scholarly journals An Optimal Hybrid Control Method for Energy-Saving of Chilled Water System in Central Air Conditioning

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Yan Zhang ◽  
Xiaoli Chu ◽  
Yongqiang Liu
Keyword(s):  
Energy Saving ◽  
Hybrid System ◽  
Air Conditioning ◽  
Control Method ◽  
System Modeling ◽  
Water System ◽  
Variable Frequency ◽  
Optimum Control ◽  
Central Air Conditioning ◽  
Frequency Behavior

Chilled water system of central air conditioning is a typical hybrid system; variable frequency behavior with amplitude limited of pumps reflects continuous and discrete dynamic characteristics. The way of energy-saving is variable water volume, via variable frequency behavior of pumps to gain adjustment of power consumption. Facing the situation of the variable frequency pumps with parallel operation, single continuous or discrete modeling cannot reflect the hybrid features. Thus, the control method will have some questions, such as bad energy-saving effect, difficult accurate adjustment of cold capacity, and low running energy efficiency. However, hybrid system modeling can reflect hybrid dynamic behavior of pumps, which is combining continuous and discrete features. The questions of nonlinear and multiparameters can be solved by control method based on hybrid system. Here, an optimum control method is proposed with the principle of the minimum, by setting the minimum power consumption as the performance function in fixed time, which realizes variable control of pumps and accurate adjustment of temperature inside room. At last, it shows the system characteristics and energy-saving affection by hybrid system modeling and the optimum control method.

scholarly journals A Modelling and Control Approach for a Type of Mixed Logical Dynamical System Using in Chilled Water System of Refrigeration System

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Yan Zhang ◽  
Xiaoli Chu ◽  
Yang Liu ◽  
Yongqiang Liu
Keyword(s):  
Energy Saving ◽  
Hybrid System ◽  
Air Conditioning ◽  
Water System ◽  
Cooling Capacity ◽  
Chilled Water ◽  
Central Air Conditioning ◽  
Chilled Water System ◽  
And Control ◽  
Mixed Logical Dynamical

The chilled water system of central air conditioning is a typical hybrid system. The dynamic adjustment of cooling capacity based on hybrid system can achieve accurate temperature control and real-time energy saving. Mixed logical dynamical (MLD) systems have advantage for solving constrained optimization problems of this type of case by numerical methods. This paper proposes a novel modified type of MLD system, which enhances the model applicability and improves the switching flexibility and control effect for the framework. In order to meet the needs of cooling capacity and energy saving, the optimal control problem is transformed as MIQP problem by defined performance index. As a numeral example of application, the model and control method is used in pumps group control for variable water volume in chilled water system of central air conditioning. At last, the dynamic and energy-saving effects of the system are simulated, which shows the ideal control results.

Study of Frequency Conversion Energy-Saving Reconstruction for Central Air-Conditioning

2014 ◽  
Vol 496-500 ◽  
pp. 1143-1146
Author(s):  
Hong Yan Hua ◽  
Zhen Zhang
Keyword(s):  
Energy Saving ◽  
Air Conditioning ◽  
Frequency Conversion ◽  
Water System ◽  
Variable Frequency ◽  
Air Conditioning System ◽  
Large Power ◽  
Central Air Conditioning ◽  
Conditioning Equipment ◽  
Control Principle

Water system is one of the significant compositions with large power consumption in air-conditioning equipment. From viewpoint of energy-saving, the variable frequency operational principle of the water system is analyzed, the merits and demerits of operating water system under power frequency or variable frequency are compared, and the control principle of the energy-saving revamping project is introduced. In addition, combining with the specific project, the benefit of energy-saving for the water system is analyzed. The result shows that after revamping, the air-conditioning system runs properly, both the indoor temperature and humidity meet the specifications; the revamping technology offers significant energy-saving effects.

Air Conditioning System Water Quality and Equipment Condition Investigation and Analysis of Energy Saving Measures

2012 ◽  
Vol 516-517 ◽  
pp. 1224-1228
Author(s):  
Na Liang ◽  
Rui Li
Keyword(s):  
Energy Saving ◽  
Air Conditioning ◽  
Water System ◽  
Building Energy ◽  
Development Trend ◽  
Air Conditioning System ◽  
Effective Utilization ◽  
Energy Saving Potential ◽  
Central Air Conditioning ◽  
Points Of View

Due to energy reserves reduces gradually and uneven distribution, all countries pay more and more attention to energy saving and improve the effective utilization of energy, China also attaches great important to this. Energy saving of buildings is a necessary development trend. Air conditioning system as a large important part of building energy consumption has a huge energy-saving potential. This article mainly introduced the related strategies of energy saving in central air conditioning water system from the following three points of view: the water treatment, the cooling tower, and the variable frequency pump.

Energy-Saving Monitoring System of Central Air-Conditioning Based on Dynamic Load

2014 ◽  
Vol 1039 ◽  
pp. 409-414
Author(s):  
Tao Han ◽  
Xue Feng Lai ◽  
Liang Wen Yan ◽  
Zai Feng Zhang
Keyword(s):  
Energy Saving ◽  
Monitoring System ◽  
Dynamic Load ◽  
Pid Control ◽  
Air Conditioning ◽  
Water System ◽  
Air Conditioning System ◽  
Advantages And Disadvantages ◽  
Hardware System ◽  
Central Air Conditioning

This paper introduces the components of central air-conditioning system and compares the advantages and disadvantages of the PID control and fuzzy control.Fuzzy control theory and inverter technology are combined to design the Energy-Saving Monitoring System based on the fuzzy control box of STM32F103C8T6,Siemens S7-200 PLC, ABB inverter as the hardware system and interfaces configuration of KingView as the software. Experimental results show that the water system can be variable flow controlled based on the dynamic load, central air-conditioning energy efficiency the COP has greatly improved under the premise of ensuring the comfort of central air-conditioning.

scholarly journals Analysis on the monitoring system of energy conservation and comfort in office buildings based on internet of things

2020 ◽  
Vol 15 (3) ◽  
pp. 351-355
Author(s):  
Dongmei Li
Keyword(s):  
Energy Efficiency ◽  
Control System ◽  
Internet Of Things ◽  
Energy Saving ◽  
Monitoring System ◽  
Air Conditioning ◽  
Control Method ◽  
Working Hours ◽  
Central Air Conditioning ◽  
Energy Saving Control

Abstract In order to reduce the cost of central air conditioning, we need to reduce its energy consumption. This paper briefly introduced Internet of Things and the energy-saving and comfort monitoring system of central air conditioning based on the Internet of Things. The system took comfort degree as constraint and energy efficiency as objective to control energy saving of central air conditioning. Company X in Guanghan, Sichuan, China, was taken as an example for analysis. The system was compared with the energy-saving control system which took temperature and power as constraints. Compared with before the energy-saving control, the proportion of air conditioning downtime in the working hours of employees increased after the implementation of the two kinds of energy-saving control systems, and the proportion of downtime under the energy-saving control system designed in this study was larger; in addition, after the control of the two kinds of energy-saving systems, the energy efficiency of the air conditioning significantly improved, and the air conditioning under the control of the energy-saving system proposed in this study had more improvement in energy efficiency and higher energy-saving efficiency. The energy-saving control method proposed in this study can effectively reduce the power consumption of the central air conditioning in the office.

Modeling and Simulation of Chilled Water System for Central Air Conditioning

2012 ◽  
Vol 204-208 ◽  
pp. 4280-4285 ◽  
Author(s):  
Jian Min Sun ◽  
Chun Dong Zhang ◽  
Ze Yang Zhou
Keyword(s):  
Control System ◽  
Energy Saving ◽  
Pid Control ◽  
Air Conditioning ◽  
Water System ◽  
Air Conditioning System ◽  
Chilled Water ◽  
Central Air Conditioning ◽  
Chilled Water System ◽  
Saving Effect

Considering the central air conditioning system is highly susceptible to interferences from external environment, this paper established a dynamic mathematical model for chilled water system with the air conditioning area, fan coil unit and air conditioning area interference factors. Selection of chilled water system as a controlled object, designed the energy saving control system for central air-conditioning. The inputs of PID controller are deviation of actual temperature and setting temperature, and the change rate of the deviation; output is operation frequency of pump. Experiment shows that, PID control system in 90% time operating at a frequency of 10Hz-40Hz, average is 32.5Hz. Compared with no control system, the pump power consumption was reduced 33.9%.In conclusion, PID control in the central air conditioning system have a good energy saving effect.

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