Availability accumulation and destruction in a DI diesel engine with special reference to the limited cooled case

C. D. Rakopoulos, E. C. Andritsakis, D. K. Kyritsis

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47 Scopus citations


This work develops a method for the calculation of both the irreversibility produced during combustion and the working medium availability at the end of the expansion process in a high speed, direct injection (DI), naturally aspirated, four-stroke diesel engine, on which experiments were conducted at the authors' laboratory. The experimental data were processed for the determination of fuel reaction rates; the combustion irreversibility production rate was then computed from the fuel reaction rates via an analytical mathematical expression which was developed by the present research group, based on the combined resolution of the first and second laws of thermodynamics. This expression is coupled with standard first law calculations and then is integrated to give the accumulated combustion irreversibility, while the working medium availability variation is also computed throughout the engine closed cycle. These calculations are applied for a wide range of measured loads, injection timings and engine rotational speeds; they are also expanded in the direction of the intensity of the rate of heat transfer loss (to the engine cooling medium) for every combination of the experimentally determined engine variables. Therefore, apart from investigating the effect of various operating parameters on the availability balance, it is possible to evaluate the effect of the engine heat transfer reduction (limited cooled engine), from the second law analysis point of view, on the potential for efficiency improvements made by using the increased exhaust heat in recovery devices (e.g. the exhaust turbine or Rankine bottoming cycle compounding). With the present second law analysis, which forms the spearhead of this work, the exhaust gas availability offers more useful information than its enthalpy counterpart (first law analysis) for the operation of such compounding devices. The irreversibility calculation also provides useful information for the combustion loss, which cannot be isolated and evaluated at all by a first law analysis.

Original languageBritish English
Pages (from-to)261-276
Number of pages16
JournalHeat Recovery Systems and CHP
Issue number3
StatePublished - May 1993


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