Potential of Bio-DME as a Transportation Fuel for India

8/3/2019 Potential of Bio-DME as a Transportation Fuel for India

1/13

Potential of bio-DME as a transportation fuel for India

M. Himabindu and R. V. RavikrishnaDepartment of Mechanical Engineering, Indian Institute of Science, Bangalore 560012,India

Received 13 April 2010; accepted 14 August 2010; published online 21 September 2010

This article discusses the potential of bio-dimethyl ether DME as a promising fuelfor India in the transportation sector where a majority of imported petroleum in theform of diesel is used. Specifically, the suitability of DME in terms of its properties

vis--vis those of diesel, ability to liquefy DME at low pressures similar to liquefiedpetroleum gas LPG, and ease of production from renewable feedstock biomass,and most importantly, very low emissions including near-zero soot levels are someof the features that make it an attractive option. A detailed review presents the

state-of-the-art on various aspects such as estimates of potential bio-DME produc-tion, methods of synthesis of bio-DME, important physicochemical properties, fuel-injection system-related concerns both conventional and common-rail system,

fuel spray characteristics which have a direct bearing on the engine performance,and finally, exhaust emissions. Future research directions covering all aspects fromproduction to utilization are summarized 2010 American Institute of Physics.doi:10.1063/1.3489529

I. INTRODUCTION

The search for clean, green, and viable energy alternatives has assumed a sense of urgencywith the rise in Indias vehicle population and petroleum consumption with every passing day. Thetotal on-road vehicle population in India was around 70 million in 2007 and estimated to increaseby seven times by 2016.1 In addition, Indias total petroleum consumption grew 6.8% to 128.94

million tons in 20072008 fiscal and it is expected to grow by 6% per year. Annual diesel

consumption in India is approximately 52 million tons, i.e., 40% of the total petro productsconsumption. Since India imports three-quarters of its crude oil needs, this places a severe burdenon the economy especially since its growing economy has led to a steady increase in the demand

for oil.Renewable fuels for transportation improve energy security by displacing petroleum and lead

toward a sustainable energy future. Research on various renewable fuels such as bioethanol andbiodiesel has been going on for a considerable time; however, the current focus is to explore thenext generation alternatives that include bio-dimethyl ether DME, syngas, and FischerTropsch

diesel. Among these, bio-DME has good potential for becoming one of the alternatives because ofthe availability of feedstock biomass in India and the cost of production. DME is not a newproduct; it has been used as an aerosol propellant for over 60 years.2 In addition, it is practicallyodorless and colorless. DME is also relatively nontoxic and noncarcinogenic. Its characteristics are

similar to other aerosols such as propane, butane, and chlorofluorocarbons in terms of being able

to be liquefied at modest pressures approximately 6 atm at ambient temperatures. The mainreasons to consider bio-DME as a viable alternative fuel for diesel engines are the following.

1 Low emissions: The exhaust and noise emissions of an engine running on DME are muchlower than a similar engine running on diesel fuel. Smoke is almost nonexistent and oxidesof nitrogen NOx emissions can be reduced to very low levels. Smokeless combustion isachieved with DME fuel under all operating conditions because the oxygenate fuel highoxygen concentration of 35% by weight and the fast diffusion combustion suppress sootformation. The low NOx levels with DME are due to the low in-cylinder temperature fuel

JOURNAL OF RENEWABLE AND SUSTAINABLE ENERGY 2, 052701 2010

2, 052701-11941-7012/2010/25 /052701/13/$30.00 2010 American Institute of Physics

Downloaded 20 Aug 2011 to 141.23.39.50. Redistribution subject to AIP license or copyright; see http://jrse.aip.org/about/rights_and_permission
http://dx.doi.org/10.1063/1.3489529http://dx.doi.org/10.1063/1.3489529http://dx.doi.org/10.1063/1.3489529http://dx.doi.org/10.1063/1.3489529http://dx.doi.org/10.1063/1.3489529http://dx.doi.org/10.1063/1.3489529


2/13

evaporates faster in addition to the shorter ignition delay in comparison with that of dieseloperation.

2 Renewability: Bio-DME can be produced from renewable sources such as biomass. Fromwell-to-wheels analysis which is discussed in detail later on in this article, it is indicated thatbio-DME has highest efficiency and lowest CO2 emissions among renewable fuels.

3 Storage and handling: DME is a gas that can easily be liquefied at low pressures and hencecan be stored and carried onboard as a liquid. DME is easy to handle as it is nontoxic,noncarcinogenic, biodegradable, and harmless to the atmosphere. DME has similar physicalproperties as liquefied petroleum gas LPG and all the safety issues related to LPG apply toDME also. However, while carrying onboard as liquid DME is likely to have greater explo-sion hazard if it is spilled due to the wide detonability limits and also due to its low vapordensity as the dispersion of DME is faster than gasoline.

Sorenson3 provided an overview of the prospects of using DME as a fuel in diesel engines,whereas Arcoumanis et al.4 provided a detailed review concerning the use of DME in compression

ignition engines specifically focusing on the engine-related aspects such as fuel injection, spray,and combustion. The focus of this paper is specifically on bio-DME, and is a country-specificanalysis providing estimates of bio-DME production and the potential to substitute diesel. Also, a

more comprehensive discussion on the bio-DME production is presented, thus providing an over-all discussion from production estimates, production pathways, and utilization in engines. Further-more, a brief mention of future research directions is also presented. The following sectionsreview various aspects of bio-DME such as potential of production, methods of production, abilityto substitute diesel, performance of DME in engines with specific reference to combustion, andspray characteristics and emissions.

II. POTENTIAL OF BIO-DME PRODUCTION

India has a huge biomass potential owing to the large quantities of agricultural forestry and

agro-industrial residue produced. Table I shows the state-wise annual biomass production data andalso the potential of DME production in India. Hence, it is important to consider renewable fuelsthat can be produced from the large quantities of biomass available. The bio-DME production

estimate from biomass has been calculated based on available estimates. 5 For 1 ton of dry woodor other solid biomass, the estimated yield of DME production is 0.37 ton, i.e., on energy basis10 212 MJ of energy can be produced.6 For the same 1 ton of biomass, the energy produced frombiogas is 9900 MJ, whereas for the producer gas it is 11 500 MJ. 7,8 Thus, in terms of energy,efficiency, and emissions, DME proves to be a potential alternative for automotive applications.From Table I, it is observed that the net production of biomass residues in India could be around

125.046106 tons.5 Based on the above information, the estimated yield of bio-DME is around46.26106 tons. As mentioned earlier, Indias annual diesel consumption is around 52106 tons. Thus, these figures indicate that bio-DME can be a potential sub stitute for diesel fuelin India. Figure 1 shows the well-to-wheels analysis for heavy-duty vehicles.9 The well-to-wheels

energy efficiency is estimated as the product of the energy efficiency of each individual utilizationstep well-to-tank and tank-to-wheels. The energy efficiencies include fuel recovery, fuel distri-bution, fuel manufacturing/processing, and also vehicle technology. Carbon dioxide equivalent isa measure to compare the emissions from various green house gases based upon their global

warming potential. The well-to-wheels CO2 emission is defined as the total CO2 emissions in gm

during the production, distribution of fuel, and utilization in vehicles delivering 1 kW h of work.The production and distribution of natural gas involve large amount of fossil fuel-based energyusage generating CO2 in large quantities since it involves extraction from deep within the ocean/

land and pumping the gas over large distances. On the other hand, bio-DME is generated typicallyin a gasification process generating relatively smaller quantities of CO2, and the transport of DMEis relatively far simpler since it is carried as a liquid at very low pressures. Although DME is avolatile organic compound, it is nontoxic, noncarcinogenic, and thus environmentally benign,

whereas NG which mainly contains CH4 is environmentally hazardous. The global warming

052701-2 M. Himabindu and R. V. Ravikrishna J. Renewable Sustainable Energy 2, 052701 2010



3/13

TABLE I. State-wise annual biomass and potential bio-DME production data.

S. No. State

Area

kHa

Crop production

MMTPA

Biomass generation

MMTPA

Biomass surplus

MMTPA

Potential of

bio-DME

production

MMTPA

1 Andhra Pradesh 6021.5 28.345 21.569 3.948 1.460 76

2 Assam 2586.6 5.945 06.625 1.362 0.503 94

3 Bihar 5833.1 13.818 20.442 4.286 1.585 82

4 Chhattisgarh 3815.5 6.143 10.124 1.908 0.705 96

5 Gao 156.3 0.555 0.929 0.181 0.066 97

6 Gujarat 6519.0 20.636 25.471 8.353 3.090 61

7 Haryana 4890.2 13.520 26.581 10.106 3.739 22

8 Himachal Pradesh 710.3 1.329 2.668 0.988 0.365 56

9 Jammu and Kashmir 368.7 0.649 1.199 0.238 0.088 06

10 Jharkhand 1299.8 1.509 2.191 0.568 0.210 16

11 Karnataka 7356.0 38.754 26.949 7.184 2.658 08

12 Kerala 2058.4 9.773 13.073 7.529 2.785 73

13 Madhya Pradesh 9937.0 14.167 28.0349 9.284 3.435 0814 Maharashtra 15 542.3 51.665 39.349 12.998 4.809 26

15 Manipur 72.6 0.159 0.319 0.032 0.011 84

16 Meghalaya 0.80 0.014 0.042 0.008 0.002 96

17 Nagaland 27.1 0.088 0.149 0.027 0.009 99

18 Orissa 2436.6 3.633 5.350 1.163 0.430 31

19 Punjab 6776.6 31.731 49.988 24.544 9.081 28

20 Rajasthan 10 748.5 12.763 25.234 7.420 2.7454

21 Tamil Nadu 2561.5 24.688 17.459 7.401 2.738 37

22 Uttar Pradesh 12 672.5 46.842 50.622 11.870 4.3919

23 Uttaranchal 66.4 0.136 0.160 0.052 0.019 24

24 West Bengal 5575.6 21.063 23.333 2.968 1.098 16

Grand total 107 763.0 347.926 398.175 125.046 46.05

FIG. 1. Well-to-wheels analysis for heavy-duty vehicles Ref. 9.

052701-3 Bio-DME as a transportation fuel J. Renewable Sustainable Energy 2, 052701 2010



4/13

potential on the basis of CO2 being 1.0 for DME is 0.3 100 yr time horizon, whereas for CH4 itis 21 100 yr time horizon. This means that emissions of 1 MMT of methane are equivalent to

emissions of 21 MMT of CO2. It also shows that bio-DME produced from wood, black liquor hasalmost negligible CO2 emissions and high WTW efficiency when compared with that producedfrom natural gas. Bio-DME can be produced relatively inexpensive from biomass and other such

products. Another rich source for bio-DME is black liquorthe waste product of paper produc-tion. India has the 15th largest paper industry in the world. 10 Hence, bio-DME has bright prospectsand has potential to become a major fuel that is suitable for Indias rising fuel demands.

III. DME SYNTHESIS

DME produced from biomass, agri-residues, forest industry by-product, etc. shows a promise

as one of the alternatives for diesel in the transportation sector. For India, agriculture-basedbiomass is an interesting option on foreseeable terms considering the availability of the same. Theviability of commercial production of DME in large quantities has been demonstrated especially incountries such as Japan and China. Biomass can be converted into solid, liquid, or gaseous fuels

through thermochemical and biological routes. Production of bio-DME in India can be a steptoward solving the energy-environment dilemma by utilizing the biomass resources.

A. Biomass gasification

Biomass gasification is a well established and a promising route for converting biomass into

liquid fuels. Gasification system basically consists of a gasifier unit, purification system, andenergy converters. The design of gasifier depends upon the type of fuel used and whether gasifieris portable or stationary. Gasification typically involves substoichiometric oxidation leading to theloss of volatiles from biomass. It is an exothermic process which generates gaseous products such

as CO, H2, and CO2. Additionally, a second reduction reaction may also be incorporated togenerate CO and CH4 from CO2.

1115 The advantage of gasification technology is decentralizedenergy conversion system which operates economically even for small scale. Thus, gasificationprocess produces syngasa mixture of CO and H2 which can be later converted into fuel chemi-

cals in a variety of catalytic processes to produce methanol, synthetic diesel, and DME. An

excellent review of the biomass gasification process is provided by Leunget al.

16

1. Indirect DME synthesis process

The conventional DME production a highly exothermic reaction is an indirect two-step

process where syngas a mixture of CO, H2, and N2 is first converted to methanol followed bymethanol dehydration to DME. Past research has shown that high quality DME is obtained withthe use of ZSM-5 molecular sieve catalyst that contains gamma Al2O3 /SiO2. However, the cost ofproducing DME from methanol is influenced by the price and availability of methanol, as it is an

expensive chemical feedstock. Also, in the two-step reaction, the equilibrium conversion of DMEis lower.

DME production from organic biomass waste such as straw and salix was carried out bymethanol dehydration by Ahlgren et al.17 Detailed study on energy balance such as production of

raw material, fuel production, fuel storage and distribution, land use, and fuel utilization was done.

The yield of DME was observed to be 0.49 MJ/MJ LHV 50% moisture content of biomass.Another similar study of DME production from biomass residues of sugarcane such as bagasseand cane trash was investigated by Chohfi.6 It involves the feasibility study of biodigestion which

consists of biological degradation of complex organic substances in the absences of free oxygen.The methane present in the biogas that produced from this process is transformed into synthesisgas which later undergoes catalytic synthesis of the H2 and CO.

2. Direct DME synthesis process

In contrast, producing DME directly from syngas has many economic and technical advan-tages over methanol dehydration. Figure 2 shows the schematic diagram of both direct and indirect




5/13

processes. Table II gives details of the synthesis reactions. It has been reported that DME can beprepared in a one-step process using syngas as a starting material, which is more thermodynami-

cally and economically favorable than the two-step process of syngas to methanol and further toDME.18,19 Lv et al.20 explored the technology of syngas production from direct biomass gasifica-

tion. The characteristics of biomass gasification gas such as ratio of H2 and CO molar percentagesH2 /CO and tar yield were studied. Dolomite and nickel-based catalyst were adopted in a fluidized

bed gasifier and in a downstream fixed-bed gasifier. The results show that a high ratio of H 2 /COranging from 1.87 to 4.45 varying the reactor temperature can be obtained from biomass cata-lytic gasification which is favorable for methanol or DME synthesis.

Available processes for the production of syngas for gas to liquid plants are based on steam

reforming, partial oxidation, or a combination of both. The most attractive and economical tech-nology is considered to be oxygen-blown autothermal reforming. New processes are being com-mercialized to produce DME in a single step via autothermal reactors if produced from naturalgas2123 and slurry phase reactors in case of biosyngas to meet the DME mass production.24 The

slurry phase reactors involve direct synthesis of DME from syngas with a dual/bicatalyst in aslurry phase reactor. This gives high conversion and high selectivity of DME, which means thatmethanol and DME syntheses occur in one reactor and overall the process is very efficient.

By-products of CO2, unreacted syngas, and small amounts of methanol obtained from the reactorare chilled and separated as liquid from unreacted gas. Recently, organizations such as JFE for-

mally NKK Corporation and Haldor Topsoe have been making progress in this technology ofdirect DME synthesis from gas using the slurry phase reactors.24 A 5 ton/day plant has been inoperation from 1999 at a coal-mining site in Hokkaido.25 With the successful operation of thisplant, a large-scale bench plant of 100 tons/day has been developed to commercialize DME

production.The two production methods discussed above have their own advantages and disadvantages.

However, synthesis of DME from biomass syngas through a single-step process is more preferredthan methanol synthesis. The advantages of this method include higher syngas conversion, higher

methanol reactor productivity, longer catalyst life, good heat control, and lesser dual deactivationand crystal growth. Some of the areas related to DME production that need to be addressed in thefuture are new hybrid catalyst technology, simulation of the reactor design, and process optimi-zation to further lower the operating costs and maximize efficiency.

Indirect Process

Direct Process

Syngas

(CO + H2)

Methanol

(CH3OH)

DME + CO2(CH3OCH3 + CO2)

Syngas

(CO + H2)

Methanol

(CH3OH)

DME + H2O

(CH3OCH3 + H2O)(1) (2)

FIG. 2. Synthesis process for methanol and DME.

TABLE II. DME synthesis reaction.

Methanol synthesis CO+2H2CH3OH, H rxn=90.3 kJ/mol

Methanol dehydration 2CH3OHCH3OCH3 +H 2O, H rxn=23.4 kJ /mol

Water-gas shift H2O+COH2 + CO2, H rxn=40.9 kJ /mol

Net reaction 3H2 +3COCH3OCH3 +CO2, H rxn=258.6 kJ/mol




6/13

IV. UTILIZATION OF DME IN IC ENGINES

Research has shown that compression ignition, direct injection engines fueled with DME canachieve ultralow emission vehicle standards while maintaining the thermal efficiency of a conven-

tional diesel. DME has been promoted as an alternative fuel for diesel engines owing to itssuperior physical and chemical characteristics,26,27 as shown in Table III. The enhanced propertiesof DME include a very high cetane number 55 leading to shorter ignition delay and thus lower

NOx levels, high oxygen content, and low boiling point 25 C. This translates into high

exhaust gas recirculation EGR tolerance, significantly lower noise levels, smokeless combustion,faster fuel/air mixing, and more efficient cold starting. Since DME is sulfur-free, the use ofeffective after treatment devices in general is more easily facilitated with DME and also nontoxicand noncarcinogenic. The disadvantages of DME are that it has a lower viscosity than that of

diesel causing fuel injection system leakage. Lubricity is also low causing wearing of engine parts

and lower calorific value.

A. Fuel injection system and spray characteristics

Studies to date have shown that the conventional pump-line-nozzle system can operate satis-

factorily and economically with DME in small 0.5l /cyl, naturally aspirated direct injectionDI diesel engines.28 Owing to its extremely low lubricity, using neat DME directly in conven-

tional diesel engine leads to damaged injection system. Hence, Wang and Zhou29 studied the effectof two kinds of vegetable oils as additives castor oil and rapeseed oil to enhance the lubricity andfound that the plunger surface of the fuel pump has no large wear scars after 200 h test. Theplunger surface was smoother with rapeseed oil than castor oil. They further concluded that smoke

emissions were negligible and NOx was comparable to diesel. The power output and efficiencywere almost maintained to diesel operation. Zhang et al.30 focused on the injection process of adiesel engine fuelled with DME. They modified the pump-line-nozzle fuel system to accommodatethe neat DME by enlarging the plunger diameter from original size of 910 mm and nozzleorifice area from 0.35 mm to 0.55 to achieve rated power.

Similar studies31 on increase in plunger diameter and advanced injection timing show anincrease in the injection duration due to the high volume of DME that has to be injected into thecylinder. Thus, DME requires 1.8 times the volume of diesel fuel to supply the same amount ofenergy due to its lower calorific value and low density. 27,32,33 As DME can atomize and evaporate

easily, the nozzle opening pressure was reduced from 18 to 15 MPa, which in turn reduces thedrive power of injection pump and increases the engine efficiency. However, further lowering theinjection pressure will cause longer injection duration and decrease the brake thermal efficiency.Large amount of energy is stored in compressed DME due to its higher compressibility than diesel

TABLE III. Physical and chemical properties of dimethyl ether Refs. 26 and 27.

Properties DME Diesel Methanol Ethanol

CNG

methane

Density g/ml 0.66 0.84 0.79 0.81

Lower calorific value MJ/kg 27.6 42.5 19.5 25 50

Cetane number 55 4055 5 8

Auto ignition temperature C 235 250 450 420 650

Octane number 111 108 130

Stoichiometric A/F ratio 9 14.6 6.5 9 17.2

Boiling point C 25 180370 65 78 162

Explosion limits percent of gas in air 3.418 066.5 5.526 3.515 515

wt % of carbon 52.2 86 37.5 52.2 75

wt % of hydrogen 13 14 12.5 13 25

wt % of oxygen 34.8 0 50 34.8 0




7/13

fuel, thus exhibiting higher-pressure oscillations during the injection process, which in turn givesrise to high residual pressure.34 Due to higher feed pressure of DME in the fuel line, the start of

nozzle opening is earlier for DME than that for diesel fuel. Other properties of injection processsuch as needle lift and line pressure are lower for DME when compared to diesel operation. Theeffect of injector configuration three-hole and four-hole injectors on the combustion and emis-

sion characteristics ofan ethanol-fuelled engine using DME as ignition promoter was investigatedby Cipolat and Bhana.35 It was found that with four-hole injector, the rate of combustion pressurerise was steeper than in the case of three-hole injector. DME releases energy in two stages andmore ethanol is being injected during the second stage and thus producing a maximum combustionchamber pressure. Total hydrocarbons and NOx emissions were investigated using both three-hole

and four-hole injectors and found that in both modes there is reduction in emissions; however,four-hole injector produced fewer emissions.

In order to satisfy more and more stringent emission regulations and with advancement intechnology and electronics, strategies such as common rail system and multiple injection have

been proposed as appropriate fuel injection concepts for DME engines. Conventional design of thecommon rail direct injection system used for diesel operation is unsuitable for DME engines dueto low lubricity of DME and the low injection pressure required around 300 bar. Higher injectionpressures deteriorate fuel economy and increase the CO and HC emissions in heavy-duty enginesoperated with DME.36 Hence, Zhang et al.30 proposed a DME common rail fuel system consisting

of solenoid valves, which directly manage the fuel flow from the high-pressure rail to the injectionnozzles unlike in conventional diesel operation. Quian et al.37 designed a new fuel system calledpump rail valve injector with a hydromechanical mechanism and electronic control unit for anindirect injection engine. The unique feature of this injection system is that the actual valve

opening pressure VOP of the injector is proportional to the pressure in the middle pressurecommon rail MPCR. It was reported that good injection characteristics were achieved withMPCR pressure of 6 MPa with an orifice diameter of 0.3 mm. Overall, the choice of the fuelsystem is based upon the application passenger cars or heavy-duty-large trucks and bus engines,

and thus there is a need for the development of a dedicated DME fuel injection system.Various groups3843 have carried out experiments on DME spray characteristics. Photographic

observations of DME injection sprays into quiescent nitrogen with a single-holed nozzle show

spray shape and penetration similar to that of diesel fuel. Ofner et al.

32

observed that DMEinjection spray with a single-holed nozzle is similar to diesel fuel in terms of shape and penetrationbetween chamber pressures of 1525 bar. However, with chamber pressure of 40 and 55 bar, thereis rapid spreading of the spray at the start of the injection itself. Figures 3 and 4 show the sprayevolution of diesel and DME with time in both ambient as well as higher pressure conditions.

Investigations by Lee et al.39 revealed that the DME spray disperses rapidly at the beginning

of injection because of flash boiling phenomenon. This phenomenon occurs when the ambientpressure is sufficiently lower than the saturated pressure of the injected fuel. Further, it was foundthat at higher injection pressures, the spray tip penetration is stronger due to increase in momen-tum and spray volume increase. Similar studies of spray development were demonstrated with a

common rail system at pressures up to 55 MPa with lower ambient pressures of 0.1 and 3.0 MPa.The spray tip penetration of the DME spray is less than or almost the same as that of a diesel fuelspray but a wider spray angle is observed compared to diesel. This is due to the enhancement of

fuel atomization by flash boiling and fast evaporation of DME.

B. Combustion and emission characteristics

Dimethyl ether combustion begins immediately after injection due to its unique physical

characteristics such as low boiling point and low viscosity that assists in quick atomization leadingto complete combustion. The maximum cylinder pressure and the rate of pressure rise of theDME-run engine are lower with values approximately half those found with diesel fuelledengine.44 Figure 5 shows the rate of pressure rise for DME and diesel engines. This also results in

high thermal efficiency and low combustion noise.Earlier experiments3234,45,46 on DME-fuelled engine reported that owing to the physical and




8/13

chemical characteristics of DME, the low C/H ratio, the lack of CC bonds, and the high oxygencontent, faster and complete combustion was achieved. Smoke, CO, and HC emissions reported

were almost negligible when compared to diesel operation. Figures 6 and 7 show the general trendof smoke, HC, and CO emissions in a DME-fuelled compression ignition CI engine.

Generally, the NOx levels are supposed to be lower in DME-fuelled engines because of theshorter ignition delay; however, Kajitani et al.28 reported that DME produced very high NOx

FIG. 3. Spray development of diesel and DME at 25 MPa of injection pressure and atmospheric chamber pressure.Reprinted with permission from J. Yu et al., SAE Paper No. 2002-01-2898 2002. 2002, SAE International.

FIG. 4. Spray development of diesel and DME at 55 MPa of injection pressure and 3 MPa chamber pressure. Reprintedwith permission from J. Yu et al., SAE Paper No. 2002-01-2898 2002. 2002, SAE International.




9/13

levels in contrast with low NOx emissions observed by others.32,33,47,48 Dimethyl ether producedvery high NOx emissions when operated at the conventional injection timing as of diesel fuel.Tests were conducted by changing the injection timing from 17 before top dead center BTDC to5 BTDC, which resulted in lower NOx emission. The typical tradeoff between NOx and smoke

that occurs during retardation of injection timing in conventional diesel-fuelled engines is notapplicable with DME-operated engines. Thus, delaying injection timing is preferred as it does notrequire any major modification to control the NOx to lower levels. Similarly, the EGR concen-tration also helps to reduce the NOx emissions in DME-fuelled engines. Ying 45 tested the effect of

both hot and cold EGR on NOx emissions in the DME engine. It was observed that NOx emissiondecreases in both modes; however, around 50% reduction in NOx level was reported with 20%cold EGR ratio, which is attributed to the large specific heats of CO2, H2O, etc. in the intakecharge, which in turn reduces the combustion temperature.

FIG. 5. Rate of pressure rise and heat release for the DME and diesel engines for a n=1800 r /min, bmep= 1.0 MPa andb n=1200 r /min, bmep= 1.0 MPa. Reprinted with permission from Z. H. Huang et al., Proc. Inst. Mech. Eng., Part DJ. Automob. Eng. 1999.




10/13

Simple techniques such as injection timing retardation and EGR influence NOx emissions in

DME-fuelled engines. Figures 8 and 9 show the reduction in NOx emission with respect to thedelayed injection timing and percentage of EGR ratio. However, with advancement in technology,various other ways such as premixed charge combustion ignition and NOx reduction storagecatalyst can curtail NOx levels largely in DME engines.46,47 Considering the advantages attributed

to the DME properties, Song et al.49 proposed a new controllable premixed combustion CPC

system, where the first stage of combustion in the premixed chamber occurs under very richcondition and the second stage of combustion in the main chamber occurs very fast under a leancondition, thus lowering the NOx emissions. The NOx levels of the DME CPC engine are lessthan one-tenth of that of the DI diesel engine. Crookes and Bob-Manuel 50 tested the use of DME

and rape seed methyl ester RME both as neat fuel and pilot fuel in a natural gas dual-fuelled

FIG. 6. Reduction of smoke emissions for a CA 498 engine. Reprinted with permission from W. Ying et al., Proc. Inst.Mech. Eng., Part D J. Automob. Eng. 2005. 2005.

FIG. 7. Reduction of HC and CO emissions of DME.




11/13

engine. It was found from the investigation that RME is a suitable alternative fuel either as a purefuel or a fuel for pilot injection for diesel. DME was observed suitable for dual fuel operation asthe specific fuel consumption is higher with single fuel operation. Also, reduction of NOx and

smoke emission levels is observed for both cases.

V. SCOPE FOR FUTURE RESEARCH

Some of the areas that need further research in order to achieve the goal of utilizing DME asa full-fledged fuel for CI engine-powered vehicles are as follows.

FIG. 8. Effect of delayed injection timing on the NOx emissions. Reprinted with permission from S. Kajitani et al., SAEPaper No. 9729738 1997. 1997, SAE International.

FIG. 9. Effect of percentage of EGR ratio on the NOx emissions. Reprinted with permission from W. Ying et al., Proc. Inst.Mech. Eng., Part D J. Automob. Eng. 2005. 2005.




12/13

1 First and foremost, DME production from biomass in a cost-effective manner is required.This will require research in chemical reaction engineering to find a suitable cost-effectivecatalyst and further optimization of the processes. Some of the areas related to DME pro-duction that need to be addressed in the future are new hybrid catalyst technology, simulationwork of reactor design, and process optimization in terms of operating cost and efficiency.

2 Fuel injector wear owing to poor lubricity of DME. Injector needs to be designed for lowerpressures and with larger orifice diameters. New materials or coatings may also be needed,especially on the fuel injection pump plunger surface and on the fuel injection valve needlesurface.

3 Current compression ignition engine combustion chamber/piston designs need to be opti-mized for DME spray. This will involve engine simulations and experiments.

4 Design of fuel storage and delivery system including a fuel pump that has low internalleakage to accommodate the low viscosity of the DME.

5 Some sealing materials are known to be incompatible with DME. More systematic anddetailed studies on identifying DME-compatible materials are required.

VI. SUMMARY

Bio-DME is one of the promising alternatives for diesel fuel. For India in particular, the mainadvantage is that there is potential for large-scale economically viable production of DME from

biomass. The estimates of bio-DME production indicate that a major portion of diesel used intransportation can be replaced with bio-DME. A review of DME production techniques indicatesthat the technology, both direct and indirect syntheses from syngas, is in a state of advanceddevelopment. The direct synthesis method seems to offer better advantages in terms of cost and

efficiency. Further, process optimization and catalyst development may be required to lower costand maximize efficiency. Engine performance tests indicate that DME has thermal efficienciesequivalent to traditional diesel fuel. Other advantages of using DME as a diesel replacementinclude the reduced NOx emissions, near-zero smoke, and less engine noise. However, there are

issues with respect to the fuel injector system. From the literature reviewed, it seems that reducingthe fuel injection pressure significantly while increasing the plunger diameter and orifice diameter

is one strategy to overcome these problems. Also, several novel fuel injector systems utilizingsolenoid and hydromechanical valves have also been proposed. Overall, bio-DME has been shown

to be a feasible alternative for meeting the transportation needs for the growing economy in India.

1 See http://www.siamindia.com/scripts/emission-standards.aspx for the Society of Indian Automobile ManufacturersSIAM.

2 L. J. H. Vander, B. R. Young, and W. Y. Svrcek, Proceedings of the American Control Conference, AK, 2002.3 S. C. Sorenson, Trans. ASME: J. Eng. Gas Turbines Power 123, 652 2001.4 C. Arcoumanis, B. Choongsik, R. Crookes, and E. Kinoshita, Fuel 87, 1014 2008.5 B. Buragohain, P. Mahanata, and V. S. Moholkar, Renewable Sustainable Energy Rev. 14, 73 2010.6 F. M. Chohfi, Discussion of the routes and potential for dimethyl ether production from the biomass available in the

sugarcane value chain, Energy for Sustainable Development, Vol. XII, No. I, 2008.7

H. N. Chanakya, B. Sushama, G. Meena, and K. S. Jagadish, Biomass Bioenergy 5, 359 1993.8 K. R. Anil, in Alternative Energy in Agriculture, edited by D. Yogi Goswami CRC, Boca Raton, FL, 1986, Vol. II,

Chap. 4, pp. 83102.9 I. Landalv, Dimethyl ether synthesis, Second European Summer School on Renewable Motor Fuels, August 2007.

10

See http://www.ipma.co.in/paper_industry_overview.asp .11 P. Vasudevan, S. Sharma, and A. Kumar, Journal of Scientific and Industrial Research 64, 822 2005.12 P. Sudha and N. H. Ravindranath, Biomass Bioenergy 16, 207 1999.13 H. S. Mukunda, Second German-Indian Conference on Research for Sustainability, United Nations University, 2009.14 S. Dasappa, P. J. Paul, H. S. Mukunda, N. K. S. Rajan, G. Sridhar, and H. V. Sridhar, Curr. Sci. 87, 845 2004.15 P. L. Spath and D. C. Dayton, Preliminary screeningTechnical and economic assessment of synthesis gas to fuels and

chemicals with emphasis on the potential for biomass derived syngas, Report No. NREL/TP-510-34929, 2003.16 Y. C. D. Leung, X. L. Yin, and C. Z. Wu, Renewable Sustainable Energy Rev. 8, 565 2004.17 S. Ahlgren, A. Baky, S. Bernesson, A. Nordberg, O. Noren, and P. A. Hansson, Biosyst. Eng. 99, 145 2008.18 P. S. Sai Prasad, W. B. Jong, H. K. Suk, J. L. Yun, and K. J. Won, Fuel Process. Technol. 89, 1281 2008.19 T. Ogawa, N. Inoue, T. Shikada, and Y. Ohno, Journal of Natural Gas Chemistry 12, 219 2003.20 P. Lv, Z. Yuan, C. Wu, L. Ma, Y. Chen, and N. Tsubaki, Energy Convers. Manage. 48, 1132 2007.21 M. Komiyama, T. Misonou, and S. Takeuchi, International Congress Series 1293, 234 2006.22

T. Ohira, Status and prospects for development of synthetic liquid fuelsliquid fuels produced from natural gas and


http://www.siamindia.com/scripts/emission-standards.aspxhttp://dx.doi.org/10.1115/1.1370373http://dx.doi.org/10.1016/j.fuel.2007.06.007http://dx.doi.org/10.1016/j.rser.2009.07.034http://dx.doi.org/10.1016/0961-9534(93)90015-Vhttp://www.ipma.co.in/paper_industry_overview.asphttp://www.ipma.co.in/paper_industry_overview.asphttp://dx.doi.org/10.1016/S0961-9534(98)00083-Xhttp://dx.doi.org/10.1016/j.rser.2003.12.010http://dx.doi.org/10.1016/j.biosystemseng.2007.09.011http://dx.doi.org/10.1016/j.fuproc.2008.07.014http://dx.doi.org/10.1016/j.enconman.2006.10.014http://dx.doi.org/10.1016/j.ics.2006.03.008http://dx.doi.org/10.1016/j.ics.2006.03.008http://dx.doi.org/10.1016/j.enconman.2006.10.014http://dx.doi.org/10.1016/j.fuproc.2008.07.014http://dx.doi.org/10.1016/j.biosystemseng.2007.09.011http://dx.doi.org/10.1016/j.rser.2003.12.010http://dx.doi.org/10.1016/S0961-9534(98)00083-Xhttp://www.ipma.co.in/paper_industry_overview.asphttp://dx.doi.org/10.1016/0961-9534(93)90015-Vhttp://dx.doi.org/10.1016/j.rser.2009.07.034http://dx.doi.org/10.1016/j.fuel.2007.06.007http://dx.doi.org/10.1115/1.1370373http://www.siamindia.com/scripts/emission-standards.aspx


13/13

biomass, Science and Technology Trends Quarterly Review No. 17, 2005.23 Y. D. Yoo, S. J. Lee, and Y. Yun, Korean J. Chem. Eng. 24, 350 2007.24 Y. Ohno, N. Inoue, T. Ogawa, M. Oso, T. Shikada, and H. Hayashi, Slurry phase synthesis and utilization of dimethyl

ether, NKK Technical Review No. 85, 2001.25 T. Mil and M. Uchida, Proceedings of the 15th Saudi-Japan Joint Symposium, 2728 November 2005.26 T. Ekbom, M. Lindblom, N. Berglin, and P. Ahlvik, Technical and commercial feasibility study of black liquor gasifi-

cation with methanol/DME production as motor fuels for automotive usesBLGMF Altener Contract No. 4.1030/Z/01-087/2001, 2003.

27 T. A. Semelsberger, L. B. Rodney, and L. G. Howard, J. Power Sources 156, 497 2006.28 S. Kajitani, Z. L. Chen, and M. Konno, Engine performance and exhaust characteristics of direct injection diesel engine

operated with DME, SAE Paper No. 972973.29 Y. Wang and L. B. Zhou, Proc. Inst. Mech. Eng., Part D J. Automob. Eng. 221, 1467 2007.30 G. D. Zhang, H. Liu, X. X. Xia, and Q. L. Yang, Proc. Inst. Mech. Eng., Part D J. Automob. Eng. 218, 1341 2004.31 B. Torab, The adaptation of solenoid actuated injector for use with dimethyl ether fuel in diesel engine, M.S. thesis,

Concordia University, 1999.32 H. Ofner, D. W. Gill, and C. Krotschec, Dimethyl ether as fuel for CI enginesa new technology and its environmental

potential, SAE Paper No. 981158.33 S. C. Sorenson, M. Glensvig, and D. L. Abata, Dimethyl ether in diesel fuel injection system, SAE Paper No. 981159.34 S. Kajitani, Z. Chen, M. Oguma, and M. Konno, Int. J. Engine Res. 3, 1 2002.35 D. Cipolat and N. Bhana, Fuel Process. Technol. 90, 1107 2009.36 Y. Sato, H. Oikawa, and T. Tsuchiya, International Symposia on Alcohol Fuels ISAF XV, USA, 2005.37 Y. Quian, C. Zuo, J. Tan, and H. Xu, Imech E Journal of Mechanical Engineering Sciences 222, 415 2008.38 J. S. Hwang, J. S. Ha, and S. Y. No, International Journal of Automotive Technology 4, 119 2003.39 H. K. Suh and C. S. Lee, Energy Fuels 87, 925 2008.40 H. K. Suh, S. W. Park, and C. S. Lee, Energy Fuels 20, 1471 2006.41 J. Yu, J. Lee, and C. Bae, Dimethyl ether DME spray characteristics compared to diesel in a common rail fuel

injection system, SAE Paper No. 2002-01-2898.42 S. W. Lee, Y. Murata, and Y. Daisho, Proc. Inst. Mech. Eng., Part D J. Automob. Eng. 219, 97 2005.43 H. Wen, Y. C. Liu, M. Wei, and Y. S. Zang, J. Zhejiang Univ., Sci. 6A, 4 2005.44 Z. H. Huang, H. W. Wang, H. Y. Chen, L. B. Zhou, and D. M. Jiang, Proc. Inst. Mech. Eng., Part D J. Automob. Eng.213, 647 1999.

45 W. Ying, Z. Longbao, Y. Zhongji, and D. Hongyi, Proc. Inst. Mech. Eng., Part D J. Automob. Eng. 219, 263 2005.46 M. Y. Kim, J. H. Lee, and C. S. Lee, Energy Fuels 22, 4206 2008.47 S. W. Lee and Y. Satio, Proc. Inst. Mech. Eng., Part D J. Automob. Eng. 389, 89 2005.48 S. C. Sorenson and S. E. Mikkelsen, Performance and emissions of a 0.273 liter direct injection diesel engine fueled

with neat dimethyl ether, SAE Paper No. 950964, 1995.49 J. Song, H. Zheng, Q. Xinqi, and W. Wang, Energy Convers. Manage. 45, 2223 2004.50 R. J. Crookes and K. D. H. Bob-Manuel, Energy Convers. Manage. 48, 2971 2007.

http://dx.doi.org/10.1007/s11814-007-5045-9http://dx.doi.org/10.1016/j.jpowsour.2005.05.082http://dx.doi.org/10.1243/1468087021545496http://dx.doi.org/10.1016/j.fuproc.2009.05.006http://dx.doi.org/10.1021/ef050420fhttp://dx.doi.org/10.1021/ef800221ghttp://dx.doi.org/10.1016/j.enconman.2003.11.004http://dx.doi.org/10.1016/j.enconman.2007.07.002http://dx.doi.org/10.1016/j.enconman.2007.07.002http://dx.doi.org/10.1016/j.enconman.2003.11.004http://dx.doi.org/10.1021/ef800221ghttp://dx.doi.org/10.1021/ef050420fhttp://dx.doi.org/10.1016/j.fuproc.2009.05.006http://dx.doi.org/10.1243/1468087021545496http://dx.doi.org/10.1016/j.jpowsour.2005.05.082http://dx.doi.org/10.1007/s11814-007-5045-9

Potential of Bio-DME as a Transportation Fuel for India

Documents

Transcript of Potential of Bio-DME as a Transportation Fuel for India