Abstract
Pulsators utilize energy of compressed air in order to destruct adverse phenomena in loose materials and make the outlets of silos permeable. The most important parameter of the pulsator is a force which can be transmitted onto the loose material bed. This impact force is related to the pressure difference but this relation is not obvious. This paper proposes a methodology for calculating an irreversibility of a high speed gas conversion with transient airflow conditions taken into account. The aim of this work is to deliver values of energy which is available for conversion to the impact force in order to adverse phenomenon could be destroyed in a silo. The exergy analysis delivers results which make it possible to determine the efficiency of the pneumatic pulsator system.
By using mean values of flow parameters such as temperature, pressure, velocity and density, the exergy analysis has been carried out. It has been assumed that the flow does not influence the environmental parameters.
The most important period of the process is observed during the first 25 ms from the start. In order to calculate energy and exergy, the corresponding fluxes are integrated in time and the total values are delivered: energy equals 682.9 kJ, and exergy is 605.2 kJ. The irreversibility of the process is, therefore, 77.7 kJ. This loss occurs in one work cycle of pulsator. The modern pulsators are designed for 1 million and more work cycles. It is easy to calculate that the irreversibility of the gas conversion during the air evacuation can reach values of over77.7 GJ.
