Authors: I.K. Prilutskiy

The efficiency of the spatial operation machines (compressors and expanders) depends on the character of the processes that are carried out in them and especially the processes of heat exchange of gas with the walls of the working chamber and the valves. In developing an experiment-calculated method for determining the local coefficient of heat transfer from gas to the cylinder wall the assumptions about the quasi-stationary state of the heat exchange processes and an one-dimensional direction of the heat current have been made. The estimated model of the processes was developed as a result of combination of the analytical approach with the founded choice of the generalized criterial dependence. The use of the model has allowed to study the influence of the design (the cylinder diameter, a piston stroke) and the mode (the degree of pressure increase in a compressor stage, the frequency of the shaft rotation) indexes on the size of the local coefficient of heat transfer under the change of the shaft rotation angle. For the model simplification the criterial expressions that characterize the change of the heat transfer coefficient have been suggested. The comparison of calculated data obtained with the use of the program «KOMDET M» with the experimental data confirmed their close correspondence.