State space model and robust control of plate heat exchanger for dynamic performance improvement

Abstract

Plate heat exchanger takes an important role in the modern industrial engineering. For large scale district heating system, plate heat exchanger is the key equipment in controlling the heat output from the heating substation. High performance control of plate heat exchanger is essential for stable and efficient operation of the heating substation. The governing equation of plate heat exchanger is a pair of partial differential equations, which is not suitable for model based control. In this work, a linear state space model was developed to describe the dynamic characteristic of plate heat exchanger. Validation results show that the proposed model can capture the dynamics of plate heat exchanger with satisfied accuracy. Based on the state space model, the two-degrees-of-freedom H∞ loop-shaping controller was designed for plate heat exchanger to enhance the control performance. The reference tracking and disturbance rejection performances of the proposed control algorithm were studied and compared with the PI control. Results show that the presented two-degrees-of-freedom H∞ loop-shaping control is superior to the PI control.