SPECIAL CONSIDERATIONS OF HEAT GENERATION IN THE INTERNAL COMBUSTION ENGINE

Abstract

Problem. The study illustrates special considerations of heat generation in the internal combustion engine. The research was conducted using hard / soft technology. An exponential analytical description is found to qualitatively reflect actual processes in an acceptable way. The study dismisses some standard notions about typical and optimal relations between parameters characterizing the course of heat generation. Goal. The purpose is to investigate the regular heat generation in an internal combustion engine by resorting to, so to speak, hard/soft technologies, combining the test bench and the computer and thus providing a «communication» of a real research engine and virtual in form computer model. Methodology. As it follows from the research, the proportion of burned fuel decreases with the decreasing load and becomes the smallest in case of idle engine running. The concept of the amount of unburned fuel is quite conditional – it characterizes incomplete chemical transformations rather than absolute inactivity of the other amount of fuel. The given value contains useful information that the heat generation capacity of the fuel mixture is underuti-lized and it displays potential environmental hazards. The analytic description contains the parameter a that is supposed to characterize a complete fuel com-bustion rather than convey a specific fixed value (namely, a=-6,908) based on the researcher’s prediction without persuasive arguments. The time parameter denoting the duration of heat genera-tion should be considered as a time stable that char-acterizes an asymptotic nature of the process rather than the actual duration of the combustion process( the combustion would have been indefinitely long). Results. There are beliefs that the actual engines have the values of the parameter m that characterises the degree of fuel combustion and of the parameter Δφ that corresponds to the duration of the combustion process: diesel engines m=0...1 - and Δφ=60…100 (and even more) degrees of rotation of the crankshaft; Otto engines - m=3...4 and Δφ=45…60 deg. The study demonstrates that the statement about Otto engine doesn’t confirm but rather reject the mentioned above. Moreover, it is also argued that special studies seem to prove the following: the combination of parameter values m=1,5 and Δφ=40…60 degrees is roughly optimal. The value m≈1,5 of degree m, appears to correspond to the moment tm of reaching the maximum combustion rate that satisfies the condition ( and - the beginning and end of the combustion process). It turned out that these parameters only formally denote the minimum of the dependence of maximum combustion rate on a set of different permissible values of the parameter m and it doesn’t reveal any physical meaning of «optimality», but rather provoke a thorough investigation of this circumstance.

Keywords

• internal combustion engine
• heat generation process
• heat-fission intensity
• exponential analytical description