Optimal Research On Methods Of Pressure Control Of Variable Air Conditioning Systems

In this paper, variable air volume air conditioning systems of the same office building model in the cities of Beijing, Shanghai&Guangzhou are as the research objects. From the perspective of energy saving and control system, the paper studies the building annual energy consumption and control characteristic of variable air volume system. Using PKPM for simulation of the annual dynamic load of building, and resistance components of air conditioning system mathematical model is established. Use graph theory knowledge, pipe network of the air conditioning system is converted into a binary tree graph. Simulate and calculates dynamic energy consumption throughout the year of fan of air system of variable air volume air conditioning under different static pressure points of by MATLAB. It analyses static point location and energy saving rate, when the energy consumption throughout the year of the fan is the smallest. Through the tests of the actual engineering project under different static pressure control methods, compare and analyses performance and energy consumption of variable air volume air conditioning systems. Through the simulation and the data of measurement, gets the following conclusions:1. Through experimental data, establishes the air volume-resistance relationship of the resistance elements (filters, coolers, VAV box, etc.).2. Using graph theory knowledge, this paper maps out all the ordered binary tree graphs of air conditioning system. On this basis, MATLAB transfers pipe network systems of the project into binary tree graphs and give each node and branch attribute values, and then calculates flow rate, resistance, static pressure, and get the fan dynamic energy consumption throughout the year of different constant static pressure points. When designers design variable air volume air conditioning, this program can be used to select the optimal constant static pressure points.3. Variable air volume air conditioning system in three cities, respectively located in cold area, hot summer and cold winter area and hot summer and warm winter area, are analyzed in this paper. When fan for minimum energy consumption, constant static pressure point is located in the end of a main air supply duct.4. By comparing the fan energy consumption of throughout the year of the optimal constant static pressure and the point on the main duct one-thirds and two-thirds from fan outlet, gets that the closer location of constant static pressure point to the main duct upstream, the greater the energy consumption. When static pressure sensor is set at the optimum static point location, the annual energy consumption of fan is the smallest.5. Variable static pressure control mode is more energy efficient than constant static pressure control method, but variable static pressure control method is more complex and the workload is bigger. Variable static pressure operation mode can be used in constant static pressure method. Through the analysis of the static pressure setting of the normal meteorological data to predict the system operation, constant static pressure control method can be used for12months different static pressure setting value, or even every day or every time with different static pressure setting value.