OF DIESEL ENGINE SPARK ARRESTOR WITH EXPERIMENTAL VERIFICATIONS

By Eng. Mohamed Mostafa Mohamed Farid Ammar B.SC., 2010 Akhbar EL-Yom Academy

A Thesis Submitted to the Faculty of Engineering at Cairo University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE in MECHANICAL DESIGN AND PRODUCTION ENGINEERING

Under the Supervision of

Prof. Dr. Tarek Abd El-Sadek Osman

Dept. of Mechanical Design and Production Engineering Faculty of Engineering, Cairo University

Dr. Waleed Mamdouh El-Sallamy

Dept. of Mechanical Engineering and Printing Technology Akhbar El-Yom Academy

FACULTY OF ENGINEERING, CAIRO UNIVERSITY GIZA, EGYPT 2016

Engineer's Name: Mohamed Mostafa Mohamed Farid Ammar Date of Birth: 08/08/1988 Nationality: Egyptian E-mail: [email protected] Phone: 02-01288036107 Address: Nasr El-Din, El-Haram, Giza Registration Date: 1/10/2011 Awarding Date: .../.../2016 Degree: Master of Science Department: Mechanical Design and Production Engineering

Supervisors: Prof. Dr. Tarek Abd El-Sadek Osman Dr. Waleed Mamdouh El-Sallamy

Examiners: Prof. Dr. Tarek Abd El-Sadek Osman (Thesis main advisor) Prof. Dr. Mohamed Alaa Eldin Radwan (Internal examiner) Prof. Dr. Mohamed Mahmoud Youseef (External examiner) Prof. of Automotive Engineering and Tractors, Faculty of Engineering, Minia University

Title of Thesis:

Design and Modeling of Diesel Engine Spark Arrestor with Experimental Verifications

Keywords: Spark arrestor; Ember; Fire, Explosion; Automotive; Diesel Engine

Summary: All diesel engines produce exhaust carbon particles. These particles are originated from the carbon deposition formed on the internal surfaces of the exhaust system and the engine. Then they may be expelled at high temperature to the atmosphere. Particles diameter larger than 0.58 mm and at temperature 649oC could ignite flammable materials upon contact, so Spark Arrestor plays critical role in impeding the embers emission as it is a device that arrests the embers and the sparks. The aim of this study is to make theoretical modeling and experimental verification to compare between two new models of diesel engine Spark Arrestors and a commercial Spark Arrestor in terms of the collection efficiency and acoustics.

Acknowledgments

First and foremost, Praise be to Allah for his help in starting this work and completing it. I would like to express my boundless gratitude and sincere appreciation to my parents, and my beloved sister for their continuous support, and encouragement overall the previous years. I would like to thank Dr. Tarek Osman, Professor of Mechanical Design, my role model, for supervising this investigation and for his encouragement, great support, valuable advices, kindness and sincere help, and for his support in my practical life. Also I would like to thank Dr. Waleed El-Sallamy, Assistant Professor of Mechanical Design at Akhbar El-Yom Academy, for suggesting this work which represents the link between the university researches and the industrial problems, also for his great support and valuable guidance throughout the course of this work from the very beginning till now, and also for his great support in my practical life. I would like to thank Dr. Tamer Elnady, Associate Professor of Design and Production department at Ain Shams University, for supporting this work, his valuable guidance throughout the course of this work, and for helping me in accomplishing the tests of this work in ASU Sound and Vibration Laboratory at Ain Shams University. It is with gratitude that I acknowledge all the staff of ''AL MOHANDES INTERNATIONAL Co.'', especially Dr. Mohamed Khamis, Chairman, and Eng. Khairy Raouf, The Head of Mechanical Design Dept., for their support to complete this work by helping me in manufacturing these Spark Arrestors, measuring their Sound Insertion Loss, and also offering me time to conduct my measurements at Ain Shams University. Last but not least, I am very grateful to the staff of ASU Sound and Vibration Laboratory, especially my thanks to Eng. Weam Elsahar, Research Assistant, for his

Abstract

The sparks and embers which are produced from combustion sources could lead to fire and explosions as a result of ignition of flammable materials which are exposed to these emissions. There are many sources of combustion that produce embers such as internal combustion engines, wood burning stoves, steel mill, cement plant,...... etc, so Spark Arrestor plays critical role in impeding the embers emission as it is a device that arrests the embers and the sparks. The aim of this study is to make theoretical modeling and experimental verification to compare between two new Prototypes of Diesel Engine spark arrestor and a commercial spark arrestor in terms of collection efficiency, acoustics, pressure drop, and cost. COMSOL software using finite element is used to model the collection efficiency while SIDLAB using two-port theory is used to model the acoustic characteristics. The two new Prototypes A and B were manufactured and tested to verify experimentally the theoretical modeling through the different test rigs. Three different flow rates were selected for the experimental verifications. On the other hand, the three Spark Arrestors were experimented on a real diesel engine of 32 KW. The theoretical models of collection efficiency were shown to be matched with the experimental verifications for Prototype A within 98.8%, Prototype B within 92.5%, and the commercial spark arrestor within 89.4%. While the theoretical models of transmission loss were shown to be matched with the experimental verifications for Prototype A within 95.2%, Prototype B within 70%, and the commercial spark arrestor within 83%. And the theoretical models of pressure drop were shown to be matched with the experimental verifications for Prototype A within 93.75%, Prototype B within 98.27%, and the commercial spark arrestor within 90%. The three spark arrestors were experimented on real diesel engine at different loads in compliance with ISO 8528-10 for diesel engine generators. Complete arrest for sparks were shown during the period of the experiment and the insertion loss measured ranges from 5.3 to 13.5 dB. According to the theoretical modeling and measurement results in terms of collection efficiency, acoustic performance, and pressure drop of the three Spark Arrestors and their cost, the Spark Arrestor Prototype B was shown to have the best performance.

Chapter 1: Introduction

1.1. Preamble Fire and Explosion have serious effect on business, economy, and life. Inefficient design, inadequate maintenance and understanding of risks may be a result of fire and explosion, [1]. Companies which use flammable materials shall put in its account the fire safety. For example in petroleum companies the flash point of their substances shall be known and put in safety environment. The flash point helps in knowing the maximum temperature that these substances may be exposed without causing fire. This work focus on Spark Arrestors' design (collection efficiency and acoustics performance), in the field of diesel engines as Spark Arrestor is part of the exhaust system. Spark Arrestors are installed at locations where sparks may be dangerous to the surrounding environment, [1].They are provided on the exhaust of source or fire where a hot particulate might be released (i.e., internal combustion engines, chimneys, incinerator stacks, etc.). Spark Arrestor is used to prevent the risk of fire due to the burning of flammable materials caused by sparks emission from diesel engine exhausts, [2].As Spark Arrestor is a device traping exhaust carbon particles to a size below 0.58 mm in diameter. If particles larger than 0.58 mm in diameter and at temperatures of 649°C are expelled then it will be capable of igniting cellulose materials upon contact, [3]. Spark Arrestor is made from stainless steel, carbon steel, or aluminized steel as aluminized steel is used to resist heat, corrosive gases, and to extend service life of arrestor, [4]. Spark Arrestor place in most of engines is in exhaust manifold where the exhaust from each cylinder of the engine is collected. Then the exhaust flows out of the manifold to a spark Arrestor or muffler or both, [3]. The Spark Arrestor inclined more than 60 degrees from its efficient operating position may not arrest sparks adequately. As the United States Department of Agriculture (USDA) Forest Service Standard 5100- 1c allows 60 degrees deviation, but at least 15 degrees should be reserved for deviations because of road grade or slope, [3]. Spark Arrestors shall have a method for removing the cumulative carbon particles such as a cleanout plug, removable end cap, snap ring or a removable end cleanout, Figure (1.1) Draft generating chimney cap, [5] [3].

1.2. Literature Review This part will show the developments of Spark Arrestor from 1830 until now and there description. 1.2.1. Historical Background The need for Spark Arrestors initiated with the establishment of wood burning locomotives in 1830 as the first design of Spark Arrestors was wire netting cap put over the top of the smoke chimney, [5]. James P. Espy in June 29, 1833, [5] patented a spark arrestor. He termed it as “Draft Generating Chimney Cap," (Figure 1.1) contains fine wire mesh that the head of a pin could not go through the meshes, it stopped the sparks. In some cases the total opening area can be increased by opening the door.

Wm. T. James, [5], as claimed by Colburn, [5], in 1833, invented another Spark arrestor. This Spark Arrestor called “bonnet pipe” (Figure 1.2), [5]. It consists of an upside down cone fixed at its outer edge and placed over the mouth of the stack deflected the embers into a surrounding casing, while the exhaust gases pass through a wire netting which covers all the top of the outer casing.

The following Figure (Figure 1.3) shows a chimney to catch the sparks which was invented by Erskine Hazard, [6], in1835. It consists of cylindrical cap which is made of iron sheet, closed at the upper end, inverted over the top of the chimney at a distance sufficient for the smoke to pass out between the cap and the chimney. The diameter of the cylindrical cap is larger than the chimney. The cap is fixed using braces which is riveted to the chimney and cap. A sheet iron case of larger diameter than the cap surrounded the upper part of the chimney and is closed at the lower end, [6]. Figure (1.3) Erskine's Chimney plan, [6] The smoke path will be turned downward and outward, and the embers, having some weight, would continue their path into the case while the smoke would rise again out to the atmosphere between the cap and the outer case, [6].

The following figure (Figure 1.4) is a portion of a square box of sheet iron, placed on top of the chimney which was invented by Erskine Hazard, [6], in 1835. The top side and front side of the square box are entirely opened. At the rear side of the box, a conical pipe is inserted which passes backward and downward, to become nearly to the ground, either outside or between the tracks of the rail-road, [6]. When the engine is at rest, the smoke rise up, as usual, through the top opening of the box, but when the engine is in motion, the air that Figure (1.2) Bonnet, [5] passes through the rear side of the box and pipe will guide the sparks and smoke to the ground, and they would not probably rise in time to annoy the passengers, [6].

On March 31, 1836, William Schultz, [5], of Philadelphia, invented Spark Arrestor (Figure 1.5) in which the exhaust nozzles were passing through the netting.

Figure (1.5) Schultz’s Stack, [5]

Then Bonnet type was modified in the form of Yankee Stack (Figure 1.6), [5], in 1841. Then modified to Diamond Stack (Figure 1.7), [5], in which the outer casing was reduced in dimensions.

Figure (1.4) Erskine's Chimney low annoyance, [6]

The two inventions of Samuel Hall, [5], on Jan. 14, 1841, and on May 9, 1842, show the earliest smoke box deflectors made of metallic perforated plate, one passing around the front ends of the tubes vertically and the other above the front ends of the tubes horizontally, and the exhaust pipe passes through it into a straight open stack (Figure 1.8), [5].

Figure (1.8) Smoke Box, [5]

R. A. Wilder, [5], Engineer and Supervisor of the Mine Hill and Schuylkill Haven Railroad, invented Wilder Stack in 1854 (Figure 1.9). The Wilder stack smoke box is made of 0.375 inch iron, spark arrestor and chimney. A tapering pipe of rough wire texture of diameter 21'' at the top, 10'' diameter at the bottom, and 3.5' height, descends 10'' below the top of the smoke box. The exhaust pipes, with nozzles 3.5'' diameter each, joined with the bottom of this pipe, otherwise closed by a perforated iron plate. The heated air and sparks ascend Figure (1.6) Yankee Stack, [5] Figure (1.7) Diamond Stack, [5] around this netting pipe. The fine sparks will be thrown down through the wire netting pipe sides into large opening in the smoke box bottom, and then it will drop into a large iron box beneath. This sparks may be then discharged through the usage of a valve in the bottom of smoke. Figure (1.9) Wilder Stack, [5]

E. May, [5], of Boston, on July 28, 1857, invented a cylinder of screen wire mesh (Figure 1.10), extending from the exhaust pipes to the Chimney.

Figure (1.10) Beattie's cone, [5]

A. S. Sweet, Jr., [5], of Detroit, invented double cylindrical. Nothing more appears to have been done in this direction from June 23, 1863, until 1870, [5]. Hovey Spark arrestor was invented on May 29, 1860, by John Thompson, [5], of Boston. Then Jacob Hovey, [5], master mechanic of the Cleveland and Pittsburgh Railroad Company, attempt to improve it. As Hovey added horizontal deflectors of screen wire mesh above the upper row of the tubes to the Thompson extended smoke box. On April 7, 1863 since the Hovey's early and unsuccessful efforts, the smoke box system (Figure 1.11) has been taken by other parties by the New York and New Haven Railroad from time to time to develop it, as they have been interested in the arrangement of the deflectors. They put the vertical iron deflector in front of the flue head at a distance of about nine inches and at a distance of about twelve inches above the bottom of the smoke box. This deflector has perforations above its lower side for a short distance. Then they extend the horizontal screen wire mesh deflector, which is above the upper row tubes, from the flue head to few inches in advance of the exhaust nozzle which passes through it. A horizontal sheet of screen wire mesh has been added extending from the horizontal deflector to the front end of the smoke box. The screen wire mesh openings are the exit for the combustion products, [5].

Figure (1.11) Hovey Spark Arrester, [5]

Another modification for bonnet pipe which was designed by John P. Laird (Figure 1.12), [50], for the Pennsylvania Railroad about 1864, in which the outer casing size reduction appears to be the distinguishing feature, [5].

Farrand Spark Figure (1.14) Hughes spark arrester, [5] Arrestor (Figure 1.13), [5], was invented on August 19, 1873. The embers are deflected and separated by the deflection at the top of the stack forward and downward into the chamber. The exhaust gases escape through the two short vertical discharge flues Figure (1.12) John P. Laird’s Bonnet Pipe in 1864, [5] while the embers may be returned to the firebox.

The Hughes spark arrestor (Figure 1.14), [5], was invented on September 16, 1873. Its consists of a deflector which contains a central disk with two separate greater diameter rings above it, and an upper additional cone Figure (1.13) Farrand spark arrester, [5] which can be adjusted in a position to vary the draught, [5].

James Dredge, [5], London, 1879, invented the Smith stack (Figure 1.15), [5].The perforated cone has, in principle, no benefit more than the diamond stack. The Smith spark arrestor does not reduce in practice the amount of cinders and sparks expelled when it is compared with a bonnet or diamond stack, [5].

Figure (1.16) schematic diagram to the deflector, [7]

Rufus Hill’s Spark Arrestor (Figure 1.16 and 1.17), [7], 1883 is the deflecting plate D. it is supported in front of the flue sheet, directly above the upper row of tubes, and at a horizontal distant from the flue sheet sufficient to afford free discharge of the products of combustion from the top row of the tubes. The deflection plate D is inclined downwardly and outwardly from the flue sheet to its lower edge so this affords a uniformly increasing area of the horizontal discharge space between the plate and the flue sheet. The sides of the deflector D is connected to the shell of the boiler and to the smoke box to allow variations in the opening beneath this deflector as engine may be required. An adjustable section, d, is attached to the deflector D in its lower side by bolts which is passed through slotted holes so as to be lowered or raised as required.

Figure (1.15) Smith stack, [5]

Merle L. Benzer, [8], patented Spark Arrestor for Diesel Locomotive Engines (Figure 1.17) in 1964. The theory of this spark arrestor is that the chamber of spark arrestor received the diesel engine exhaust gas from the inlet pipe. This exhaust gas maybe associated with carbon particles in which this mixture impinges the inclined end plate at the inlet side which results in deflection of the mixture to the upper protuberance which then deflected to the lower protuberance and impinge it. The mixture then deflected to the inclined end plate at the outlet side which then the mixture deflected to the outlet. These impinges of carbon particles during its pass through the spark arrestor result in fragment of carbon particles, [8]. As shown in figure 1.17, the resulted eddies reduce the friction between the exhaust gas and the spark arrestor case, [8]. To reduce the back pressure, the outlet area shall be larger than the inlet area, [8].

Ronalled L. Hall, Oliver L. Greuel, [9], patented External Spark Arrestor (Figure 1.18) in 1992. The Spark Arrestor consists of four parts; Screen with openings diameter 0.1662 mm, Outer Cover with openings diameter 3.175mm, a Fastener, and a Tight Seal, [9]. This External Spark Arrestor is assembled with the muffler through a fastener over the exhaust port. The outer cover of Spark Arrestor protects the screen from physical damage and ensures contact of outwardly extending lip of the screen with outer shell surface of the muffler, [9]. The screen is used to arrest Sparks discharged by muffler and to form an Exhaust receiving chamber A. The screen is formed of fine wire mesh of openings 0.1662 mm in diameter that effectively arrest sparks associated the exhaust gas. The outer cover of Spark Arrestor is formed to provide another Exhaust receiving chamber B for receiving the sparks which pass through chamber A and the screen wire mesh. The Tight Seal is formed between the extending lip of the screen and the outer shell surface of the muffler as well as between center portion of the screen and the outer shell surface so that the exhaust gas may not escape around peripheral edge of the extending screen lip, [9]. The advantage of the External Spark Arrestor is that the assembly may be easily disassembled by removing a single fastener for quick and convenient servicing or replacement of the filter screen, [9].

Figure (1.18) External Spark Arrestor, [9]

Figure (1.17) Spark Arrestor for diesel locomotive engines, [8] engines

1.2.2. Spark Arrestor Acoustics Acoustics can be regarded as the science of sound and vibration. Spark Arrestors contain variable types of ducts and other baffles which affect the sound propagation inside it. In the next part, some patents will be discussed. P.S.Moller, [10], patented Exhaust Muffler and Spark Arrestor (Figure 1.19) in 1971. The spark arrestor depends on centrifugal force, [10]. The muffler consists of inlet pipe, circular cylindrical wall 13, Spiral wall 33, absorption material between the circular cylindrical wall and the spiral wall, ribs 63, plug used for removal of large carbon particles, support wall 36, and outlet opening 31 between ribs, [10]. The theory of this patent is that the exhaust gas discharges into the muffler through the inlet pipe. Then the exhaust gas passes through the muffler until it reaches the middle tube and discharges to the atmosphere through the outlet opening, but large carbon particles associated with the exhaust gas will never discharge to the atmosphere as a result of centrifugal force. The carbon particles pass with the exhaust gas until they reach the support wall. Then the carbon particles pass and precipitate behind the support wall in a position to be removed whenever the outlet plug is removed, [10]. While the sound waves represented by the dashed line 66 incident on the opposite wall, then they are reflected on the spiral wall. As the spiral wall is made either of an appropriate metallic screen or of a perforated metallic strip. If it made of a perforated metallic strip, the sound wave passes to the absorption material making the sound energy transfers to heat energy which mitigates the noise, [10].

a

Figure (1.19) Exhaust Muffler and Spark Arrestor, [10]

b

Paul S. Moller, [11], patented Engine Muffler and Spark Arrestor (Figure 1.20) in 1976. The muffler consists of inlet pipe, an outer tapered tube extends from the inlet pipe to the outlet portion 11, inner perforated cylinder, end wall 13, sound absorbing material as fiber glass, central tube, cups 21, resonator arrester 46, cap 51, and through bolt, [11]. The theory of this patent is that the Exhaust gas discharges into the Spark Arrestor Muffler through the inlet pipe. Then it travels through the inner perforated cylinder until it reaches the central tube and the end plate. The Exhaust gas that reaches the central tube will discharge directly through it, while the another part of the Exhaust gas will return back again to discharge through the central tube. Since the central tube is relatively narrow, so most of the kinetic energy in the gas is recovered in one direction of flow and the back flow is inhibited by the central tube. The gas then passes into the resonator arrestor, so the gas makes a sharp U-turn back upon itself Figure (1.21) Engine Muffler and Spark Arrestor Modification, [11] whereas the heavy embers are deposited in chamber. The Exhaust gas then travels in a reverse direction through the central opening in the annular nested cups as it prevented from traveling backward by the barrier wall 36. The flanges of the cups because of its thickness and inclination, the associated lead particles in the exhaust gas is intercepted and deposited on it. Then the Exhaust gas passes freely without lead particles through the narrow annular openings. Finally, the Exhaust gas discharges to the atmosphere through the outer openings between the outer edges of the nested cups, [11]. It is possible to assemble an array of any number of cups depending upon the desired capacity of the muffler and upon the amount of the exhaust area required, [11]. The sound waves which pass through the perforations in the inner tube to the absorption material will be dissipated as sound energy will be converted to heat energy.

Fig.1.21 is a modification to fig.1.20 as it is used for higher frequencies. The modifications which were happened in the inner tube allows higher gas Figure (1.20) Engine Muffler and Spark Arrestor, [11] velocity, the central tube becomes shorter, and also the wall 63 is extended to provide a short resonator tube 66. The sound attenuates because of the resonator arrester. The particles that associate the flow and reach the resonator arrester will precipitate in it and will never flow back toward the outlet, [11].

Theodore W. Ormond; Kenneth J. Kicinski, both of Stoughton, Wis, [12] patented Combination Spark Arrestor and Aspirating Muffler (Figure 1.22) in 1978, [12] which it is installed in vertical position for tractors. The muffler consists of outer oval tube, lower head, baffle 6, baffle 8, baffle 15, baffle 4a, perforated inner tube, plug , Venture, Louvers, Collection chamber 20 and air tube 24, [12]. The exhaust gas is introduced into the muffler through the perforated inner tube. Then the exhaust gas passes through the perforations in the perforated inner tube which is introduced to attenuate sound as sound energy passes through the perforations in tube to space between it and the outer oval tube. Then the exhaust gas passes through the openings between louvers. The exhaust gas is swirled outwardly against the inner surface of the tube. The solid particles having a greater weight will be thrown outwardly by centrifugal force against the inner surface of the tube and move downstream through the annular clearance between tube 12 and tube 14 into the collection chamber. A pair of cleanout plugs is threaded within holes at the bottom of collection chamber to permit periodic removal of the collected solid particles. Then the Exhaust gas discharges into the venture. Due to the conical shape, the exhaust gas increases its velocity with a resulting pressure drop to provide an aspirating action. The tube 14 is formed with a plurality of perforations 22 which provide communication between the throat section 19 and chamber 23. Air tube extends along the oval body where the inner end of the air tube communicates chamber 23 while the outer end is connected to the pre-cleaner of the engine, [12]. Due to pressure drop at the throat section 19 of the venture, air is drawn through the air inlet tube from the engine pre-cleaner and passes through the chambers 23 and perforations 22 into the throat section 19 for discharge through the venture, [12].

Kory J. Schuhmacher, Oregon, WI (US); Andrew D. Aleson, Madison, WI (US), [13], patented Compact Economical Spark Arrestor and Muffler (Figure 1.23) in 2001. The theory of this patent is that the muffler has a housing to get a silent exhaust flow from the inlet 14 to the outlet 16. The interior portion includes an inner and outer tube spaced radially. Between the inner tube and the outer tube there is a resonator chamber which is filled with packing material as it used to mitigate the sound energy. A cylindrical screen Spark Arrestor installed at inlet side as it is overlapped the outer pipe of the interior portion in concentric relation and is crimped by a crimp ring. As the exhaust gas discharges into the muffler through the inlet pipe then the exhaust gas and its associating particles pass to the tubular screen Spark Arrestor as carbon particles are blocked. Then the exhaust gas passes through the interior portion directly to the outlet pipe 16, [13].

Figure (1.22) Combination Spark Arrestor and Aspirating Muffler, [12]

Figure (1.23) Compact Economical Spark Arrestor and Muffler, [13]