Investigation of oil flow in a hermetic reciprocating compressor

In the present study, the path followed by the oil and the rotation of the crankshaft in a lubrication system of a hermetic reciprocating compressor have been visualized by the means of a high speed camera. Then, the climbing time and the time variation in the speed of the crankshaft have been computed by the means of FLUENT software. The variation of the crankshaft speed with respect to time has been used as an input of the simulation. The predicted climbing time, on the other hand, was the output of the computations, evaluated as a tool to validate the model. Both the accelerated and constant start-up conditions have been considered for the modeling. The change of the crankshaft speed at the start-up has been correlated and used as the initial condition, by writing a step function in the Fluent software. For the sake of applicability and simplicity, no refrigerant is used in the experiments and the computations. Due to the Reynolds number calculated based on the channel diameter, laminar flow conditions have been considered. The two-phase flow of the air–oil pair has been studied by both VOF and Eulerian models.

► The path followed by the oil in a hermetic reciprocating compressor has been visualized.
► The climbing time and the time variation in the speed of the crankshaft have been computed.
► The change of the crankshaft speed at the start-up has been correlated.
► The two-phase flow of the air–oil pair has been studied by both VOF and Eulerian models.