Performance evaluation of a diesel engine by using producer gas from some under-utilized biomass on

J Cent. South Univ(2012)19: 1583-1589DoI:10.1007/s1177-012-118052 sprPerformance evaluation of a diesel engine by using producer gas from someunder-utilized biomass on dual-fuel mode of diesel cum producer gasD K DasS P Dash.M K. Ghosal'1. Department of Farm Machinery and Power, College of Agricultural Engineering and Technology,Orissa University of Agriculture and Technology, Bhubnaneswar-751003, Orissa, India2. Department of Water Resources, Orissa Lift imigation Corporation, Government of Orissa, IndiaC Central South University Press and Springer-Verlag Berlin Heidelberg 2012Abstract: Producer gas through gasification of biomass can be used as an altemate fuel in rural areas due to high potential ofbiomass resources in India. Experiments were conducted to study the performance of a diesel engine(four stroke, single cylinder,5. 25 kW)with respect to its thermal efficiency, spccific fuel consumption and diesel substitution by use of diesel alone and producergas-cum-diesel( dual fuel mode). Three types of biomass, i.e. wood chips, Pigeon pea stalks and con cobs were used for generationof producer gas. a producer gas system consisting of a downdraft gasifier, a cooling cum cleaning unit, a filtering unit and a gas airmixing device was designed, fabricated and used to power a 5.25 kw diesel engine on dual fuel mode. Performance of the enginewas reported by keeping biomass moisture contents as 8%, 12%, 16%, and 21%, engine speed as 1 600 r/min and with varableengine loads. The average value of thermal efficiency on dual fuel mode was found slightly lower than that of diesel mode. Thespecific diesel consumption was found to be 60%64%less in dual fuel mode than that in diesel mode for the same amount of energyoutput. The average diesel substitution of 74% was observed with wood chips followed by com cobs (78%)and pigeon pea stalks82%) Based on the performance studied, the producer gas may be used as a substitute or as supplementary fuel for dieselnservation, particularly for stationary engines in agricultural operations in the farm.Key words: biomass gasification; producer gas; downdraft gasifier; diesel enginestock is thermally decomposed and the end products are1 Introductionprincipally in gaseous form, with the main combustiblecomponents being carbon monoxide and hydrogen. TheThe escalating oil prices and scarcity of fuel oils main advantages of gases as a fuel over liquid or solidcoupled with exploding population have resulted in fuels are that 1)gases burn with higher efficiency thanus energy crisis. There is thus a pressing needthe solid or liquid fuels; 2)they have a higher rate of heatdevelop technology for utilizing the renewable energy release: 3)the rate of energy output is easily controlledsources that can make significant contribution to the and adjustable; 4) gaseous fuels with good energyeconomy and the well being of the rural people.utilization can be used for power sources. a good qualityOf all the altemative sources of energy for rural producer gas has an energy content of aboutproducer gas from biomass appears to have the 5 200 kJ/(N-m). a gas producer requires 2.5-3 kg oft potential. As an agricultural country, India has wood to generate about the same energy as I L of dieselupply of biomass resources. It is estimated that [7Jabout 40%-60% of agricultural residues are either lost orDiesel engines are widely used in Indianput to inefficient use. This calls for better utilization of agricultural farms for a variety of stationary and mobilethese resources by thermo-chemically converting into operations. The usual approach of producer gasproducer gas in the current context of limitedness of utilization in diesel engines consists of operating existingpetroleum based fuels for use in intemal combustion compression ignition engines on producer gas cum dieselengines. Producer gas is generated from solid dual-fuel mode. The thermal efficiency of gasifiers imcarbonaceous fuels such as wood, charcoal, coal, which producer gas is produced has been found to beagricultural and forest residues and also animal wastes 70%-80% and that of the gasifier-engine system to be[1-6中国煤化工 ute and serious inirreversible thermo-chemical process by which feedH-un motor vehicleCNMHGReceived date: 2011-07-26; Accepted date: 2011-l1-14Corresponding author: M. K Ghosal; Associate Professor, PhD; Tel: +91-9556271208; B-mail: mkghosall@rediffmail com584J. Cent. South Univ.(2012)19: 1583-1589particularly for agricultural operations [8-12]. Previous hearth which was closed during gasification and openedstudies[13-16] indicate that a very little effort has been only while starting to introduce fire. Ash pit was coveredmade in this direction. There is also a lack of information with a metal filter known as grate through which ash andon the use of different types and conditions of biomass to soot particles were collected. A hand blower wasgenerate producer gas as a supplement fuel for diesel attached to the gasifier for initial charging. Theengines. Therefore, an effort was made to develop a gas cooler-cum-cleaner unit consisted of a radiator to radiateproducer system utilizing the locally available raw heat from hot water, a venturi to provide sufficient spacematerials to power a 5.25 kw(7 hp), single cylinder for cooling the gas and a water tank. The otherdiesel engine that can be used on small horse power attachment to the cooling system was a fan driven by atractors, known as power tillers. The major objectives in 0.375 kW motor to lift water from the tank to the radiatorthis work are as follows:a two stage filtering unit was developed to filter the dust1)To design and fabricate the different components and soot particles. The first stage consisted of gravel,of a gas producer system to operate a 5. 25 kW(7 hp) charcoal, coconut coir and cotton layers of 15 cm indiesel engine.thickness whereas the second stage consisted of only two2)To evaluate the performance of the above engine layers of cotton of 15 cm in thickness. Both the filteringith respect to thermal efficiency, specific diesel units were packed in different boxesconsumption and diesel substitution by using differenttypes of biomass3 Methodology2 Design and fabrication of gas producer 3. 1 Gas producer systemystemA single-cylinder 4-stroke 5.25 kw diesel engine ofa commercial power tiller was used for the experimenA gas producer system consisting of a gasifier, a The intake manifold of the engine was modified using acooler cum cleaner unit, a filtration unit and a mixing T-section to introduce the mixture of air and gas into thedevice was designed and fabricated to operate a 5. 25 kw engine during suction stroke. The quantities of gas anddiesel engine on dual fuel mode(Fig. 1). A downdraft air flowing to the engine were measured separately withtype gasifier operating under suction induced flow was the help of two venturi sections provided in the T-sectiondesigned for a maximum engine gas requirement of The U-tube manometers were connected to the venturi10.70 Nm/h taking a maximum hearth load of section with polythene tube to measure the pressure drop0.9 Nm/(cm?h). The upper part of the gasifier was the across them. The original fuel supply of the engine fromfuel container and the lower part was the hearth with ash its fuel tank was cut off for the operation on dual fuelpit. The hearth section of the gasifier was V-shapedmode and the diesel fuel was supplied from an auxiliaryThe primary air intake was through a pipe extended tank provided with a fuel measuring set-up. In order tofrom top to the hearth with a provision to adjust the air measure the load applied to the engine, a pronyinlet height. The ignition tube was passed through the dynamometer was used, A strain gauge transducer中国煤化工CNMHGFig 1 Gas producer system: 1-Gasifier; 2-Venturi tube; 3-Radiator; 4-Primary filter; 5-Secondary filter; 6-Mixing device;7-Diesel engine; 8-Auxiliary fuel tank; -ManometersJ Cent. South Univ(2012)19: 1583-15891585used to measure the temperatures of oxidation and Fa is the volume of diesel consumed, cm; Pa is thethe gasifier and the exit gas from the density of diesel, kg/L; t is the time required to consumegasifier and the filtration unit.Vd, s, P is the engine power, kw3.2 Performance evaluation of engineThe thermal efficiency is expressed as the ratio ofThe diesel engine( specifications given in Table 1) output power to the power supplied by the fuel.1)Thermal efficiency of engine on diesel aloneengine speed 1 600 r/min and six loads(7.5, 12.5, 20, 3040 and 50 N). For dual fuel operation, the types of given byThermal efficiency of engine on diesel alone isbiomass used were pigeon pea stalks, wood chips andcorn cobs. Three materials were used at four differentmoisture contents (8%, 12%, 16% and 21% on wetPbasis). Each test was conducted for a period of 5 minwith two replications. During each test on diesel, theThe power input from fuel in Eq (2)is given bymeasured. The observed data were utilizedP3600the engine theermaemciency, specIconsumption and percent diesel substitution.Thewhere Pg is the brake power of the engine; Pr is theperformance of a diesel engine operated on dual-fuelpower input from fuel, kW; ca is the calorific value ofwas generally evaluated in terms of specific dieseldiesel, 39 M/kg; Pa is the density of diesel, 640 kg/m femption,engine thermal efficiency and percent is the fuel consumed, cm/hdiesel substitution. These parameters were determined asSubstituting the values of ca and pa, Eq(3)yields840xf eP36009.1Table I Specifications of gas producer engine system underUsing Eq. (4), Eq (2)givesSystemParameteriesel engine2)Thermal efficiency of engine on dual fuel modeThe formula used for calculating the thermaleficiency of engine on dual fuel mode is given by丌tCrank shaft speed(rated(rmin)2200Power input from producer gas is given byRated capacity/kwgePgGrade of oilSAE 30FuelHigh speed dieselwhere Ps is the power from producer gas, kW;cr is thecalorific value of producer gas, k/(N m); ge is the gasCooling systemWater-cooledconsumption, N'm/hMoving bed,Substituting Eqs. (5)and(7)in Eq (6), there iso-current Down draftMaterial of constructionMild steel9.1f。geHearth opening/mmGrate mesh size/mm3.2.3 Diesel substitutionTotal mass/kgThe perDd-Dag.2.1 Specific diesel consumption(SCD)SDC is given bywhere中国煤化工3600VDa is the dieseldPA=3consuCNMH Gone, cm/;Da,is10001P(1)the diesel consumption by the engine on dual fuel modewhere CsD is the specific diesel consumption, g/(kW-h ) cmhCent. sth Univ.(2012)19:1583-1589thermal efficiency at 1 600 r/min is shown in Fig. 5. The4 Results and discussiontrend shows that there is adual-fuelcompared to thatThe relationship between engine load and thermal on diesel alone. Based on mean values, it may befficiency at the four levels of moisture content(8%, reported that the theerma erIc12%, 16% and 21%)for the different types of biomass when tested, drops from 32. 3% on diesel fuel mode to(pigeon pea stalks, wood chips, com cobs)is shown in 30.5% on dual-fuel mode using pigeon pea stalksFigs. 2, 3 and 4 at engine speed of 1 600 r/min. The However, the efficiency of engine on dual-fuel modetrend shows that the thermal efficiency increases with a using wood chips and com cobs is found almost at pardecreasing rate with the increase in engine load for all with that on diesel mode. This shows that the combustionthe biomass fuels at all the biomass moisture levels of air-gas mixture while using wood chips and com cobstested. This may be due to better combustion of is better compared to pigeon pea stalks, even though therelatively rich gas-air mixture at higher loads. It is also energy content of pigeon pea stalks is relatively highobserved that with the increase in biomass moisture from The variations of specific diesel consumption and dieselto 21%, the thermal efficiency also increases substitution with engine load on dual-fuel mode of amarginally from 28%to 31% with pigeon pea stalks,diesel engine at different biomass moisture levels are30% to 32% with wood chips and 29%to 32% with corn shown in Figs. 6-ll The trend of the curves shows thatcobs. The slight increase in thermal efficiency from 8% the specific diesel consumption, in general, decreasesto 21% moisture range might have been caused due to with the increase in engine load at different moisturebetter combustion of premixed mixture of gas and air on levels for all the three types of biomass used. However, adual-fuel mode resulting in reduced requirement of total definite trend of variation of diesel substitution withenergy input at different loadsengine load has not been established. It has shownThe effect of different types of fuel on engine increasing trend with load in most of the cases, whereasBiomassBiomassmoisture contentmoisture contentEngine speed 1 600 r/minEngine speed 1 600 r/mink-21%20Engine load/kwEngine load/kwFlg. 2 Variation of thermal efficiency with engine load on dual Fig. 4 Variation of thermal efficiency with engine load on dualfuel mode at different moisture contents of wood chipsfuel mode at different moisture contents of com cobsBiomass moisture content 8%Engine speed 1 600 r/minDiesel+gas from com ceBiomass22Engine speed 1 600 r/min中国煤化工CNMHGFig 3 variation of thermal efficiency with engine load on dual Fig. 5 Effect of engine load on thermal efficiency with differentfuel mode at diferent moisture contents of pigeon pea stalkstypes of fuelJ Cent. South Univ(2012)19: 1583-1589Engine speed I 600 r/minl1021%3-6Biomass moisture contentEngine speed 1 600r/min12%21%sEngine load/kWEngine load/kWFig. 6 Variation of specific diesel consumption withFig. 9 Variation of diesel substitution with engine loadload on dual fuel mode at different moisture contents ofdual fuel mode at different moisture contents of pigeonchipsstalksBiomassl10moisture content二5e ]0Biomass moisture contentEngine speed 1 600 r/minEngine load/kWEngine load/WFig. 7 Variation of diesel substitution with engine load on dual Fig. 10 Variation of specific diesel consumption with enginefuel mode at different moisture contents of wood chipsload on dual fuel mode at different moisture contents of comcob110omassmoisture contentl6%Engine speed 1 600 r/minEngine speed 1 600 r/minEngine load/kWFig.8 Variation of specific diesel consumption with engineEngine load/kWload on dual fuel mode at different moisture contents of pigeon Fig. 11 Variation of diesel substitution with engine load on dualfuel m中国煤化工in a few cases a decreasing patten has also been higherCNMH Gon of diesel fuelobserved. This kind of trend is not common in the and thus aage vI uIcscI fuel replacement.existing literatures. It is usually reported that if But if the quality of the gas in terms of its energy contentthe energy content of the gas remains relatively stable, a is not stable, an increase in load can also increase the158J. Cent. South Univ(2012)19: 1583-1589percentage of diesel fuel substitution. The decrease inComparing the performance ofthe basispecific diesel consumption with load is primarily due to of the mean values of specific diesel consumption, it isthe increase in diesel fuel consumption at a decreasing observed that the engine consumes 60%-64% less dieselrate. From the mean values of specific diesel on dual-fuel mode than that on diesel mode for the sameconsumption and diesel substitution in the test engine at amount of energy output. The effect of engine load ondifferent operational parameters(taking all loads into percent diesel substitution for different types of biomassconsideration), it is observed that the specific diesel is shown in Fig. 13. The trend shows increasing patternnsumption of engine on dual-fuel mode using pigeon of diesel substitution with engine load as explainedpea stalks decreases from 87.9 g/(kw. h)at 8% moisture earlier. Based on the mean values of diesel substitution, itlevel to 75.9 g/(kWh)at 12% moisture level beyond can be pointed out that the average diesel substitution ofwhich it again increases and rises to 161.8 g/(kWh )at a 64% is found with wood chips followed by corn cobsbiomass moisture level of 21%. The diesel substitution (63%)and pigeon pea stalks (62%)throughout the rangeon the other hand, varies from 50.5% to 68.8% in the of biomass moisture. From the results discussed above, itsame moisture range showing the maximum value of can be stated that the gasifier system developed for 5.2572.3% at a moisture level of 12%. Similar trends of kw diesel engine has indicated satisfactory performancevariation of specific diesel consumption and diesel by showing on an average 60%-65% saving in dieselsubstitution are also noticed in the case of the other two consumption while utilizing three types of locallybiomass fuels. For the sake of comparison, the minimum available biomass fuelsvalues of specific diesel consumption using wood chipsand corn cobs are observed to be 82 and 87 g/(kw-b)respectively, whereas the maximum values of dieselEngine speed 1 600 r/minsubstitution for these fuels are found to be about 71.3%Diesel+gas from wood chipsat a moisture level of 12%. This shows that the minimumDiesel+gas from corn cobsvalues of specific diesel consumption are denved at aDiesel+gas from pigeon pea stalkparticular biomass moisture level (12%)where dieselsubstitution is maximum. This is perhaps due to better870by its higher CO content resulting in better combustionof air gas mixture. The variation of specific dieselconsumption with engine load for the test enginediesel mode as well as on dual- fuel mode using differenttypes of biomass is shown in Fig. 12 for a particular setEngine load/kwof operating parameters. The data indicate a slight Fig. 13 Effect of engine load on diesel substitution withdecrease in specific diesel consumption with engine load different types of fuelboth on diesel as well as on dual fuel operations. Asexpected, the specific diesel consumption on diesel mode 5 Conclusionsis much higher than that on dual-fuel mode for all theengine loads testedI)The gas producer system designed and developedfor a 5.25 kw diesel engine is found to perform2350satisfactorily by using different types of biomass such aspigeon pea stalks, wood chips and com cobs2) The average value of thermal efficiency of engine250 Biomass moisture content 8%is found to drop slightly from 32.3%on diesel mode toEngine speed 1 600 r/min28.7% on dual fuel mode using pigeon pea stalks asbiomass fuel. However, the efficiency found on dual fuelDiesel+gas from pigeon pea stalkmode with wood chips and com cobs is comparable toDieseltgas from com cobsthat on diesel modevalues of specific dieselof engine on dual-fuel mode for all the three biomassfuelsed to dietde and their diesel中国煤化工Engine load/kwCNMH Gion in a 5.25 EWFig. 12 Effect of engine load on specific diesel consumptionIl uc range of 62%-64% usIwith different types of fuelthree types of biomass fuels.J Cent. South Univ(2012)19:1583-1589References[9] TIWARI G SARKAR B, GHOSH L, Design parameters for a ricehusk throatless gasifier reactor Agricultural Engineering[] HINDSGAUL C, SCHRAMM J, GRATZ L, HENRIKSAN UInternational: The CIGR Journal of Scientific Research andBENTZEN J D PhysicaDevelopment, 2006. 8: 88-93chemical characterization of particles [10 SINGH RN, JENA U, PATELJ B, SHARMA A M. 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