Mohand Tazerout

Edwin Geo Varuvel

Nadia Mrad

Fethi Aloui

Experimental analysis of fuel from fish processing industry waste in a diesel engine

Keywords: Fish processing industry waste, Catalytic cracking, Biofuel, Distillation and diesel engine

Introduction

Transportation is the main reason why Europe depends so heavily on crude oil. Crude oil is imported from foreign countries majorly from Persian Gulf (this region provides one-fourth of the world's current consumption of oil and nearly two-thirds of the world's oil reserves). Due to supply depletion and distribution instability, reliance on fossil fuel is inevitable. Oil is a finite resource, which means that its supply is limited and cannot be reproduced. It took millions of years for these oil reserves to accumulate, and it has been used up in less than two hundred years. It is estimated that the current known reserves of oil on earth will only be able to supply total world demand for the next 40 years. When these reserves are completely exhausted, the total world will have to use alternative fuel sources. Most of these alternative fuels are renewable which means that their supply is infinite and that they can be produced and supplied forever without any fear of depletion [START_REF] Nigam | Production of liquid biofuels from renewable resources[END_REF]No2011;[START_REF] Ban ˜os | Optimization methods applied to renewable and sustainable energy: a review[END_REF]). In addition, these fuels can be produced within the country itself. Hence, there is no need to depend on foreign countries for fuel supply. Currently, throughout the world, many researchers are working to find the alternative renewable sources of fuel for their countries [START_REF] Sobrino | Critical analysis on hydrogen as an alternative to fossil fuels and biofuels for vehicles in Europe[END_REF][START_REF] Ajanovic | On the economics of hydrogen from renewable energy sources as an alternative fuel in transport sector in Austria[END_REF][START_REF] Ediger | Renewable energy potential as an alternative to fossil fuels in Turkey[END_REF][START_REF] Misra | Jatropa-the future fuel of India[END_REF][START_REF] Jayed | Prospects of dedicated biodiesel engine vehicles in Malaysia and Indonesia[END_REF].

There are several environmental issues generated due to fossil fuel use in internal combustion engines. The main pollutants from the engines are particulate matter, oxides of nitrogen, sulfur dioxide, carbon monoxide (CO) and carbon dioxide (CO 2 ) emissions [START_REF] Lif | Reduction of soot emissions from a direct injection diesel engine using water-indiesel emulsion and microemulsion fuels[END_REF][START_REF] Jerry | Simultaneous control of particulate and NOx emissions from diesel engines[END_REF][START_REF] Krishnamurthy | Cost of lower NOx emissions: increased CO 2 emissions from heavyduty diesel engines[END_REF]). Other than these common environmental issues, it degrades the environment in other indirect ways too. Water pollution associated with gasoline includes marine oil spills, groundwater contamination from underground gasoline storage tanks and runoff resulting from fuel spills [START_REF] Middleditch | Environmental effects of offshore oil pollution-the buccaneer gas and oil field study[END_REF][START_REF] Meo | Lung function in subjects exposed to crude oil spill into sea water[END_REF][START_REF] Rodrı ´guez-Trigo | Health effects of exposure to oil spills[END_REF]. Biofuels can replace the most toxic parts of gasoline with fuels that quickly biodegrade in water, reducing the threat that gasoline poses to waterways and groundwater. Spills or leaks of biofuels do not constitute an environmental hazard.

Rapid increase in volume and types of biomass waste as a result of intensive industrialization in the wake of population growth and improved living standards is becoming a burgeoning problem as rotten biomass waste emits methane and leachate, and open burning by the humans to clear the lands generates CO 2 and other local pollutants [START_REF] Zhang | Methane emissions from MSW landfill with sandy soil covers under leachate recirculation and subsurface irrigation[END_REF][START_REF] Dolk | Risk of congenital anomalies near hazardous-waste landfill sites in Europe: the EUROHAZCON study[END_REF]. Hence, improper management of biomass waste is contributing toward climate change, water and soil contamination, and localized air pollution. Furthermore, this waste is of high value with respect to material and energy recovery. Almost half the landfills in the Europe are close to capacity and are expected to close in the near future. To make matters worse, the rate at which the production of waste continues to increase is alarming. Disposal costs increase as available landfill space decreases. In addition, some segments of the agricultural and products from industries produce huge amounts of waste each year. Much of the waste is made of lignocellulosic material that can be converted to biofuels [START_REF] Canakci | The potential of restaurant waste lipids as biodiesel feedstocks[END_REF][START_REF] Encinar | Study of biodiesel production from animal fats with high free fatty acid content[END_REF][START_REF] Gu ¨ru | Biodiesel production from waste chicken fat based sources and evaluation with Mg based additive in a diesel engine[END_REF]. This form of recycling could help relieve our exponentially growing waste problem while at the same time replacing a portion of our fossil fuel usage. With the global campaign to combat climate change, countries are now looking for alternative sources of energy to minimize greenhouse gas (GHG) emissions. Aside from being carbon neutral, the use of biomass for energy reduces dependency on the consumption of fossil fuel, hence contributing to energy security and climate change mitigation.

From the above, our dependence on petroleum for fueling the transportation sector threatens our energy security, affects environment and weakens economy. Several compelling issues drive a national effort to develop and improve technology to make biofuels. Developing the technology to produce and use biofuels will create transportation fuel options that can positively impact these issues and establish safe, clean and sustainable alternatives to fossil fuels. There are several processes to derive the energy from biomass waste [START_REF] Demirbas | Comparison of transesterification methods for production of biodiesel from vegetable oils and fats[END_REF][START_REF] Ito | Biodiesel production from waste animal fats using pyrolysis method[END_REF][START_REF] Liu | Fast biodiesel production from beef tallow with radio frequency heating[END_REF][START_REF] Shakinaz | Production of biodiesel using the microwave technique[END_REF][START_REF] Hilten | Production of fuel from the catalytic cracking of pyrolyzed poultry DAF skimmings[END_REF][START_REF] Munasinghe | Biomass-derived syngas fermentation into biofuels: opportunities and challenges[END_REF][START_REF] Zhang | Automotive fuels from biomass via gasification[END_REF]. The two important conversion processes are thermochemical and biochemical.

The main objectives of the present work are to identify the biomass source and assess environmentally sound technologies for converting and upgrading lignocellulosic biomass into biofuel and also to find the suitability of biofuel in internal combustion engines. In this regard, the waste from fish processing industry has been identified as biomass waste to derive biofuel. Biofuel from fish processing industry waste through pyrolysis has a very high acid value of 131.1 mg KOH /g oil by [START_REF] Wiggers | Biofuels from waste fish oil pyrolysis: continuous production in a pilot plant[END_REF]. Hence, pyrolysis with the presence of catalyst (catalytic cracking) was selected to valorize the biofuel from fish processing industry waste. The biofuel was upgraded through distillation process to optimize its quality on par with diesel fuel. Finally, the upgraded biofuel (distilled) was tested in diesel engine and the performance, emission and combustion characteristics were compared with undistilled biofuel and diesel fuel.

Biofuel preparation and analysis

Preparation of biofuel

The feedstock used in this work is a fish processing industry waste obtained from SIRH group specialized in vegetable, animal and marine oils located in north of France. This waste is the residue of marine oil treatment which is brown in color and was used without any special purification treatment. The typical fatty acid composition has been analyzed by gas chromatography analysis (GC/ FID). The saturated acids C14:0, C16:0 and C18:0 were identified. The major fatty acids found are the unsaturated acids C18:1 and C18:2 responsible for 45.6 and 20.6%, respectively, of the total composition. The important properties of fish processing industry waste are given in Table 1.

To prepare the biofuel, catalytic cracking experiments were carried out at temperatures ranging from 350 to 480 °C with a slow heating rate of 2-3 °C/min using a laboratory-scale reactor. The fat was introduced in the reactor and then heated by an external electric resistance. The catalyst was placed just above the fat on a bed with small holes. When the temperature inside the reactor reached 350 °C, the reaction started. The generated vapor was passed directly over the catalyst surface before leaving through the top of the reactor. Then, it enters in a watercooled, counter flow, heat exchange, which was kept at 15 °C. As a result, three fractions of liquids were collected in the flask: The first is the pyrolysis water, and the second liquid fraction recovered until the temperature reached 400 °C. The last fraction is the bio-oil recovered from 400 to 480 °C. After acidity analysis, it was found that the second fraction was so acidic (acid value equal to 20 mg KOH /g) compared to the third one (acid value equal to 0.8 mg KOH /g). For this, the main interest is focused on third fraction which is called biofuel.

Distillation of biofuel

The flashpoint of biofuel is very low (27 °C) compared to the diesel fuel (56 °C). The volatile compounds reflect low flashpoint of biofuel. Hence, distillation was performed to extract the most volatile hydrocarbons from biofuel. The distillation was conducted at temperatures between 130 and 140 °C, and the mass recovered from the volatile hydrocarbon represents 5% of the total mass of biofuel. After gas chromatography-mass spectrometry (GC/MS) analysis, it was found that the organic compounds present in the biofuel were divided into eight classes: alkene, alkane, cycloalkane, acetone, aromatic compound, chlorinated compound, phenol and ester. The major components were alkene, alkane and acetone.

Analysis of biofuel

The flashpoint was measured by NPM 440 model (PENSKY-MARTENS). The acid value was determined by titration with KOH/C 2 H 5 OH solution using phenolphthalein as an indicator. The density of the bio-oil was estimated with a pycnometer. The gross heating value was measured using an oxygen bomb calorimeter (model 6200, Parr Instruments Company). To identify the dynamic viscosity, a SV 10 Fibro viscometer was used. The elemental compositions of the main organic elements (C, O, H, S and N) were determined using an Elemental Analyzer (Flash EA 1112, CE Instruments). In order to estimate the chemical compounds of the biofuel, a GC/MS analysis was carried out. For this purpose, a Perkin-Elmer TurboMass Gold Mass Spectrometer coupled with a gas chromatograph CLARUS 500 was used. The column was SBLTM-5 ms capillary type, 30 m in length and 0.25 mm in internal diameter. The properties of biofuel UD (undistilled biofuel), biofuel and standard diesel fuel are given in Table 2.

Experimental setup Performance instrumentation

A single-cylinder, four-stroke, air-cooled, direct injection, and constant speed diesel engine developing power output of 4.5 kW was used for this work. Test engine specifications are given in Table 3. The engine was mounted on a fixed table and coupled with an eddy current dynamometer that converts mechanical energy generated by the engine power directly to the network. The flow of intake air was measured by a differential pressure transmitter, type LPX 5481. For temperature measurements, the test engine was equipped with a series of thermocouples type K. Ambient temperature was measured by an active transmitter for humidity and temperature, type HD 2012 TC/150. The fuel flow was measured using a Coriolis mass flow meter. Torque measurement was made using a force sensor used in tension and compression of the FN3148 series. It has an accuracy of 0.05% of range of the measure. The CI engine was run for 3 h continuously to conduct one set of load test (five loading conditions). After attaining the steady state, the readings were taken. Inline measurements were taken for air flow, fuel flow, temperatures and torque measurements. The tests were repeated for five times to check the repeatability of the readings.

Emission instrumentation

For measuring emissions, a bay of analysis (Crystal COSMA 500) placed on the line of engine exhaust gas was used to analyze the main pollutant gases. Emissions of hydrocarbons (HC) were measured by FID flame ionization using a heated hydrocarbon analyzer (model GRAPHITE 52 M); emissions of nitric oxide (NO) and nitrogen oxides (NOx) were measured via a chemiluminescence nitrogen oxide analyzer TOPAZE 32 M. Emissions of carbon monoxide (CO), carbon dioxide (CO 2 ) and oxygen (O 2 ) were measured by absorption of infrared radiation using a 2 M MIR analyzer. Part of the exhaust gas was bypassed, and measurements were taken for emissions parameters like NOx, UHC, CO and CO 2 . Each sampling was conducted for 10-min duration. Particulate emissions were measured using a dust analyzer in real time (TEOM model 1105), for measurement and continuous weighing of the mass concentration of particulate exhaust.

Combustion instrumentation

A control system was installed to measure high-frequency signal, which mainly concerns the cylinder pressure, fuel injection pressure and also the angular position of the crankshaft. The pressure in the cylinder was measured at a frequency of 90 kHz using a piezoelectric pressure sensor, water-cooled, type AVL QH32D. The injection pressure was measured by a piezoelectric pressure transducer, type AVL QH33D, located in between the injection pump and the fuel injector. The angular position of the crankshaft was measured by an encoder, type AVL 364C, placed on the flywheel. Cylinder pressure was recorded for 100 cycles; then, mean was taken for calculating heat release and other combustion parameters. The schematic of test engine setup is shown in Fig. 1.

Results and discussion

Performance parameters

Brake thermal efficiency

Figure 2 compares the brake thermal efficiency of diesel, biofuel UD (undistilled biofuel) and biofuel with brake power. It is observed that the brake thermal efficiency of biofuel is higher compared to diesel fuel and biofuel UD at various load conditions. There is a slight decrease in brake thermal efficiency with all test fuels at full load. The brake thermal efficiency is about 30.8% with biofuel, 28.69% with diesel and 30.5% with biofuel UD at maximum load.

It is maximum at 80% load. The brake thermal efficiency

Fuel injection timing 20°bTDC

Fuel injection pressure 250 bar

Compression ratio 18:1 Rated power 4.5 kW @ 1500 rpm for biofuel, diesel and biofuel UD at 80% load is 32.4, 29.98 and 32.12%, respectively. The decrease in brake thermal efficiency is lesser with biofuel UD compared to biofuel at higher loads. This is due to better mixture formation as a result of high volatility of hydrocarbons leading to better combustion. The brake thermal efficiency mainly depends on amount of energy released during the initial phase of combustion (premixed combustion). This can be easily observed from heat release rate diagram (Fig. 12). It shows that the premixed combustion is very sharp with biofuel and biofuel UD compared to diesel.

Exhaust gas temperature

Figure 3 shows the variation of exhaust gas temperature for different test fuels with brake power. The exhaust gas temperature is lower with biofuel and higher with diesel. It is 422, 495 and 431 °C for biofuel, diesel and biofuel UD at maximum load condition, respectively. Lower viscosity and good volatility of biofuel Fig. 3 Variation of exhaust gas temperature with brake power and biofuel UD lead to better mixture formation, and hence, higher premixed combustion phase makes the heat release shorter. Also, lower ignition delay starts the combustion earlier and shortens the combustion duration results in lower exhaust gas temperature compared to diesel. Although combustion starts earlier with biofuel UD due to lower ignition delay, the intensity of premixed combustion is not wide compared to biofuel which is evident from heat release diagram. The amount of fuel prepared during the ignition delay is very low due to high volatile hydrocarbons present in the biofuel UD. Hence, more amount of fuel is burnt during diffusion combustion phase, which leads to higher exhaust gas temperature with biofuel UD compared to biofuel.

Emission parameters

Oxides of nitrogen emissions (NOx)

The variation of oxides of nitrogen (NOx) levels for biofuel, biofuel UD and diesel with brake power is shown in Fig. 4. The formation of NOx is mainly due to the reaction between the nitrogen and oxygen at higher combustion temperature. The combustion temperature mainly depends on the initial phase of combustion (premixed combustion). NOx increases from 20 to 80% load and reduces slightly at maximum load with all test fuels. As the load increases, the combustion temperature increases due to that higher NOx. As seen in Fig. 4, NOx emissions with biofuel UD are high compared to diesel and biofuel at all loads. NOx emissions for biofuel UD, diesel and biofuel are 994, 780 and 857 ppm, respectively, at full load and 1001, 852 and 917 ppm, respectively, at maximum efficiency point (80% load). Higher NOx with biofuel UD is due to lower flashpoint and highly volatile hydrocarbons of fuel which initiates the strong premixed combustion. Heat release shows that the premixed combustion is very sharp with biofuel UD than diesel and biofuel. Hence, higher NOx is with biofuel UD than diesel and biofuel.

Unburned hydrocarbon emissions (UHC)

Figure 5 shows the variation of unburned hydrocarbons with brake power. UHC in the exhaust shows the unutilized energy during combustion process. This is due to the fuel droplets unable to reach the ignition temperature, leading to incomplete combustion. It is also due to insufficient quantity of oxygen to oxidize the fuel present in the combustion chamber. It is clearly shown that the UHC is lower with biofuel compared to diesel and biofuel UD. The UHC emission for biofuel, diesel and biofuel UD at maximum load is 502, 575 and 518 ppm, respectively. Lower UHC for biofuel is mainly due to the early start and end of combustion of biofuel. The increase in UHC emission with biofuel UD is mainly due to more fuel being burned at diffusion part of combustion though the ignition starts earlier.

Carbon monoxide emission (CO)

The variation of carbon monoxide for biofuel, diesel and biofuel UD with brake power is shown in Fig. 6.A t maximum load, the CO emission with biofuel and biofuel UD is 0.39 and 0.41%, respectively, whereas it is 0.59% with diesel. CO emission reduces with biofuel UD, and it is further reduced with biofuel. Due to the good spray characteristics as a result of low viscosity of biofuel and biofuel UD, all the fuel droplets are mixed with air at the end part of the compression stroke, leading to better oxidation reaction of the fuel which results in complete combustion. Also, biofuel and biofuel UD itself have higher oxygen content tending to increase the oxidation process. The slight increase in CO emission with biofuel UD is due to longer combustion duration compared to biofuel.

Carbon dioxide emission (CO 2 )

Figure 7 shows the variation of carbon dioxide emission for different fuels with respect to brake power.CO 2 present in the exhaust gas reflects the combustion efficiency. Combustion improved if CO 2 is more in the exhaust. But, nowadays, the CO 2 is a pollutant which is one of the gases for the formation of green house effect. CO 2 emission at the rated power is about 9.74% with biofuel, 9.28% with biofuel UD and 9.15% with diesel. The increase in CO 2 emission with biofuel is due to higher oxygen present in the molecular chain, leading to better combustion than diesel. Although the biofuel UD has higher oxygen concentration, the CO 2 emission reduced marginally. This is mainly due to more fuel being burned in the later part of combustion which reduces the combustion efficiency.

Oxygen (O 2 )

The variation of oxygen percentage in the exhaust with brake power is shown in Fig. 8. The amount of oxygen present in the exhaust indicates combustion is complete. As seen in the graph, the oxygen percentage is higher with biofuel UD and it is reduced with diesel and biofuel. The value of oxygen emission for biofuel, diesel and biofuel UD is 8.5, 9.45 and 9.57%, respectively, at maximum load. Normally, oxygen present in the air reacts with fuel and excess oxygen leaves the combustion chamber during exhaust process. Biofuel UD has higher oxygen percentage (5.42%) itself. Also, the combustion of biofuel UD is poor compared to biofuel which leads to higher oxygen percentage in the exhaust. Increase in the combustion process of biofuel leads to complete combustion which exhibits low oxygen emission in the exhaust.

Particulate matter (PM)

The results of particulate matter (PM) emissions of the three fuels are superimposed in Fig. 9. PM consists of a solid portion (carbon and ash), soluble organic fraction and sulfates. The SOF is hydrocarbons (mostly heavy hydrocarbons) that have condensed on the carbon particles. The solid carbon portion and soluble organic fraction are formed by incomplete combustion of the fuel. This occurs at low airfuel ratios such as high load and during transient events when boost pressure is limited. High cylinder temperatures and the availability of oxygen increase the oxidization of the solid carbon particles and hydrocarbons to carbon monoxide and carbon dioxide. The highest particulate emission is obtained with diesel, and the value is about 0.03 g/h at maximum load. The PM emission reduces with biofuel UD and biofuel; it is about 0.029 and 0.028 g/h at maximum load, respectively. In general, the formation of PM is mainly dependant on the intensity of diffusion combustion. The intensity of diffusion combustion is higher with diesel followed by biofuel UD, which indicates that more quantity of fuel is burned during this combustion phase. It is very low with biofuel, and hence, more quantity of fuel has taken part in premixed combustion phase which reflects on the formation of NOx emissions. The PM for biofuel, diesel and biofuel UD at 80% load (maximum efficiency point) is 0.01, 0.014 and 0.011 g/h, respectively, which is lower compared to maximum load condition.

Combustion parameters

Cylinder peak pressure

The variation of cylinder peak pressure with brake power is shown in Fig. 10. It is seen that biofuel UD has higher peak pressure than diesel and biofuel. However, the cylinder pressure for both biofuel UD and biofuel is almost same at all load conditions. It is about 90.1 bar with biofuel UD and 89.7 bar with biofuel at maximum load. The slight increase over biofuel is due to early ignition of biofuel UD and again, due to high volatile components of biofuel UD, leads to low flashpoint (27 °C). The cylinder peak pressure depends strongly on the initial combustion rate in diesel engines, which in turn depends on the amount of fuel taking part in the premixed combustion phase. Even though the ignition delay of biofuel UD is less, the premixed combustion rate is quite high with biofuel. The cylinder peak pressure for diesel is 85.6 bar at maximum load.

Cylinder pressure

Figure 11 clearly shows the variation of cylinder pressure with crank angle (CA) for biofuel, diesel and biofuel UD at maximum load. It can be seen that the maximum peak pressure is shifted by about 4.7 °CA with biofuel UD and 4.3 °CA with biofuel after TDC. It is almost same for both biofuel and biofuel UD. But for diesel, it is about 6.1 °CA after TDC. The peak pressure of diesel is shifted due to longer ignition delay compared to biofuel, which may delay the start of combustion process. The ignition started earlier with biofuel UD, but intensity of premixed combustion is not wide compared to biofuel. Hence, for both diesel and biofuel UD, more energy is released in the later part of the expansion process.

Rate of heat release

The rate of heat release with crank angle for biofuel, diesel and biofuel UD at maximum load is shown in Fig. 12. The heat release rate is divided into two parts: the premixed combustion and diffusion combustion. Particular interest with combustion studies has been with premixed combustion. The maximum premixed heat release is the indication of higher brake thermal efficiency and NOx emissions. This can be realized from Figs. 2 and4. Also, higher diffusion combustion is the indication of high particulate matter emission, which is evident from Fig. 9. The end of the premixed combustion has been defined as the dip after the premix spike, leading to the diffusion combustion. The 11 Variation of cylinder pressure crank angle at maximum load intensity of premixed combustion is higher with biofuel, followed by biofuel UD and diesel, which shows the improved combustion with biofuel and biofuel UD compared to diesel. The occurrence of maximum premixed heat release rate is advanced by 8.3 °CA before top dead center (TDC) with both biofuel UD and biofuel, and it is 7.1 °CA before TDC with diesel. The limited advance of premixed combustion may lead to improvement in expansion ratio. The diffusion burning, indicated by the second peak, is higher with diesel due to the burning of more quantity of fuel in the later part of combustion, which leads to lower thermal efficiency and higher exhaust gas temperature.

Ignition delay

The variation of ignition delay with brake power for biofuel, diesel and biofuel UD is shown in Fig. 13. Ignition delay is the time interval between the start of fuel injection and combustion measured by the sudden change in the slope of pressure crank angle diagram. Ignition delay provides an indication of the combustibility of the fuel injected and the mixing of the fuel and air. It is very high with diesel compared to biofuel UD and biofuel. The ignition delay for biofuel, diesel and biofuel UD at maximum load is 9.9, 10.5 and 9.1 °CA, respectively. The undistilled biofuel has more high volatile hydrocarbons, and hence, it converts quickly to vapor form and easily mixes with air. The flash point of biofuel UD is low (27 °C), which helps to start the combustion earlier.

Combustion duration

Figure 14 depicts the variation of combustion duration of the three fuels with brake power. Combustion duration is the time interval between the start of combustion to the 90% of fuel mass burnt. Combustion duration generally increases with increase in power output of the engine with all fuels due to increase in the quantity of fuel injected. It is marginally higher with diesel compared to biofuel and biofuel UD. Long combustion duration with diesel and biofuel UD indicates that too much fuel is injected to maintain the same power as the cylinder cools down during the expansion stroke, potentially causing incomplete combustion that leads to higher unburned hydrocarbons and particulate matter compared to biofuel. This is evident from Figs. 5 and9. Combustion duration is 41.2 °CA with biofuel, 43.5 °CA with biofuel UD and 44.7 °CA with diesel. This decrease in combustion duration with biofuel is due to increase in intensity of premixed combustion rate as a result of better mixing of fuel and air, which is clear from the heat release rate curve as seen in Fig. 12.

Conclusions

Biofuel results in highest brake thermal efficiency of 32.4%, whereas biofuel UD results in 32.12% at 80% load. There is not much difference in brake thermal efficiency with these fuels. Biofuel results in lower exhaust gas temperatures in comparison with biofuel UD on account of faster combustion. NOx emissions for the biofuel operation are 857 and 994 ppm with biofuel UD at full load. NOx emissions are higher with biofuel UD than biofuel because of highly volatile components making the initial combustion very fast. The CO and HC emissions are higher and CO 2 emission is lower with biofuel UD compared to biofuel due to incomplete combustion. PM level of biofuel is lower as compared to biofuel UD. The PM level for biofuel is 0.028 and 0.029 g/h for biofuel UD at full load. This is due to more amount of fuel being burned in the later part of combustion. There is not much change in cylinder peak pressure with biofuel and biofuel UD. It is 90.1 bar with biofuel UD and 89.7 bar with biofuel at full load. Heat release with biofuel UD indicates higher diffusion burning and lower intensity premixed burning rates as compared to biofuel. Ignition delay is lower with biofuel UD due to high volatile components, and combustion duration is long due to higher diffusion burning. At full load, the ignition delay and combustion duration are 9.1 and 43.5 °CA, respectively, and with biofuel UD compared to biofuel, it is 9.9 and 41.2 °CA.

From the performance, emission and combustion analysis, the biofuel derived from fish processing industry waste can be considered as a viable substitute for diesel fuel compared to undistilled biofuel.

Fig. 1

 1 Fig. 1 Schematic diagram of the engine setup.(1) Test engine, (2) biofuel tank, (3) diesel fuel tank, (4) exhaust gas analyzer, (5) eddy current dynamometer, (6) particulate matter analyzer, (7) lowfrequency data acquisition system, (8) charge amplifier, (9) high-frequency data acquisition system, (10) crank angle encoder/speed sensor, (11) injection pressure signal and (12) cylinder pressure signal

Fig. 4 Fig. 5

 45 Fig.4Variation of oxides of nitrogen with brake power

Fig. 7 Fig. 9

 79 Fig.6Variation of carbon monoxide with brake power

Fig. 10

 10 Fig.10Variation of cylinder peak pressure with brake power

Fig. 13 Fig. 14

 1314 Fig.12Variation of heat release rate with crank angle at maximum load

Table 1

 1 Main properties of the

	waste fish fat	Properties	Waste fish fat
		Visual aspect	Liquid at 60 °C, brown color, typical smell
		Water content (%)	\0.05%
		Flash point (°C)	318
		High heating value (kJ/kg)	39,000
		Kinematic viscosity (mm 2 /s)	27
		Density (kg/m 3 )	0.893
		Composition of fatty acids (%)
		Mysteric	1.05
		Palmitoleic	5.00
		Palmitic	16.00
		Stearic	10.50
		Oleic	45.60
		Linoleic	20.60

Table 3

 3 Specifications of test engine

	Table 2 Properties of undistilled biofuel (biofuel UD),	Properties	Unit	Undistilled biofuel	Biofuel	Diesel fuel
	biofuel and diesel	Flash point	°C2 7	5 7	5 6
		Acidity	mg KOH /g	0.2	0.8	-
		HHV	MJ/kg	45.25	45.10	45.71
		LHV	MJ/kg	42.87	42.74	43.36
		Dynamic viscosity at 20 °C	Ns/m 2	2.11	2.32	2.52
		Density at 20 °C	kg/m 3	818	825	830
		Kinematic viscosity at 20 °Cm m 2 /s	1.72	1.7	2
		Auto-ignition temperature	°C	-	230	220
		Cetane index		-	57	52
		Cloud point	°C9	9-
		Pour point	°C	-5	-5-
		Cold filter plugging point	°C1 4	1 4	-
	Make	Lister petter
	No of cylinders	One
	Type of cooling	Air cooled
	Bore 9 stroke	95.5 9 88.94 mm
	Length of connecting rod	165.3 mm
	Displacement	630 cm 3

Acknowledgements GEPEA Laboratory and the Department of Energetic and Environmental Systems (DSEE) supported this research at the E ´cole des Mines de Nantes. These supports are gratefully acknowledged.


Some observations on the concept of Tianxia from a comparative, historical and legal perspective

Florian Couveinhes Matsumoto 21 June 2019, Beijing Institute of Technologies, Faculty of Law Distinguished professors, Ladies and Gentlemen, Today I would like to make a few comments on two books: this book, which is a conversation between Zhao Tingyang, who we have the privilege to have with us, and the French philosopher Régis Debray. And more importantly, this book which focuses on the concept of Tianxia.

But let me start with a few quotations:

"Behind the lack of world order, we find States, with their desire for independence, their responsibility for domestic interests, and the rivalries dividing them. This is why what is currently called international law is simply a set of rules without any consistency or guiding principle, except States' interests. However, the technical conditions that are necessary to the emergence of a truly universal society are not far from being met. Today, complementarities exert more pressure than tensions. Economic complementarities but also cultural and technical complementarities. As a result, if a specific civilization were to grow from the amazing scientific development of our time, it could only be a civilization without borders". "It would be childish to believe it is mere coincidence. [On the contrary] it is the result of material solidarity that unites people still politically divided (…). [But] frontiers are an anachronism from an economic, social and cultural point of view. (…) The whole world seems to be mad [but] it is in a process of organization. [People could regain confidence] by building this [new world order]. But there is a primary condition to this ambition: they have to develop an [interest in a common world order] and to choose a formula to realize this world".

A formula like the Tianxia.

Apart from the last sentence, these quotations are not taken from Zhao Tingyang's famous books on the concept of Tianxia, but from the books of two French lawyers, whom I call the two Georges: Georges Burdeau in 1966 and Georges Scelle in 1942.

The similarities between their discourses and Zaho Tingyang's narrative struck me and help me to realize two facts: 1) first, the fact that at various times thinkers have believed that an entirely interconnected world is emerging, and a new political form is emerging, because of technological developments. This fact makes us cautious about these assertions, and about the hypothesis that technological powers directly and mechanically determine the size and nature of political entities. Technics may certainly have an influence, but such influence seems not to be at all clear. It does not seem to have an immediate impact on the size of political entities. For instance, France and many other States have existed for centuries, while technics have changed a lot during this time.

2) The second fact my reading of the book, and its similarities with other books help me to understand that the emergence of cosmopolitan projects generally come from thinkers of great powers, or former or emerging great powers, and that they often precedes or are contemporary of imperialistic and colonial projects, regardless of the content of the cosmopolitan theory or the intention of their inventor. This leads us to be suspicious about the practical effect of very abstract and general projects. And while examining them, prudence, classical or Aristotelian prudence requires us to fulfill two tasks: a) First, this leads us to ask the decisive questions of classical political philosophy about a cosmopolitan project or concept, and b) Second this leads us to try to anticipate the political exploitation of these theories and to ask ourselves what elements of the theories could easily be exploited by powers pursuing imperialistic and colonialist aims, and what elements could be opposed to them.

These form the two parts of my presentation.

I. The decisive questions of classical political philosophy

According to Zhao Tingyang, who relies on both Chinese history and Chinese thinking, the concept of Tianxia is the correct or the best political world order. It implies a) that the whole world should be politically organized and, b) in a way, united under the banner of only one political power.

Under this banner, no one should be considered as a foreigner or an enemy, but only as a citizen of a vassal State and potentially as a criminal.

The three classical questions that come to mind about this Tianxia are: 1. Who? Who will be in charge? Who will command? Is it a State? A person? Everyone? Randomly chosen citizens of all States in a Democracy? Or representatives in a representative regime? Or States' representatives in an international organization? Or one or a few people that imposed their power by force, in a tyranny? If we do not answer this question precisely, a judgment or even an analysis of the project is premature and maybe even pointless. 2. Then: How will this political power be exercised? Through which channel? Which institutions? Applying which procedure? And who will take the benefits of the most probable application of this procedure, at the end of the day? 3. Finally, how can this project be achieved? Will it be through a universal and rational discussion?

We have to express our doubts about this hypothesis, because who really wants to have this discussion? States' representatives? No. Citizens? I don't think so. Then, who? Philosophers? Elites? Investment funds and CEOs of social media? It may seems funny but is a fact that it is this kind of person who usually favors cosmopolitan projects. And would their project, imposed to others, really be for the better? If a world political society should not be established this way, then how? Through a war, a new World war or a great destruction?

Well, the most probable hypothesis is that an entity willing to promote the Tianxia or to establish the corresponding world power will encounter the opposition of most States of the world and launch a war or at least a great confrontation.

These questions have been asked many times to cosmopolitan thinkers. But when the great thinkers of cosmopolitanism were asked to address these objections, they usually ignored them and refused to answer. They simply systematically set these questions aside.

For instance, Kant did not answer Rousseau's objections in the 18th Century, Hans Kelsen did not answer Leo Strauss' objections in the middle of the 20th Century, And Norberto Bobbio did not answer Danilo Zolo's objections at the end of the 20th Century.

Of course, I was eager to know what Zhao Tingyang answers to these questions.

During my reading of his books, I thought he did not notice them. However, he did… at the end of this book, in the last five pages.

Nevertheless -I may be wrong, tell me if I am -Zhao Tingyang says that these questions are very important, but in both books, he omitted to answer them, or says he does not know how to answer them. The only part of the answer I found in the Tianxia book is that the world power of the Tianxia may be exercised by a collective organization bringing together all States of the world. This proposal for the political organization of the world is understandable -I approve -but it is also rather surprising.

It is surprising because Zhao's answer could be translated into legal language as "It should be an international organization, based on international treaties". Yet the book is full of assertions such as "treaties are not trustworthy, they are not reliable", or an "international organization such as the UN is without political power", or "international economic organizations are the expression of United States imperialism". I think these assertions on treaties and international organizations, which are very common in the US by the way, are not sufficiently persuasive from my viewpoint: for instance, many small States support the World Trade Organization, want to joint it, ask for an extension of the application of trade rules, etc. while the US criticizes this organization and rules all the time. If these organizations and rules were the pure transcription of US interests or imperialism, these criticisms would not be understandable. investment treaties, they established international organizations and international courts, precisely in order to achieve this. This means: great powers have made this happen, and they can make it disappear as they did before World War I. The Huawei case is currently an illustration of this. Globalization is not an autonomous power and still less an homogeneous power which can pursue projects. Globalization itself has no project, it is no one.

This was the first element: globalization. But great powers are behind globalization. And according to Zhao, States cannot establish the Tianxia through treaties and classical international Law. If it is not globalization that will impose the Tianxia, who could it be?

The last three elements point in the same direction:

Indeed, the second element is a set of assertions made by Zhao Tingyang about Tianxia: 2. he asserts that there is no political society without hierarchy, that it is necessary to the good functioning of societies (p. 81). Consequently, the Tianxia will be dominated by the greatest political power that exists. Historically, the origin of Tianxia is a specific situation of a small tribe having beaten a big one, but it is a reality that, at that moment in time, the small tribe had more power than the other and was thus the strongest. It may be similar in other cases of application of Tianxia. 3. The third element is the set of peculiarities of the Tianxia system in Chinese history, that are outlined in the book. For instance, during the Tianxia system, there were "vassal States" (p. 82), there was a "world sovereign" exercising "world sovereignty" (p. 147), he was the owner of the Tianxia territory (p. 84) and he reigned over other countries like a parent over his child (p. 92). There was a center, China, which thought it was developed, and there was a periphery that the center usually considered to be retarded (p. 89) or like a child (p. 92).

I could continue in this vein for a very long time but I think that this is sufficient to agree with Anthony Carty's assertion that the Tianxia system was Sino-centric and hierarchical. It is in fact not very far from a colonial logic, which is not based on the recognition of alterity, but on the will to include everyone and to treat other people as children, under the pretext of taking good care of them and helping them to develop themselves as they want, but within the protection of the civilized family.

4. The fourth and last element is Zhao Tingyang's choice not to answer to another decisive question. This question is: "What will happen to two countries that may refuse to enter the political organization of the Tianxia, or what will happen if, more probably, only half of the world or a third or quarter of the world accept to unite but not the rest?". The right answer is clear: the ideal of Tianxia might be exploited by political power in order to impose its own power on others.

At this point, the risk of political manipulation of the theory by great powers is obvious.

However, elements of the theory that resist political manipulation are also obvious.

*

II. The risk of manipulation of the theory for an imperialistic purpose

Zhao's claim concerning the universal application of the concept of Tianxia raises the same questions and problems as did and still do similar claims and concepts coming from the West. Most of these questions and problems can be reduced to only two:

1. the claim to apply an inevitably particular concept on a universal scale, and 2. the use of power or violence to universally impose the practical implication of the concept.

As regards the first point, the particularity of the concept of And for instance, when the author asserts that the difference between monotheism and Chinese religiosity leads to respect for religious minorities in China and to intolerance towards such minorities in the West (!), I think this analysis may convince Chinese people, but -to say the least -not Western people.

The second question is the question of violence, or domination. And it strikes me that this question is not addressed at length in the book. This question is central because, as I said, we have to face the hypothesis in which many countries do not want to be part of a political structure, but are forced to join this structure, by a greater political or economic power.

But the question of violence and domination is also central because political powers exist in order to promote their interests and that great political powers will always exploit theories about the international community in order to do so, to promote their interests.

Have we, in the case of Tianxia theory, the resources to criticize manipulation? Zhao gives several examples of these resources and I assume they exist.

But they also exist in the case of liberalism, human rights and Christianity. Liberalism, human rights and Christianity have been enormously mobilized to fight imperialism and colonialism -and much more than Tianxia against Chinese foreign policy for instance. But that did not prevented liberalism, human rights and Christianity to be used to justify imperialism and colonialism.

Therefore, the problem is not only the resources but also the identity of the interpreter. In the Tianxia system, who will have the power to decide that a certain use of the concept is abusive or unfair?

In practice, I have no doubt that political powers will find slavish and well-paid "lawyers" and "intellectuals" to explain that their abuses are the perfect illustration of what the Tianxia implies.

Conclusion:

In conclusion, I want to take a step back, and say that my reticence about Tianxia may come from my knowledge of European history, of the Westphalian system which permitted peace and self-determination in Europe; and Zhao's reticence about sovereign equality and international law might come from his knowledge of a completely different history, in which the plurality of political entities was synonymous with war, and the Tianxia system with peace and harmony. These differences in sensibility may be enshrined in the history of our countries and in our education.

This difference may be the expression of the plurality of civilizations, countries, and peoplea plurality that is outlined in the book. But this plurality is not a problem at all. It is a wealth that international politics should always preserve, at least because it enables each and every one to have a dialogue with people who have other opinions and make us think harder, and better.

Thank you very much for your attention.

a World political organization cannot come from a discussion and agreement of States, of classical political international Law, because

  And the defense of the Organization by China would not be understandable either. More importantly, Zhao Tingyang explains repeatedly, as did Georges Burdeau and (to a lesser extent) Georges Scelle, that conflicting States' interests prevent a truly global interest emerging and being expressed in global rules and institutions. Even if we accept this assertion, which I do not, no one can affirm that globalization emerged spontaneously from private persons. Globalization -namely growing economic interdependence, technological development and the weakening of the State in relation to transnational corporations -is the direct

	But if a true world organization cannot be established by States or by other political
	representatives, who or what might do it? How could this organization emerge?
	As I said, there is no clear answer to these questions in Zhao's book.

However, there are four elements in the book that may help to provide an answer: 1. according to the first page of the introduction, "globalization sweeps everything along, and does it everywhere, and nothing exists outside this phenomenon henceforth."

result of foreign policies of hegemonic Western States between (roughly) 1989 and 2009.

  The European States, the United States and other States concluded thousands of treaties, trade and

has been applied in China for a very long time, Chinese thinkers have huge respect for the concept.

  Tianxia is extreme: it not only comes from ancient China, but it As Zhao writes it, China

is the State that has the Tianxia gene, the State that is implicitly organized in accordance with the Tianxia structure, and China is a scale model of the Tianxia.

  In other words, although this concept is completely unknown in most of the world, it is very important in China, and many Chinese people have a strong feeling about it. In this context, it

is difficult to recognize that, as Zhao wrote in the book on Tianxia, the Tianxia does not establish a cultural frontier.

  As long as China is in the middle of the Tianxia and determines the global culture, China will surely admit that there is no limit to the Tianxia. But if Saudi Arabia was in the middle of the Tianxia, or if the global culture was determined

by the United States, or by the West, or

  even by the rest of the World, I am pretty sure that China would ask for a cultural frontier. From a European perspective, it is also striking that the whole book on Tianxia values the concept of Tianxia and values

Chinese history, culture and religiosity, and criticizes Western history, culture and religion

  . I have to express doubts about this manner of demonstrating that the promotion of Tianxia does not relate to

the promotion of China itself, and that universal application of Tianxia would not launch a new clash of civilizations but

would be a way of reconciling different civilizations.