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Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells
Journal Pre-proof Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells
Mohit Sharma, Rajneesh Kaushal PII:
S0360-5442(19)32420-X
DOI:
https://doi.org/10.1016/j.energy.2019.116725
Reference:
EGY 116725
To appear in:
Energy
Received Date:
03 October 2019
Accepted Date:
06 December 2019
Please cite this article as: Mohit Sharma, Rajneesh Kaushal, Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells, Energy (2019), https://doi.org/10.1016/j.energy.2019.116725
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Journal Pre-proof Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells Mohit Sharmaa,*, Rajneesh Kaushalb aNational
Institute of Technology, Kurukshetra 136118, Haryana, India
bNational
Institute of Technology, Kurukshetra 136118, Haryana, India
Email: [email protected],*, [email protected]
Abstract In the present scenario, due to atrocious rise in energy demand interest has been grown in extracting energy from renewable sources such as waste biomass. In this study, preparation of producer gas from walnut shell gasification has been done for the purpose of partially substituting diesel with producer gas for VCR dual fuel (DF) diesel engine working in dual mode. Experiments have been conducted at different brake power and compression ratio for predicting the engine performance and emission characteristics. A comparative result analysis has been done for both diesel and dual mode. The results revealed that maximum fuel saving of 58.18% was achieved in dual mode operation. Brake thermal efficiency (ηbth) attained a maximum value of 25.63 and 21.61% in diesel and dual mode respectively. At brake power of 3.44 kW for diesel mode, NOX emission was 16.09-45.23% more as compared with dual mode. With dual mode CO and hydrocarbon emission were increased in the range of 62.2172.53% and 83.25-87.60% correspondingly as compared to diesel mode. Further, diesel mode maximum CO2 fraction was 2.13% and 3.41% for dual mode.
Keywords: Gasification; Walnut shells; Producer gas; Dual fuel; Emission characteristics; Performance characteristics.
Abbreviations
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VCR
variable compression ratio
N2
nitrogen
CI
compression ignition
O2
oxygen
DF
dual fuel
MSW
municipal solid waste
IC
internal combustion
LPG
liquefied petroleum gas
SI
spark ignition
HOME
Hongo oil methyl ester
NOX
nitrogen oxide
BSFC
brake specific fuel consumption
CO
carbon monoxide
HHV
higher heating value
CO2
carbon dioxide
ppm
parts per million
HC
hydrocarbon
CR
compression ratio
SOX
sulphur oxide
kW
kilowatts
CH4
methane
ECU
electronic control unit
H2S
hydrogen sulphide
dBA
decibels
H2
hydrogen
1. Introduction The energy level associated with biomass is considerably very high. In context of CO2 emission biomass has null effect on environment. Every year 500 million metric ton of biomass is accessible in India [1, 2]. Thermochemical processes (combustion, gasification and pyrolysis) are generally used for extracting energy from biomass [3]. Regardless of the method adopted biomass produced significant airborne emission. The energy associated with biomass can be further used for applications like power generation, direct heating and transportation. Wide range of biomass like agriculture waste, MSW, waste from industries, wood waste etc. is produced in India. In remote areas where there is a scarcity of power gasification proved to be a promising technology for power generation. During gasification carbon enriched biomass is partially combusted with the aid of gasifying agent such as air, oxygen, steam etc. Sequences of processes that are occurring inside the gasifier are a) Drying b) pyrolysis c) combustion d) reduction. Air to fuel ratio in gasification process ranging from 1.5:1 to 1.8:1. The end product of gasification i.e. “Producer gas” is used for running internal combustion (IC) engine whether it may be spark ignition (SI) or compression ignition (CI) engine. A lot of appreciable work has been done by Indian government for the effective utilization of biomass [4]. Many researchers extended their work on CI engine by operating it on a dual fuel (DF) mode (diesel & producer gas). It has been observed that nitric oxide (NOX) emission decreases and consequently carbon monoxide (CO) and hydrocarbon (HC) emission increases in dual mode
Journal Pre-proof operation. It has also been noticed that up to 60 – 80% diesel fuel saving is obtained by this technology [5-7]. H. E. Saleh [8] proposed DF engine operating at low load with five different LPG composition and diesel for predicting the performance and emission characteristics. It has been reported that with LPG composition (70% propane and 30% butane) engine gave the same performance as in case of pure diesel operation except at part load. For the abovementioned composition, NOX emission is reduced by 25% at full load and by 35% at part load. N.R. Banapurmath et al. [7] considered Hongo oil methyl ester (HOME) with producer gas for investigating DF mode CI engine performance. Enhanced performance and decreased emission have been obtained with HOME and producer gas in comparison with diesel. Emad Elnajjar et al. [6] studied the effect of different LPG composition on the performance of DF engine. The results revealed that LPG composition has insignificant effect on engine performance. A.E. Dhole et al. [9]used hydrogen and producer gas in a DF diesel engine as a secondary fuel. The experimental outcome revealed that rate of heat release is lower in case of producer gas compared to diesel. B.B. Sahoo et al. [10] critically examined the consequence of engine variables and secondary fuel on the DF engine performance. Pisaran Sombatwang et al. [5] studied the emission and performance features of DF diesel engine. Results highlighted that on increasing the amount of secondary fuel engine efficiency increases and CO emanation decreases. Sohan Lal et al. [4] predicted the emission and performance characteristics of variable compression ratio (VCR) DF diesel engine. It has been reported that both NOX and sulphur oxide (SOX) emission reduced. Further, maximum diesel saving of 64.3% was achieved at 18 compression ratio. Nicolas Castro et al. [11] reported that addition of hydrogen as a secondary fuel in diesel engine operated in DF mode reduces the specific diesel consumption. Chandrakanta Nayak et. al. [12] reported the effect of gaseous fuel obtained from waste biomass on the emission characteristics of DF diesel engine. Further, carbon dioxide and hydrocarbon emission level in dual mode is lower as compared to diesel mode. Richard Bates et al. [13] utilized gas produced through gasification of wood chips for running a dual fuel diesel engine. Few eminent researchers utilized producer gas extracted from babul wood, charcoal, coir pitch and rice husk in a duel fuel diesel engine for determining the emission and performance properties [5, 9, 14-16]. In the above-reported literature, emission and performance analysis of duel fuel engine has been done by using pretended fuel (viz. methane gas (CH4), LPG, CO and H2) with diesel. However, defined literature is available on DF engine using producer gas as one of the fuel for performance prediction. In these meager existing work, biomass waste like rice husk [9], charcoal [5], cashew nut shell [17], peanut shell [18], jatropha seed husk [19], seasame wood [20], pine leaf [21], groundnut shell [22] etc. is used for generating producer gas in a gasifier by researchers. Extensive literature survey suggested no literature is reported on DF diesel engine utilizing producer gas generated from walnut shells. Further, no investigation has been done so for determining its emission and performance parameters (BSFC, brake thermal efficiency, diesel saving, exhaust gas temperature). Also very few studies have been reported on emission and performance parameters determination of variable compression ratio DF diesel engine operating with producer gas. Keeping above mentioned limitations in
Journal Pre-proof considerations, the aim of the present work is developed. This research work is significant considering huge quantity of biomass waste in India and its scope in power production sector. Biomass is defined as biological matter that was obtained from agro and animal waste. In India a variety of biomass resources are accessible in different forms. The categorization of different biomass available in India is depicted in Fig. 1. [23].
Biomass Resources
Agro Industries Waste: paper mill wastes, molasses, pulp waste, textile industries waste etc.
Agricultural waste: Pulses and cereals straw, oil seed coats, sugarcane trash, paddy husk etc.
MSW: Green waste, kitchen and food waste, cloths, fabrics etc.
Forest waste: Leaves, chips, logs, barks, sawdust etc.
Energy crops: Bamboo, prosopis, leuceana etc.
Fig.1. Classification of biomass resources in India.
Walnut is the most imperative clement nut cultivated in India. It is generally grown in four states of India that are Jammu & Kashmir, Himachal Pradesh, Uttar Pradesh and Arunachal Pradesh. In India area under walnut cultivation is 67053 hectares with annual walnut yield of around 71758 metric tons. In terms of overall walnut production Himachal Pradesh ranks first with total production of 1500 metric tons/hectare followed by Jammu & Kashmir with yield of 900 metric tons/hectare. Walnut shells find its applicability in cleaning, polishing, filteration, blasting and cosmetics. Further, they are used as a feedstock during gasification process due to its considerable heating value [24]. In the present work, walnut shells have been used in a downdraft gasifier for generating producer gas. Further, this producer gas is utilized by variable compression ratio DF diesel engine to determine emission and performance properties for diesel and DF (diesel and producer gas) mode.
2. Materials and methods 2.1. Experimental arrangement In this experimental work, a downdraft gasifier unit (Fig.2) is equipped with blower, charcoal filter, water pump, venturi scrubber (gas cooling), fine filter and fabric filter was used to make producer gas via. walnut shells. The details of the gasifier are highlighted in Table 1.
Journal Pre-proof Table 1. Details of the gasifier. Item
Detail
Model
CPW- 10
Type
Downdraft
Temperature
> 1000°C
Startup
Through electric blower
Storage capacity
120 kg
Conversion efficiency
> 75%
Fig.2. Downdraft gasifier unit.
An eddy current dynamometer having measuring devices is coupled to a constant speed variable compression ratio DF four-stroke diesel engine (single-cylinder, water-cooled) via. propeller shaft (Fig.3).
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Diesel supply
Fig. 3. VCR DF diesel engine. Engine specifications are tabulated in Table 2. Digital regulator is provided for the measurement of pressure, load and temperature. The schematic diagram of the experimental test rig is depicted in Fig. 4. Biomass (Walnut shells) and air
Air inlet Water inlet
Producer gas
5
1
Exhaust gas
12 13 10 3
7
4
11
8
9
6
Water outlet
2
Fig. 4. Schematic diagram of the experimental test rig. 1. Downdraft gasifier, 2. Grate, 3. Coarse filter, 4. Venturi, 5. Test flare, 6. Valve, 7. Fine filter, 8. Fabric filter, 9. Dynamometer, 10. VCR engine, 11. Data logger, 12. Thermocouples, 13. Diesel tank with fuel flow meter.
Table 2. Engine details. Device
Detail
No. Of cylinders
01
No. Of strokes
04
Stroke length
110 mm
Bore diameter
87.5 mm
Journal Pre-proof Cooling type
Water cooled
Power
3.5 kW
CR range
12:1 to 18:1
Dynamometer model and type
AG 10 and eddy current (water-cooled)with loading unit
Calorimeter
Pipe in pipe
Fuel storage
15 litre, double compartment with glass pipe for fuel metering
Injector
Solenoid type
Crank angle sensor
Resolution 1 degree, 5500 RPM with TDC pulse
Piezo sensor range
350 bar
Temperature sensor
RTD, PT100 and K type thermocouple
Loading sensor
Strain gauge (0-50 kg)
Data attainment device
NI USB-6210, 16- bit
Software
“Enginesoft”
Air flow transmitter
Pressure transmitter, (-) 250 mm of WC
Fuel flow transmitter
DP transmitter, 0-500 mm of WC
Rotameter
Engine cooling 40-400 LPH
ECU software
Nira i7r
Water pump
Kirloskar make, monoblock type
2.2. Experimental procedure Initially, the biomass (walnut shells) is supplied to the gasifier through the open core on its top. The biomass properties are illustrated in Table 3. Table 3. Description of biomass used. Parameters Biomass feedstock Walnut Shell
Moisture content (% ) 9.53
Volatile matter (% ) 75.49
Fixed carbon (% ) 14.05
Ash (% ) HHV calculated (MJ/kg) 0.91 16.72
Carbon (%) 49.9
Hydrogen (%) 6.2
Nitrogen (%) 1.4
Oxygen (%) 42.4
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Now, the blower forced the air to pass through the oxidation zone in order to initiate the process of producer gas generation. Diesel (30 ml) is used to start the combustion process inside the gasifier. Once the combustion is initiated inside the gasifier whole of the diesel get ignited due to its explosive nature at elevated temperature. At this time actual gasification process is commenced. Gasifier is fed regularly with feedstock for maintaining the constant feedstock level. Producer gas leaves from the bottom end of gasifier at temperature of about 800°C. The properties of producer gas obtained are shown in Table 4. Table 4. Producer gas properties. Sr. No.
Parameter
Fraction (average) (%)
1.
N2
35.82
2.
O2
1.41
3.
H2
15.37
4.
CO
23.63
5.
CO2
17.10
6.
CH4
5.86
7.
H2S
0.77
8.
Heating value
7.30 MJ/Nm3
Producer gas then passed across the charcoal filter and venturi water scrubber for gas cleaning and cooling. Water has the affinity to absorb gases like sulphur dioxide etc. Producer gas then allowed to flow through test flare where it is combusted for ensuring its heating potential. For further cleaning, producer gas is passed through fine and fabric filter respectively. Finally grate is rotated for the removal of charcoal and ash. The gasification process is accomplished at an equivalence ratio of 0.212. Now this low temperature producer gas is considered to be safe for its use in DF diesel engine. In DF mode, the engine was running by using producer gas with diesel. The experimental results were obtained by varying compression ratio (12, 14, 16 and 18) for diesel and DF mode at different value of brake power (0, 0.86, 1.72, 2.56 and 3.44 kW). At each compression ratio value the load is applied on an engine and varied by rotating the knob provided on dynamometer loading unit as depicted in Fig. 5. The engine load is indicated by load indicator. In this experimental work the engine loading is accomplished at different load values (0, 3, 6, 9, 12 kg). The obtained results from engine test rig (Apex make) were stored in an excel sheet by using a data storage device (NI USB-6210) having different sensors
Journal Pre-proof (piezo, load and temperature sensor). The emission results like fraction of HC, NOX, CO2 and CO were also predicted by AVL DITEST GAS 1000 (modular diagnostic system) as shown in Fig. 6.
Loading knob
Fig. 5. Dynamometer loading unit.
Fig. 6. AVL DITEST GAS 1000. The noise intensity produced during the commencement of experiment was measured by digital noise level meter (model: SC310, CESVA instruments) with range 23-137dBA. The technical detail of the AVL DITEST GAS 1000 is highlighted in Table 5.
Journal Pre-proof Table 5. Technical specifications of AVL DITEST GAS 1000. Measured Parameters
Range
Resolution
Accuracy
CO
0-15% vol
0.01% vol
< 10.0% vol : ± 0.02% vol ≥10.0% vol : ± 5% v.M.
CO2
0-20% vol.
0.01% vol
< 16% vol : ± 0.3% vol ≥ 16% vol : ± 5% v.M.
HC
0-3000 ppm vol
1 ppm vol
< 2000 ppm vol : ± 4 ppm vol ≥ 5000 ppm vol: ± 5% v.M. ≥ 10000ppm vol : ± 10% v.M.
O2
0-25% vol
0.01% vol
± 0.02% vol.
NOX
0-5000 ppm vol
1 ppm vol
± 5 ppm vol.
3. Results and discussion 3.1. Performance parameters 3.1.1. Diesel consumption The DF engine certainly benefited in terms of its diesel consumption by running it on dual mode i.e. diesel and producer gas. The mass flow rate of diesel and producer gas is shown in Table 6. Results revealed that as compression ratio (CR) increases consequently producer gas consumption rises. Increased compression ratio results in higher engine cylinder temperature which further assists combustion of producer gas. The trend is similar irrespective of the brake power value. The consumption of diesel with respect to brake power for both modes (diesel and diesel + producer gas) is depicted in Fig. 7(1 and 2). Results revealed that maximum saving of diesel consumption was 12%, 26.66%, 38% and 58.18% respectively corresponding to compression ratio of 12, 14, 16 and 18. Maximum saving of diesel for 12 and 16 CR was observed at 2.56 kW brake power. Similarly, 1.72 kW and 0.86 kW for compression ratio 14 and 18 respectively. Sohan lal et al. [4] predicted maximum diesel substitution of 64.30%. Likewise, Yaliwal et al. [14] reported maximum saving of 65% in diesel consumption for DF mode. In the present work, maximum diesel saving of 58.18% was reported for 18 compression ratio. Table 6. Consumption of diesel and producer gas.
Journal Pre-proof CR
12
14
16
18
1)
Brake power (kW)
Diesel mode
Dual mode
Diesel (kg/hr)
Diesel (kg/hr)
0
0.60
0.54
1.71
0.26
0.86
0.65
0.61
1.54
0.43
1.72
0.85
0.76
1.34
0.65
2.56
1.00
0.88
1.13
0.84
3.44
1.25
1.19
0.82
1.12
0
0.40
0.32
1.69
0.29
0.86
0.60
0.47
1.48
0.52
1.72
0.75
0.55
1.24
0.76
2.56
0.95
0.70
1.03
0.94
3.44
1.20
1.02
0.70
1.25
0
0.35
0.22
1.55
0.41
0.86
0.55
0.38
1.22
0.74
1.72
0.75
0.48
0.84
1.11
2.56
1.00
0.62
0.75
1.19
3.44
1.15
0.97
0.61
1.34
0
0.30
0.18
1.37
0.56
0.86
0.55
0.23
1.18
0.77
1.72
0.70
0.35
0.82
1.13
2.56
1.00
0.52
0.69
1.25
3.44
1.25
0.81
0.44
1.48
Air(kg/hr)
Producer gas (kg/hr)
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2)
Fig. 7. Deviation of diesel consumption w.r.t brake power for diesel and DF mode at different CR. 3.1.2. Sound intensity The intensity of sound produced by the DF engine in diesel and DF mode was measured for different compression ratio (CR) and brake power values as depicted in Fig. 8(1 and 2). The noise level meter (model: SC310, CESVA instruments) was used for this purpose. In diesel mode, for 3.44 kW brake power and at 18 CR maximum sound intensity recorded was 98.90 dBA. Similarly, for dual mode this value was 98 dBA under the same conditions. Sohan lal et al. [4] reported maximum sound intensity of 89.6 dBA in their experimentation. It was noticed that increase in compression ratio results in decrease of sound intensity for dual and
Journal Pre-proof diesel mode of operation. As per Environment Protection Rules, 1986 [25]acceptable limit for noise intensity is set up and in present work outcomes fall in limits mentioned above.
1)
2)
Fig. 8. Deviation of sound intensity w.r.t brake power for diesel and DF mode at different CR.
3.1.3. Brake specific fuel consumption (BSFC)
Journal Pre-proof Brake specific fuel consumption (BSFC) provides a means to determine the fuel consumption of an engine. Mathematically, BSFC is calculated via. expression (1) given below. Bsfc
Fuel consumption(kg / hr) Brake power(kW)
(1)
It was noticed from Fig. 9(1 and 2) that BSFC in dual mode is higher in comparison to diesel mode because of higher fuel consumption. Further, results suggested that irrespective of compression ratio BSFC decreases with load. In the present work, at 18 compression ratio and for 3.44 kW brake power maximum BSFC calculated for diesel mode was 0.363 kg/kWhr and for dual mode, this value was 0.665 kg/kWhr. Shrivastava et al. [15] revealed maximum BSFC obtained for diesel and DF mode was 0.30 and 0.40 kg/kWhr respectively. For similar situation, Sohan lal et al. [4] reported maximum BSFC of 0.33 and 0.54 kg/kWhr respectively. In DF mode BSFC is notably higher than as reported in previous studies because DF mode BSFC relies on the calorific value of producer gas and its used fraction. 1)
2)
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Fig. 9. Deviation of BSFC w.r.t brake power for diesel and DF mode at different CR.
3.1.4. Brake thermal efficiency (ηbth) Brake thermal efficiency (ηbth) is a measure to predict the energy associated with brake power as produced by an engine. Brake thermal efficiency (ηbth) value of engine running in diesel and DF mode is depicted in Fig. 10 (1 and 2). It is clear from expression (2) brake thermal efficiency depends on the fuel consumption, brake power and calorific value of fuel. The properties of diesel are given in Table 7. It has been found that ηbth in diesel mode is higher than DF mode. The reason being, duration of delay periods increases because of low fuel mixture strength resulting due to small time period of diesel spraying in DF mode. In the present study, maximum ηbth was 25.63% and 21.61% in diesel and dual mode respectively. Yaliwal et al. [14] calculated maximum ηbth in diesel and DF mode was 24% and 19% respectively. Shrivastava et al. [15] observed maximum ηbth for diesel and dual mode was 27.5% and 26% respectively. bth
1)
Brake power Fuel consumption Calorific value
(2)
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2)
Fig. 10. Deviation of brake thermal efficiency w.r.t brake power for diesel and DF mode at different CR. Table 7. Characteristics of diesel. Density (kg/m3)
Calorific value (MJ/kg)
Cetane number
830
42
51.2
3.2. Engine exhaust analysis
Journal Pre-proof In this section results obtained during emission analysis of engine running on diesel and DF mode has been presented. 3.2.1. Exhaust gas temperature The variation of exhaust gas temperature with brake power for diesel and dual mode at a different value of compression ratio is depicted in Fig. 11 (1 and 2). It has been noticed that exhaust gas temperature in dual mode is higher than diesel mode because significant amount of heat energy is available in producer gas. Further, in both modes exhaust gas temperature decreases with increase in compression ratio from 12 to 18. In diesel mode maximum exhaust gas temperature noted was 348° C at full load whereas it was 453° C for dual mode. It was noted that results revealed in present study are in accordance with the previous literature. Sohan lal et al. [4] observed maximum exhaust gas temperature in diesel and DF mode was 330°C and 380°C respectively. Sombatwong et al. [5] revealed maximum exhaust gas temperature in diesel and DF mode was 260°C and 320°C respectively. 1)
2)
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Fig. 11. Deviation of exhaust gas temperature w.r.t brake power for diesel and DF mode at different CR.
3.2.2. NOX emission The higher temperature of the fuel mixture and availability of oxygen in substantial amount favours the formation of NOX in the engine cylinder. The deviation of NOX emission for different compression ratio at altered brake power is depicted in Fig. 12 (1 and 2). It was observed that in diesel mode NOX emission achieved a maximum value of 234 ppm whereas maximum NOX emission was 173 ppm in dual mode. In diesel mode for 3.44 kW brake power NOX emission was 16.09-45.23% more as compared with dual mode. The reason being, in dual mode presence of producer gas results in lower concentration of oxygen in fuel mixture. Further producer gas lowers the temperature due to imperfect premixed combustion process. Sohan lal et al. [4] reported NOX emission in diesel and DF mode was 200 ppm and 80 ppm respectively. 1)
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2)
Fig. 12. Deviation of NOX emission w.r.t brake power for diesel and DF mode at different CR.
3.2.3 CO emission The variation of CO emission with respect to brake power for different compression ratio in diesel and dual mode is shown in Fig. 13 (1 and 2). It is well known that the formation of CO in engine cylinder relies on oxidation and decomposition rate of fuel [26, 27]. It was observed that in dual mode CO emission is more than diesel mode. For 3.44 kW brake power CO emission in dual mode shows a rise of 62.21-72.53% in comparison with diesel mode. This may be due to less quantity of oxygen in producer gas does not provide conditions favours the complete combustion. It was also noted that as load increases formation of CO decreases
Journal Pre-proof because for increased load more air-fuel mixture (i.e. rich mixture) is admitted in the engine cylinder which eventually favours complete combustion and less quantity of CO is produced. For CR of 18 and at 80% engine load condition, Sohan lal et al. [4] revealed maximum CO emission was 0.03 ppm for diesel and 0.1025 ppm for DF mode. Sombatwong et al. [5] observed maximum CO emission was 0.01 ppm for diesel and 0.05 ppm for DF mode. 1)
2)
Fig. 13. Deviation of CO emission w.r.t brake power for diesel and DF mode at different CR.
Journal Pre-proof 3.2.4. Hydrocarbon emission In diesel mode, hydrocarbon emission is higher than dual mode operation as depicted in Fig. 14 (1 and 2). Hydrocarbon emission is undeviating consequence of imperfect combustion. Therefore, hydrocarbon emission quantity gives an idea about combustion process accomplishment [26, 27]. It was noted that for 3.44 kW brake power in dual mode hydrocarbon emission increased about 83.25-87.60% in comparison with diesel mode. Further, for both modes as compression ratio changes from 12 to 18 hydrocarbon emission decreases. The reason being pressure and temperature of charge during compression stroke increases due to higher compression ratio. Therefore, during the combustion process the chances of complete combustion rises. In present work, at 18 CR maximum hydrocarbon emission concentration was 178 ppm and 1269 ppm for diesel and dual mode respectively. Sohan lal et al. [4] observed maximum hydrocarbon emission was 480 ppm and 1250 ppm for diesel and DF mode respectively. Shrivastava et al. [15] reported maximum hydrocarbon emission was 15 ppm and 20 ppm in diesel and dual mode respectively. 1)
2)
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Fig. 14. Deviation of hydrocarbon emission w.r.t brake power for diesel and DF mode at different CR.
3.2.5. CO2 emission Complete combustion leads to a lower fraction of CO2 in exhaust gases coming out of engine cylinder. In dual mode CO2 emission is more than diesel mode operation as illustrated in Fig. 15 (1 and 2). The reason being, ample quantity of CO2 is present in producer gas. Results revealed that for dual mode and corresponding to 3.44 kW brake power CO2 emission was 13.02-39.29% more than diesel mode. Further it was found that because of increase in pressure and temperature with engine load the fraction of CO2 in exhaust increases. In present research, for diesel mode maximum fraction of CO2 was 2.13% and it was 3.41% for dual mode. Sohan lal et al. [4] observed maximum CO2 emission of 8.62% and 11.41% for diesel and DF mode respectively. 1)
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2)
Fig. 15. Deviation of CO2 emission w.r.t brake power for diesel and DF mode at different CR. 4. Comparison of performance and emission parameters The performance and emission parameters obtained during experimental studies conducted by different researchers depend on factors such as used biomass, range of compression ratio and brake power. Table 8 presented the experimental results obtained by various researchers at 18 compression ratio.
Table 8. Comparison of experimental results with existing literature [4, 5, 14, 15]. Diesel mode
Investigators
Maximum Sound level (dBA)
BSFC
Sohan lal et al.
Dual mode
Exhaust gas temperature (°C)
NOX (ppm)
CO (%)
HC (ppm)
CO2
(kg/kW/hr)
Brake thermal efficiency (%)
89
0.330
__
330
200
0.03
Sombatwong et al.
__
0.282
33.4
260
__
Yaliwal al.
__
__
24
__
Shrivastava et al.
__
0.300
27.5
Present study
102.7
0.363
25.63
et
Maximum Sound level (dBA)
BSFC (kg/kW/hr)
Brake thermal efficiency
Exhaust gas temperature (°C)
NOX (ppm)
CO (%)
HC (ppm)
CO2
(%)
Diesel saving (%)
480
8.62
64.30
89.6
0.540
__
380
80
0.1025
1250
11.41
0.01
__
__
64.21
__
0.400
26.65
320
__
0.05
__
__
__
__
__
__
65.0
__
__
19
__
110
0.025
__
__
250
325
0.001
15
__
__
__
0.400
26
300
180
0.025
20
__
348
234
0.82
178
2.07
58.18
99.84
0.665
21.61
453
173
2.17
1269
3.41
(%)
Journal Pre-proof 5. Conclusions Present study investigated the performance and emission characteristics of VCR diesel engine (DF) running on producer gas obtained through walnut shells gasification.
Maximum saving in diesel consumption was 12%, 26.66%, 38% and 58.18% respectively for dual mode operation corresponding to CR value of 12, 14, 16 and 18. The maximum intensity of sound produced by the engine during diesel mode was 102.7 dBA and 99.84 dBA for dual mode at compression ratio 18. At 18 compression ratio and for 3.44 kW brake power maximum BSFC calculated for diesel mode was 0.363 kg/kWhr and for dual mode, this value was 0.665 kg/kWhr. Maximum brake thermal efficiency (ηbth) was 25.63% and 21.61% in diesel and dual mode respectively. Exhaust gas temperature decreases as CR changes from 12 to 18. In diesel mode, maximum exhaust gas temperature was 348° C and it was 453° C for dual mode. In diesel mode, for 3.44 kW brake power NOX emission was 16.09-45.23% more as compared with dual mode. Under similar conditions, CO emission in dual mode shows a rise of 62.21-72.53% in comparison with diesel mode. In dual mode corresponding to 3.44 kW brake power hydrocarbon emission increased about 83.25-87.60% in comparison with diesel mode. Additionally, in both modes as compression ratio varied from 12 to 18 hydrocarbon emission decreases. For dual mode and corresponding to 3.44 Kw brake power CO2 emission was 13.0239.29% more than diesel mode.
Acknowledgement The authors would like to acknowledge Chanderpur works private limited, Yamunanagar (India) for helping in creating the facility of biomass gasification at NIT, Kurukshetra (India) and for giving the access of Thermal Engineering Laboratory. The authors are also greatful to Mechanical Engineering Department of NIT, Kurukshetra for supporting the installation of the gasification unit near to Thermal Engineering Laboratory of the department.
Journal Pre-proof References 1. 2. 3. 4. 5. 6. 7.
8. 9. 10. 11. 12. 13. 14. 15. 16. 17.
Sharma, M. and R. Kaushal, Advances and challenges in the generation of bio-based fuels using gasifiers: a comprehensive review. International Journal of Ambient Energy, 2018: p. 1-19. Kumar, A., D. Jones, and M. Hanna, Thermochemical biomass gasification: a review of the current status of the technology. Energies, 2009. 2(3): p. 556-581. Horne, P.A. and P.T. Williams, Influence of temperature on the products from the flash pyrolysis of biomass. Fuel, 1996. 75(9): p. 1051-1059. Lal, S. and S. Mohapatra, The effect of compression ratio on the performance and emission characteristics of a dual fuel diesel engine using biomass derived producer gas. Applied Thermal Engineering, 2017. 119: p. 63-72. Sombatwong, P., P. Thaiyasuit, and K. Pianthong, Effect of pilot fuel quantity on the performance and emission of a dual producer gas–diesel engine. Energy procedia, 2013. 34: p. 218-227. Elnajjar, E., M.O. Hamdan, and M.Y. Selim, Experimental investigation of dual engine performance using variable LPG composition fuel. Renewable Energy, 2013. 56: p. 110-116. Banapurmath, N. and P. Tewari, Comparative performance studies of a 4-stroke CI engine operated on dual fuel mode with producer gas and Honge oil and its methyl ester (HOME) with and without carburetor. Renewable Energy, 2009. 34(4): p. 10091015. Saleh, H., Effect of variation in LPG composition on emissions and performance in a dual fuel diesel engine. Fuel, 2008. 87(13-14): p. 3031-3039. Dhole, A., et al., Effect on performance and emissions of a dual fuel diesel engine using hydrogen and producer gas as secondary fuels. International Journal of Hydrogen Energy, 2014. 39(15): p. 8087-8097. Sahoo, B., N. Sahoo, and U. Saha, Effect of engine parameters and type of gaseous fuel on the performance of dual-fuel gas diesel engines—A critical review. Renewable and Sustainable Energy Reviews, 2009. 13(6-7): p. 1151-1184. Castro, N., M. Toledo, and G. Amador, An experimental investigation of the performance and emissions of a hydrogen-diesel dual fuel compression ignition internal combustion engine. Applied Thermal Engineering, 2019. 156: p. 660-667. Nayak, C., S.S. Sahoo, and L.N. Rout, Emission analysis of a dual fuel diesel engine fuelled with different gaseous fuels generated from waste biomass. International Journal of Ambient Energy, 2019: p. 1-6. Bates, R. and K. Dölle, Dual Fueling a Diesel Engine with Producer Gas Produced from Woodchips. Advances in Research, 2018: p. 1-9. Yaliwal, V., et al., Effect of nozzle and combustion chamber geometry on the performance of a diesel engine operated on dual fuel mode using renewable fuels. Renewable energy, 2016. 93: p. 483-501. Shrivastava, V., et al., Performance and emission studies of a CI engine coupled with gasifier running in dual fuel mode. Procedia Engineering, 2013. 51: p. 600-608. Ramadhas, A., S. Jayaraj, and C. Muraleedharan, Dual fuel mode operation in diesel engines using renewable fuels: Rubber seed oil and coir-pith producer gas. Renewable Energy, 2008. 33(9): p. 2077-2083. Singh, R., et al., Feasibility study of cashew nut shells as an open core gasifier feedstock. Renewable energy, 2006. 31(4): p. 481-487.
Journal Pre-proof 18. 19. 20. 21. 22. 23. 24. 25. 26. 27.
Nisamaneenate, J., et al., Fuel gas production from peanut shell waste using a modular downdraft gasifier with the thermal integrated unit. Renewable energy, 2015. 79: p. 45-50. Vyas, D. and R. Singh, Feasibility study of Jatropha seed husk as an open core gasifier feedstock. Renewable energy, 2007. 32(3): p. 512-517. Sheth, P.N. and B. Babu, Experimental studies on producer gas generation from wood waste in a downdraft biomass gasifier. Bioresource technology, 2009. 100(12): p. 3127-3133. Kumar, A. and R. Randa, Experimental analysis of a producer gas generated by a chir pine needle (leaf) in a downdraft biomass gasifier. International journal of engineering research and applications, 2014. 4: p. 122-130. Natarajan, E. and S. Baskara Sethupathy, Gasification of groundnut shells. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2015. 37(9): p. 980-986. Kumar, A., et al., A review on biomass energy resources, potential, conversion and policy in India. Renewable and Sustainable Energy Reviews, 2015. 45: p. 530-539. Sharma, S. and K. Kumar. Present status and problems of walnut cultivation in India. in IV International Walnut Symposium 544. 1999. Kumar, B. and S.V. Oberoi, Aspects of Legislative Cognizance of Noise Pollution in India. Journal of environmental science & engineering, 2011. 53(2): p. 219-226. Heywood, J.B., Internal combustion engine fundamentals. 1988. Benson, R.S. and N.D. Whitehouse, Internal combustion engines: a detailed introduction to the thermodynamics of spark and compression ignition engines, their design and development. Vol. 1. 2013: Elsevier.
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Conflict of Interest and Authorship Conformation Form Please check the following as appropriate: o
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Author’s name Mohit Sharma Dr. Rajneesh Kaushal
Affiliation NIT, Kurukshetra NIT, Kurukshetra
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Declaration of interests ☐The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Author’s name Mohit Sharma Dr. Rajneesh Kaushal
Affiliation NIT, Kurukshetra NIT, Kurukshetra
Journal Pre-proof Highlights
Maximum diesel saving of 58.18% was reported for 18 compression ratio in dual mode. Brake thermal efficiency achieved a maximum value of 25.63% and 21.61% in diesel and dual mode respectively. CO emission in dual mode shows a rise of 62.21-72.53% in comparison with diesel mode. For 3.44 Kw brake power, CO2 emission in case of dual mode was 13.02-39.29% more than diesel mode. For 3.44 kW brake power, in dual mode hydrocarbon emission increased about 83.2587.60% in comparison with diesel mode.
Mohit Sharma, Rajneesh Kaushal PII:
S0360-5442(19)32420-X
DOI:
https://doi.org/10.1016/j.energy.2019.116725
Reference:
EGY 116725
To appear in:
Energy
Received Date:
03 October 2019
Accepted Date:
06 December 2019
Please cite this article as: Mohit Sharma, Rajneesh Kaushal, Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells, Energy (2019), https://doi.org/10.1016/j.energy.2019.116725
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Journal Pre-proof Performance and emission analysis of a dual fuel variable compression ratio (VCR) CI engine utilizing producer gas derived from walnut shells Mohit Sharmaa,*, Rajneesh Kaushalb aNational
Institute of Technology, Kurukshetra 136118, Haryana, India
bNational
Institute of Technology, Kurukshetra 136118, Haryana, India
Email: [email protected],*, [email protected]
Abstract In the present scenario, due to atrocious rise in energy demand interest has been grown in extracting energy from renewable sources such as waste biomass. In this study, preparation of producer gas from walnut shell gasification has been done for the purpose of partially substituting diesel with producer gas for VCR dual fuel (DF) diesel engine working in dual mode. Experiments have been conducted at different brake power and compression ratio for predicting the engine performance and emission characteristics. A comparative result analysis has been done for both diesel and dual mode. The results revealed that maximum fuel saving of 58.18% was achieved in dual mode operation. Brake thermal efficiency (ηbth) attained a maximum value of 25.63 and 21.61% in diesel and dual mode respectively. At brake power of 3.44 kW for diesel mode, NOX emission was 16.09-45.23% more as compared with dual mode. With dual mode CO and hydrocarbon emission were increased in the range of 62.2172.53% and 83.25-87.60% correspondingly as compared to diesel mode. Further, diesel mode maximum CO2 fraction was 2.13% and 3.41% for dual mode.
Keywords: Gasification; Walnut shells; Producer gas; Dual fuel; Emission characteristics; Performance characteristics.
Abbreviations
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VCR
variable compression ratio
N2
nitrogen
CI
compression ignition
O2
oxygen
DF
dual fuel
MSW
municipal solid waste
IC
internal combustion
LPG
liquefied petroleum gas
SI
spark ignition
HOME
Hongo oil methyl ester
NOX
nitrogen oxide
BSFC
brake specific fuel consumption
CO
carbon monoxide
HHV
higher heating value
CO2
carbon dioxide
ppm
parts per million
HC
hydrocarbon
CR
compression ratio
SOX
sulphur oxide
kW
kilowatts
CH4
methane
ECU
electronic control unit
H2S
hydrogen sulphide
dBA
decibels
H2
hydrogen
1. Introduction The energy level associated with biomass is considerably very high. In context of CO2 emission biomass has null effect on environment. Every year 500 million metric ton of biomass is accessible in India [1, 2]. Thermochemical processes (combustion, gasification and pyrolysis) are generally used for extracting energy from biomass [3]. Regardless of the method adopted biomass produced significant airborne emission. The energy associated with biomass can be further used for applications like power generation, direct heating and transportation. Wide range of biomass like agriculture waste, MSW, waste from industries, wood waste etc. is produced in India. In remote areas where there is a scarcity of power gasification proved to be a promising technology for power generation. During gasification carbon enriched biomass is partially combusted with the aid of gasifying agent such as air, oxygen, steam etc. Sequences of processes that are occurring inside the gasifier are a) Drying b) pyrolysis c) combustion d) reduction. Air to fuel ratio in gasification process ranging from 1.5:1 to 1.8:1. The end product of gasification i.e. “Producer gas” is used for running internal combustion (IC) engine whether it may be spark ignition (SI) or compression ignition (CI) engine. A lot of appreciable work has been done by Indian government for the effective utilization of biomass [4]. Many researchers extended their work on CI engine by operating it on a dual fuel (DF) mode (diesel & producer gas). It has been observed that nitric oxide (NOX) emission decreases and consequently carbon monoxide (CO) and hydrocarbon (HC) emission increases in dual mode
Journal Pre-proof operation. It has also been noticed that up to 60 – 80% diesel fuel saving is obtained by this technology [5-7]. H. E. Saleh [8] proposed DF engine operating at low load with five different LPG composition and diesel for predicting the performance and emission characteristics. It has been reported that with LPG composition (70% propane and 30% butane) engine gave the same performance as in case of pure diesel operation except at part load. For the abovementioned composition, NOX emission is reduced by 25% at full load and by 35% at part load. N.R. Banapurmath et al. [7] considered Hongo oil methyl ester (HOME) with producer gas for investigating DF mode CI engine performance. Enhanced performance and decreased emission have been obtained with HOME and producer gas in comparison with diesel. Emad Elnajjar et al. [6] studied the effect of different LPG composition on the performance of DF engine. The results revealed that LPG composition has insignificant effect on engine performance. A.E. Dhole et al. [9]used hydrogen and producer gas in a DF diesel engine as a secondary fuel. The experimental outcome revealed that rate of heat release is lower in case of producer gas compared to diesel. B.B. Sahoo et al. [10] critically examined the consequence of engine variables and secondary fuel on the DF engine performance. Pisaran Sombatwang et al. [5] studied the emission and performance features of DF diesel engine. Results highlighted that on increasing the amount of secondary fuel engine efficiency increases and CO emanation decreases. Sohan Lal et al. [4] predicted the emission and performance characteristics of variable compression ratio (VCR) DF diesel engine. It has been reported that both NOX and sulphur oxide (SOX) emission reduced. Further, maximum diesel saving of 64.3% was achieved at 18 compression ratio. Nicolas Castro et al. [11] reported that addition of hydrogen as a secondary fuel in diesel engine operated in DF mode reduces the specific diesel consumption. Chandrakanta Nayak et. al. [12] reported the effect of gaseous fuel obtained from waste biomass on the emission characteristics of DF diesel engine. Further, carbon dioxide and hydrocarbon emission level in dual mode is lower as compared to diesel mode. Richard Bates et al. [13] utilized gas produced through gasification of wood chips for running a dual fuel diesel engine. Few eminent researchers utilized producer gas extracted from babul wood, charcoal, coir pitch and rice husk in a duel fuel diesel engine for determining the emission and performance properties [5, 9, 14-16]. In the above-reported literature, emission and performance analysis of duel fuel engine has been done by using pretended fuel (viz. methane gas (CH4), LPG, CO and H2) with diesel. However, defined literature is available on DF engine using producer gas as one of the fuel for performance prediction. In these meager existing work, biomass waste like rice husk [9], charcoal [5], cashew nut shell [17], peanut shell [18], jatropha seed husk [19], seasame wood [20], pine leaf [21], groundnut shell [22] etc. is used for generating producer gas in a gasifier by researchers. Extensive literature survey suggested no literature is reported on DF diesel engine utilizing producer gas generated from walnut shells. Further, no investigation has been done so for determining its emission and performance parameters (BSFC, brake thermal efficiency, diesel saving, exhaust gas temperature). Also very few studies have been reported on emission and performance parameters determination of variable compression ratio DF diesel engine operating with producer gas. Keeping above mentioned limitations in
Journal Pre-proof considerations, the aim of the present work is developed. This research work is significant considering huge quantity of biomass waste in India and its scope in power production sector. Biomass is defined as biological matter that was obtained from agro and animal waste. In India a variety of biomass resources are accessible in different forms. The categorization of different biomass available in India is depicted in Fig. 1. [23].
Biomass Resources
Agro Industries Waste: paper mill wastes, molasses, pulp waste, textile industries waste etc.
Agricultural waste: Pulses and cereals straw, oil seed coats, sugarcane trash, paddy husk etc.
MSW: Green waste, kitchen and food waste, cloths, fabrics etc.
Forest waste: Leaves, chips, logs, barks, sawdust etc.
Energy crops: Bamboo, prosopis, leuceana etc.
Fig.1. Classification of biomass resources in India.
Walnut is the most imperative clement nut cultivated in India. It is generally grown in four states of India that are Jammu & Kashmir, Himachal Pradesh, Uttar Pradesh and Arunachal Pradesh. In India area under walnut cultivation is 67053 hectares with annual walnut yield of around 71758 metric tons. In terms of overall walnut production Himachal Pradesh ranks first with total production of 1500 metric tons/hectare followed by Jammu & Kashmir with yield of 900 metric tons/hectare. Walnut shells find its applicability in cleaning, polishing, filteration, blasting and cosmetics. Further, they are used as a feedstock during gasification process due to its considerable heating value [24]. In the present work, walnut shells have been used in a downdraft gasifier for generating producer gas. Further, this producer gas is utilized by variable compression ratio DF diesel engine to determine emission and performance properties for diesel and DF (diesel and producer gas) mode.
2. Materials and methods 2.1. Experimental arrangement In this experimental work, a downdraft gasifier unit (Fig.2) is equipped with blower, charcoal filter, water pump, venturi scrubber (gas cooling), fine filter and fabric filter was used to make producer gas via. walnut shells. The details of the gasifier are highlighted in Table 1.
Journal Pre-proof Table 1. Details of the gasifier. Item
Detail
Model
CPW- 10
Type
Downdraft
Temperature
> 1000°C
Startup
Through electric blower
Storage capacity
120 kg
Conversion efficiency
> 75%
Fig.2. Downdraft gasifier unit.
An eddy current dynamometer having measuring devices is coupled to a constant speed variable compression ratio DF four-stroke diesel engine (single-cylinder, water-cooled) via. propeller shaft (Fig.3).
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Diesel supply
Fig. 3. VCR DF diesel engine. Engine specifications are tabulated in Table 2. Digital regulator is provided for the measurement of pressure, load and temperature. The schematic diagram of the experimental test rig is depicted in Fig. 4. Biomass (Walnut shells) and air
Air inlet Water inlet
Producer gas
5
1
Exhaust gas
12 13 10 3
7
4
11
8
9
6
Water outlet
2
Fig. 4. Schematic diagram of the experimental test rig. 1. Downdraft gasifier, 2. Grate, 3. Coarse filter, 4. Venturi, 5. Test flare, 6. Valve, 7. Fine filter, 8. Fabric filter, 9. Dynamometer, 10. VCR engine, 11. Data logger, 12. Thermocouples, 13. Diesel tank with fuel flow meter.
Table 2. Engine details. Device
Detail
No. Of cylinders
01
No. Of strokes
04
Stroke length
110 mm
Bore diameter
87.5 mm
Journal Pre-proof Cooling type
Water cooled
Power
3.5 kW
CR range
12:1 to 18:1
Dynamometer model and type
AG 10 and eddy current (water-cooled)with loading unit
Calorimeter
Pipe in pipe
Fuel storage
15 litre, double compartment with glass pipe for fuel metering
Injector
Solenoid type
Crank angle sensor
Resolution 1 degree, 5500 RPM with TDC pulse
Piezo sensor range
350 bar
Temperature sensor
RTD, PT100 and K type thermocouple
Loading sensor
Strain gauge (0-50 kg)
Data attainment device
NI USB-6210, 16- bit
Software
“Enginesoft”
Air flow transmitter
Pressure transmitter, (-) 250 mm of WC
Fuel flow transmitter
DP transmitter, 0-500 mm of WC
Rotameter
Engine cooling 40-400 LPH
ECU software
Nira i7r
Water pump
Kirloskar make, monoblock type
2.2. Experimental procedure Initially, the biomass (walnut shells) is supplied to the gasifier through the open core on its top. The biomass properties are illustrated in Table 3. Table 3. Description of biomass used. Parameters Biomass feedstock Walnut Shell
Moisture content (% ) 9.53
Volatile matter (% ) 75.49
Fixed carbon (% ) 14.05
Ash (% ) HHV calculated (MJ/kg) 0.91 16.72
Carbon (%) 49.9
Hydrogen (%) 6.2
Nitrogen (%) 1.4
Oxygen (%) 42.4
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Now, the blower forced the air to pass through the oxidation zone in order to initiate the process of producer gas generation. Diesel (30 ml) is used to start the combustion process inside the gasifier. Once the combustion is initiated inside the gasifier whole of the diesel get ignited due to its explosive nature at elevated temperature. At this time actual gasification process is commenced. Gasifier is fed regularly with feedstock for maintaining the constant feedstock level. Producer gas leaves from the bottom end of gasifier at temperature of about 800°C. The properties of producer gas obtained are shown in Table 4. Table 4. Producer gas properties. Sr. No.
Parameter
Fraction (average) (%)
1.
N2
35.82
2.
O2
1.41
3.
H2
15.37
4.
CO
23.63
5.
CO2
17.10
6.
CH4
5.86
7.
H2S
0.77
8.
Heating value
7.30 MJ/Nm3
Producer gas then passed across the charcoal filter and venturi water scrubber for gas cleaning and cooling. Water has the affinity to absorb gases like sulphur dioxide etc. Producer gas then allowed to flow through test flare where it is combusted for ensuring its heating potential. For further cleaning, producer gas is passed through fine and fabric filter respectively. Finally grate is rotated for the removal of charcoal and ash. The gasification process is accomplished at an equivalence ratio of 0.212. Now this low temperature producer gas is considered to be safe for its use in DF diesel engine. In DF mode, the engine was running by using producer gas with diesel. The experimental results were obtained by varying compression ratio (12, 14, 16 and 18) for diesel and DF mode at different value of brake power (0, 0.86, 1.72, 2.56 and 3.44 kW). At each compression ratio value the load is applied on an engine and varied by rotating the knob provided on dynamometer loading unit as depicted in Fig. 5. The engine load is indicated by load indicator. In this experimental work the engine loading is accomplished at different load values (0, 3, 6, 9, 12 kg). The obtained results from engine test rig (Apex make) were stored in an excel sheet by using a data storage device (NI USB-6210) having different sensors
Journal Pre-proof (piezo, load and temperature sensor). The emission results like fraction of HC, NOX, CO2 and CO were also predicted by AVL DITEST GAS 1000 (modular diagnostic system) as shown in Fig. 6.
Loading knob
Fig. 5. Dynamometer loading unit.
Fig. 6. AVL DITEST GAS 1000. The noise intensity produced during the commencement of experiment was measured by digital noise level meter (model: SC310, CESVA instruments) with range 23-137dBA. The technical detail of the AVL DITEST GAS 1000 is highlighted in Table 5.
Journal Pre-proof Table 5. Technical specifications of AVL DITEST GAS 1000. Measured Parameters
Range
Resolution
Accuracy
CO
0-15% vol
0.01% vol
< 10.0% vol : ± 0.02% vol ≥10.0% vol : ± 5% v.M.
CO2
0-20% vol.
0.01% vol
< 16% vol : ± 0.3% vol ≥ 16% vol : ± 5% v.M.
HC
0-3000 ppm vol
1 ppm vol
< 2000 ppm vol : ± 4 ppm vol ≥ 5000 ppm vol: ± 5% v.M. ≥ 10000ppm vol : ± 10% v.M.
O2
0-25% vol
0.01% vol
± 0.02% vol.
NOX
0-5000 ppm vol
1 ppm vol
± 5 ppm vol.
3. Results and discussion 3.1. Performance parameters 3.1.1. Diesel consumption The DF engine certainly benefited in terms of its diesel consumption by running it on dual mode i.e. diesel and producer gas. The mass flow rate of diesel and producer gas is shown in Table 6. Results revealed that as compression ratio (CR) increases consequently producer gas consumption rises. Increased compression ratio results in higher engine cylinder temperature which further assists combustion of producer gas. The trend is similar irrespective of the brake power value. The consumption of diesel with respect to brake power for both modes (diesel and diesel + producer gas) is depicted in Fig. 7(1 and 2). Results revealed that maximum saving of diesel consumption was 12%, 26.66%, 38% and 58.18% respectively corresponding to compression ratio of 12, 14, 16 and 18. Maximum saving of diesel for 12 and 16 CR was observed at 2.56 kW brake power. Similarly, 1.72 kW and 0.86 kW for compression ratio 14 and 18 respectively. Sohan lal et al. [4] predicted maximum diesel substitution of 64.30%. Likewise, Yaliwal et al. [14] reported maximum saving of 65% in diesel consumption for DF mode. In the present work, maximum diesel saving of 58.18% was reported for 18 compression ratio. Table 6. Consumption of diesel and producer gas.
Journal Pre-proof CR
12
14
16
18
1)
Brake power (kW)
Diesel mode
Dual mode
Diesel (kg/hr)
Diesel (kg/hr)
0
0.60
0.54
1.71
0.26
0.86
0.65
0.61
1.54
0.43
1.72
0.85
0.76
1.34
0.65
2.56
1.00
0.88
1.13
0.84
3.44
1.25
1.19
0.82
1.12
0
0.40
0.32
1.69
0.29
0.86
0.60
0.47
1.48
0.52
1.72
0.75
0.55
1.24
0.76
2.56
0.95
0.70
1.03
0.94
3.44
1.20
1.02
0.70
1.25
0
0.35
0.22
1.55
0.41
0.86
0.55
0.38
1.22
0.74
1.72
0.75
0.48
0.84
1.11
2.56
1.00
0.62
0.75
1.19
3.44
1.15
0.97
0.61
1.34
0
0.30
0.18
1.37
0.56
0.86
0.55
0.23
1.18
0.77
1.72
0.70
0.35
0.82
1.13
2.56
1.00
0.52
0.69
1.25
3.44
1.25
0.81
0.44
1.48
Air(kg/hr)
Producer gas (kg/hr)
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2)
Fig. 7. Deviation of diesel consumption w.r.t brake power for diesel and DF mode at different CR. 3.1.2. Sound intensity The intensity of sound produced by the DF engine in diesel and DF mode was measured for different compression ratio (CR) and brake power values as depicted in Fig. 8(1 and 2). The noise level meter (model: SC310, CESVA instruments) was used for this purpose. In diesel mode, for 3.44 kW brake power and at 18 CR maximum sound intensity recorded was 98.90 dBA. Similarly, for dual mode this value was 98 dBA under the same conditions. Sohan lal et al. [4] reported maximum sound intensity of 89.6 dBA in their experimentation. It was noticed that increase in compression ratio results in decrease of sound intensity for dual and
Journal Pre-proof diesel mode of operation. As per Environment Protection Rules, 1986 [25]acceptable limit for noise intensity is set up and in present work outcomes fall in limits mentioned above.
1)
2)
Fig. 8. Deviation of sound intensity w.r.t brake power for diesel and DF mode at different CR.
3.1.3. Brake specific fuel consumption (BSFC)
Journal Pre-proof Brake specific fuel consumption (BSFC) provides a means to determine the fuel consumption of an engine. Mathematically, BSFC is calculated via. expression (1) given below. Bsfc
Fuel consumption(kg / hr) Brake power(kW)
(1)
It was noticed from Fig. 9(1 and 2) that BSFC in dual mode is higher in comparison to diesel mode because of higher fuel consumption. Further, results suggested that irrespective of compression ratio BSFC decreases with load. In the present work, at 18 compression ratio and for 3.44 kW brake power maximum BSFC calculated for diesel mode was 0.363 kg/kWhr and for dual mode, this value was 0.665 kg/kWhr. Shrivastava et al. [15] revealed maximum BSFC obtained for diesel and DF mode was 0.30 and 0.40 kg/kWhr respectively. For similar situation, Sohan lal et al. [4] reported maximum BSFC of 0.33 and 0.54 kg/kWhr respectively. In DF mode BSFC is notably higher than as reported in previous studies because DF mode BSFC relies on the calorific value of producer gas and its used fraction. 1)
2)
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Fig. 9. Deviation of BSFC w.r.t brake power for diesel and DF mode at different CR.
3.1.4. Brake thermal efficiency (ηbth) Brake thermal efficiency (ηbth) is a measure to predict the energy associated with brake power as produced by an engine. Brake thermal efficiency (ηbth) value of engine running in diesel and DF mode is depicted in Fig. 10 (1 and 2). It is clear from expression (2) brake thermal efficiency depends on the fuel consumption, brake power and calorific value of fuel. The properties of diesel are given in Table 7. It has been found that ηbth in diesel mode is higher than DF mode. The reason being, duration of delay periods increases because of low fuel mixture strength resulting due to small time period of diesel spraying in DF mode. In the present study, maximum ηbth was 25.63% and 21.61% in diesel and dual mode respectively. Yaliwal et al. [14] calculated maximum ηbth in diesel and DF mode was 24% and 19% respectively. Shrivastava et al. [15] observed maximum ηbth for diesel and dual mode was 27.5% and 26% respectively. bth
1)
Brake power Fuel consumption Calorific value
(2)
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2)
Fig. 10. Deviation of brake thermal efficiency w.r.t brake power for diesel and DF mode at different CR. Table 7. Characteristics of diesel. Density (kg/m3)
Calorific value (MJ/kg)
Cetane number
830
42
51.2
3.2. Engine exhaust analysis
Journal Pre-proof In this section results obtained during emission analysis of engine running on diesel and DF mode has been presented. 3.2.1. Exhaust gas temperature The variation of exhaust gas temperature with brake power for diesel and dual mode at a different value of compression ratio is depicted in Fig. 11 (1 and 2). It has been noticed that exhaust gas temperature in dual mode is higher than diesel mode because significant amount of heat energy is available in producer gas. Further, in both modes exhaust gas temperature decreases with increase in compression ratio from 12 to 18. In diesel mode maximum exhaust gas temperature noted was 348° C at full load whereas it was 453° C for dual mode. It was noted that results revealed in present study are in accordance with the previous literature. Sohan lal et al. [4] observed maximum exhaust gas temperature in diesel and DF mode was 330°C and 380°C respectively. Sombatwong et al. [5] revealed maximum exhaust gas temperature in diesel and DF mode was 260°C and 320°C respectively. 1)
2)
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Fig. 11. Deviation of exhaust gas temperature w.r.t brake power for diesel and DF mode at different CR.
3.2.2. NOX emission The higher temperature of the fuel mixture and availability of oxygen in substantial amount favours the formation of NOX in the engine cylinder. The deviation of NOX emission for different compression ratio at altered brake power is depicted in Fig. 12 (1 and 2). It was observed that in diesel mode NOX emission achieved a maximum value of 234 ppm whereas maximum NOX emission was 173 ppm in dual mode. In diesel mode for 3.44 kW brake power NOX emission was 16.09-45.23% more as compared with dual mode. The reason being, in dual mode presence of producer gas results in lower concentration of oxygen in fuel mixture. Further producer gas lowers the temperature due to imperfect premixed combustion process. Sohan lal et al. [4] reported NOX emission in diesel and DF mode was 200 ppm and 80 ppm respectively. 1)
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2)
Fig. 12. Deviation of NOX emission w.r.t brake power for diesel and DF mode at different CR.
3.2.3 CO emission The variation of CO emission with respect to brake power for different compression ratio in diesel and dual mode is shown in Fig. 13 (1 and 2). It is well known that the formation of CO in engine cylinder relies on oxidation and decomposition rate of fuel [26, 27]. It was observed that in dual mode CO emission is more than diesel mode. For 3.44 kW brake power CO emission in dual mode shows a rise of 62.21-72.53% in comparison with diesel mode. This may be due to less quantity of oxygen in producer gas does not provide conditions favours the complete combustion. It was also noted that as load increases formation of CO decreases
Journal Pre-proof because for increased load more air-fuel mixture (i.e. rich mixture) is admitted in the engine cylinder which eventually favours complete combustion and less quantity of CO is produced. For CR of 18 and at 80% engine load condition, Sohan lal et al. [4] revealed maximum CO emission was 0.03 ppm for diesel and 0.1025 ppm for DF mode. Sombatwong et al. [5] observed maximum CO emission was 0.01 ppm for diesel and 0.05 ppm for DF mode. 1)
2)
Fig. 13. Deviation of CO emission w.r.t brake power for diesel and DF mode at different CR.
Journal Pre-proof 3.2.4. Hydrocarbon emission In diesel mode, hydrocarbon emission is higher than dual mode operation as depicted in Fig. 14 (1 and 2). Hydrocarbon emission is undeviating consequence of imperfect combustion. Therefore, hydrocarbon emission quantity gives an idea about combustion process accomplishment [26, 27]. It was noted that for 3.44 kW brake power in dual mode hydrocarbon emission increased about 83.25-87.60% in comparison with diesel mode. Further, for both modes as compression ratio changes from 12 to 18 hydrocarbon emission decreases. The reason being pressure and temperature of charge during compression stroke increases due to higher compression ratio. Therefore, during the combustion process the chances of complete combustion rises. In present work, at 18 CR maximum hydrocarbon emission concentration was 178 ppm and 1269 ppm for diesel and dual mode respectively. Sohan lal et al. [4] observed maximum hydrocarbon emission was 480 ppm and 1250 ppm for diesel and DF mode respectively. Shrivastava et al. [15] reported maximum hydrocarbon emission was 15 ppm and 20 ppm in diesel and dual mode respectively. 1)
2)
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Fig. 14. Deviation of hydrocarbon emission w.r.t brake power for diesel and DF mode at different CR.
3.2.5. CO2 emission Complete combustion leads to a lower fraction of CO2 in exhaust gases coming out of engine cylinder. In dual mode CO2 emission is more than diesel mode operation as illustrated in Fig. 15 (1 and 2). The reason being, ample quantity of CO2 is present in producer gas. Results revealed that for dual mode and corresponding to 3.44 kW brake power CO2 emission was 13.02-39.29% more than diesel mode. Further it was found that because of increase in pressure and temperature with engine load the fraction of CO2 in exhaust increases. In present research, for diesel mode maximum fraction of CO2 was 2.13% and it was 3.41% for dual mode. Sohan lal et al. [4] observed maximum CO2 emission of 8.62% and 11.41% for diesel and DF mode respectively. 1)
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2)
Fig. 15. Deviation of CO2 emission w.r.t brake power for diesel and DF mode at different CR. 4. Comparison of performance and emission parameters The performance and emission parameters obtained during experimental studies conducted by different researchers depend on factors such as used biomass, range of compression ratio and brake power. Table 8 presented the experimental results obtained by various researchers at 18 compression ratio.
Table 8. Comparison of experimental results with existing literature [4, 5, 14, 15]. Diesel mode
Investigators
Maximum Sound level (dBA)
BSFC
Sohan lal et al.
Dual mode
Exhaust gas temperature (°C)
NOX (ppm)
CO (%)
HC (ppm)
CO2
(kg/kW/hr)
Brake thermal efficiency (%)
89
0.330
__
330
200
0.03
Sombatwong et al.
__
0.282
33.4
260
__
Yaliwal al.
__
__
24
__
Shrivastava et al.
__
0.300
27.5
Present study
102.7
0.363
25.63
et
Maximum Sound level (dBA)
BSFC (kg/kW/hr)
Brake thermal efficiency
Exhaust gas temperature (°C)
NOX (ppm)
CO (%)
HC (ppm)
CO2
(%)
Diesel saving (%)
480
8.62
64.30
89.6
0.540
__
380
80
0.1025
1250
11.41
0.01
__
__
64.21
__
0.400
26.65
320
__
0.05
__
__
__
__
__
__
65.0
__
__
19
__
110
0.025
__
__
250
325
0.001
15
__
__
__
0.400
26
300
180
0.025
20
__
348
234
0.82
178
2.07
58.18
99.84
0.665
21.61
453
173
2.17
1269
3.41
(%)
Journal Pre-proof 5. Conclusions Present study investigated the performance and emission characteristics of VCR diesel engine (DF) running on producer gas obtained through walnut shells gasification.
Maximum saving in diesel consumption was 12%, 26.66%, 38% and 58.18% respectively for dual mode operation corresponding to CR value of 12, 14, 16 and 18. The maximum intensity of sound produced by the engine during diesel mode was 102.7 dBA and 99.84 dBA for dual mode at compression ratio 18. At 18 compression ratio and for 3.44 kW brake power maximum BSFC calculated for diesel mode was 0.363 kg/kWhr and for dual mode, this value was 0.665 kg/kWhr. Maximum brake thermal efficiency (ηbth) was 25.63% and 21.61% in diesel and dual mode respectively. Exhaust gas temperature decreases as CR changes from 12 to 18. In diesel mode, maximum exhaust gas temperature was 348° C and it was 453° C for dual mode. In diesel mode, for 3.44 kW brake power NOX emission was 16.09-45.23% more as compared with dual mode. Under similar conditions, CO emission in dual mode shows a rise of 62.21-72.53% in comparison with diesel mode. In dual mode corresponding to 3.44 kW brake power hydrocarbon emission increased about 83.25-87.60% in comparison with diesel mode. Additionally, in both modes as compression ratio varied from 12 to 18 hydrocarbon emission decreases. For dual mode and corresponding to 3.44 Kw brake power CO2 emission was 13.0239.29% more than diesel mode.
Acknowledgement The authors would like to acknowledge Chanderpur works private limited, Yamunanagar (India) for helping in creating the facility of biomass gasification at NIT, Kurukshetra (India) and for giving the access of Thermal Engineering Laboratory. The authors are also greatful to Mechanical Engineering Department of NIT, Kurukshetra for supporting the installation of the gasification unit near to Thermal Engineering Laboratory of the department.
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Conflict of Interest and Authorship Conformation Form Please check the following as appropriate: o
All authors have participated in (a) conception and design, or analysis and interpretation of the data; (b) drafting the article or revising it critically for important intellectual content; and (c) approval of the final version.
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This manuscript has not been submitted to, nor is under review at, another journal or other publishing venue.
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The authors have no affiliation with any organization with a direct or indirect financial interest in the subject matter discussed in the manuscript
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Author’s name Mohit Sharma Dr. Rajneesh Kaushal
Affiliation NIT, Kurukshetra NIT, Kurukshetra
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Declaration of interests ☐The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Author’s name Mohit Sharma Dr. Rajneesh Kaushal
Affiliation NIT, Kurukshetra NIT, Kurukshetra
Journal Pre-proof Highlights
Maximum diesel saving of 58.18% was reported for 18 compression ratio in dual mode. Brake thermal efficiency achieved a maximum value of 25.63% and 21.61% in diesel and dual mode respectively. CO emission in dual mode shows a rise of 62.21-72.53% in comparison with diesel mode. For 3.44 Kw brake power, CO2 emission in case of dual mode was 13.02-39.29% more than diesel mode. For 3.44 kW brake power, in dual mode hydrocarbon emission increased about 83.2587.60% in comparison with diesel mode.