Search Results

Effective heat transfer is the most important duty of an engine coolant. The heat exchange characteristics of the cooling system are primarily defined by the physical properties of the coolant, the presence of coatings and air resistance. Good heat transfer properties result in lower local temperatures (reducing the risk of corrosion at heat rejecting surfaces) and allow for more efficient engine designs (less coolant is needed to achieve the same amount of heat transfer, therefore, smaller radiators, heater cores and coolant overflow bottles could be used). If a coating is present, it not only interferes with heat transfer by acting as an insulator, but it may also result in hot spots from the uneven heat distribution and induce localized corrosion. This paper will compare the heat exchange characteristics of silicate and carboxylate-based engine coolants by measuring the rate of heat transfer in a heater core exposed to an air current.

The objective of this research was to characterize the effects of fuel component volatility on gasoline direct injection (GDI) engine cold start. Three different fuel components, representing gasoline light end, mid-point and heavy end components, were used to form three fuel blends of different volatility. Performance tests and in-cylinder fuel distribution imaging tests using these fuel blends were carried out in a firing single-cylinder optically-accessible engine following a simulated cold start test schedule. Performance results, based on in-cylinder pressure and engine-out hydrocarbon measurements, during the initial transient phase of GDI cold start showed significantly degraded performance with the low volatility fuel blend, while the high volatility blend showed slightly improved performance. Neither the low nor high volatility fuel, however, showed a discernable effect on the quasi-steady state cold start performance.

The effects of platinum and palladium catalysts on the enhancement of methanol combustion were investigated in a high pressure flow reactor and in a single-cylinder, D.I. Diesel engine. Initial studies were carried out in the flow reactor to determine the effect of catalyst temperature and equivalence ratio on the products of methanol combustion. Afterwards, Diesel engine studies were performed with in-cylinder catalysts applied to the exhaust valves in order to maintain high catalyst temperature required for high reactivity. Comparisons were based on performance, combustion characteristics, and emissions. Results of the flow reactor studies show that the catalytic ignition temperature, found to be 570 K, did not vary significantly with equivalence ratio. The Diesel engine experiments revealed that a decrease in glow plug temperature of 400 K was achievable while providing better performance and reduced emissions, including aldehydes, compared to the non-catalytic case.

Sequential four-ball wear tests have been used to evaluate automotive crankcase oils for use as heavy-duty hydraulic fluids and automotive crankcase lubricants. This test technique has been adapted for use with steel-on-steel, steel-on-ceramic and ceramic-on-ceramic bearing systems. In addition to the conventional “run in” and “steady-state” wear studies, the data produced have been used to interpret bearing unit load levels for the various bearing systems involved. The data produced show that in many cases hybrid bearing systems (steel-on-ceramic) and ceramic-on-ceramic bearing systems may be useful at higher unit loadings than the conventional steel-on-steel systems. These studies focused on achieving low boundary lubricated wear rates. The bearing unit loadings were obtained from the unit bearing pressures after the “run in” of the specific bearing system.

An experimental study of the effect of spark power on the growth rate of spark-ignited flame kernels was conducted in a turbulent flow system at 1 atm, 300 K conditions. All measurements were made with premixed, propane-air at a fuel/air equivalence ratio of 0.93, with 0%, 8% or 14% dilution. Two flow conditions were studied: a low turbulence intensity case with a mean velocity of 1.25 m/sec and a turbulence intensity of 0.33 m/sec, and a high turbulence intensity case with a mean velocity of 1.04 m/sec and a turbulence intensity of 0.88 m/sec. The growth of the spark-ignited flame kernel was recorded over a time interval from 83 μsec to 20 msec following the start of ignition using high speed laser shadowgraphy.

Flame kernel growth and cylinder pressure data were simultaneously obtained from an optically-accessible, square piston, SI engine. Flame kernel growth was measured using simultaneous, orthogonal, Schlieren photography, while cylinder pressure was measured using a piezoelectric pressure transducer. The data were analyzed on a cycle-resolved basis to determine the correlation between cyclic fluctuations in flame kernel growth and cylinder pressure. The engine was operated at 875 RPM with premixed, prevaporized, stoichiometric isooctane in air. The engine, designed with ported intake and exhaust, was fired every tenth cycle to ensure complete scavenging. Tests were conducted with and without nitrogen dilution, while ignition timing was fixed at 25° BTDC. With 0% dilution the percent variation in the maximum cylinder pressure was 8.5%, while with 10% dilution the percent variation increased to 14%.

The majority of crankcase lubricants are now formulated to contain polymeric additives to improve the viscosity temperature properties to provide a better lubricating film in the various bearing systems in an internal combustion engine. These VI (viscosity index) improved lubricants are non-Newtonian under the high shear conditions that exist in most automotive bearing systems. The conditions of interest range from starting the engine at temperatures of as low as -40°C to operating the engine at normal operating conditions including bearing temperatures of 150°C or higher. This paper presents a method for predicting the viscosity shear relationship for a series of SAE multigrade engine oils as a function of temperature and shear stress. The method is demonstrated using three types of polymeric VI improvers currently used in SAE multigrade engine oils. The polymer types include olefin copolymers (OCP), polymethacrylates (PMA), and styrene-isoprene copolymers (SI).

This paper summarizes an investigation of the changes in combustion and particulate emissions caused by thermal barrier coatings placed in the combustion chamber of a diesel engine. The engine was a Yanmar TS 180 single cylinder diesel utility engine with a continuous rating of 15 HP (11.2 kw) @2400 RPM. The test protocol was the International Standards Organization (ISO) 8178 Standard Type-E3 test which simulates a marine diesel engine. Total particular matter emissions were measured by collection on Pallflex, filters via fractional sampling using a Sierra Instruments BG-1 Micro-Dilution Test Stand. The engine was operated with and without the thermal barrier coatings. The coated parts are the piston crown, the cylinder head (fire deck), and the valves. Scanning electron micrography (SEM) provided analysis of particulate size, microscopic structure and elemental composition of the particulate samples.

Investigations have concluded that methane does not appear to be photochemically reactive in the atmospheric system and does not participate in smog formation. Since methane is “nonreactive,” and may in the future be excluded from the total unburned hydrocarbon emissions, an instrument was designed and developed (termed the “methane analytical system”) enabling methane emissions to be quantified separately from total unburned hydrocarbon emissions. The instrument employed gas chromatographic principles whereby a molecular sieve column operating isothermally separated methane from the nonmethane hydrocarbons. Direct on-line sampling occurred via constant volume sample loops. The effluent was monitored with a flame ionization detector. The instrument was fully calibrated (i.e., extremely linear response over a large concentration range) for use with Diesel engines as part of an ongoing alternative fuels research program.

The effects of intake-generated swirl and tumble on cold start performance have been investigated in a firing single-cylinder Gasoline Direct-Injection (GDI) engine. The engine utilizes a Ford Zetec cylinder head modified for GDI operation and a fused silica cylinder which provides extensive optical access to the combustion chamber. Uniquely designed port-inserts were positioned in the intake ports to generate enhanced swirling or tumbling motion inside the cylinder. Experiments were conducted using a constant speed (∼ 900 rpm) simulated cold start procedure, where the engine is motored for approximately 40 cycles, after which fuel injection and spark ignition commence and continue for 190 cycles and then the engine is stopped. Measurements were made of the various engine temperatures, engine-out total hydrocarbon emissions, and in-cylinder pressure throughout the test period.

Thermal barrier coatings have been shown to be effective at reducing particulate emissions from diesel engines. Prior work by the authors has demonstrated a significant decrease in particulate emissions from a thermal barrier coated, single-cylinder, indirect injection (IDI) diesel engine, primarily through reduction of the volatile (VOF) and soluble (SOF) fraction of the particulate. Most of this prior work relied on conventional, commercially available, petroleum-based lubricants. Recently, the authors demonstrated additional particulate emissions reductions when a high oleic sunflower-based lubricant was used instead of a conventional petroleum-based lubricant. This paper concerns the manner in which the particulate was reduced, and reports on the changes in particulate composition and morphology between the two lubricants. Composition was examined quantitatively through thermal analysis of the particulate from a single-cylinder IDI diesel engine.

For several years now, organic acid based coolants and heat exchange fluids have been introduced on the automotive and industrial market place. The organic acid based coolants provide improved high temperature aluminum corrosion protection and longer drain intervals when compared to traditional coolants. In order to evaluate the organic acid based coolant quality in the field; the end user needs to be able to check several physico-chemical parameters of the coolant. First of all the amount of carboxylate based inhibitors should be determined because the customers can top the system with water. As a result the carboxylates can drop under the minimum required inhibitor level.

A fleet test using Propylene Glycol (PG) based coolant, recycled PG based coolant and PG mixed with ethylene glycol (EG) coolant was conducted using a fleet of employee vehicles. These coolants were all formulated using extended life, silicate free additive technology. This fleet consisted of a wide range of vehicle types and was run to verify the effectiveness of utilizing a PG based coolant across a broad spectrum of vehicle types. The results from this fleet test will be discussed. Results will include coolant analysis, parts inspection and vehicle repair histories. The environmental (toxicological) benefits of such a coolant will also be discussed.

Previous studies examined the effect of low levels of silicate (∼<75ppm Si) on hot aluminum corrosion protection. The corrosion protection provided by different coolant technologies was evaluated at different silicate levels. The results indicated that small amounts of silicate have a negative effect on the corrosion protection of aluminum. This work will examine these results and evaluate the effectiveness of different laboratory tests for determining coolant “compatibility.” Results will be examined from several bench and fleet tests showing the effect of coolant mixing on the corrosion rates in various environments. The bench test results will include laboratory glassware and dynamic tests that have been used historically to evaluate coolant compatibility. Differences between the test methods will also be evaluated to determine the relevance of each test procedure in light of the fleet observations.

Several oxygenates have been proposed and tested for use with or as diesel fuel. This paper examines two such oxygenates, CETANER™ and dimethyl ether (DME), partially or wholly produced by Air Products and Chemicals, Inc's Liquid Phase Technology. In previous studies on a single cylinder compression ignition engine and a Volkswagen TDI four cylinder engine, significant reductions in particulate matter emissions were observed with blends of CETANER™ in diesel fuel. In this study, experiments were performed on a multi-cylinder Navistar 7.3L Turbodiesel engine confirmed and extended the observations from the earlier studies. This is an important step in not only showing that the fuel does perform on each type of engine in similar fashion, but also in showing that DME and its derivatives can give consistent, significant results in lowering emissions. The oxygenated fuels were blended to achieve a net addition of 2 wt.% oxygen in the blended fuel.