7th Asian DME Conference

Development of Fuel System and Combustion Technique for DME as a Alternative Fuel

q What is DME ? § A liquified gas with handling characteristics similar to those of LPG § Produced from a variety of feed-stock such as natural gas, crude oil, residual oil, coal, waste products and bio-mass § An excellent and efficient alternative fuel for use in a diesel engine, with almost smoke-free combustion

q DME engine does not need DPF because DME is the PM-free fuel. But, that has emitted CO, HC, and NOx. Therefore, it is necessary to the development of combustion technique in order to meet EURO-5 emission limit. q Common-rail fuel injection equipment for DME fuel has the lubrication problem. DME needs the improvement of lubricity because the viscosity of DME is lower than that of diesel.

q High oxygen content and the absence of C-C bonds : high oxidation rates and smokeless combustion q Low boiling point

: quick evaporation in a combustion chamber

q High cetane number : low auto-ignition temperature and instantaneous vaporization Property

DME

Diesel

Propane

CH3-O-CH3

-

C3H8

Lower heating value (MJ/kg)

27.6

42.5

46.3

Liquid density(kg/㎥)

667

831

500

Cetane number

>55

40∼55

-

Air-Fuel Ratio

9.0

14.6

15.8

Ignition Temperature (℃)

235

250

470

Boiling Point (℃)

-20

180/370

-42

460(-20℃)

250

372

% wt. Carbon

52.2

86.0

82

% wt. Hydrogen

13.0

14.0

18

% wt. Oxygen

34.8

0

0

Chemical structure

Latent heat of gasification (kJ/kg)

Merit High Thermal Efficiency : Equal to DI Diesel E/G Compression Ignition : about 60 of Cetane Number Smokeless Combustion : nearly Zero PM High EGR Tolerance : NOx can be Reduced Combustion Noise Reduced LPG Infra can be Used : Liquefied at 5∼6 bar

Demerit Low Lubricity & Viscosity : Wear & Leakage Problem High Compressibility : Difficult to Injection Control Elastomer Attack : Sealing Problem

LPG-DME blend fuel market (for cooking and transportation fuels) Industrial boiler (district heating) Diesel alternative fuel (Bus, Truck) (Unit : 1000ton)

2013

2014

2015

2016

2017

2018

2019

2020

2021

For family useLPG DME(20%)

254

241

228

215

204

193

182

172

163

TransportationLPG DME(5%)

265

275

286

297

309

321

334

347

360

Industrial Boiler (district heating)

99

94

90

86

82

78

75

71

68

Diesel alternative Fuel (Bus, Truck)

105

209

314

418

628

732

837

941

1,046

Total

723

819

918

1,017

1,222

1,324

1,427

1,532

1,637

※ DME Prospects in Korea (KOGAS)

Fundamental study, simulation study, and combustion study of DME engine Study of DME Engine and Vehicle (Korea)

HD DME Engine & Vehicle with IDI Fuel System (KIER)

DME HP Pump of common-rail system (KATECH)

Spray Visualization of DME Fuel (Hanyang Univ.)

Combustion Characteristics of DME Engine (KAIST)

Objectives Development of Fuel System and Combustion Technique for DME as a Alternative Fuel

Contents

Development of High Pressure Pump and Injector for DME Fuel Development of CommonCommon-rail DME Fuel Supply System Development of 33-liter CommonCommon-rail DME Engine Evaluation of Power and Emission Performance for DME Engine Investigation of CommonCommon-rail DME Vehicle

Design of Injector Nozzle and Needle using Nozzle Flow Model Production of DME Injector Prototype by 3D Design and Numerical Analysis Enlargement of DME Flow Rate Production of DME Injector

Nozzle Design of DME Injector Nozzle Design (Type II)

Specifications of Injectors

Nozzle Design (Type III & IV)

3D Design

Processing of Nozzle Hole

Leak, Response, Injection Rate, Fluctuation Rate of DME Injector Pulsation of Fuel Pressure Test Results of DME Injector

Experimental Set-up Leak Test

Injection Rate

Multi-Injection (I)

Multi-Injection (II)

Comparison of spray visualization test results with numerical analysis Breakup and evaporation of DME droplet occur rapidly in the early period of injection Momentum magnitude of droplet is directly related to the droplet break-up Spray Development and Pattern

※ Experiment & analysis condition Fuel pressure : 350 bar Ambient pressure : 50 bar

Comparison of Test with Analysis

Design and production of high pressure pump for DME fuel DME High Pressure Pump 1st DME High pressure pump (3L)

2nd DME High pressure pump (3L)

Type

Eccentric cam

Wobble plate

No. of plunger

2

5

Bore (mm)

9

10.5

Stroke (mm)

10

-

Flow rate (kg/h)

50@1,000 rpm

135@2,000 rpm

System pressure (bar)

600

500

Speed (rpm)

2,000

2,000

Photo

Specification analysis of high pressure pump Performance test on effect of inlet metering valve, inlet fuel pressure, and common-rail pressure Experiment Setup

Test Results of DME HP Pump Analysis of Required Flow Rate

Effect of Inlet Pressure

Effect of C/rail Pressure

Specification of Common-rail DME Engine Item

Specification

Displacement Volume

2,902cc

Bore × Stroke

98 mm × 101.5mm

Compression Ratio

17.4 : 1

Idle speed

800 ± 10 rpm

Intake timing

BTDC 26° / ABDC 50°

Exhaust timing

BBDC 72° / ATDC 32°

Fuel system

Common-rail direct injection

Performance Test of DME Engine

Installation of DME HP Pump

Installation of DME Injector

Calibration of fuel rate, fuel pressure, injection timing, injection duration, boost pressure, and EGR rate Development and application of control logic for cold starting ECU System of DME Engine Universal ECU : MotoTron Built-in Algorithm : CI Base(Diesel) Engine Controller MotoTune : ECU Calibration Tools Universal Injector Driver : Control of DME Injector ECU Calibration of DME Engine

ECU System of DME Engine

Common-rail DME Engine

DME Fuel Supply System

Emission of DME Engine (Tailpipe-out )

Optimization of Flow Rate, Injection Timing, Injection Duration, Fuel Pressure and EGR rate of DME Engine DME Engine Calibration Fuel Consumption

EGR Rate

Main Injection Timing

Injection Duration

1.7 times for Fuel Consumption of Base Diesel Engine Fuel Consumption of DME Engine

80% for CO2 Emission of Base Diesel Engine CO2 Emission of DME Engine

Emission DME Engine (Engine-out)

Installed DME Fuel Supply System for DME Vehicle Developed Drivability of DME Vehicle using Calibration Data of DME Engine Max. DME Vehicle Speed : 110km/h Fuel Economy of DME Vehicle : 5.7km/L Common-rail DME Vehicle

Common-rail DME Vehicle Road Test

NEDC Mode Test

The injector and high pressure pump for DME fuel were developed, and the DME-fueled engine was made with 3-liter diesel engine of a common-rail direct injection system. The ECU system for common-rail DME engine was developed, and the power performances and emission characteristics of DME engine were investigated with this system. DME engine had over 90% full torque performance in comparison with base diesel engine. The emission performance of DME engine is the same as that of base diesel engine under equal EGR rate by the optimization of injection timing, injection duration, and fuel pressure of DME engine. The drivability of DME vehicle was developed using calibration data of DME engine and DME fuel supply system. 5.7km/L was achieved in the fuel economy of DME vehicle.