scroll pressure-volume diagram
This paper presents the results of tests led with scroll compressors to establish pressure-volume diagrams. Two compressors were thinly instrumented with pressure and displacement sensors so as to follow the whole compression process, from suction to exhaust. A gear coder was set to mark off the closing and opening of gas pockets, and to study the speed variations occurring during a single rotation. These tests help to understand the various phenomena met in a compressor, such as back-flow, overshoot, leakages, at the different operating points. Comparing an ideal pressure-volume diagram to the experimental one enables identification of improvement possibilities. One of the compressors was equipped with Inlet Discharge Valves that could be deactivated. Comparative tests for points at low pressure ratio showed precisely the influence of these devices on the distribution of pressure inside the machine.
Pressure-volume diagrams of scroll compressors at various operating points