Tóm tắt luận án tiến sĩ research on the use of ULSD biodiesel fuel blend on marine diesel engines

Due to this reason, the combination of two fuel types such as ultra viscosity ULSD and high-viscosity Biodiesel BO fuel aiming to form a new fuel type, which satisfies not only the requi

TRAN VIET DUNG

RESEARCH ON THE USE OF ULSD-BIODIESEL FUEL

BLEND ON MARINE DIESEL ENGINES

Speciality: Mechanical Engineering

Code: 9520116

Supervisors 1: Assoc Prof Dr Hoang Anh Tuan

Supervisors 2: Prof Dr Le Anh Tuan

PHD DISSERTATION SUMARY

HO CHI MINH CITY - 2021

1

Supervisors 1: Assoc Prof Dr Hoang Anh Tuan

Supervisors 2: Prof Dr Le Anh Tuan

This dissertation can be found at the library:

- Library of Ho Chi Minh City University of Transport;

- Nationnal Library of Viet Nam

INTRODUCTION Urgency

The International Maritime Organization (IMO) mandated the use of ultra-low sulfur diesel (ULSD) fuel in shipping from January 1, 2020 Compliance with the new regulation on sulfur content in the fuel used for ships when ships operate in

an emission control area can be achieved by using fuel with a sulfur content of 0,0015% at all times of ship operation or switching from high-sulfur fuel to 0,0015% sulfur fuel when the ship enters an emission control area

Fuel switching during the ship operation can present a number of problems related to fuel characteristics such as viscosity, lubricity, flash point, combustion quality Therefore, for ships using ULSD fuel, it is necessary to equip a cooler system to overcome the disadvantage of ultra-low viscosity like ULSD

Due to this reason, the combination of two fuel types such as ultra viscosity ULSD and high-viscosity Biodiesel (BO) fuel aiming to form a new fuel type, which satisfies not only the required viscosity and renewable properties but also the requirement of reducing the cost of ship operation will have a great significance in terms of economy, technology and emissions However, the homogeneity of the fuel after mixing is found to depend mainly on the mixing method

low-Currently, mechanical fuel mixing technologies have been being mainly used, indicating that the quality of mixed fuel only stands at an acceptable level as well

as the mixing time is quite long Meanwhile, using ultrasonic waves to create shocks from the bubbles appearing within the 2 liquid phases is considered as a potential solution to improve the homogeneity of the 2 liquid-phase blend such as ULSD fuel and Biodiesel

Based on the above-mentioned reasons, the method of using ultrasonic waves has been chosen to mix ULSD and Biodiesel fuels to produce a homogeneous fuel type with some properties similar to traditional diesel fuel for the using purpose for ships aiming to meet IMO regulations, to reduce operating costs, and to protect the environment

Therefore, the issue of "Research on the use of ULSD-Biodiesel fuel blend

on marine diesel engines" was selected as a novel topic in this doctoral

dissertation

Goals

- Overview on solutions of using ULSD fuel for marine diesel engines;

- Research, design, and fabrication of equipment/system using ultrasonic waves

to produce homogeneous fuel blend of ULSD and Biodiesel;

- Carrying out experimental studies to evaluate the techno-economic aspects, and emission and combustion characteristics, and performance parameters of a marine diesel engine when using the homogenous fuel blend of ULSD-Biodiesel

as an alternative fuel

Object and scope

- Small ship diesel engines with the range of power from 50 hp to 100 hp;

- Traditional diesel fuel with 0.05% sulfur content, ULSD with 0.001% sulfur content, and Biodiesel originated from coconut oil;

- Fabrication of ultrasonic wave-based equipment/system to produce homogeneous fuel blend;

- Fuel supply system, exhaust system, and control and test system of the engine;

- Testing equipment for engine power and emissions parameters

Methodology

- Theoretical research methods on the breakup mechanism of molecular structure by ultrasonic waves with experimental studies on determining the relationship between ultrasonic power and wavelength were applied;

- Updated models associated with the fuel injection, mixture formation, and combustion in diesel engines as using ULSD-Biodiesel homogenous fuels in order to evaluate the influence of ULSD-Biodiesel homogenous fuels on the economic and technical parameters of the tested diesel engine were studied;

- The experimentally controlled method to evaluate the impact of switching marine diesel engines using ULSD-Biodiesel homogenous fuels on the economic and technical parameters compared to the case of using traditional diesel fuel was used In addition, The injection characteristics of ULSD-Biodiesel homogenous

fuels were also performed as a basis for explaining the process of fuel-air mixture formation, combustion, and emissions

Scientific and practical significance

Scientific significance

The results obtained from this doctoral dissertation are considered as a reliable scientific basis and could be used as a good reference for research institutes and universities in the maritime field for teaching and researching the use of very low sulfur fuel for marine diesel engines

Practical significance

Combining ultra-low viscosity fuel (ULSD) with high-viscosity Biodiesel fuel

to form a homogeneous blend with the required viscosity, renewable properties, and reduced operating costs has offered great significance in terms of economy, technology, and emissions

Novelty

- Building and systemizing the theoretical basis for homogenous mixing of two liquid phases by ultrasonic waves;

- Successful design and fabrication of a system for produce a homogenous blend

of ULSD-Biodiesel by ultrasonic waves aiming to meet the current technical and quality standards of Vietnam;

- Carrying out the standard tests and critical evaluation of the techno-economic characteristics of marine diesel engines when using ULSD-Biodiesel homogenous fuel blend

Structure

The doctoral dissertation consists of an introduction, 4 chapters of main study content, a general conclusion, and a development direction The entire doctoral dissertation is presented in 123 pages, 27 tables, and 56 figures and graphs

CHAPTER 1 OVERVIEW 1.1 Overview of fuels used for marine diesel engines and MARPOL 73/78 Annex

1.2 Overview of ULSD fuel

1.2.1 ULSD properties

Fuel with sulfur content up to 0.0015% is called ultra-low sulfur fuel (ULSD), up to 0.05% is low sulfur diesel (Low Sulfur Diesel) and up to 0, 5% is conventional diesel

1.2.2 Study trend on using ULSD

1.2.2.1 Direct use of ULSD

Deniz F Aktas [4] studied the corrosion characteristics of ULSD Mayekawa [5] investigated and designed the cooling system for MGO and ULSD fuel to equip ships operating in ECA emission control areas

1.2.2.2 Blending ULSD with Biodiesel

The characteristics of ULSD fuel can be overcome by mixing ULSD with 1–2 vol% biodiesel as the research results of Lin et al [7]

Mangus et al [11] conducted experimental studies by examining temperature liquid flow, low-temperature filter clogging and striation points of seven biodiesel types blended with ULSD to provide information and data on the cooling liquid flow of ULSD as used for diesel engines Andrew M Duncan [12] reported that after mixing ULSD with Biodiesel at the ratios of 5, 10, 20, 40, 80%,

low-it showed that the fuel viscoslow-ity reached the optimum result wlow-ith the ratio of 5%, 10%, and 20% Biodiesel Lin et al [14] conducted a study (canola methyl ester)

on blending biodiesel with ULSD and compared the as-prepared fuel blend with standard fuel sources

1.2.3 Study trend on fuel-mixing technology

The mixing chamber with the help of mechanical impellers (turbine-typed

impellers) was proposed to mix fuel [21]

1.3 Scientific basis of the doctoral dissertation

The key point of this doctoral dissertation is to find a solution that combines the use of ULSD and biodiesel without the need for a converting device Therefore, it reduces both costs in operation and harmful emissions to the environment At the same time, it could meet the requirements when ships operate

in SECA Based on, the experience and research results, it shows that, CO, HC,

and soot emissions are reduced, while NOx emissions increase when using Biodiesel

Besides, when using ULSD for ships, it could completely reduce SOx emissions The combination of these two fuels into a homogenous fuel is the research direction that has been taken into account by some countries around the world, but it has not yet come up with a solution to ensure the homogeneity of the two fuel types after mixing Thus, the use of ultrasound for blending of ULSD and Biodiesel aiming to produce a homogeneous fuel having a viscosity similar

to that of traditional diesel fuel is a very effective solution

In Vietnam, up to now, there have been a number of studies on solutions to convert marine diesel engines to the use of a blend of biodiesel and petroleum through the design of propeller-type stirring mixers to continuously add vegetable oil - diesel blend for marine diesel engines However, the mass and size of the assemblies are quite cumbersome, difficult to install in the very limited space of the ship's engine room, and the blending quality is not good if it is not heated before mixing

Therefore, in order to improve the homogeneity of the fuel after mixing, and at the same time, to reduce the size and accompanying equipment for the mixing system so that it can be easily integrated into the fuel system on board ships, the solution proposed by the author here is to use ultrasound technology to mix the fuel of biodiesel and ULSD

1.4 Conclusion of Chapter 1

By understanding the research trend in Vietnam and abroad, the use of the ULSD-Biodiesel fuel blend on ships could be considered as a basis for the author

to find the gaps that need to be studied for this doctoral dissertation Direct mixing

of ULSD with biodiesel by applying ultrasound technology is deemed as an effective solution to improve the low-viscosity characteristics of ULSD and to ensure energy security for the shipping industry when fossil fuel resources are depleting

CHAPTER 2 THEORETICAL BASIS OF MIXING ULSD AND BIODIESEL FUEL AND APPLICABILITY IN DIESEL ENGINES OF

SHIPS 2.1 General introduction

2.2 Theoretical basis of mixing fuel

The mixing of liquids is understood as the transformation of a heterogeneous system into a homogeneous system A compound of a liquid is said to be homogeneous or homogenized when the fused structure of any volume fraction

of a large body of liquid does not differ from the average fused structure of the whole mass

2.2.1 Some typical mixing principles

- The vane type (the simplest one);

- Grinding mixers;

- Mixing equipment

2.2.2 Some typical mixing equipment

- Straight S-shaped static mixer;

- Stirring type mixing device

2.3 Theoretical basis of calculation for ultrasound-generating device

- Formation of bubbles in the solution;

- Number of bubbles formed in the solution;

- Factors affecting the formation of bubbles in solution;

- Mechanism of bubble development and bursting;

- Dynamic analysis of bubbles

2.4 Theoretical basis for evaluating the feasibility of mixing equipment

In principle, biodiesel and ULSD are not miscible This requires equipment capable of disrupting the structure of two fuel molecules Therefore, ultrasonic mixing is the most advanced method to form emulsions with small sizes at a large processing scale

2.5 The theoretical basis of combustion of ULSD-Biodiesel fuel blend in marine diesel engines

- Combustion process;

- Emission formation mechanism: Including NOx, soot, HC, and CO emissions

2.6 Conclusion Chapter 2

In Chapter 2, the author has learned the theoretical basis of calculation, the equipment for mixing fuel by ultrasonic waves to create the basis for the calculation and design of the ULSD and biofuel mixing system

At the same time, the theories of combustion and emission formation of diesel engines when using ULSD-Biodiesel blend were also studied by the author as a basis for experimenting with ULSD-Biodiesel blend on diesel engines

CHAPTER 3 DESIGN, MANUFACTURING, AND ASSESSMENT OF ULTRASOUND MIXING-EQUIPMENT QUALITY FOR ULSD AND

BIODIESEL 3.1 General introduction

Based on the theoretical bases presented in Chapter 2, the author successfully calculated and designed the ultrasound mixing system for ULSD and Biodiesel, satisfying the technical requirements in QCVN 1:2015/ BKHCN

3.2 Design of ultrasound mixing device

3.2.1 System overview

The central controller has the role of generating a variable frequency ultrasonic signal, the ultrasonic signal is fed into the buffer and isolation controller Then the ultrasonic signal is fed to a large power amplifier to drive the speaker to generate ultrasonic waves through the mixing tank

3.2.2 Control system hardware design

- Control block;

- Power amplifiers;

- Ultrasonic transmitter

3.2.3 Calculation and selection of liquid fuel tanks in ultrasonic processing

Building technical criteria for the continuous mixing equipment of coconut oil-based biodiesel and ULSD oil is based on the following standards:

- SOLAS Code 74 specifies requirements for fuel systems for marine diesel engines and safety requirements;

- Technical standards for liquid mixing equipment to achieve the quality of the liquid blend after mixing The technical standards here are related to the mixing time, the size of the mixing tank, the working mode of the mixing process;

- Flow pattern of the liquid in the mixing tank when different ultrasonic frequencies are applied

The equipment for continuous mixing of coconut oil-based biodiesel and ULSD is built on the basis of using ultrasonic generators for the purpose of producing a fuel blend of high quality The continuous mixing device ensures a constant supply to the engine and a balance between the amount of fuel supplied

to the mixer and the fuel consumption of the engine

For mixing equipment of coconut oil-based biodiesel with ULSD for marine diesel engines, the volume requirement of the mixing tank has not been specified However, for ships using heavy oil (FO) and diesel fuel (DO), there is also a mixing tank on board but only used for the purpose of mixing when converting fuel type

Figure 3 11 System model with vertical amplifier

3.3 System model design

There are two system layout options: A system model with a horizontal amplifier and a system model with a vertical amplifier

The principle of operation of the ultrasonic mixing device is suitable for all subjects When powered on, the system operates in the default mode of 28KHz of

ultrasonic waves Users can set the operating mode of the system such as allowing

to set the parameters of system operating time and ultrasonic power

From the above analysis, and in accordance with the processing conditions and equipment available in the country today, the study will choose a system with a fuel tank with a vertical amplifier as shown in Figure 3.11, with the following parameters:

- Dimensions of the fuel tank (length, width, height):

LxBxH = 250mmx250mmx250mm

- Number of ultrasonic amplifier heads: 9 (pieces)

- Ultrasonic source with power: 900W

3.4 Evaluation of the blend quality of ULSD and Biodiesel

The author conducted experiments with 8 samples at different blending ratios

to prepare ULSD and COB blends based on the correlation of viscosity in order

to find the optimal blending ratio for ULSD and COB

As a result, the stability of the ULSD-COB emulsion reached 98.5% after 17 min of ultrasonic treatment with a mixing ratio of 50% (ULSD): 50% (COB) in the case of ultrasonic horn tip to tip distance of 90 mm In addition, the similarity

of injection characteristics, penetration length, and cone angle, for ULSD-COB emulsion compared with diesel oil was reported The ultrasonically generated ULSD-COB emulsion provides ultra-low sulfur fuel and increased oxygen content The fuel mix diagram in this test is arranged as H.3.12

Figure 3 12 Diagram of ultrasound-based fuel mixing system

3.4.1 Selection of ULSD-COB blending ratio

It can be clearly seen that the viscosity (µ) of the ULSD-COB blend with 50% ULSD and 50% COB is 3.70 cSt compared with 3.60 cSt of DO at 30°C The viscosity (µ) of the ULSD-COB blend is 2.7% higher than that of DO But since the deviation is less than 5%, the mixing ratio of the ULSD-COB blend as presented is considered as the most suitable value The 50%:50% blending ratio for ULSD and COB was selected to perform the next experiments

3.4.2 Effect of horn tip position on the stability of the ULSD-COB blend

The effect of ultrasonic horn tip position on the stability of the ULSD-COB emulsion for a blend of 50% COB and 50% ULSD prepared after 10 min of ultrasonic treatment is shown in Figure 3.13

Figure 3 13 Relationship between SEP (stability of emulsion phase, %) and the distance from the bottom to the top of the ultrasonic horn tip h (mm)

The relationship between the distance from the ultrasonic horn tip to the bottom of the emulsification chamber h (mm) and the degree of stability of the produced ULSD-COB emulsion is clearly observed in Figure 3.13 The lowest stability of the ULSD-COB emulsion is only 86.2% when h = 5 mm, and it increases with the increase of h distance The highest degree of stability is 98.5% with the longest distance h = 90 mm

3.4.3 Properties of ULSD –COB emulsion

After 10 min of ultrasonic treatment, the properties of the ULSD-COB emulsion were determined and measured on the basis of the above-mentioned instruments The results on three characteristics of ULSD-COB emulsion including density, kinematic viscosity, and surface tension are given in Table 3.1 However, the remaining key parameters were LHV and CN related to the

combustion of the ULSD-COB emulsion which was predictable and the CN of COB was higher than ULSD and DO Meanwhile, the LHV of COB was not significantly lower than that of ULSD and DO

Table 3.1 Properties of ULSD-COB emulsion after mixing

is very small, equal to 0.54% Finally, the SEP and µ of the ULSD-COB emulsion

as a function of the ultrasonic treatment time at a distance (h) of 90 mm are plotted

in Figure 3.14

Figure 3.14 Change of SEP (%) and kinematic viscosity (KV) of ULSD-COB

emulsion with various ultrasonic times (t) at h = 90mm

Figure 3.14 shows the change of SEP and this change increases sharply in the first 10 min After that, the SEP changed insignificantly and was kept relatively stable Similar changes in µ also occurred after 10 min of ultrasonic wave treatment However, the trends of SEP and µ seem to occur in opposite directions,