Experimental Modeling of Pressure Dynamics through Compressed Air Network for Estimating Air Consumption and Predicting End-use Pressure

 This note addresses the modeling of a compressed air network system, which supplies compressed air from air compressors through a pipe network to end-use points. Compressors' discharge pressure is set according to the maximum air demand, implying that discharge pressure is unnecessarily high when end-use devices consume low volume of air. It is energy-efficient to reduce discharge pressure while keeping air pressure at end-use points at the minimum level necessary to drive the devices.

 However, compressors operation has not been aware of air consumption at end-use points because of the two reasons. First, the layout of pipe networks used in manufacturing processes is often unknown, making it impossible to construct their physical models. Second, flow meters are expensive compared to the economic benefit due to the reduction of discharge pressure so that these cannot be installed at end-use points during operation.

 To solve these problems, this note develops a method for estimating air consumption from available measurement and predicting end-use pressure from the estimation. Based on physical deduction, we introduce an ARX model that describes the end-use pressure with air consumption and discharge pressure, and design how to identify model parameters based on experimental measurement. The model enables to estimate air consumption from pressure measurement and predict end-use pressure based on the estimation. The performance of the model is verified with measurement data for an in-house factory.