Browse Topic: Kerosene
Alternative fuels are sought after because they produce lower emissions and sometimes, they have feedstock and production advantages over fossil fuels, but their wear effects on engine components are largely unknown. In this study, the lubricity properties of a Fischer-Tropsch Gas-to-Liquid alternative fuel (Synthetic Paraffinic Kerosene-S8) and of Jet-A fuel were investigated and compared to those of Ultra Low Sulphur Diesel (ULSD). A pin-on-disk tribometer was employed to test wear and friction for a material pair of an AISI 316 steel ball on an AISI 1018 steel disk when lubricated by the fuels in this research work. Advanced digital microscopy was used to compare the wear patterns of the disks. Viscosity and density analysis of the tested fluids were also carried out. Tribometry for the fuel showed that S8 fell between Jet-A and ULSD when friction force was calculated and showed higher wear over time and after each test when compared to that of Jet-A and ULSD. An initially higher running-in friction force of 0.35N to 0.38N was observed for all three tested fluids, and then quasi-steady-state lower values of friction force of .310N for S8, 0.320 N for Jet-A and 0.295N for ULSD (the lowest observed).Wear values obtained by mass loss of the tested AISI 108 steel disks show that Jet-A and the reference fuel ULSD may yield lower wear (which is associated to better lubricity) than that of S8, and microscopy images are consistent with the wear results.
Considerable amounts of water accumulate in aircraft fuel tanks due to condensation of vapor during flight or directly during fueling with contaminated kerosene. This can result in a misreading of the fuel meters. In certain aircraft types, ice blocks resulting from the low temperatures at high altitude flights or in winter time can even interfere with the nozzles of the fuel supply pipes from the tanks to the engines. Therefore, as part of the maintenance operations, water has to be drained in certain intervals ensuring that no remaining ice is present. In the absence of an established method for determining residual ice blocks inside, the aircraft operator has to wait long enough, in some cases too long, to start the draining procedure, leading potentially to an unnecessary long ground time. A promising technology to determine melting ice uses acoustic signals generated and emitted during ice melting. With acoustic emissions, mainly situated in the ultrasonic frequency range, a very high number of events can be recorded to characterize stress relaxation processes that occur during conversions from ice to water. In the present paper, in addition to the case of the fuel tank, the icing of a fuselage panel is also considered. The results obtained provide evidence that it is possible to determine the moment when all ice has melted. However, it is not possible to give exact figures on the amount of ice remaining or melted, which is not a limitation in practice.
Today unmanned aerial vehicle applications are powered by Wankel rotary engines due to their high power-to-weight ratio and smooth operation. Most of modern propulsion units for unmanned aerial vehicles are designed to run on high volatile fuels such as aviation gasoline (AvGas). However, the refueling infrastructure in aviation is geared toward the most used aviation fuel, kerosene. This and other reasons, such as significantly lower price and easier fire protection regulations, lead to the desire to be able to operate these propulsion units with kerosene. Opposed to reciprocating engines, the low compression ratio of rotary engines prevents the implementation of compression ignition combustion processes. Therefore, the purpose of this paper is to discuss the operation of a spark-ignited rotary engine on different fuels. In detail, different qualities of kerosene as well as gasoline/kerosene blends are compared together. In this respect, a thermodynamic analysis of the individual operations is undertaken. In order to make a statement about the efficiency and quality of the combustion, the investigation is carried out to determine the optimal rotor angle range for the center of combustion, with maximal efficiency and torque. On the basis of measurement data, it was possible to show that rotary engines also have an optimal rotor angle for the center of combustion, almost regardless of the operating point and mixture composition. Only the fuel used has little influence on the location of the optimal center of combustion. In addition to the comparison of the combustion characteristics of the individual fuels, the problems of operating with kerosene are examined in detail. Due to the low knock resistance of kerosene, restrictions in the operational area can be observed. Nevertheless, despite the different properties of the fuels, approximately similar torques and power outputs can be generated.
Wankel rotary engines (REs) are often used for unmanned aerial vehicle (UAV) applications due to their excellent power-to-weight ratio and their smooth operation. Existing RE propulsion units are mainly designed to run on high-volatility fuels like aviation gasoline or regular gasoline. However, specific applications require a jet fuel or even multi-fuel capability. Due to their geometry, the low compression ratio (CR) of REs prevents the implementation of compression ignition (CI) combustion processes. While publications of modified spark-ignition engines that are able to run on low-volatile fuels are already few in number, publications of heavy-fuel spark-ignited (SI) REs can hardly be found at all. The purpose of this paper is as follows: The operation of a SI RE operated on kerosene is discussed. Accordingly, a thermodynamic analysis is carried out at warmed-up operation with kerosene. It is shown that sufficient performance and power output can be achieved on kerosene for full-load behavior. Furthermore, cold-start tests are carried out to investigate the limits of kerosene operation. Therefore, a low-temperature test bench is developed that allows the investigation of engine starts down to −30°C. The challenges of mixture formation for heavy fuels in port fuel injection systems for REs at cold-start conditions are investigated and discussed. It is demonstrated that cold starting a SI RE down to −25°C is possible with correct measures.
The principal objective of the present work is to investigate the fundamental characteristics of a commercially available outwardly opening twin-fluid injector, which utilizes air-assisted atomization principle to attain pulse-type injection of fuel-air mixture. The electromagnetic characteristics of this injector were simulated and the effects of dominating parameters on the electromagnetic force to drive injector were ascertained. On that basis, this paper elaborates on the fundamental characteristics of air-assisted spray using gasoline and kerosene with the employment of two types of optical testing techniques. The spray morphological evolution under varied fuel injection durations and ambient pressures were captured with high-speed shadowgraph thus the corresponding external macroscopic characteristics were obtained and further compared. Spray droplet velocity and diameter at fixed monitoring location were measured by using PDPA (Phase Doppler Particle Analyzer). The results indicate that the gas-phase flow in the spray field possesses a comparatively high velocity, which makes the spray highly turbulent with the calculated Reynolds number ranging in the order of 104-105. The arithmetic mean diameter of spray droplets was found to increase as the injection duration increases, and also increase as the ambient pressure increases. Due to the negative impact of relatively high fluid viscosity on liquid disintegration, the diameters of kerosene spray droplets are generally larger than that of gasoline under the same working conditions. The twin-fluid injector was applied to an unmanned aerial vehicle engine prototype and the combustion and engine performances of gasoline and kerosene were compared. Under the premise of ensuring stable operation of the engine, it was found that the combustion of kerosene lagged behind gasoline apparently, and the power performance was also inferior to gasoline.
In the present article, the knock tendency and pre-ignition resistance (PIR) were determined experimentally for different blends of kerosene and jojoba bio-gasoline. The effects of varying equivalence ratios, rotational speed, inlet air temperature and pressure, and ignition timing on knock tendency and PIR were investigated. The influence of compression ratio on PIR was also studied. Jojoba bio-gasoline was synthesized using transesterification method through performing a chemical reaction between well-stirred jojoba raw oil and alcohol. Experiments were carried out on a Ricardo E6/MS variable compression ratio spark-ignition (SI) engine fuelled by jojoba bio-gasoline/kerosene blends of volumetric percentages of 0%, 5%, 10%, 15%, and 20% jojoba bio-gasoline. The onset of pre-ignition and knock were detected by observing the pressure oscillations using a piezoelectric pressure transducer, a synchronizing magnetic sensor, and a degree-marking probe. The results showed that increasing the percentage of bio-gasoline in the blends with kerosene leads to a significant increase in PIR and a remarkable decrease in the knock tendency. This will lead to the design of a more efficient engine by increasing its compression ratio when fuelled by jojoba bio-gasoline. Analytical correlations were developed to assess the knock tendency and PIR for different fuel blends taking into consideration the various design and operating variables.
In internal combustion engine, it is necessary to grasp droplet evaporation for using liquid fuel efficiency and improving exhaust gas composition. However, it has not known completely yet. In this study, fuel droplet of approximately 20μm diameter that is assumed to be in combustion chamber is injected by experimental apparatus. After that, droplet goes to butane flame. We observed by high-speed camera, and experimentally considered the effects of heat flux on the fuel droplet evaporation and breakup phenomenon. For the sample fuel, we use kerosene and diesel oil. It is important for understanding evaporation condition to know temperature around droplet in butane flame. Thus, flame temperature is measured by sheathed thermocouple. Heat flux is changed by initial velocity. From experiment, we found some result. Time that from injector tube to location of breakup of the droplet is short by increasing heat flux. In terms of breakup phenomenon, it is found that kerosene is broken up in relatively small heat flux condition. The breakup diameter is not dependent on heat flux. Evaporation rate is increased linearly by increase in heat flux. The value of evaporation rate that kerosene and diesel oil is almost equal.
As of today, most transport vehicles use petroleum-based fuels. Although there are alternative-fueled technology demonstrators such as the Mahindra E2O or Tesla battery-electric models currently available, it will take time for these alternatives to compete with petroleum-based fuels and achieve commercial acceptance. A selection of various transport vehicles and the fuels typically used to power them: Cars and motorcycles/scooters: gasoline, diesel, CNG, LPG, battery-electric Commercial trucks: diesel Buses: diesel, CNG, battery-electric Rail: electricity, diesel, coal Small aircraft with reciprocating-engines: gasoline or Avgas Larger aircraft with turbine engines: jet fuel or kerosene
In this study, Premixed Charge Compression Ignition (PCCI) was investigated with alternative fuels, S8 and n-butanol. The S8 fuel is a Fischer Tropsch (FT) synthetic paraffinic kerosene (SPK) produced from natural gas. PCCI was achieved with a dual-fuel combustion incorporating 65% (by mass) port fuel injection (PFI) of n-butanol and 35% (by mass) direct injection (DI) of S8 with 35% exhaust gas recirculation. The experiments were conducted at 1500 rpm and varied loads of 1-5 bar brake mean effective pressure (BMEP). The PCCI tests were compared to an ultra-low sulfur diesel no. 2 (ULSD#2) baseline in order to determine how the alternative fuels effects combustion, emissions, and efficiencies. At 3 and 5 bar BMEP, the heat release in the PCCI mode exhibited two regions of high temperature heat release, one occurring near top dead center (TDC) and corresponds to the ignition of S8 (CN 62), and a second stage occurring ATDC from n-butanol combustion (CN 28). At 1 bar BMEP, S8 PCCI displayed a single high temperature heat release with an extended diffusion burn phase. Each PCCI experiment exhibited a drastic decrease in NOx emissions up to 95%. However, at 5 bar BMEP with EGR, the smoke limit was reached and as a result, the soot increased by over 500% and that can be attributed to the near stoichiometric combustion. At the lower loads, a simultaneous reduction in soot and NOx was observed for the PCCI case when compared to ULSD#2. At 3 bar BMEP, the soot decreased by 18% and NOx decreased by 92%. At 1 bar BMEP, soot decreased by 46% and NOx by 82%. A spike in carbon monoxide and unburned hydrocarbon emissions was observed for all PCCI cases. This increase can be attributed to wall wetting and crevice phenomenon coupled with cold EGR during the port fuel injection of n-butanol. The alternative dual-fuels used in this study proved to be capable of achieving PCCI combustion at lower engine loads. Future studies include the use of a supercharger to increase the intake pressure and restore the relative air/fuel ratio and mitigate the soot emissions at higher loads with high EGR.
High-speed planar laser Mie scattering and Laser Induced Fluorescence (PLIF) were employed for the determination of Sauter Mean Diameter (SMD) distribution in non-evaporating diesel sprays. The effect of rail pressure, distillation profile, and consequent fuel viscosity on the drop size distribution developing during primary and secondary atomization was investigated. Samples of conventional crude-oil derived middle-distillate diesel and light distillate kerosene were delivered into an optically accessible mini-sac injector, using a customized high-pressure common rail diesel fuel injection system. Two optical channels were employed to capture images of elastic Mie and inelastic LIF scattering simultaneously on a high-speed video camera at 10 kHz. Results are presented for sprays obtained at maximum needle lift during the injection. These reveal that the emergent sprays exhibit axial asymmetry and vorticity. An increase in the rail pressure was observed to lead to finer atomization, with larger droplets observable in the neighbourhood of the central axis of the spray, decreasing with radius towards the spray boundaries. Finally, the light kerosene was observed to produce smaller droplets (as measured by Sauter mean diameter), relative to the conventional diesel, suggesting a correlation between distillation profile and viscosity, and mean spray droplet size.
In this study, the internal nozzle flow and macroscopic spray characteristics of a kind of wide distillation fuel (WDF) - kerosene were investigated both with numerical and experimental approaches. Simulation results indicate that compared with diesel fuel, kerosene cavitates more due to higher turbulent kinetic energy as a result of lower viscosity. The results from experiment indicate that under lower charge density, the spray penetration for kerosene is obviously shorter than that for diesel, especially for the lower injection pressure. This is because lower fuel viscosity results in a reduction in the size of the spray droplets, leading to lower momentum. However the spray angle of kerosene is larger compared with diesel due to stronger turbulence in the nozzle flow caused by increased cavitation for kerosene, which also accords well with the simulation results.
The US Navy is in the process of evaluating Catalytic Hydrothermal Conversion Jet fuel (CHCJ-5) for inclusion in the JP-5 specification, MIL-DTL-5624, and evaluating Catalytic Hydrothermal Conversion Diesel fuel (CHCD-76) for inclusion in the F-76 specification, MILDTL-16884. CHC fuels are produced from renewable feedstocks such as triglycerides, plant oils, and fatty acids. A Catalytic Hydrothermolysis process chemically converts these feedstocks into a mixture of paraffins, cycloparaffins, aromatics, olefins, and organic acids. The resulting mixture is then hydroprocessed and fractionated to produce a kerosene (or diesel) product having a distillation profile comparable to traditional petroleum derived fuels. The end product is a fuel that is able to meet the jet (or diesel) chemical and physical MIL-SPEC requirements without blending with conventional petroleum fuels. Detailed physical and chemical characterizations are presented showing these new renewable fuels in neat form have similar properties as compared to their natural petroleum counterparts (JP-5 and F-76). Engine testing was performed using three highly instrumented engines (Waukesha, Yanmar and AM General). CHCJ-5 was compared to the combustion performance of JP-5, while CHCD-76 was compared to conventional diesel NATO F-76. Engine data from this testing was processed to compare the fuels on the basis of relative combustion metric changes. The results of this testing and analysis show that, in general, ignition delay is similar to or slightly shorter than the base fuel. Combustion phasing shifts are quite small, with the maximum rate of heat release showing a modest decrease with the CHC fuels due to their moderately higher cetane values. Overall, both CHC fuels have combustion changes that fall within Navy acceptance standards. Engine operation (including cold starting) with these new renewable neat fuels was similar to the base natural petroleum fuels with no concerns noted.
The present study was carried to explore the potential suitability of biodiesel as an extender of Kerosene in an off road dual fuel (gasoline start, kerosene run) generator set and results were compared with kerosene base line data. The biodiesel was blended with kerosene in two different proportions; 2.5% and 5% by volume. Physico-chemical properties of blends were also found to be comparable with kerosene. Engine tests were performed on three test fuels namely K100 (Kerosene 100%), KB 2.5 (Kerosene 97.5% + Biodiesel 2.5%) and KB5 (Kerosene 95% + Biodiesel 5%). It was found that brake thermal efficiency [BTE] increases up to 3.9% while brake specific energy consumption [BSEC] decreases up to 2.2% with increasing 5% volume fraction of biodiesel in kerosene. The exhaust temperature for blends was lower than kerosene. The test engine emitted reduced Carbon monoxide [CO] emission was 7.4 % less than using neat kerosene as compared to kerosene-biodiesel blends. The emission of Oxides of Nitrogen [NOx] was found to be comparable for all test fuels at lower loads. However, at higher loads, a reduction in the NOx emission (11%) for all the blends was observed as compared to kerosene. Hydrocarbon emission of kerosene was also partially reduced in compare to that of K100. It could be summarized that addition of biodiesel in kerosene as an extender can be successfully employed for running a dual fuel SI engine without detrimental effect on engine performance and better emission characteristics.
Diesel engines provide the necessary power for accomplishing heavy tasks across the industries, but are known to produce high levels of noise. Additionally, each type of fuel possesses unique combustion characteristics that lead to different sound and vibration signatures. Noise is an indication of vibration, and components under excessive vibration may wear prematurely, leading to repair costs and downtime. New fuels that are sought to reduce emissions, and promote sustainability and energy independence must be investigated for compatibility from a sound and vibrations point-of-view also. In this research, the sound and vibration levels were analyzed for an omnivorous, single cylinder, CI research engine with alternative fuels and an advanced combustion strategy, RCCI. The fuels used were ULSD#2 as baseline, natural gas derived synthetic kerosene, and a low reactivity fuel n-Butanol for the PFI in the RCCI process. This combination of fuels was never analyzed from NVH point of view in RCCI mode. The sound and vibration signatures were measured using a B&K condenser type microphone and a piezoelectric, triaxial accelerometer. The data were analyzed with CPB and FFT Analysis, and Angle Domain Analysis with B&K Pulse platform software. The tests were conducted at 1500 rpm and 4 bar IMEP load, with 40% EGR, and 65% by mass PFI of n-Butanol. The COV for RCCI with S-8 and ULSD#2 were 5.14 and 4.80, respectively. The max values of the heat release for RCCI was 97 and 112 J/CAD for S-8 and ULSD#2, respectively. The results indicated that a difference of 5.5 dB(A) was achieved between RCCI with S-8, and RCCI with ULSD#2.
A comparative study was performed by use of blends of Jatropha oil-diesel fuel and Jatropha oil-kerosene in order to investigate the feasibility of direct utilization of Jatropha oil in a DI diesel engine. Experimental results at low load demonstrated that mixing 60 vol.% of Jatropha oil into both diesel fuel and kerosene gave less impact on indicated thermal efficiency, whereas further increase of Jatropha oil deteriorated it. Jatropha oil-kerosene decreased particulate matter compared to Jatropha oil-diesel fuel, although particulate matter increased with the increase of Jatropha oil fraction. At partial load where double injection was applied, mixing 80 vol.% of Jatropha oil gave no significant impact on indicated thermal efficiency, exhaust gas emissions and particulate matter and no significant difference was observed between diesel fuel blends and kerosene blends. Combustion visualization was also performed in an optically accessible engine in order to gain insight into the ignition and combustion processes at low load.
This study reports gaseous and particle (ultrafine and black carbon (BC)) emissions from a turbofan engine core on standard Jet A-1 and three alternative fuels, including 100% hydrothermolysis synthetic kerosene with aromatics (CH-SKA), 50% Hydro-processed Esters and Fatty Acid paraffinic kerosene (HEFA-SPK), and 100% Fischer Tropsch (FT-SPK). Gaseous emissions from this engine for various fuels were similar but significant differences in particle emissions were observed. During the idle condition, it was observed that the non-refractory mass fraction in the emitted particles were higher than during higher engine load condition. This observation is consistent for all test fuels. The 100% CH-SKA fuel was found to have noticeable reductions in BC emissions when compared to Jet A-1 by 28-38% by different BC instruments (and 7% in refractory particle number (PN) emissions) at take-off condition. BC emissions from this fuel were lower than from Jet A-1 by 45-50% (and 25-26% in refractory PN) at idle or cruise condition. The 100% CH-SKA fuel was observed to have a minimum influence on non-refractory PN emissions. A lower volume in naphthalene in the 100% CH-SKA fuel was hypothesized to be one of the factors attributing to the reduced BC emissions when compared to Jet A-1 emissions. For the 50% HEFA-SPK fuel, BC emissions were lower than the BC emissions from Jet A-1 by 58-86% for various engine load conditions. BC emissions from the 100% FT-SPK fuel were lower than from the Jet A-1 by 70-98%. Both the refractory and non-refractory PN emissions from these fuels were lower by comparable magnitude when compared to that from Jet A-1.
The U.S. Army currently uses JP-8 for global operations according to the ‘one fuel forward policy’ in order to reduce the logistics burden of supplying a variety of fuels for given Department of Defense ground vehicle applications. One particular challenge with using global JP-8 is the lack of or too broad a range of specified combustion affecting properties including ignition quality, high temperature viscosity, and density. In particular, the ignition quality of JP-8 has dramatically varied throughout the past decade on a global basis covering a range of 29 to 70 cetane index. This key combustion affecting parameter was explored in this study by evaluating a synthesized low ignition quality jet fuel blended in 25% volumetric proportions with JP-8 to effectively cover a cetane number range of 25 to 45 in a single cylinder diesel engine operated at various light, medium, and high load operating conditions. The low ignition quality fuel was a Fischer-Tropsch Synthesized, coal-to-liquid (CTL) paraffinic kerosene (FT-SPK) which exhibited low temperature chemistry behavior at light load operating conditions including unstable combustion at lower engine speeds. To better understand this latter combustion behavior, supplemental single cylinder experiments were conducted to explore the impact of cylinder charge density on the ignition delay of the CTL FT-SPK covering mean charge densities of 19, 25, and 30 kg/m3 and a temperature range of 750 K to 950 K. Such experiments revealed a peninsula of excessive ignition delay at mean ignition pressures of less than 55 bar and mean ignition temperatures less than 800 K that were representative of the unstable lower load operating points. Blending the CTL FT-SPK with an ‘average’ JP-8 increased the low temperature activity and yielded stable combustion at lower, light load engine speeds. In particular, the 50-50 blend ratio alleviated any ignition concerns with the CTL FT-SPK at the test conditions included in this study while the 25-75 blend ratio (JP-8/CTL FT-SPK) addressed a major portion of such ignition concerns at full, medium, and certain light load operating conditions. These results are highly sensitive to the initial injection rate. The main purpose of this submission is to explore the effect of blending JP-8 with a known poor ignition quality SPK to assess any potential performance impacts on military relevant diesel engines.
For handheld power tools, a four-stroke engine allows compliance with exhaust emissions regulations although four-stroke engines available tend to have unfavorable power to weight. The requirement for a low cost diecast block compromises valve sizes and port flow. While dynamic valve train limitations restrict maximum engine speeds. The use of a rotary valve as opposed to poppet valves avoids these issues and results in an engine with competitive performance. The engine block can be diecast and the engine can operate up to 14,000 rpm without valve related issues. This paper describes the evolution of a rotary valve concept and its application to two 35cc handheld development engines. The HRCV35 is based on a belt driven rotary valve horizontally mounted parallel to the crankshaft axis. The VRCV35 is based on a gear driven rotary valve vertically mounted on the cylinder axis. In both configurations, the rotary valve exposes inlet and exhaust ports providing unrestricted flow. The valve generates turbulence for easy starting and can operate on low volatility fuels such as aviation kerosene or JP8. Development of a competitive handheld engine requires a balance between; power, emissions, noise, weight, cost and durability. Prototypes for both configurations have been evaluated. The VRCV35 produces more power but is expected to have an unfavorable manufacturing cost. The HRCV35, considered more suitable for handheld applications, has been taken through performance and durability development. Compared to existing two-stroke and four-stroke engines; the HRCV35 shows competitive performance and potential advantages with starting and high rpm capability.
Legislative restrictions on the currently limited exhaust gas components and the future CO2 emissions limits have led to intensive research in the field of alternative fuels and innovative combustion approaches. Increased homogeneity of air-fuel mixture through advanced injection is one combustion approach, which potentially reduces engine-out nitrogen oxide and particulate emissions, with good fuel consumption in certain load ranges. Ignition characteristics under homogenous combustion conditions differ from those under heterogeneous conditions. Among other reasons, this is due to the increased role of low temperature chemistry with increasing homogeneity. The ignition behaviour of diesel fuels is characterised by the Cetane number (CN), which is, however, determined at significant higher temperatures than those prevalent during ignition under homogenous combustion. As a result, its relevance as a fuel characteristic number requires evaluation. In this work, the relevance of CN and other candidates as a characteristic number has been analysed under partly homogeneous combustion conditions. The investigations have been performed on a single cylinder heavy duty diesel engine. Increased mixture homogeneity was achieved through multiple pilot injections in addition to a main injection in the vicinity of ignition top dead centre (TDC). In order to identify a global characteristic number, fuels with different properties, including types of diesel, kerosene and naphtha-based fuels, were selected for the study. The ignition delay measured at the engine were validated with shock tube measurements, The correlation between the ignition delay and the candidate characteristic numbers like initial boiling point, molecular weight and activation energy have been analytically evaluated.
In this study, the background gas of the droplet vaporization was concerned and simulated numerically using ANSYS fluent code. The new type, engine-like, condition of high pressure chamber and high temperature environment was considered to conduct experiment on kerosene droplet evaporation. 2D geometry of domain simulation was discretized in the very fine quadrilateral meshes. The numerical approach was solved using implicit scheme of compressible gas solver (density based). Temperature dependent properties of air are expressed for gas material properties. As the study concerning on high pressure condition the equation state of Peng-Robinson was expressed in simulation. Governing equations of mass, momentum and energy were solved by the second order upwind for flow, turbulent kinetic energy and turbulent dissipation rate. Standard k-ε model was used to solve turbulence flow in the spatial discretization. The effects of the non-ideal gas phase behavior were found to be important for prediction background gas of droplet vaporization especially in high pressure environment. It can be concluded that we can predict the environment of high temperature and high pressure condition, however the quantitative measurement of droplet evaporation is still facing problem on physical devices. The environmental conditions has significant effect on droplet behavior inside the chamber.
An experimental study has been conducted at small kerosene droplet behavior near well-defined butane diffusion flame for the critical need on high efficient and cleaner energy technology. High temperature of background gas was generated using butane flame. Microflame from butane can reach the maximum temperature around 1200K at tip of outer glass. Single droplet of kerosene was injected by a small injector tube (30 μm-diameter) in to hot environment. Droplet of kerosene was released by attachment of piezo actuator on wall injector. Once the droplet is exposed to the hot atmosphere of micro flame, the temporal regression of the droplet surface was recorded. Droplet diameter was observed by CCD camera with strobe light flash at 180ns. The images captured in this experiment were analyzed by post-processing software to determine the vaporization of droplet. Temperature of background gas was measured by K-type thermocouple and speed of droplet released from injector was also measured to investigate the effect of relative velocity between droplet and background gas. The result shows that the linear changing point of droplet diameter is started at different droplet temperature and different initial velocity. For further movement to high temperatures environment the vaporization rate of droplet is almost linear with time.
In emergency, it is not easy to get enough fuel for generator and the usage of kerosene with small spark ignition engine for normal gasoline was investigated. As too much kerosene will cause knock, EGR (exhaust gas recirculation) system was used to reduce the knock strength. The displacement was 290cc and the compression ratio was 8.4. The knock strength was evaluated with a highpass-filtered strain sensor and 0.6V was measured at MBT (Minimum advance for Best Torque) with normal gasoline, 1800rpm, 10Nm. The engine speed was almost 1800±100rpm and the torque was almost 10±0.1Nm. As a result, the EGR system could reduce the knock strength in any kerosene mixture fuel with the control of the ignition timing.
Cold operability is estimated by fuel's cold filter plugging point (CFPP). However, correlation of CFPP with diesel vehicle performance originates from a period when simple in-line or distributor fuel injection systems were applied and fuels did not contain biocomponents. Today, common rail fuel injection systems are used and there seem to be remarkable differences in their design between vehicle models. Seven cars were tested in a climate chamber. The best cars operated down to 8°C below fuel's CFPP but the worst get into problems 5°C above CFPP with the same fuel. It is challenging to define what CFPP is needed in order to guarantee trouble-free winter performance because there are big differences between car models. It is fundamental to get the fuel temperature of a vehicle's fuel filter above the fuel's cloud point during driving, and this depends on fuel system design factors, such as location and size of fuel filter and fuel heater if it is used. Oil companies prefer diesel fuels which do not have unnecessary good cold properties because better cold properties reduce the diesel fuel yield at refineries at a time when there is shortage of diesel fuels in Europe. Light middle distillate fractions suitable for winter grades are needed also for aviation kerosene production. Cold operability problems related to biocomponents can be avoided by using isomerized HVO. Trouble-free operation in cold conditions is important for all stakeholders: oil companies, automotive companies and vehicle owners. Further exchange of information and cooperation between oil, automotive and fuel additive companies would be valuable as well as more vehicle testing.
Textile-based energy absorbers are under consideration for possible use as load-limiting devices for heavy payload tie-down systems in rotorcraft. In the event of a hard landing, these devices could prevent failure of the mounting system and subsequent uncontrolled motion of the payload. A series of environmental conditioning regimens were imposed on the textile load limiters, which are polyester tear webbings and nylon stitch-ripping devices. These test specimens were exposed to: ambient conditions; salt-fog spray; isopropyl alcohol; hydraulic fluid; hot-water immersion; kerosene; and either high or low temperatures. The results, based on performance measures of: specific energy absorption, volumetric energy absorption, linear energy absorption, and coefficient of variation of force, demonstrated that the high temperature conditioning caused the most prominent decrease in performance while the other conditions showed only small variations. Both devices were also tested at rates as high as 15 m/s in ambient conditions. The devices were found to have only a slight reduction in performance under dynamic testing conditions versus quasi-static conditions.
A finite diffusion method is presented in this paper to model droplet evaporation for complex liquid mixture composed of different homogeneous groups. Multiple components fuel mixture is represented by separate distribution functions to describe the composition of each homogeneous group in the mixture. Only a few parameters are required to describe the mixture. Quasi-steady assumption is applied in the determination of evaporation rates and heat flux to the droplet, and the effects of surface regression, finite diffusion and preferential vaporization of the mixture are included in the liquid phase equations using an effective properties approach. The proposed model was validated by comparing against experimental measurements for single, isolated droplets of n-decane, kerosene, heptane-decane and diesel-butanol. The present model was applied to simulate the evaporation of isolated droplets with composition of typical diesel. Computations showed that the model captured the main distillation characteristics of commercial fuels reasonably well. The proposed model is capable in capturing the vaporization characteristics of complex liquid mixtures.
Certifying Army Aviation Platforms for use with Fischer-Tropsch Synthetic Paraffinic Kerosene Fuel Blends.
Air traffic has been steadily increasing for the last years. Moreover, fuel availability at a reasonable cost seems more and more uncertain. Climate change implies that greenhouse gases emissions should be reduced. In this context, the search for new alternative fuels for aircraft seems to be a promising solution. Nevertheless, aeronautic represents a very specific transportation mode, due to its usage (short range, middle range, long range with the same fuel, worldwide distribution of the fuel…) and its compulsory security constraints. In the first part of the European project ALFA-BIRD (Alternative Fuels and Biofuels for Aircraft development - FP7), a selection of the best candidates to become the fuels for the future of aircraft has been done. The selection process was very complex, due to multiple criteria (physical properties, economical issued, environmental issues…). A first matrix of 12 blends has been defined including: FSJF (Fully Synthetic Jet Fuel), FT-SPK (Fischer-Tropsch Synthetic Paraffinic Kerosene), Naphthenic cut, HVO (Hydrotreated Vegetable Oils), hexanol, furane and FAE (Fatty Acid Esters) in different amounts. The FSJF consists of 50% FT-SPK and 50% of severely hydrogenated coal tar kerosene. FT-SPK and HVO are paraffinic compounds. FT-SPK fuels are well known products and a huge work has already been done to certify this product, leading to ASTM D7566. Moreover, there is a strong potential in term of availability due to multiple sources (Biomass, Coal, Gas, Waste). HVO displays chemical composition and physical properties close to FT-SPK ones, but their certification for aircraft use is still under discussion in May 2011 and could lead to a standardization before the end of the year. The naphthenic compounds represent products that come from direct liquefaction/pyrolysis of coal or biomass. Concerning the oxygenated compounds, the study of their potential use in aeronautics is very original and can be considered as a long-term view. This first fuel matrix of 12 blends were evaluated following the standard jet fuel characterization. Thanks to this first study, 4 fuels were pointed out : FSJF, FT-SPK, a blend of FT-SPK and 50% naphthenic cut, and a blend of FT-SPK and 20% hexanol. This fuel matrix allows evaluating the potential of several chemical families: paraffinic, naphthenic and oxygenated compounds. This is also representative of a short, middle, and long term views. These 4 fuels will be deeply evaluated in term of combustion, material compatibility, stability during the second part of the ALFA-BIRD project.
Compact and computationally efficient reaction models capable of accurately predicting ignition delay and heat release rates are a prerequisite for the development of strategies to control and optimize HCCI engines. In particular for full boiling range fuels exhibiting two-stage ignition a tremendous demand exists in the engine development community. To this end, in a previous investigation, a global reaction mechanism was developed and fitted to data from shock tube experiments for n-heptane and five full boiling range fuels. By means of a genetic algorithm, for each of these fuels, a set of reaction rate parameters (consisting of pre-exponential factors, activation energies and concentration exponents) has been defined, without any change to the model form. In the present paper, an extensive validation of the model using these existing and unaltered parameters from the shock tube optimization is presented, by comparing calculated pressures, heat release rates and ignition delays with data from HCCI engine experiments. The validation is performed for all fuels at a wide range of HCCI operating conditions: load was varied from 2 to 6 bar IMEP, intake temperatures from 40 to 80°C and exhaust gas recirculation rates (EGR) from 0 to 65%. The results of the 3D-CFD simulations show a good overall agreement with the HCCI experiments for each of the fuels considered for the majority of the operating conditions investigated. The efficiency and good predictive capability of the model, even for the complex gasolines and kerosenes considered here, make the model particularly suited to study the impact of changing operating conditions on the ignition behavior and heat release in real HCCI applications. The promising results obtained furthermore indicate that the model could, in principle, be applied to any hydrocarbon fuel, providing suitable adjustments to the model parameters are carried out.
Tightening of emission norms necessitate intensified research in the field of emissions reduction. Fuel research opens up a vast area of potential improvement, since combustion behavior and the nature of the combustion products can be heavily influenced by fuel composition. In this paper, the effects of fuel properties on combustion and emissions shall be discussed, based on the study of standard diesel fuel, two types of diesel-like fuels and a kerosene fuel. Investigations were conducted on a single cylinder heavy duty direct-injected diesel engine operating under part-homogeneous combustion in the part-load operating range. For this purpose, a statistical design of experiments method (DOE) was utilized in order to evaluate the influence of each fuel property and, thus, develop a model for all selected fuels. Variation in EGR rates, injection and air patterns have significant effects on the combustion in the fuels under investigation. Therefore, common DOE plans with the same engine DOE parameters and ranges have been considered for all investigated fuels. On the other hand, the centroid of combustion was maintained constant for each operating point for all the fuels, to have the same evaluation basis. This investigation contains the experimental results obtained at the test cell, followed up with heat release calculations, to analyze combustion rates. Based on these investigations, the impact of the different fuels on the efficiency and raw engine emissions shall be discussed. Results show the potential of each fuel, based on its physical and chemical properties. Kerosene, with its high volatility and zero aromatic content appears desirable for application in heavy duty diesel engines. Further, part homogeneous combustion offers a possibility to reduce the amount of exhaust after-treatment.
Air travel has continued to increase dramatically and all indications are that the rapid rate, approximately 4% per annum, will continue into the foreseeable future. One major barrier to this growth is related to fuel. There exist major technical challenges in supplying fuels and in reducing exhaust pollutants. Transport propulsion is dependent on limited sources, mainly fossil fuels, which have a peak production predicted to be around 2005, and crude oil sources are limited and will eventually run out. Commercial air transport is responsible for around 700 million tons of jet-fuel derived CO₂ today, about 2.31% of total anthropogenic carbon dioxide, future forecasts of aviation growth show CO₂ emissions from the sector rising rapidly and inexorably to more than 1 billion tons by 2025 and this is unlikely to be acceptable. The future rate of gains in 15-20% aviation fuel efficiency (excluding dramatic improvement in fuel efficiency since the first commercial turbine aircraft which entered service in the 1960s) is not sufficient, nor likely to be matched into the future, to offset the growth rate of air travel (about 5.3% per year between 2000 and 2007, resulting in an increase of passenger traffic of 38%) particularly as many of the relatively easy technical improvements have already been incorporated. Any growth in air travel will lead to higher fuel demand. This will require the problem of meeting fuel requirements to be addressed including crude oil availability and cost, oil security, and concerns about global warming and climate change. For the growth of air travel to continue fuel alternates for aviation have to be found. Biokerosene manufactured from vegetable oils is expected to have similar properties to conventional kerosene. The fuel is one of the candidates for aviation fuels due to its renewability and its availability, and its ability to mix with the traditional fuel. The source of materials for these is more widely, and thus reliably available when compared with their fossilized counterparts. Vegetable oils consist of long-chain fatty acid alkyl esters organic compounds and can be derived from a broad variety of renewable resources such as soybean, grape, jatropha, and algae oils. The oils have high viscosity, high freezing points, poor thermal stability compared to conventional kerosene, at this state, the oils cannot be viable fuels for aviation. Therefore, the sources of fuels need to be converted into biokerosene through techniques like pyrolysis and hydrodeoxygenation. This paper gives an overview of alternative aviation fuel applications, the production of biokerosene aviation fuels, and outlines the first stage of our efforts to develop an experimental strategy for the manufacture of biokerosene from vegetable oil sources by pyrolysis that could presents a solution to the fuel shortage in the future.
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