Spray Characteristics Of Dimethyl Ether Research Articles

Macroscopic and Microscopic Spray Characteristics of Dimethyl Ether in a Constant Volume Spray Chamber Using a Mechanical Fuel Injection System for Automotive Applications

Abstract Spray investigations are critical for understanding internal combustion engine combustion. Optimised spray atomisation helps improve engine output/performance and reduce tailpipe emissions. The spray from the injector nozzle depends on nozzle hole diameter, fuel injection pressure, ambient density, pressure and temperature in the spray chamber, and test fuel properties. This study evaluated macroscopic and microscopic spray characteristics of dimethyl ether (DME) and baseline diesel under atmospheric conditions (1.013 bar pressure at 298 K temperature). It correlated the spray parameters with distinctive physicochemical properties of diesel and DME using dimensionless numbers, namely Reynolds number, Weber number, and Ohnesorge number. The fuel injection system consisted of a high-pressure mechanical injection pump and mechanical fuel injectors having an original equipment manufacturer fixed nozzle opening pressure in the constant volume spray chamber. The microscopic spray investigations were performed using a phase Doppler interferometer along the spray direction at three axial distances (50, 70, and 90 mm) from the nozzle. The three orthogonal spray droplet velocities of diesel and DME were compared. The droplet number-size distributions for baseline diesel and DME were compared. Macroscopic spray characteristics were evaluated using high-speed imaging. Reynolds number was higher for DME, leading to more turbulence in the spray and accelerating the spray breakup phenomenon. Weber number of DME was also much higher than baseline diesel due to its lower surface tension. The higher Weber and lower Ohnesorge numbers justified the finer droplets of DME sprays. DME showed superior spray atomization characteristics than baseline diesel, leading to superior fuel–air mixing and efficient and sootless combustion.

Influence of nozzle hole diameter and orifice diameter on dme spray to get the similar heat value with diesel spray using the constant volume chamber

Low heating value (LHV) of di-methyl ether (DME) is lower than that of diesel. To get the similar heat value with diesel from the diesel engine operation, single injection quantity of DME should be increased. This investigation was tried to increase the injection quantity of DME by the modified diesel injector and investigated the penetration length and spray angle of DME spray. DME was injected by using three-type modified diesel injectors those nozzle-hole diameters (Injector 1: 1.66 mm, Injector 2 and 3: 0.25 mm) and orifice diameters were different (Injector 1 and 2: 0.6 mm, Injector 3: 1 mm). Spray characteristics of DME was investigated with a various ambient pressures (2.5, 5.0 MPa) in the constant volume chamber and a fuel was injected by varied injection pressure from 35 to 70 MPa by interval of 5 MPa using a DME common rail fuel injection system. The result shows that DME injection quantity by Injector 3 was 1.69 ~ 2.02 times larger than that of diesel injection quantity by Injector 1. In this case, DME spray got the similar heat value compared with diesel spray. The penetration speed of DME spray by Injector 3 was the fastest, thus when the spray development was end, the penetration length of DME spray by Injector 3 was the longest compared with the other cases. In case of the spray angle, Injector 2 and 3 had the similar spray angle and these were larger than that of diesel and DME sprays by Injector 1. As the result, Injector 3 was the solution for how to solve the low heating value of DME.

Numerical analysis of spray characteristics of dimethyl ether and diethyl ether fuel

In this work, the spray characteristics of ether fuels such as dimethyl ether (DME) and diethyl ether (DEE) have been numerically investigated using KIVA-4 CFD code. A new hybrid spray model developed by coupling the standard KHRT model to cavitation sub model was used. The detailed thermo-physical properties of ether fuels have been predicted and validated with experimental results available from literature. The cavitation inception inside the injector nozzle hole has been studied for ether fuels in comparison with diesel fuel. It was found that ether fuels cavitates higher compared to that of conventional diesel fuel because of its low viscosity. The spray tip penetration of diesel fuel was longer than that of ether fuels due to high viscosity and density of diesel fuel. Ether fuels characterized by low Ohnesorge number and high Reynolds number showed better atomization behavior compared to that of the diesel fuel.

Application of background oriented Schlieren (BOS) method for visualization of evaporating impinged spray

The background oriented Schlieren (BOS) method for the visualization of impinged evaporating spray is presented to analyze macroscopic spray characteristics and evolution processes. The spray characteristics of dimethyl ether (DME), DME blends, biodiesel and diesel on the impinged wall in a pressurized chamber are effectively visualized for the spray evolution processes, spray depth, and spray area at various elapsed times. The visualization results of impinged spray on the wall by BOS method compared those with the scattering method. It is confirmed that the BOS method is an effective method for measurement and visualization of impinged evaporating sprays. The spray depth for the impinged wall increased with the increase of DME mixing fraction and the evolution patterns showed the stepped increasing due to impinged effect of plane wall.

DME (ジメチルエーテル) の燃料・噴霧特性 - エネルギー多様化に対応する合成燃料

DME (ジメチルエーテル) の燃料・噴霧特性 - エネルギー多様化に対応する合成燃料

Macroscopic spray characteristics and breakup performance of dimethyl ether (DME) fuel at high fuel temperatures and ambient conditions

The purpose of this work was to investigate, both experimentally and numerically, the spray behavior and atomization characteristics of dimethyl ether (DME) at high fuel temperatures and under various ambient conditions. In order to compare the theoretical and measured spray characteristics of DME fuel, macroscopic characteristics such as spray tip penetration and spray cone angle were investigated using spray visualization system with a heating system. DME atomization performance was calculated under various conditions from KIVA-3 V code and studied via analysis of the overall Sauter mean diameter (SMD) map, which is related to ambient gas temperature, ambient pressure, and fuel temperature. DME spray was found to exhibit behavior that differs from diesel spray under atmospheric condition. However, at high ambient pressure conditions, DME and diesel sprays display similar behavior. At ambient atmospheric condition, the spray cone angle of DME fuel is larger than that of diesel spray due to the occurrence of flash boiling. Variation in DME fuel temperature had little effect on spray tip penetration and spray cone angle characteristics. An increase in ambient air temperature caused an increase in DME spray cone angle due to an enhancement of the flash boiling effect. However, the DME spray cone angle showed a decreasing trend at high ambient pressure conditions when the ambient air temperature was increased. This was due to the disappearance of flash boiling and the evaporation of droplets at the exterior of the spray cone. In the overall SMD map, the increase of the ambient gas temperature and fuel temperature induced the increase of DME overall droplet size. On the other hand, the ambient gas pressure have slightly influenced on the overall SMD at a low ambient gas temperature and low fuel temperature, but the effect of the ambient gas pressure is significant at high ambient gas temperature and high fuel temperature. At high ambient gas temperature, the increase of the ambient gas pressure causes the increase of the overall SMD. At high DME fuel temperature, the decrease of the ambient gas pressure induces the increase of the overall SMD.

A study on an application of a hybrid break-up model for dimethyl ether atomization in a common-rail injection system

In this study, experimental and numerical investigations were performed to analyse the spray characteristics of dimethyl ether (DME) fuel in a common-rail fuel injection system. In order to analyse the DME fuel spray, overall spray characteristics such as the spray tip penetration, the spray evolution process, and the droplet size distribution were investigated by an application of the hybrid break-up model combined with primary and secondary break-up phenomena. The spray development process and spray tip penetration were measured experimentally from injected DME spray images obtained using a visualization system, while the microscopic characteristics were experimentally measured by a phase Doppler particle analyser system. Calculations based on hybrid break-up models were validated against the experimental results, and the associated break-up constants were optimized after the validation. Based on the optimized break-up constant, the calculated results under various experimental conditions were compared with measured results such as the spray development, the spray tip penetration, the Sauter mean diameter (SMD), and the SMD distribution.

Overall Spray Characteristics of Dimethyl ether and Biodiesel Fuel under the Ambient Pressure Conditions in a High Pressure Chamber

The purpose of this paper is to investigate the effect of the ambient pressure on the overall spray characteristics of dimethyl ether (DME) and biodiesel fuel spray in a high-pressure combustion chamber. In order to investigate the spray performance under the various ambient pressure conditions, the high-pressure combustion chamber, which can be controlled by nitrogen gas to obtain the ambient pressure conditions, was applied. To determine the macroscopic structure of the spray, such as the spray development process and the axial/radial distance, frozen images of the spray can be obtained directly using a high-speed camera with a light source according to the elapsed time after energizing begins. At the same time, the results from the DME and biodiesel spray under atmospheric conditions were compared with the results from the spray under various ambient pressure conditions in the chamber. According to the spray characteristics, the axial and maximum radial distances of the biodiesel and DME spray decreased with an increase in the ambient pressure. Also, it was shown that the SMD (Sauter mean diameter) of droplets becomes smaller than that of the spray under the atmosphere condition as the ambient pressure in the high pressure chamber increases.

Experimental and analytical study on the spray characteristics of dimethyl ether (DME) and diesel fuels within a common-rail injection system in a diesel engine

This paper investigates the effect of injection parameters on the characteristics of dimethyl ether (DME) as an alternative fuel in a diesel engine with experimental and analytical models based on empirical equations. In order to study macroscopic and microscopic characteristics of DME fuel, this work focuses on the atomization characteristics of DME and compares experimental and predicted results for spray development obtained by empirical models for diesel and DME fuel. Detailed comparisons of spray tip penetration from three different empirical correlations and from visualization experiments of diesel and DME fuels were conducted under various fuel injection conditions. In comparison with the results of different empirical equations for measured spray tip penetration, the experimental results of this study provide good agreement with the calculation results based on empirical equations, except during the earliest stage of the injected spray sequence. The results of atomization characteristics indicate that DME showed better spray characteristics than conventional diesel fuel. Also, the fuel injection delay and maximum injection rate of DME fuel are shorter and lower than those of diesel fuel at the same injection conditions, respectively.

Atomization Characteristics of Dimethyl Ether Fuel as an Alternative Fuel Injected through a Common-Rail Injection System

The objective of this work is to analyze the macroscopic development and atomization characteristics of dimethyl ether (DME) and diesel fuel spray injected through a common-rail injection system in a diesel engine. To investigate the spray behavior of DME fuel, the macroscopic and microscopic spray characteristics of DME were analyzed in terms of spray development, spray tip penetration, spray cone angle, impingement timing, mean droplet size, and the mean velocity. The process of macroscopic DME spray development was visualized according to various injection parameters such as injection duration, ambient and injection pressures, ambient temperature, and combustion chamber geometry via a spray visualization system composed of an neodymium-doped yttrium aluminum garnet (Nd:YAG) laser and an intensified charge coupled device (ICCD) camera. DME fuel atomization characteristics in a high-pressure spray chamber such as axial mean velocity and droplet size distribution were measured with a phase Doppler particl...

4829 DME減圧沸騰噴霧特性に関する研究 : 第1報:臨界温度・圧力以下の噴霧特性(J10-3 次世代燃料及び潤滑油のためのエンジン適合技術(3),J10 次世代燃料及び潤滑油のためのエンジン適合技術)

In this study, it is focused on spray characteristics of Dimethyl ether (DME) injected into low temperature or pressure ambient. Quiescent ambient made in a constant volume chamber, and shadowgraph method or laser scattered method was conducted to visualize a shape of DME spray or liquid phase DME. Penetration of DME spray and liquid phase were measured with acquired images of DME spray and scattered lights. The results obtained in this experiment describe below. As injected DME sprays in a low pressure ambient, flash boiling phenomena occurs. As an ambient density increases, dispersion angle of DME spray with flash boiling decreases. As DME spray develops without flash boiling, the spray dispersion angle increases with the increases in the ambient density.

Dimethyl ether (DME) spray characteristics in a common-rail fuel injection system

AbstractThe fundamental spray characteristics of dimethyl ether (DME) and conventional diesel were investigated in a constant-volume vessel pressurized by nitrogen gas. A common-rail fuel injection system was adopted with a sac-type injector. DME and diesel were injected into the chamber at two different chamber pressures (atmospheric and 3 MPa) and three different injection pressures (25, 40 and 55 MPa) under room temperature condition. A charge coupled device (CCD) camera was employed to capture time series of spray images, so that spray cone angles and penetrations of the DME spray were characterized and compared with those of diesel. For evaluation of the evaporation characteristics, shadowgraphy of the DME spray using an Ar ion laser and an intensified charge coupled device (ICCD) camera was adopted, in conjunction with the Mie scattering imaging technique for single-hole spray. Intermittent hesitating DME spray was observed, depending on the injection conditions, and might be due to the unstable for...

NUMERICAL SIMULATION OF INJECTION SPRAY IN A SMALL D.I. DIESEL ENGINE: A COMPARISON OF DIMETHYL ETHER AND DIESEL FUEL

This study focuses on the spray behaviors of DME (dimethyl ether) in a small D.I. diesel engine, and herein investigated are the spray characteristics of DME and its interaction with the gas flow field. We attempt to understand how the DME spray interacts with the gas flow field in a small D.I. diesel engine’s combustion chamber with the KIVA–3 CFD code, and then compare it to the spray behaviors of diesel fuel. We have successfully simulated the injection spray of a small D.I. diesel engine with DME and diesel fuel, and we have obtained data from analyzing the spray droplet development, gas density distribution, gas temperature distribution, and flow field in the combustion chamber. The results shed light on the different spray behaviors of DME and diesel fuel.

00/01769 Preparation of dimethyl ether

This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application. DME’s diesel engine-compatible properties are its high cetane number and low auto-ignition temperature. In addition, its simple chemical structure and high oxygen content result in soot-free combustion in engines. Fuel injection of DME can be achieved through both conventional mechanical and current common-rail systems but requires slight modification of the standard system to prevent corrosion and overcome low lubricity. The spray characteristics of DME enable its application to compression-ignition engines despite some differences in its properties such as easier evaporation and lower density. Overall, the low particulate matter production of DME provides adequate justification for its consideration as a candidate fuel in compression-ignition engines. Recent research and development shows comparable output performance to a diesel fuel led engine but with lower particulate emissions. NOx emissions from DME-fuelled engines can meet future regulations with high exhaust gas recirculation in combination with a lean NOx trap. Although more development work has focused on medium or heavy-duty engines, this paper provides a comprehensive review of the technical feasibility of DME as a candidate fuel for environmentally-friendly compression-ignition engines independent of size or application.