scholarly journals Study on the Elman Neural Network Operation Control Strategy of the Central Air Conditioning Chilled Water System*

2019 ◽  
Vol 07 (02) ◽  
pp. 73-82
Author(s):  
Jianwei Li ◽  
Qingchang Ren ◽  
Hai Long ◽  
Zengxi Feng
Keyword(s):  
Neural Network ◽  
Control Strategy ◽  
Air Conditioning ◽  
Water System ◽  
Elman Neural Network ◽  
Chilled Water ◽  
Network Operation ◽  
Central Air Conditioning ◽  
Operation Control ◽  
Chilled Water System

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.

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.

scholarly journals Simplified Thermal Model and Optimal Control for Chilled Water Pipe in Air-Conditioning System

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Zhida Zhao ◽  
Nanyang Yu ◽  
Tao Yu ◽  
Lisha Ye
Keyword(s):  
Control Strategy ◽  
Thermal Model ◽  
Air Conditioning ◽  
Thermal Characteristic ◽  
State Space Model ◽  
Water System ◽  
Water Pipe ◽  
Preview Control ◽  
Air Conditioning System ◽  
Chilled Water

As an important subsystem in air-conditioning system, water system connects the chiller and terminal equipment. Therefore, it is necessary to develop an accurate thermal model for chilled water pipe to create the suitable indoor temperature and humidity environment. In this paper, the thermal model of the pipe was considered by utilizing the simplified thermal time-delay state-space model with the mass, energy balance, and heat consumption equations. Based on this improved model, the preview control as control strategy for water pipe temperature was proposed, and its robustness and stability were discussed. Subsequently, the performances of this model and control strategy were tested in a fan-coil system simulating with MATLAB and TRNSYS (Transient System Simulation Program). Explicitly, the results show that this model accurately predicts the thermal characteristic, and the average mean squared errors for water temperature were 11.14% and 12.82%, respectively. Meanwhile, the tracking effect of valve controller was better than the control strategy with no preview control.

Mixed Programming Using FORTRAN and VB of Pipe Network for Heating and Air Condition Water System

2012 ◽  
Vol 610-613 ◽  
pp. 2478-2482
Author(s):  
Yang Cui ◽  
Lei Huang
Keyword(s):  
Air Conditioning ◽  
Simulation Analysis ◽  
Water System ◽  
Pipe Network ◽  
Air Conditioning System ◽  
Mixed Programming ◽  
Simulating Analysis ◽  
Chilled Water ◽  
Fortran Language ◽  
Chilled Water System

As the scale of the air conditioning system is constantly increasing, some problems still exist and remain to be solved in the chilled water system. Among them, the leading problems lie in the insufficient research of the overall character on the user side and lack of simulation analysis. Corresponding calculating procedures are mixed programmed using VB and FORTRAN language to conduct to simulating analysis, to testify reliability and feasibility of the method.

Development of the Chilled Water System Analysis Tool for Assessing Energy Conservation Opportunities

2013 ◽  
Author(s):  
Ghanshyam Gaudani ◽  
Alex Quintal ◽  
Dragoljub Kosanovic
Keyword(s):  
Energy Consumption ◽  
Cost Reduction ◽  
Air Conditioning ◽  
System Analysis ◽  
Water System ◽  
Water Systems ◽  
Analysis Tool ◽  
Chilled Water ◽  
System Energy ◽  
Chilled Water System

Chilled water systems constitute a major portion of energy consumption in air conditioning systems of the large buildings and process cooling of the manufacturing plants. These systems do not operate optimally in most of the cases because of the operating parameters set and/or the components used. The Chilled water system analysis tool software (CWSAT) is developed as a primary screening tool for energy evaluation. This tool quantifies the energy usage of the various chilled water systems and typical measures that can be applied to these systems to conserve energy. The tool requires minimum number of inputs to analyze the component-wise energy consumption and incurred overall cost. Both air-cooled and water-cooled systems can be analyzed with this tool; however, this paper focuses on water-cooled systems. The tool uses weather data of the chilled water system location and loading schedules to calculate the chilled water system energy consumption. The Air-Conditioning and Refrigeration Institute (ARI) standard 550/590 typical loading schedule is also incorporated for the chiller(s) loading. The tool is capable of comparing economics by analyzing the energy consumption and relevant cost of the existing system and the new system with cost reduction opportunities considered like: (1) increase chilled water temperature set point, (2) lowering the condenser cooing water supply temperature set point, (3) replace chiller(s), (4) Apply variable speed control to chilled and/or condenser water pumps, (5) upgrade cooling tower fan speed control, (6) Use free cooling when possible for water-cooled systems. The savings can be calculated separately for each cost reduction opportunity or can be combined. The economics comparison can be a primary decision criterion for further detailed engineering and cost analysis related with system changes. The comparison between actual system energy consumption and CWSAT results are also shown.

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