Set-Point Optimization And Software Development For Air Handling Units In The Heating Ventilating Air Conditioning System Based On Lonworks Technology

The energy cost of the heating ventilating and air-conditioning(HVAC) system is about 55 percent of a whole building,while the energy cost of the air handling units is about 35 percent of the energy cost of whole system.So it is important for the energy conservation of the whole HVAC to reduce the energy of the air handling units.In fact. a majority of HVAC systems runs inefficiently,and wastes a mass of energy.The HVAC system is usually run on the part loads,thus it can efficiently reduce the energy consumption of the HVAC system to optimize on-line the air handling units,which make them work at the optimal set points within the entire load range.According to the operating process and the characteristics of energy consumption of various devices in the HVAC system,this thesis proposes to optimize the work point of the air handling units on-line,to make the system run on the optimum process to satisfy the requirement of the loads and reduce the energy consumption.For the air handling units,the least square method and BP neutral network method are developed to identify the device models with the experiment data.The models identified approximate to the experiment equipment very closely.Based on anglicizing the characteristics of the practical HVAC system and combining with the models,the cost function and constraints of the air handling units are determined.The optimization problem of this subsystem is a multivariable nonlinear optimization problem with equation and inequality constraints.The sequential unconstrained minimization method(SUMT) based on improved Powell is used to solve the optimization problem. Using this optimizing method on air handling units,the supply temperature and the supply press can be obtained,which can be used to optimize the system.On account of experiment equipment based on LonWorks technology,the optimization software is developed using Visual C++.The software includes four function modules,which are data maintenance,equipment modeling,on-line optimization and tracing.Also,friendly interface is achieved.