Energy Fuels 2010, 24, 1565–1572 Published on Web 01/07/2010
: DOI:10.1021/ef901194z
Comparative Evaluation of Combustion, Performance, and Emissions of Jatropha Methyl Ester and Karanj Methyl Ester in a Direct Injection Diesel Engine S. Jindal,*,† Bhagwati P. Nandwana,† and Narendra S. Rathore‡ †
Mechanical Engineering Deptt, ‡Renewable Energy Sources Deptt, College of Technology and Engineering, Udaipur 313001 India Received October 20, 2009. Revised Manuscript Received December 12, 2009
Biodiesel prepared from different vegetable oils and fats are likely to have some comparative advantages and disadvantages. Two major oil varieties, considered suitable for biodiesel making are Jatropha curcas and Pongamia pinnata. This study targets at making a comparison of the methyl esters of these oils in a diesel engine against diesel fuel. The performances of the fuels was evaluated in terms of thermal efficiency, specific fuel consumption, power output and mean effective pressure, cylinder pressure, rate of pressure rise, and heat release rates. The emissions of carbon monoxide (CO), carbon dioxide (CO2), unburnt hydrocarbon (HC), oxides of nitrogen (NOx), and smoke opacity with the three fuels were also compared. Both varieties of the oil, after transesterification, exhibit the major properties within acceptable limits of biodiesel standards set by many countries. Karanj methyl ester (KME) performed better than jatropha methyl ester (JME), whereas the shortest ignition delay is observed with JME. Both the esters performed poorer than diesel, but emissions of HC, NOx, and smoke were found to be lower with esters. The three fuels delivered almost the same brake power, even when the indicated power was higher with diesel.
sometimes its comparatively higher emission of nitrogen oxides.1 Biodiesel obtained from some feed stocks might produce slightly more oxides of nitrogen (1-6%), which is an ozone depressor, than that of fossil origin fuels but can be managed with the utilization of blended fuel of biodiesel and high speed diesel fuel.2 It has been reported that the lower concentrations of biodiesel blends improve the thermal efficiency. Reduction in emission and brake-specific fuel consumption is also observed while using B10.3 Most of the research studies concluded that a 20% blend of biodiesel with diesel works well in the existing design of engine and parameters at which engines are operating.3 Biodiesel made from different feed stocks have been tried by many, and the effect of feedstock on engine performance and emissions are well documented. Jatropha and karanj are the two major feed stocks that are object of research in India. Jatropha curcas, locally known as ratanjyot, belongs to the family of Euphorbiaceae. It is a quick yielding plant that survives in degraded, barren, forest land and draft-prone areas and is cultivated as a hedge on the farm boundaries (Figure 1). The deoiled cake is excellent organic manure that retains soil moisture. This oil is gaining popularity due to its good properties and has been accepted and recommended by National Biodiesel Board of India4 as a source of alternative fuel for blending in the commercial diesel. Karanj (Pongamia pinnata) is an underutilized plant that is grown in many parts of India (Figure 2). Sometimes the oil contains high free fatty acids (FFAs) depending upon the moisture content in the seed
1. Introduction Fuels of bio-origin provide a feasible solution to the twin crises of “fossil fuel depletion” and “environmental degradation” by substituting the petroleum fuels used in internal combustion engines. The fuels of bio-origin may be alcohol, vegetable oils, biomass, and biogas. Some of these fuels can be used directly whereas others need to be formulated to bring the relevant properties close to conventional fuels. A significant research effort has been directed toward using vegetable oils and their derivatives as fuels for diesel engines. Nonedible vegetable oils in their natural form, called straight vegetable oils (SVO); methyl or ethyl esters known as treated vegetable oils; and esterified vegetable oils, referred to as biodiesel, fall in the category of bio fuels. There exists a number of vegetables/plants that produce oil and hydrocarbon substances as a part of their natural metabolism. These vegetable oils from oil seeds crops such as soybean, sunflower, groundnut mustard, etc. and oil seed from tree origin have 90-95% of the energy value of diesel on a volume basis, comparable cetane number, and can be substituted 20-100%. Biodiesel is considered a promising alternative fuel for use in diesel engines, boilers, and other combustion equipment. Compared to fossil diesel fuel, biodiesel has several superior combustion characteristics. The fuel characteristics of biodiesel are approximately the same as those of fossil diesel fuel and thus may be directly used as a fuel for diesel engines without any modification of the design or equipment. In addition, these are biodegradable, can be mixed with diesel in any ratio, and are free from sulfur. Although biodiesel has many advantages over diesel fuel, there are several problems that need to be addressed, such as its lower calorific value, higher flash point, higher viscosity, poor cold flow properties, poor oxidative stability, and
(1) Lin, C.-Y.; Lin, H.-A. Fuel 2006, 85, 298–305. (2) Yohaness, F. Fuelling a Small Capacity Agricultural Unmodified Diesel Engine With Macroemulsified Ethanol, Diesel and Jatropha Derived Biodiesel: Performance & Emission Studies. M.E. Thesis, Mechanical Engg Deptt, Delhi College of Engg, Delhi, 2003. (3) Ramadhas, A. S.; Muraleedharan, C.; Jayaraj, S. Renew. Energy 2005, 30, 1789–1800. (4) Report of the committee on development of biofuel, Planning commission, Government of India, 2003.
*To whom correspondence should be addressed. Telephone: þ91 294 2490664. Fax: þ91 294 2420196. E-mail:
[email protected]. r 2010 American Chemical Society
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Energy Fuels 2010, 24, 1565–1572
: DOI:10.1021/ef901194z
Jindal et al.
2. Experiment and Procedure In the study, the selected two vegetable oils were transesterified and the effect on major properties was evaluated. Further, the evaluation of the two methyl esters was done in a compression ignition engine for combustion, performance, and emissions. The results were compared against the diesel fuel results. Transesterification. The transesterification of these oil samples was carried out in the lab using standard procedures adopted commonly through out the world.13 As jatropha oil contains low FFA (less than 5%), methanol with KOH as catalyst was used. For karanj oil (FFA more than 5%), the FFA was reduced first by acid-catalyzed esterification (using methanol in presence of sulphuric acid) and then alkalicatalyzed esterification (using methanol in presence of KOH) was done. After separation of glycerol, the ester was water washed to remove unreacted methoxide. It was then heated to remove the water traces to obtain clear biodiesel. The methyl ester (biodiesel) thus produced by this process was totally miscible with mineral diesel in any proportion. The properties of so prepared biodiesel were tested in the laboratory using standard test procedures as per ASTM/BIS and are listed in Table 3. The properties tested were relative density (standard RD bottles of 50 mL capacity), calorific value (adiabatic bomb calorimeter), kinematic viscosity (Redwood No.1 viscometer), flash point (Pensky-Marten closed cup apparatus), cloud and pour points, free fatty acid contents (chemical titration method), and iodine value (using Wij’s solution). Experimental Setup. The study was carried out in the laboratory on an advanced fully computerized experimental engine test rig comprised of a single cylinder, water cooled, naturally aspirated, four-stroke diesel engine, commonly used in agriculture sector for minor irrigation needs, connected to an eddy current type dynamometer for loading. The setup (Figure 3) includes necessary instruments for online measurement of cylinder pressure, injection pressure, and crank-angle. One piezo sensor is mounted on the engine head through a sleeve and the other is mounted on the fuel line near the injector for measurement of pressures. The setup has transmitters for air and fuel flow measurements, process indicator, and engine indicator. Rotameters are provided for cooling water and calorimeter water flow measurement. Provision is also made for online measurement of temperature of exhaust, cooling water, and calorimeter water inlet and outlet and load on the engine. These signals are interfaced to a computer through a data acquisition system, and the software displays the P-θ and P-V diagrams. Windows-based engine performance analysis software package “Enginesoft LV” is used for on-line performance evaluation. The setup enables study of engine performance for power, mean effective pressure, thermal efficiency, specific fuel consumption, air-fuel (A/F) ratio, and heat balance. The specifications of the engine and details of instrumentation are given in Tables 4 and 5, respectively. Emission Measurement. The exhaust gases were sampled from the exhaust line through a specially designed arrangement for diverting the exhaust to a sampling line without increasing the back pressure and was then analyzed using a
Figure 1. Plant, fruit, and seed of Jatropha curcas.
Figure 2. Tree, fruit, and seed of karanj.
during collection. It is a fast growing leguminous tree with the potential for high oil seed production and the added benefit of an ability to grow on marginal land. These properties support the suitability of this plant for large-scale vegetable oil production needed for a sustainable biodiesel industry. The potential of jatropha oil5-7 and karanj oil8-10 as a source of fuel for the biodiesel industry is well recognized. The important characteristics of these oils are given in Table 1, and fatty acid composition is given in Table 2. Looking to the availability and their biodiesel potential, these oils are becoming more and more popular in many other countries as well. Evaluation of jatropha esters11 and karanj esters12 indicates their superiority over many other vegetable oils in terms of engine performance, emissions, ease of use, and availability. All of the studies made so far with these oils were independently done in different types of engines in different conditions. An effort is made in this study to compare the combustion, engine performance, and emissions with the methyl esters of these oils in one engine, keeping all other conditions same, for establishing the suitability of these esters against diesel fuel. (5) Berchmans, H. J.; Hirata, S. Bioresour. Technol. 2008, 99, 1716– 1721. (6) Ramesh, D.; Sampathrajan, A. Investigations on Performance and Emission Characteristics of Diesel Engine With Jatropha Biodiesel and Its Blends. Agricultural Engineering International: the CIGRE Journal. Manuscript EE 07 013. Vol. X. March, 2008. (7) Pramanik, K. Renew. Energy 2003, 28, 239–248. (8) Srivastava, P. K.; Verma, M. Fuel 2007, doi:10.1016/j. fuel.2007.08.018. (9) Sharma, Y. C.; Singh, B. Fuel 2007, doi:10.1016/j.fuel.2007.08.001. (10) Karmee, S. K.; Chadha, A. Bioresour. Technol. 2005, 96, 1425– 1429. (11) Agarwal, D.; Agarwal, A. K. Applied Thermal Eng. 2007, 27, 2314–2323. (12) Agarwal, A. K.; Rajamanoharan, K. Applied Energy 2009, 86, 106–112.
(13) Van Gerpen, J.; Shanks, B.; Pruszko, R.; Clements, D.; Knothe, G. Biodiesel Production Technology. Subcontractor report prepared under National Renewable Energy Laboratory, CO; available electronically at http://www.osti.gov/bridge.
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Energy Fuels 2010, 24, 1565–1572
: DOI:10.1021/ef901194z
Jindal et al.
Table 1. Characteristics of Jatropha and Karanja 1 2 3
english name botanical name distribution/ climate
4
promising states
5
morphology
6 7 8 9 10
propagation collection period sowing time gestation period yield potential (a) seed (b) oil contents (a) oil (b) protein uses (a) oil (b) cake density acid value saponification value iodine value unsaponifiable matter
11 12 13 14 15 16 17 a
jatropha Jatropha curcas throughout India excluding temperate region, farm boundaries, waste land, alongside railway track Rajasthan, Andhra Pradesh, Chhattisgarh, Jharkhand, Karnataka, Madhaya Pradesh, Maharashtra, Uttar Pradesh, and West Bengal short plant (shrub) with big leafs and ample spreading, Quite hardy, drought resistant and tolerate to salinity seed, cuttings Winter July-August 2 years (max)
karanj Pongamia pinnata throughout India excluding temperate region, road side, railway track
2.5-5 t/ha 0.9 - 1.6 t/ha
5-8 t/ha 1.5-2.4 t/ha
28-30% (seed) ; 50-60% (kernel) 18%
27-39% (kernel) 30-40%
biodiesel, soap, industrial organic manure 0.92 g/cm3
