scholarly journals The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures. II.—Pentane-air mixtures

1933 ◽  
Vol 143 (848) ◽  
pp. 168-176 ◽  
Keyword(s):  
Atmospheric Pressure ◽  
Internal Combustion Engines ◽  
Critical Pressure ◽  
Initial Pressure ◽  
Spontaneous Ignition ◽  
Combustion Engines ◽  
Compression Method ◽  
Ignition Point ◽  
Hydrocarbon Combustion ◽  
The One

In a recent communication an account was given of an investigation into the influence of varying initial pressure on the spontaneous ignition of butane-air mixtures. Whereas at atmospheric pressure the known values of ignition temperatures for these mixtures were between circa 550 and 600°C. at higher pressures as, for example, those employed in the adiabatic compression method they had been located at circa 300°C. By progressively increasing the pressure from atmospheric to 15 atmospheres we were able to show that the ignition points actually fell into two well-defined groups the one above 450° C. for pressures not exceeding about 3 atmospheres and the other below 370°C. for higher pressures. Transference of an ignition point from the higher to the lower group occurred at a definite critical pressure which depended upon the composition of the mixture. This new features of hydrocarbon combustion seemed of undoubted importance in regard to the phenomenon of "knock" in internal combustion engines, the more so when it was discovered that the presence of 0·05% of lead tetraethyl was capable at pressure near the critical transition pressure of raising the ignition point from the lower to the higher group. On this account we have been determining the critical pressure regions in other explosive media and our results for pentane-air mixtures are incorporated in this paper.

scholarly journals The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures III—Hexane- and isobutane-air mixtures

1934 ◽  
Vol 146 (856) ◽  
pp. 113-129 ◽  
Keyword(s):  
Critical Pressure ◽  
High Pressures ◽  
Initial Pressure ◽  
Liquid Fuels ◽  
Spontaneous Ignition ◽  
Lower Range ◽  
Ignition Point ◽  
Wide Range ◽  
Temperature Ranges ◽  
Low Pressures

In two recent communications we described the results of investigations into the influence of varying initial pressure up to 15 atmospheres on the spontaneous ignition of butane- and pentane-air mixtures, showing that in each case the ignition were located in two distinct and widely separated temperature ranges, location in the higher range occurring at low pressures and in the lower range at high pressures. Transference of an ignition point from the higher to the lower range occurred sharply, at a critical pressure, which depended upon the hydrocarbon concerned and the composition of its mixture with air. The bearing of these observations upon the problem of knock was also discussed. A wide range of explosive media, comprising mainly the higher hydrocarbons contained in liquid fuels, is now being systematically studied, and the present paper summarizes the results obtained for hexane- and isobutane-air mixtures. So far, our results support the view (also recently endorsed by Neumann and Estrovitch) that the lower group of ignition points is the outcome of the survival and further rapid oxidation of certain intermediate bodies, a process favoured by high pressure. whereas the higher group results from ignitions mainly of the products of their thermal decompositions which are favoured by low pressure.

scholarly journals The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures. I.—Butane-air mixtures

1933 ◽  
Vol 141 (844) ◽  
pp. 484-493 ◽  
Keyword(s):  
Internal Combustion Engines ◽  
Elevated Temperatures ◽  
Internal Combustion ◽  
Adiabatic Compression ◽  
Spontaneous Ignition ◽  
Time Lags ◽  
Combustion Engines ◽  
Compression Method ◽  
Present Communication ◽  
Slow Combustion

As part of an investigation into explosions of various hydrocarbon-air media at elevated temperatures and pressures, we have recently been deter­mining the influence of varying initial pressures up to 15 atmospheres on their reactivities during slow combustion up to their ultimate ignition points. And as the results obtained in the experiments on the spontoneous ignition of butane-air mixtures have presented some very striking new features, which seem of undoubted importance in regard to the problem of “knock” in internal combustion engines, we are submitting them in the present communication. Hitherto, few investigators have determined spontaneous ignition tempera­tures under pressure and, in particular, little is known concerning the behaviours of mixtures with air of the higher members of the paraffin hydrocarbons. The principal research on this problem has been that of Tizard and Pye, who, employing the adiabatic compression method, found with pentane-, hexane-, heptane-, and octane-air mixtures that with compression ratios of 6·09 to 1 ignition occurred at temperatures of circa 300° C. which ( a ) were dependent upon the observed time-lags between compression and ignition, ( b ) varied but little with mixture composition, and ( c ) were lowered slightly as the paraffin series was ascended.

scholarly journals The influence of pressure on the spontaneous ignition of inflammable gas-air mixtures—the simpler olefines

1937 ◽  
Vol 160 (901) ◽  
pp. 174-187 ◽  
Keyword(s):  
Internal Combustion Engines ◽  
Chemical Reactivity ◽  
Time Lag ◽  
Spontaneous Ignition ◽  
Combustion Engines ◽  
Temperature Range ◽  
Cool Flames ◽  
Lower Temperature Range ◽  
Lower Temperature ◽  
Short Time

The investigations described in previous papers on this subject have related mainly to the paraffin hydrocarbons (Townend and Mandlekar 1933 a,b ; Townend, Cohen and Mandlekar 1934; Townend and Chamberlain 1936, 1937). It has been found that mixtures with air of the members containing three or more carbon atoms, while not spontaneously ignitible at low pressures below about 500° C., give rise abruptly to ignition at higher pressures in a temperature range between about 310 and 370° C., where normally only cool flames are initiated; and although neither methane- nor ethane-air mixtures appear to develop cool flames, the latter are ultimately ignitible in a lower temperature system which is less complex than that characteristic of the higher paraffins. Moreover, it is now recognized that “knock” in internal combustion engines arises in circumstances responsible for pronounced chemical reactivity in the unburnt explosive medium characteristic of that occurring in the lower temperature range (cf. Egerton and Ubbelohde 1935; Ubbelohde 1935), and the investigations referred to have indicated that the “knock-ratings” of the paraffins when used as fuels in such engines are related to the pressures requisite for the occurrence of spontaneous ignition in this range within an appropriate short time lag (Townend and Chamberlain 1936, p. 104, cf. Prettre 1936 a and b )

scholarly journals The slow combustion of acetylene

1937 ◽  
Vol 162 (911) ◽  
pp. 502-511 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Borosilicate Glass ◽  
Atmospheric Pressure ◽  
Early Stage ◽  
Initial Pressure ◽  
Ignition Point ◽  
Whole Process ◽  
Slow Combustion ◽  
Lower Temperature ◽  
Explosive Combustion

In 1905 one of us in conjunction with Andrew published the results of extensive experiments upon the combustion of acetylene which showed that when a 2C 2 H 2 + O 2 or C 2 H 2 + O 2 mixture was sealed up in borosilicate glass bulbs at atmospheric pressure and afterwards heated, reaction set in at 250°, or even at a somewhat lower temperature, and proceeded rapidly at 300°. Explosive combustion set in at about 350°, the ignition point being raised either by reducing the initial pressure or by addition of oxygen to the equimolecular mixture. With regard to the slow combustion, it was shown that carbonic oxide and formaldehyde arise simultaneously at an early stage of the process, probably as the result of the thermal decomposition of an unstable C 2 H 2 O 2 which might possibly be C. OH ... C. OH, although only a form of polyglycolide (C 2 H 2 O 2 ) x was actually isolated. The formation of formaldehyde preceded that of steam, and the whole process, it was thought, might be represented by the scheme:

scholarly journals Geometry of shape of profiles of the sliding surface of ring seals in the aspect of friction losses and oil film parameters

2016 ◽  
Vol 167 (4) ◽  
pp. 38-52 ◽  
Author(s):  
Piotr WRÓBLEWSKI ◽  
Antoni ISKRA
Keyword(s):  
Internal Combustion Engines ◽  
Surface Profile ◽  
Combustion Engines ◽  
Sliding Surface ◽  
Oil Consumption ◽  
Oil Film ◽  
Close Relationship ◽  
Ring Seal ◽  
The One ◽  
The Impact

The article describes the results of simulations of the approved variations of sliding surfaces of ring seals in relation to a reference symmetrical barrel profile which is most often used in piston internal combustion engines. In particular the paper discusses the impact of the five assumed variants of sliding profiles of ring seals onto the thickness of oil film left on the cylinder face by a bottom and upper ring seal, the distribution of internal friction force in oil film between the ring seal set and the cylinder face, finally the oil film cover on a sliding surface of the upper ring seal. The results presented in the article show a close relationship between the sliding surface profile of ring seals and a unit oil consumption. A relationship between these parameters for the elements lying in the movement plane of a wrist pin axis was proven, as well as for the one lying in the plane perpendicular to it. Exemplary parameters of oil film and friction losses were presented while assuming a constant total axial values of the height and depth of circumferential grooves. The shapes of these grooves on the sliding surface of the ring seals in free state can be made with electroerosion microprocessing or ablative laser microprocessing.

scholarly journals Application Isssues of the Semi-Markov Reliability Model

2015 ◽  
Vol 22 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Jacek Rudnicki
Keyword(s):  
Internal Combustion Engines ◽  
Combustion Engines ◽  
Mechanical Device ◽  
The Past ◽  
Engine Piston ◽  
Complex Process ◽  
State Changes ◽  
The One ◽  
Infinite Set ◽  
Random Nature

Abstract Predicting the reliability of marine internal combustion engines, for instance, is of particular importance, as it makes it possible to predict their future reliability states based on the information on the past states. Correct reliability prediction is a complex process which consists in processing empirical results obtained from operating practice, complemented by analytical considerations. The process of technical state changes of each mechanical device is stochastic and continuous in states and time, hence the need to divide this infinite set of engine states into a finite number of subsets (classes), which can be clearly and permanently identified using the existing diagnosing system. Using the engine piston-crankshaft system as an example, the article presents a proposal for a mathematical model of reliability which, on the one hand, takes into account random nature of phenomena leading to the damage, and at the same time reveals certain application flexibility and the resultant practical usability.

Nitrogen oxides in internal combustion engine gases

1937 ◽  
Vol 163 (912) ◽  
pp. 90-100 ◽  
Keyword(s):  
Nitric Oxide ◽  
Nitrogen Oxides ◽  
Internal Combustion Engine ◽  
Analytical Methods ◽  
Internal Combustion Engines ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Combustion Engines ◽  
Hydrocarbon Combustion ◽  
Made In

An account was given in a paper entitled “Proknocks and Hydrocarbon Combustion” (Ubbelohde, Drinkwater and Egerton 1935) of some experiments made to trace the source of the nitrogen peroxide which had been found by sampling the products from the cylinder of a petrol engine at various stages of the stroke. Those experiments indicated that it was not simply a matter of nitric oxide formed by the flame giving rise to the nitrogen peroxide, for different results were obtained using different exhaust-valve surfaces. Nevertheless it seemed probable that the flame should be mainly responsible for the formation of nitric oxide, and so further experiments have been made. In order to make progress it was essential to determine the amount of nitric oxide as well as the amount of nitrogen peroxide, and analytical methods had to be devised to do this. The first part of this note deals with the methods of determining small quantities (of the order of 10 -4 mol. fraction) of total nitrogen oxides and of nitrogen peroxide, and the second part with the results of analyses of the gases sampled from the cylinder of internal combustion engines by the methods described by Egerton, Smith and Ubbelohde (1935) and by Drinkwater and Egerton for the C. I. engine in a paper shortly to be published.

Thermodynamics of indirect water injection in internal combustion engines: Analysis of the fresh mixture cooling effect

2018 ◽  
Vol 20 (5) ◽  
pp. 527-539 ◽  
Author(s):  
Alexandre Vaudrey
Keyword(s):  
Internal Combustion Engines ◽  
Water Injection ◽  
Internal Combustion ◽  
Intake Manifold ◽  
Combustion Engines ◽  
Fresh Mixture ◽  
Mixture Density ◽  
Set Up ◽  
The One ◽  
Air Conditioning Systems

Water injection is a well-known efficient way to improve the performance of internal combustion engines. Amazingly, most of previous studies have yet only assess this process in an experimental manner, depriving us of an understanding of its specific influence on different operating phases of the engine – density of the aspirated fresh mixture, work required by the compression stroke, and so on – but also of the possibility to predict its effects if set up on an existing engine. Thanks to a theoretical framework specifically developed, and similar to the one commonly used for the analysis of air conditioning systems, we start in this article to untangle in a theoretical manner the different consequences of water injection on internal combustion engines. This first study is specifically focused on the fresh mixture density increase, due to the vaporisation of liquid water in the intake manifold. Results show that in the best scenarios, we cannot expect to increase the amount of fuel finally aspirated into the cylinders by more than 10%. The methodology presented here can be of a precious help for the optimisation of such process if applied to existing or future engines.

The Effect of Atmospheric Pressure and Temperature upon the Performance of a Petrol Engine

1921 ◽  
Vol 25 (128) ◽  
pp. 421-454
Author(s):  
E. G. Ritchie
Keyword(s):  
Atmospheric Pressure ◽  
Internal Combustion Engines ◽  
Engine Performance ◽  
Large Degree ◽  
Appreciable Effect ◽  
Combustion Engines ◽  
Atmospheric Density ◽  
Compression Pressure ◽  
Aero Engine ◽  
The Mean

The efficiency of all internal combustion engines is influenced to a large degree by the density of the charge prior to ignition. In the stationary engine operating at normal ground density, the variation in compression pressure throughout the range of working conditions is so small as to have no appreciable effect upon engine performance. In the aero engine, however, the conditions obtaining in flight are such as to produce wide variation in the suction pressure and therefore in the compression pressure due to changes in atmospheric density. Table I has been prepared to show the variation in air pressure, temperature and density with height, the figures given representing the mean conditions obtaining in the south of England.

scholarly journals Thermodynamics of indirect water injection in internal combustion engines: theoretical assessment of the fresh mixture cooling effect

2017 ◽  
Author(s):  
Alexandre Vaudrey
Keyword(s):  
Internal Combustion Engines ◽  
Water Injection ◽  
Internal Combustion ◽  
Intake Manifold ◽  
Combustion Engines ◽  
Fresh Mixture ◽  
Mixture Density ◽  
Set Up ◽  
The One ◽  
Air Conditioning Systems

Water injection is a well-known efficient way to improve the performance of internal combustion engines. Amazingly, most of previous studies have yet only assess this process in an experimental manner, depriving us of an understanding of its specific influence on different operating phases of the engine (density of the aspirated fresh mixture, work required by the compression stroke, and so on) but also of the possibility to predict its effects if set up on an existing engine. Thanks to a theoretical framework specifically developed, and similar to the one commonly used for the analysis of air conditioning systems, we start in this paper to untangle in a theoretical manner the different consequences of water injection on internal combustion engines.This first study is specifically focused on the fresh mixture density increase, due to the vaporisation of liquid water in the intake manifold. Results show that, in the best scenarios, we cannot expect to increase the amount of fuel finally aspirated into the cylinders by more than 10%. The methodology presented here, as well as the python software specifically developed, can be of a precious help for the optimisation of such process if applied to existing or future engines.

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