leftover material thickness and char depth were used to determine the fire origin. The char layer and total thickness in the flame regions were found to be respectively deeper and thinner than the rest parts of the compartment. The ventilation condition also affects the char depth profile; therefore, it cannot be ignored from analysis. At the end, a strategy of fire origin determination is proposed. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Investigations on Thermal Radiative Characteristics of LPG Combustion: Effect of Alumina Nanoparticles Addition

Use of nanoparticles in thermal applications has attained large interest in recent years because of their improved heat transfer characteristics. The effect of nanoparticle addition on radiative heat transfer characteristics in gaseous fuel combustion has been studied in this research. Radiative heat fluxes (RHFs) are considered to play a very important role in improving the thermal efficiency in furnaces by controlling the heat transfer from the flame to the furnace wall. The current research work is focused on investigating the effect of addition of noncombustible metal oxide (Al2O3) nanoparticles on radiative heat transfer capabilities in liquefied petroleum gas (LPG) combustion. Concentration of nanoparticles in water suspensions was varied up to 3.40 wt% to avoid choking of the feeding capillary. Temperature data inside the furnace was obtained and significantly lower peak temperatures were observed with lower concentration of nanoparticles, and with an increase in concentration, peak temperature also increases. Heat flux data was recorded at the furnace wall, and heat fluxes were significantly influenced by varying the nanoparticle concentration. An overall increase in RHF was observed, with increased contribution of RHF to total heat flux (THF). A higher contribution of RHF led to a substantial increase in the THF.

Sources of C2–C4 alkenes, the most important ozone nonmethane hydrocarbon precursors in the Pearl River Delta region

Surface ozone is becoming an increasing concern in China's megacities such as the urban centers located in the highly industrialized and densely populated Pearl River Delta (PRD) region, where previous studies suggested that ozone production is sensitive to VOC emissions with alkenes being important precursors. However, little was known about sources of alkenes. Here we present our monitoring of ambient volatile organic compounds at four representative urban, suburban and rural sites in the PRD region during November–December 2009, which experienced frequent ozone episodes. C2–C4 alkenes, whose total mixing ratios were 11–20% of non-methane hydrocarbons (NMHCs) quantified, accounted for 38–64% of ozone formation potentials (OFPs) and 30–50% of the total hydroxyl radical (OH) reactivity by NMHCs. Ethylene was the most abundant alkene, accounting for 8–15% in total mixing ratios of NMHCs and contributed 25–46% of OFPs. Correlations between C2–C4 alkenes and typical source tracers suggested that ethylene might be largely related to vehicle exhausts and industry activities, while propene and butenes were much more LPG-related. Positive Matrix Factorization (PMF) confirmed that vehicle exhaust and liquefied petroleum gas (LPG) were two major sources that altogether accounted for 52–62%, 58–77%, 73–83%, 68–79% and 73–84% for ethylene, propene, 1-butene, trans-2-butene and cis-2-butene, respectively. Vehicle exhausts alone contributed 32–49% ethylene and 35–41% propene. Industry activities contributed 13–23% ethylene and 7–20% propene. LPG instead contributed the most to butenes (38–65%) and substantially to propene (23–36%). Extensive tests confirmed high fractions of propene and butenes in LPG then used in Guangzhou and in LPG combustion plumes; therefore, limiting alkene contents in LPG would benefit regional ozone control.

Experimental Determination of Liquefied Petroleum Gas–Gasoline Mixtures Knock Resistance

The results of previous experimental researches showed that great advantages can be achieved, both in terms of fuel consumption and pollutant emissions, in bifuel vehicles by means of the double-fuel combustion, i.e., the simultaneous combustion of gasoline and a gaseous fuel, such as liquefied petroleum gas (LPG) or natural gas (NG). The substantial increase in knock resistance pursued by adding LPG to gasoline, which allowed to maintain an overall stoichiometric proportion with air also at full load, is not documented in the scientific literature and induced the authors to perform a proper experimental campaign. The motor octane number (MON) of LPG–gasoline mixtures has been hence determined on a standard cooperative fuel research (CFR) engine, equipped with a double-fuel injection system in order to realize different proportions between the two fuels and electronically control the overall air–fuels mixture. The results of the measurement show a quadratic dependence of the MON of the mixture as function of the LPG concentration evaluated on a mass basis, with higher increase for the lower LPG content. A good linear relation, instead, has been determined on the basis of the evaluated LPG molar fraction. The simultaneous combustion of LPG and gasoline may become a third operative mode of bifuel vehicles, allowing to optimize fuel economy, performances, and pollutant emissions; turbocharged bifuel engines could strongly take advantage of the knock resistance of the fuels mixture thus adopting high compression ratio (CR) both in pure gas and double-fuel mode, hence maximizing performance and reducing engine size. The two correlations determined in this work, hence, can be useful for the design of future bifuel engines running with knock safe simultaneous combustion of LPG and gasoline.

Artificial neural network prediction of exhaust emissions and flame temperature in LPG (liquefied petroleum gas) fueled low swirl burner

This study deals with ANN (artificial neural network) modeling of a swirl burner. The model was used to predict the flame temperature and pollutant emissions (CO (carbon monoxide) and NOx (nitrogen oxide)) from combustion of LPG (liquefied petroleum gas) in the swirl burner. The data for the training and testing of the proposed ANN was obtained by combusting LPG at various equivalent ratios (LPG/air ratios) and swirler's vane angles in a low swirl burner. Vane angles of 35–60° in steps of 5° and equivalent ratios of 0.94, 0.90, 0.85, 0.80, 0.75, 0.71, 0.66 and 0.61 were considered. An ANN model based on standard back-propagation algorithms for the swirl burner was developed using some of the experimental data for training and validation. The performance of the ANN was tested by comparing the predicted outputs with the experimental values that were not used in training the network. R values of 0.94 were obtained for CO and NOx and 0.99 for flame temperature. These results show that very strong correlation exists between the ANN predicted values and the experimental results. Therefore, this study demonstrates that the performance and emissions of swirl burner can be accurately predicted using ANN approach.

Thermal Efficiency of LPG and PNG-fired burners: Experimental and numerical studies

In the present work, the thermal efficiency of a conventional domestic burner is studied both experimentally and numerically for liquefied petroleum gas (LPG) and piped natural gas (PNG) fuels. Three-dimensional computational fluid dynamic (CFD) modeling of the steady-state flow, combustion and heat transfer to the vessel is reported for the first time in such burners. Based on the insights from the CFD model concerning the flow and heat transfer, design modifications in the form of a circular insert and a radiant sheet are proposed which are observed to increase thermal efficiency for LPG. For PNG, predictions showed that loading height was a much more important factor affecting efficiency than these design modifications and an optimal loading height could be identified. Experiments confirm these trends by showing an improvement in burner thermal efficiency of 2.5% for LPG with the modified design, and 10% for PNG with the optimal loading height, demonstrating that the CFD modeling approach developed in the present work is a useful tool to study domestic burners.

A comparative experimental study of the interactions between platinum and a range of hydrocarbon fuels

This paper presents the reactivity of different alkanes ranging from C1 to C4 over platinum. The four fuels used are compressed natural gas (CNG), liquefied petroleum gas (LPG), butane, and ethane. Experiments are performed to study the effects of varying the temperature of the incoming mixture (Tjet), its equivalence ratio (φ) and the Reynolds number (Re), on the reactivity limits and species distributions. Platinum surface temperatures as well as species profiles streamwise and transverse to the plate are investigated. The reactivity limits of ethane over platinum are discussed in details.For flameless combustion (defined by the the presence of reactions on the plate without a gaseous flame), it is found that the plate temperatures of ethane/air peak at moderately rich mixtures (φ=1.3) and the reactivity limits broaden in the presence of platinum plate compared to the gaseous flammability limits. The main products of burning these four hydrocarbon fuels over platinum are CO2 and H2O while CNG showing the highest selectivity to CO and H2. Species such as methane (CH4), acetylene (C2H2), ethane (C2H6), dimethyl ether (C2H6O), propylene (C3H6), and propane (C3H8) appear in the products when burning LPG and butane over platinum. The streamwise profiles of species indicate the presence of two reacting zones along the plate which are described as: (i) the leading edge zone where high gradients of species mole fractions are observed and (ii) the trailing zone where the profiles are more flat and stable. The transverse profiles highlight the presence of two reactive layers: (i) the inner boundary where peaks of CO, CO2, and H2 occur and (ii) the outer layer where formation of the other hydrocarbons is observed. Heavier alkanes result in oxygen/fuel ratio near the plate higher than those injected in the free stream and this may be largely due to differential molecular as well as thermal diffusion.

Experimental Study on the Combustion and NOx Emission Characteristics of DME/LPG Blended Fuel Using Counterflow Burner

Dimethyl ether (DME) continues to be considered as an alternative fuel to conventional hydrocarbon fuels. Specifically, DME has been considered as a substitute fuel for liquefied petroleum gas (LPG) because the physical and chemical characteristics of DME are similar to those of LPG. However, the combustion performance for DME has not yet been established. In this study, the combustion and NOx-emission characteristics of LPG, DME, and an LPG/DME-blended fuel were experimentally investigated in a counterflow nonpremixed flame. The flame structure, flame temperature, NOx concentration, and distribution of OH radicals are reported. In this experimental study, the types of LPG used were butane 100%, butane 80% + propane 20%, and butane 75% + propane 25% by mass with DME mole fraction varied from 0 to 100 mole%. The experimental results indicated that the combustion and NOx emission characteristics of LPG fuels varied with the DME mole fraction. As the DME mole fraction increased, the flame thickness increased, but the flame length decreased. Also, the flame became wider, and its origin moved closer to the oxidizer nozzle with increasing DME mole fraction. In addition, as the DME mole fraction increased, the maximum flame temperature increased due to fast pyrolysis of DME as a result of the high oxygen content (∼35% by mass) in DME. Moreover, NOx concentration decreased with increasing DME mole fraction in all LPGs.

The Experiment Device Design of LPG Fire Radiation

Liquefied petroleum gas (LPG) is an important energy which is widely used in various fields of the national economy, and is one of the top 10 dangerous chemicals with inflammable, explosive dangerous. According to the need of LPG combustion and rescue, a set of LPG fire radiation experiment device was designed. The temperature and heat radiation flux of LPG flame can be gotten under different pressures and flow rates. The design is benefit for combustion and and emergency rescue research of large LPG tanks.