Development of internal heat transfer correlations for the cylinders of reciprocating machines

Highlights: • Correlations for internal heat transfer coefficients in reciprocating machinery are reviewed and gathered together. • Discussion on fields of applications of the heat transfer correlations. • Restrictions in use of the mentioned correlations are discussed. • Discussion on the measurment apparatus, techniques and limitations is provided. The paper presents a review of heat transfer correlations available for cylinder-piston, reciprocating machinery. For the purpose of this work, this includes correlations, either dimensional or non-dimensional, describing the convective heat transfer coefficient on the cylinder wall surface. This is in most cases a function of gas parameters inside the cylinder, gas composition, piston velocity and position. Papers published between the nineteen twenties and the current day have been thoroughly reviewed, and the correlations have been updated into a form coherent with the SI system of units. The methodologies and test apparatus used to create each correlation are also described. In all, in this almost one hundred year period only about twenty five correlations have been found to have been published. The small number of applicable correlations is results from the fact that the measurements of instantaneous in-cylinder conditions can be considered difficult in practice. Most of the correlations found had been created for internal combustion engines, majority of them for diesels. Nonetheless, correlations for compressors and Stirling machines have also been found. The dimensions of the test apparatus and test parameters have also been shown if they were available. The paper can serve as a practical reference for the use in piston machinery research. It has been created as a prelude to the authors experimental work in Stirling Engine heat transfer.