Pek-Yew Tan

Cooling Coil Unit dynamic control of in HVAC system

In this paper, a dynamic Cooling Coil Unit (CCU) model is firstly developed by extending the CCU engineering model [1], and by combining the model with the mass and energy balance equations. Unlike other existing CCU models for dynamic control, this modeling method with only six model parameters is relatively simple and exactly captures the nonlinear characteristics over a wide operating range of CCU without requiring much calibration effort and geometric specification, which is very convenient in real time engineering control practice. Afterward, the nonlinear model of CCU is linearized using Jacobian matrix method and PID-action controller as linear control systems are developed on linear model to adjust the outlet air temperature and outlet chilled water temperature. Experiments on a centralized Heating, Ventilation and Air Conditioning (HVAC) pilot plant are conducted to show that the method is robust and gives an accurate match to real performance over the wide operating conditions.

A hybrid water-cooled centrifugal chiller model

This paper proposed a hybrid model for water cooled centrifugal chiller. The modeling method takes advantages of both physical and empirical modeling approaches and can accurately predict performance in wide operating range and in real-time, which can significantly reduce the computational burden and increase the prediction accuracy. The model is verified with the experimental data taken from a testing system. The testing results show that the proposed model can predict accurately the performance of the real-time operating chiller. The developed models will have wide applications in operational optimization, performance assessment, fault detection and diagnosis.