Study On The Regulating Method For Chilled Water System Of Central Air Conditioning

In recent years, with the rapid economic development of China, many large-scalepublic buildings in China are equipped with large central air conditioning systems.Chilled water systems are responsible for the transportation of refrigerating capacityin central air conditioning systems. The current regulating methods of chilled watersystem are so complicated that significant amount of effort and material resources aredemanded to proceed, while the result is not quite good as expected. The “Large flowrate with low temperature difference” phenomenon is very common. Therefore, it isnecessary to develop an accurate and convenient regulating method.The scope of this is to develop an accurate and convenient method for theregulation of chilled water system. The main work of this research is as follows:1. Obtain the topological structure of chilled water system and characteristicparameters of the pipes and equipments through actual building design drawings andon-site construction situation. A chilled water model for simulating actual buildingwas built based on the above work. The model is a powerful tool for the simulating ofchilled water system and research on hydraulic characteristics.2. The hydraulic parameters of chilled water systems are obtained by thesimulating and the increased resistance needed in system regulating is calculatedbased on the fundamental equations of chilled water transmission system. Tworegulation methods are developed, direct regulating method and flow rate monitoringmethod. These two methods are all combined numerical simulation with actual projectapplication, and are more convenient and accurate than existing methods.3. Point out the disadvantage of present regulation method which just regulatesthe pipes with large flow rate difference rather than the pipes with small flow ratedifference by simulating. This method ignores the coupling characteristics of thewhole chilled water system. When the coupling influence of the system is strong, theregulation of other pipes will greatly influence the flow rate of the pipes withoutregulation. Therefore, the original pipe with small flow difference will becomehydraulic disorder after the present regulation. 4. Develop a method to determine whether the chilled water system can beregulated to hydraulic balance for the situation when some pipes have no valves inactual project. And provide a reasonable regulation method to the situation whensome pipes have no valves.