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An instrument was developed to measure absolute monochromatic infrared emission rates within an operating diesel engine. The instrument and data reduction system were developed for use in obtaining potential instantaneous rates of radiant heat transfer within an operating engine. Data are presented for variations of: engine speed, fuel-air ratio, fuel injection timing, intake air pressure, fuel injector nozzle spray patterns, fuel cetane numbers, fuel family, and fuel additives (tetraeythl lead and amyl nitrate). Also presented is an empirical correlation for instantaneous radiant heat transfer rates and some conclusions regarding radiant emission sources within the engine and their relationships to combustion processes.

Instantaneous heat transfer rates at the interface of the working gas and the walls of a motored engine were studied. This paper details the influence on heat fluxes of engine speed, compression ratio, intake pressure, swirl ratio, location on the cylinder head surface, and the shape of the piston top. Equations are given to show the method of calculation used in deriving the data on heat transfer rates.

An evaluation of the many new devices proposed, in recent years, for power production. Among these are fuel cells, thermoelectric generators, thermionic generators, and solar cells. Comparisons of these energy converting devices are based on ultimate efficiency (thermodynamic principles), weight, size, and cost, when possible.

The purpose of the tests conducted on a single-cylinder laboratory engine was to determine the mechanism of combustion that affect exhaust emissions and the relationship of those mechanisms to engine design and operating variables. For the engine used in this study, the exhaust emissions were found to have the following dependence on various engine variables. Hydrocarbon emission was reduced by lean operation, increased manifold pressure, retarded spark, increased exhaust temperature, increased coolant temperature, increased exhaust back pressure, and decreased compression ratio. Carbon monoxide emission was affected by air-fuel ratio and premixing the charge. Oxides of nitrogen (NO + NO2 is called NOx) emission is primarily a function of the O2 available and the peak temperature attained during the cycle. Decreased manifold pressure and retarded spark decrease NOx emission. Hydrocarbons were found to react to some extent in the exhaust port and exhaust system.

Digital computer methods were used to investigate the behavior of engine operating characteristics with a time-varying gas-film heat-transfer coefficient and gradual buildup of combustion-chamber deposits. Simulated engine runs were made with a “clean” engine having different wall materials and operating at different engine speeds as a basis for comparison. From the data calculated, heat transfer rates were established and inferences drawn regarding trends of detonation, preignition, and volumetric efficiency during the deposit buildup period. It was found that, while thermal resistance (x/k)d of the deposit layer is the most important parameter, a secondary parameter of interest is the thermal penetration, , in comparing the effects of deposits of different properties.

The reasons for conducting research in a university are presented and discussed. It is concluded that fuel-engine studies are compatible with these reasons and therefore are well suited for university research. Past studies in this field are summarized and unanswered questions and future topics suitable for university investigation are suggested. Included in the topics discussed are: instrumentation, thermodynamic description of working fluids, fuel vaporization and atomization, combustion, and instantaneous heat transfer and mass flow rates. The steps that need to be taken to ensure continuing university interest in fuel-engine studies are presented.

A detailed mathematical model of the thermodynamic events of a crankcase scavenged, two-stroke, SI engine is described. The engine is divided into three thermodynamic systems: the cylinder gases, the crankcase gases, and the inlet system gases. Energy balances, mass continuity equations, the ideal gas law, and thermodynamic property relationships are combined to give a set of coupled ordinary differential equations which describe the thermodynamic states encountered by the systems of the engine during one cycle of operation. A computer program is used to integrate the equations, starting with estimated initial thermodynamic conditions and estimated metal surface temperatures. The program iterates the cycle, adjusting the initial estimates, until the final conditions agree with the beginning conditions, that is, until a cycle results.

This paper reviews the source of the different emissions from an automobile. The exhaust is the major source of air pollution. This is composed of completely oxidized constituents such as H2O and CO2, both of which are considered harmless. Emphasis is placed on the partially oxidized components -- nitrogen oxide, carbon monoxide, and hydrocarbons -- as being the major pollutants. NO and CO are formed primarily in the bulk gases, whereas hydrocarbons are formed in the quench area. Discussed are several possible methods that could be considered in attempting to eliminate these pollutants. The authors are confident an answer will be found to this emission problem and that internal combustion engines will be used to power private vehicles rather than electricity.

By the use of surface thermocouples to measure instantaneous temperatures, the instantaneous heat fluxes are calculated at several positions on the cylinder head and sleeve of a direct injection diesel engine for both motored and fired operation. Existing correlations are shown to be unable to predict these data. An analysis of convective heat transfer in the engine leads to a boundary layer model which adequately correlates the data for motored operation. The extension of this motored correlation to fired operation demonstrates the need for instantaneous local gas velocity and temperature data.

A technique for making a radiometric measurement of the deposit surface temperature in a methane-fired engine was developed. The wavelength region between 3.5 and 4.1 μm was investigated. It was determined that while the combustion gases were relatively transparent, the surface temperature measurements would contain some gas radiation. A method of averaging the measurements of many cycles and correcting these data for the gas radiation was developed. Time-averaged surface temperature was used in a steady-state heat transfer analysis to determine deposit thermal conductivity. Deposit thermal diffusivity was determined from a transient experiment in which the engine’s ignition system was turned off and the cooling response of the deposit and wall were measured.

Preliminary computer studies indicated that the delayed mixing stratified charge engine concept might produce low emissions of nitrogen oxide and still provide reasonable efficiency and power. In the delayed mixing stratified charge engine concept a fuel-rich region is burned followed by air being mixed into the rich products. Nitrogen oxide formation was initially limited in the rich product mixtures because of the lack of oxygen and after mixing by the relatively low temperatures due to charge expansion. A single cylinder engine was used to simulate the delayed mixing stratified charge combustion process. A rich charge was drawn into the engine through the carburetor. Combustion was initiated with a spark; later air was injected to complete the combustion process. The results showed that emissions could be controlled by the delayed mixing combustion process. The engine specific power was also at reasonable levels. However, the engine efficiency was low.

Problem areas in engine simulation where the required information is lacking are discussed. The need for improved heat transfer, combustion, friction, and turbocharger models is discussed as are instrumentation needs for measurements of accurate pressure, radiant heat transfer, time-varying cylinder velocities, and instantaneous mass flow rates.

Fine-wire resistance thermometers were used to measure compression gas temperatures in a motoring (nonfiring) cycle CFR engine. Temperature versus crankangle curves were obtained for the compression and expansion strokes by means of tungsten wires ranging in diameter from 0.15–1.00 mils and at speeds from 600–1800 rpm. The results were compared with the infrared pyrometer; the peak temperature and peak crankangle lags were determined as a function of the wire diameter and engine speed. Attempts to evaluate the instantaneous energy balance around the wire resulted in a negative heat transfer coefficient, for which no current satisfactory explanation is available, although other observers have reported similar phenomena. The tungsten resistance thermometer is simple to build, easy to install, and requires no modification of the engine block for use during motoring. Thus, it is suitable for comparing the compression temperatures of different design engines.

The ratio of two temperature gradients across the combustion-chamber wall in a diesel engine is used to provide a heat flow ratio showing the radiant heat transfer as a per cent of local total heat transfer. The temperature gradients were obtained with a thermocouple junction on each side of the combustion-chamber wall. The first temperature gradient was obtained by covering the thermocouple at the cylinder gas-wall interface with a thin sapphire window, while the second was obtained without the window. Results show that the time-average radiant heat transfer is of significant magnitude in a diesel engine, and is probably even more significant in heat transfer during combustion and expansion.

Life histories of droplets evaporating on a hot plate under pressure were obtained. The curves are similar to those obtained by one investigator at atmospheric pressure but are displaced to higher temperatures at higher pressures. Similarities between boiling heat transfer and the life history curves are pointed out. Also, that the liquid will most probably reach critical pressure and temperature at temperatures existing inside an engine. The effects of reaching the critical temperature on heat transfer and on vaporization and diffusion are discussed.