Modelling and Experimental Investigation of Unsteady Behaviour of a Screw Compressor Plant

Majority of air compressor plants installed worldwide operate permanently under unsteady conditions, however, there is still a lack of published papers which describe the plant dynamics and offer quantification parameters of the phenomenon. An experimental and analytical study of a screw compressor operation under unsteady conditions has been carried out. For this purpose a one dimensional model of the processes within a screw compressor based on the differential equations of conservation of mass and energy was extended to include other plant components, taking into account tanks and connecting piping. The analytical model was then further developed to demonstrate the whole plant transient operation when a screw compressor is connected with other plant elements in a complete complex air compressor plant which consists of the positive displacement compressor, then the low pressure and high pressure tanks and communications between them and auxiliary equipment, like control valves, storage tanks and heat exchangers, like oil and air coolers. Results of such a model are verified with the experimental data and presented in diagrams which confirm good agreement between experiment and simulation. This model allows simulation of unsteady plant operation under various scenarios which may occur within engineering practice and calculates plant dynamics at any given time