USE OF WASTE COOKING OIL
Ø ABSTRACT:
Ø INTRODUCTION:
Ø RECYCLING OF WASTE COOKING OIL:
Ø TEST MATERIALS AND METHODS:
Ø EXPERIMENTAL SETUP:
Ø SCHEMATIC DIAGRAM:
Ø RESULTS AND DISCUSSIONS:
§ LIMITS FOR REUSE OF USED COOKING OILS:
Ø PERFORMANCE AND EMISSIONS:
§ BRAKE THERMAL EFFICIENCY vs. BRAKE POWER:
§ BRAKE SEC.POWER vs. BRAKE POWER:
§ EXHAUST GAS TEMPERATURE vs. BRAKE POWER:
§ NOX EMISSIONS vs. BRAKE POWER:
§ HYDROCARBON EMISSIONS vs. BRAKE POWER:
Ø CONCLUSION:
ABSTRACT:
Today’s world is driven by automobiles. As a result of it, carbon di-oxide blanket is growing day by day. An economical method to tackle it is discussed in this paper. Fried food items are popular in the coastal regions of India. The cooking oils after their use are very harmful if they are re-used. Their inappropriate disposal also causes water pollution. A chemical alternative is to convert WCO (Waste Cooking Oil) into alcohol ester by trans-esterification process and utilize it as a substitute fuel for diesel. The major advantages of this bio diesel are its renewability, better-quality exhaust gas emissions and bio-degradability. However WCO cannot be used in its crude form as it causes many operational problems. The performance test was conducted on a single cylinder, four stroke, naturally aspirated, open chamber water cooled computerized diesel engine test-rig. When the level of Total Polar Compounds reaches 25%, it can be chemically treated and converted into bio diesel.
Testing was conducted at various loads starting from no load condition to full load condition using diesel and WCO-biodiesel. The thermal performance of the WCO biodiesel is marginally less due to higher viscosity and lower Cetane index. In WCO biodiesel, combustion is also delayed due to higher physical delay period. As the exhaust gas temperature is slightly high when compared to that of diesel some afterburning occurs. Inspite of these few disadvantages, the hydrocarbon emission is very less in WCO biodiesel when compared to that of conventional diesel. The WCO biodiesel has virtually no sulphur or heavy metal element and hence sulphates emissions are eliminated.
The findings of this paper clearly indicate that, biodiesel derived from waste cooking oil is perhaps the greenest liquid fuel available. A chemical route to convert WCO into WCO-biodiesel is recommended in this paper.
The day of automobiles running in WCO biodiesel is not far off.
USE OF WASTE COOKING OIL AS AN
ALTERNATE FUEL FOR IC ENGINES
ü INTRODUCTION:
Fried food items are very popular in the coastal regions of India. Generally cooking oil used for frying are sunflower oil, palm oil, coconut oil etc., as they are easily available, and especially, so of the coconut oil which is abundantly available in south India. It is well known fact that, when oils such as these are heated for an extended time (abuse), they undergo oxidation (degradation) and give rise to oxides. Many of these such as hydro peroxides, epoxides and polymeric substances have shown adverse health/ biological effects such as growth retardation, increase in liver and kidney size as well as cellular damage to different organs when fed to laboratory animals. Thus, used cooking oils constitute a waste generated from activities in the food sectors (industries and large catering or community restaurants), which have greatly increased in recent years. Most of the waste (overused/abused) cooking oil is disposed inappropriately, mostly let into the municipal drainage, leading to water pollution. The primary end use of Waste CookingOil (WCO) in existence now is to utilize it as a fuel in residential and industrial heating devices. An alternative to prevent inappropriate disposal of WCO is by recycling it.
Another alternative is a chemical route, where WCO is chemically treated and converted into alcohol ester by trans-esterification process and utilized as a substitute fuel for diesel.
ü RECYCLING OF WASTE COOKING OIL:
The trans-esterification process is a chemical process in which linear mono-hydroxy alcohols react with WCOs, which are triglycerides of fatty acids, in the presence of catalyst. The products are alcohol ester of WCOs and glycerin as a by-product. Alcohol esters of WCO possess characteristics that are very close to those of diesel fuel, and thus are known as biodiesel. The major advantages of using biodiesel are its renewability, better-quality exhaust gas emissions, and its biodegradability. However, crude untreated WCO’s cannot be used directly as a fuel for diesel engine as it causes many operational problems. Major problems in engine operation are reported mainly due to WCO’s high viscosity and very low volatility including serious carbon deposits, injector fouling, starting difficulties in low temperatures, etc. Thus only the best way to utilize the WCO’s is to trans-esterify it and convert it into the esters of WCO’s [Biodiesel].
The objective of the present study was:
- To assess the health risk involved in direct or indirect consumption WCO.
- To examine the potential of WCO as an alternative source of thermal energy.
The hostel mess, canteens and other public eateries of the Manipal Institute of Technology, Manipal, produce large quantities of WCO, the majority of which are disposed inappropriately. Consequently, this study was initiated to examine the potential of WCO-biodiesel (derived using WCO’s as feedstock) to substitute the petroleum based-diesel and investigate the emissions and performance of a CI engine running on 100% Biodiesel.
ü TEST MATERIALS AND METHODS
The waste cooking oil, (WCO) was collected from different hostel kitchens and cafeterias and was tested at mechanical laboratory of MIT, Manipal. The WCO samples collected were allowed to stand for about 2-3 days so that impurities would settle down. Then WCO was filtered to remove food residues and solid precipitate in the oil. Before transesterification process, it was ensured that the oil contained very little amounts of water in it because every molecule of water would destroy a molecule of catalyst. The filtered WCO was subjected to drying by heating at 80°C for atleast ten minutes. The samples of WCO were decanted and then transesterified using methanol in presence of sodium hydroxide to get fatty acid methyl ester, which is commonly called “Biodiesel”. All the WCO samples used in this study were derived from used palm oil since most of the hostel kitchens use palm oil. Fuel properties of biodiesel along with those of diesel fuel and raw WCO are shown in Table 1.
TABLE 1 TEST FUEL PROPERTIES
Characteristics | Procedure | Raw WCO | Esters of WCO (Biodiesel) | Diesel |
Density at 15°C(Kg/m³) | IS1448 P: 16 | 911.2 | 876.08 | 835..56 |
Specific Gravity at 15.5◦C/15..5°C | IS P: 32 | 0.90126 | 0.866411 | 0.82423 |
Flash Point ° C | IS 1448 P: 20 | 264 | 160 | 53 |
Fire Point º C | IS 1448 P: 20 | 270 | 164 | 58 |
Kinematic Viscosity at 40ºC(mm²/s) | IS 1448 P: 25 | 41.015 | 3.65808 | 1.833 |
Calorific value(KJ \ KG) | D240 | NA | 39767.06 | 41585. 2 |
A.P.I. Gravity | - | 25. 5 | 30. 0149 | 40. 1725 |
Cetane Index | IS 1448 P: 18 | NA | 43 | 46 |
Aniline Point [C] | IS P: 3 | NA | NA | 77.5 |
Note: Tests were conducted at laboratory standards. “NA” stands for not available.
ü EXPERIMENTAL SETUP:
The performance test was conducted on a single cylinder, four-stroke, naturally aspirated, open chamber (direct injection) water-cooled, 5.2 KW output computerized diesel engine test-rig. The schematic diagram of the experimental setup is as shown in Fig. 1. The engine was directly coupled to an Eddy current dynamometer that permitted engine motoring either fully or partially. Test-rig was provided with necessary equipment and instruments for combustion pressure and crank-angle measurements.
Provision was made for interfacing airflow, fuel flow, temperatures and load measurement with computer. The setup facilitates the study of engine performance for brake power, indicated power, frictional power, BMEP, IMEP, brake thermal efficiency, indicated thermal efficiency, mechanical efficiency, volumetric efficiency, specific fuel consumption, A/F ratio and heat balance.
TABLE 2 EXPERIMENTAL SETUP SPECIFICATIONS
Engine | Four-Stroke, single cylinder, constant speed, water cooled diesel engine |
BHP | 7BHP@ 1500 rpm |
Bore x Stroke | 87.5 x 110 mm |
Stroke Volume | 661.5 cc |
Compression Ratio | 17.5:1 |
Connecting rod length | 234 mm |
Dynamometer | Eddy Current |
Length of the load cell from axis of crank shaft | 175 mm |
Load measurement | Strain gauge load cell |
Water flow measurement | Rota meter |
Fuel and air measurement | Differential pressure unit |
Speed measurement | Rotary encoder |
Interfacing with Computer | ADC card |
Emissions measurement | 5 gas analyzer, MRU make. |
ü SCHEMATIC DIAGRAM:
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T1, T3 Inlet Water Temperature F2 Air Intake DP unit
T2 Outlet Engine Jacket Water Temperature PT Pressure Transducer
T4 Outlet Calorimeter Water Temperature N RPM Decoder
T5 Exhaust Gas Temperature before Calorimeter SM Smoke Meter
T6 Exhaust Gas Temperature after Calorimeter EGA Exhaust Gas
F1 Fuel Flow DP (Differential Pressure) Unit Analyzer (5.gas)
Windows based Engine performance Analysis software package was used for online performance evaluation. During the test, the engine exhaust was measured for the emissions like NO, CO, CO2, O2. A German make MRU 5-Gas analyzer was used for the emission measurement.
ü LIMIT FOR REUSE OF USED COOKING OILS:
The products of degradation generated in overused cooking oils have unfavourable effects on sensory quality, and in some cases also have harmful effects on the consumer’s health, above certain concentrations. In response to observations of harmful or toxic effects from excessive reuse of cooking oils, international bodies and the administration have issued recommendations and legal provisions that regulate the use and maximum life of oils and fats subjected to frying.
The most accepted system of limitation for control is the parameter called Total polar compounds (%PC). It gives an approximate evaluation of the total degradation compounds in the oil. Most countries limit the concentration of these polar compounds to less than 25% of the sample.
When the level of polar compounds reaches 25%, the oil must be discarded, and therefore this is where it becomes waste cooking oil (WCO) to be recycled or use a chemical route to utilize it as a substitute fuel for diesel.
ü RESULTS AND DISCUSSIONS:
The following part discusses the performance of waste cooking oil as biodiesel. Various tests were conducted and graphs were drawn for parameters such as brake thermal efficiency, brake power, exhaust gas temperature, nitrate emissions, hydrocarbon emissions
ü PERFORMANCE AND EMISSIONS:
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The performance test was carried out on a 5KW output diesel engine. Testing was carried out at various loads starting from no load condition to the rated full load condition using diesel and WCO-biodiesel. The test was conducted at a constant speed equal to the engine rated speed.
Fig.3. shows the variation of brake thermal efficiency with brake power for baseline diesel and WCO-biodiesel. The thermal performance of the WCO-biodiesel is marginally less by 1-1.5% compared to base line diesel operation. The poor performance of the WCO diesel may be attributed to its higher viscosity and lower Cetane index.
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Viscosity of WCO-biodiesel is almost double that of diesel as depicted in Table 1. Because of its higher viscosity spray characteristics are greatly affected as high viscous nature of fuel minimizes the fineness of atomization. On the other hand, the Cetane index of the WCO-biodiesel is lower than the diesel by 3 units. Hence both factors combine to increase the physical delay period, which results in poor engine performance. Since, the performance of the WCO-biodiesel is marginally poor than the base line diesel the engine requires higher input energy per kilowatt output as depicted in Fig.4
In WCO-biodiesel operation the combustion is delayed due to higher physical delay period. As the combustion is delayed, injected WCO-biodiesel fuel particles may not get enough time to burn completely before TDC, hence some fuel mixtures tend to burn during the early part of expansion, consequently after burning occurs.
The exhaust gas temperature is a convenient scale to study the extent of afterburning. And it was observed that the exhaust gas temperature was reasonably higher for WCO-biodiesel compared to baseline diesel as depicted in Fig 5. Hence some afterburning persists in the WCO biodiesel operation.
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However, the NOx emission of WCO-biodiesel was marginally higher than that of baseline diesel fuel as depicted in Fig 6. NOx emission is a function of combustion pressure, temperature and oxygen concentration. One of the interesting characteristics of the biodiesel is that it contains some oxygen in it. So higher oxygen concentration in fuel might have influenced the NOxformation.
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FIG 7. HYDROCARBON EMISSIONS VS. BRAKE POWER
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However, other emissions of WCO-biodiesel such as CO, CO2, and O2 were almost same as that of baseline diesel operation. On the other hand the waste cooking oil has virtually no sulphur or heavy metal element contamination. Hence the sulphates emissions are eliminated.
ü CONCLUSIONS:
The findings of this work clearly indicate that, biodiesel derived from waste cooking oil {WCO}, is perhaps the greenest liquid fuel available because of the primary ingredient being a post-consumer waste product. Public should be made aware of the ill effect that WCO (overused or abused) oil has on health and utilizing the recycled WCO for human consumption in any way is not advisable from health standpoint. A chemical route to convert this WCO into WCO-biodiesel is recommended in this paper.
WCO-biodiesel when used in CI engine has shown impressive performance and emission characteristics. They are:
- Performance of the 100% WCO-biodiesel was only marginally poorer at part loads compared to the base line diesel performance.
- At higher loads engine suffers from nearly 1 to 1.5% brake thermal efficiency loss.
- From emission standpoint the NOx, CO and CO2 emissions were approximately same as that of base line diesel emissions.
- Interestingly hydrocarbon emissions of WCO biodiesel fuel were lower than base line diesel operation.
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