Abstract: This paper introduces the feasibility analysis of applying frequency converters in the field of central air conditioning, and provides a comprehensive analysis of the application of frequency converters in volumetric chillers and centrifugal chillers. It points out that frequency converters are not adaptable to all situations and should be analyzed specifically according to the characteristics of the system.
Keywords : frequency converter, central air conditioning, refrigeration unit
introduction
According to electrical engineering, the relationship between the speed of an electric motor and the frequency of the power supply is as follows:
n = 60f(1-S)/P Where: n—speed, r/min; f—power supply frequency, Hz; s—motor slip; P—number of poles of the motor.
As shown in equation (1), changing the power supply frequency can change the speed of the motor. Compared with traditional speed control methods, changing the motor speed by frequency conversion has the following advantages: 1) wide speed range; 2) stepless smooth speed regulation; 3) comparable to DC speed regulation; 4) soft start, reducing the impact of starting current on the power grid. Due to these advantages, frequency converters have been widely used in many fields in recent years.
In the refrigeration and air conditioning industry, equipment such as refrigeration units mostly operate under partial load. The greater the deviation of the operating conditions from the design conditions, the lower the equipment efficiency. To improve the operating efficiency of equipment such as refrigeration units and water pumps and achieve energy-saving operation, the application of frequency converters provides the best solution.
The application of frequency converters in central air conditioning is mostly concentrated in the secondary circulation system of chilled water. Regarding their application in the main unit, unless the main unit manufacturer directly provides the main unit with frequency converter control, there are very few cases of retrofitting the main unit with frequency converters, although there are a few reports of successful retrofits.
Due to the diversity of central air conditioning equipment and the complexity of system design, applying frequency converters in this field is not simply a matter of modifying the electrical control system. Rather, it requires improvements to the control methods based on the characteristics of various equipment and systems to achieve improved control quality and energy savings. This paper analyzes the feasibility of applying frequency converters to the central air conditioning field for reference by colleagues in the field.
For detailed information, please click: Analysis of the Application of Frequency Converters in Central Air Conditioning
