scholarly journals Energy-saving Analysis of Chilled Water System for Large Temperature Difference Air Conditioning

2019 ◽  
Vol 252 ◽  
pp. 032112
Author(s):  
Chengwen Lee ◽  
Yungchung Chang
Keyword(s):  
Energy Saving ◽  
Temperature Difference ◽  
Air Conditioning ◽  
Water System ◽  
Large Temperature ◽  
Large Temperature Difference ◽  
Chilled Water ◽  
Chilled Water System

scholarly journals Exergy analysis of large temperature difference series air conditioners in subway stations

2020 ◽  
Vol 165 ◽  
pp. 04067
Author(s):  
Kong Xiang jian ◽  
Bi Hai quan ◽  
He Lei
Keyword(s):  
Temperature Difference ◽  
Air Conditioning ◽  
Cooling System ◽  
Water System ◽  
Exergy Efficiency ◽  
Subway Station ◽  
Large Temperature ◽  
Refrigeration System ◽  
Large Temperature Difference ◽  
Difference Series

In view of the large difference in the heat and humidity ratio of each air-conditioning zone in the subway, the unified cooling and dehumidification method is adopted, which changes the traditional connection mode of air-conditioning terminal in parallel. A cooling system of air-conditioning terminal surface cooler in series, i.e. large temperature difference series cooling system, is applied to the subway station. The large temperature difference series cooling system is divided into three subsystems: cooling water system, chilled water system and end refrigeration system. The second law of thermodynamics, namely the law of exergy equilibrium and thermoeconomics, is used to analyze the feasibility and economy of the large temperature difference series system and its subsystems. After comparing energy consumption and economy with the conventional air conditioning system, it was found that the exergy efficiency of the chilled water system using the large temperature difference series cooling system was reduced. However, the exergy efficiency of the end refrigeration system in the subway equipment area has been significantly improved, saving electricity costs, and the investment can be recovered in 3.7 years, and the exergy cost has dropped significantly. The use of a large temperature difference series cooling system in a subway station can achieve the effect of energy saving and cost reduction.

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.

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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