Abstract: Three-dimensional force control configuration software provides a powerful software development platform for the design of real-time monitoring systems. It features robust data acquisition and processing capabilities and a dynamically displayed human-machine interface. The design of an experimental measurement and control system for a variable-capacity water-cooled chiller unit based on the three-dimensional force control configuration software ideally realizes real-time monitoring of various measurement and control points on the chiller unit's experimental platform, ensuring the reliable, efficient, and safe operation of the equipment system. Keywords: Variable-capacity water-cooled chiller unit; Three-dimensional force control configuration software; Dynamic display; Status monitoring. Application in the Variable Capacity Refrigeration Loop Test Platform of Forcecontrol Abstract: An Variable Capacity Refrigeration Loop Test Platform with a control system based on Forcecontrol, a powerful industrial control configuration software module, has been introduced. The practice has proved that it's reliable, efficient and simple in function. Keyword: variable capacity chiller, refrigeration loop performance, test platform, PCAUTO, dynamic display, real-time monitoring Overview: Variable capacity air conditioners [1][2] have good regulation characteristics and high energy efficiency ratio [3][4], and are increasingly widely used in household air conditioners and variable frequency multi-split units (VRV) [5]. Usually, variable capacity air conditioners are designed according to rated operating conditions or maximum operating conditions. However, in actual operation, variable capacity air conditioners often operate under partial load conditions, deviating from the design operating point. Especially when operating at low load, the working state of the refrigeration cycle is further away from the design operating condition. Therefore, the performance of the refrigeration cycle under partial load conditions is different from that under design conditions. Analyzing the operating characteristics of variable capacity air conditioning systems is of great significance for studying their cooling efficiency (COP), seasonal energy efficiency ratio (SEER), energy saving, and control. Advanced control systems and flexible configuration software provide the technical foundation for real-time monitoring and control. The variable capacity water-cooled chiller experimental measurement and control system based on ForceControl configuration software has developed flexible and diverse configuration methods, providing a user-friendly interface and simple usage, making it very easy to implement and complete various control functions of a computer-integrated system. It is a real-time monitoring system for an experimental platform built on a computer system, capable of computer acquisition of various experimental data, real-time/historical curve display, data reporting, simulation control, and a series of other functions. 1. System Overview 1.1 Unit Overview The principle of the experimental device is shown in Figure 1, and its overall structure is similar to a small variable capacity water-cooled chiller unit. The refrigeration cycle consists of a variable frequency compressor 1 (with its own suction gas-liquid separator 11), condenser 2, high-pressure liquid receiver 5, solenoid valve 6, filter 7, sight glass 8, electronic expansion valve 3, evaporator 4, etc. The refrigerant flow rate of the refrigeration cycle is adjusted by setting the speed of the compressor (frequency 30Hz ~ 100Hz), and the outlet state of the evaporator is adjusted by setting the opening degree of the electronic expansion valve (0% ~ 100%). The chilled water circulation system adopts a closed loop, consisting of a chilled water constant temperature tank 12, water pump 13, valve 14, evaporator 4, etc. The cooling water circulation adopts a mixed water circulation, consisting of a cooling water constant temperature tank 15, water pump 16, valve 17, condenser 2, bypass valve 18, etc. The unit runs on R22 refrigerant. 1.2 Functions of the experimental measurement and control system The experimental platform of the variable capacity water-cooled chiller mainly includes the following functions: (1) Monitoring of basic parameters of the experimental platform (2) Simulation control of equipment start-up and shutdown and parameter setting. (3) Secondary calculation, recording and automatic analysis of data. 1.3 Composition of data acquisition module The data acquisition uses a 5510E motherboard and a 5018 thermocouple module and a 5017UH analog module (Advantech Taiwan Co., Ltd.). It is connected to a PC through an RS232C serial port. The 5510E motherboard is a PC-based PLC developed by Advantech Taiwan Co., Ltd. It has 8 expansion slots. The input and output interfaces of its expansion modules use connector terminals, which are easy to plug and unplug. Therefore, the 5510E host can also be shared. 1.4 Main measurement parameters of the experimental platform Temperature parameters: evaporator inlet temperature, compressor outlet temperature, chilled water inlet temperature, chilled water outlet temperature, cooling water inlet temperature, cooling water outlet temperature. Pressure parameters: pressure before electronic expansion valve, liquid storage tank outlet pressure, evaporation pressure, pressure difference before and after evaporator, atmospheric pressure. 1.5 Fitting calculation and heat balance equation As the experimental system measurement and control software, simply collecting temperature and pressure data is not enough to meet the requirements of "analyzing" experimental characteristics. Combining the thermophysical property fitting curves and heat balance equations of R22 refrigerant, the collected temperature and pressure values ​​are directly calculated in the application actions of the configuration software to obtain refrigeration characteristic parameters such as saturated liquid (gas) specific enthalpy, superheated gas specific enthalpy, cooling (heating) capacity, and COP, which are then stored as process quantities. 2. Monitoring System Software Platform Design The experimental measurement and control system platform uses the Windows XP operating system. The human-machine interface and database of the application software are developed using ForceControl 6.0 monitoring configuration software. ForceControl 6.0 monitoring configuration software is a high-end product designed and developed by ForceControl Technology based on current trends in automation technology, summarizing years of development and practical experience, and numerous user needs. It is the culmination of the collective wisdom of all R&D engineers at ForceControl Technology. This product is mainly positioned for the domestic high-end automation market and applications, serving as a powerful data processing platform for enterprise informatization. The product is developed using .NET technology, employing advanced software engineering methods. Compared with earlier ForceControl products, ForceControl 6.0 represents a significant leap forward in data processing performance, fault tolerance, interface containers, and reporting capabilities. 2.1 Define I/O Devices: Locate and expand the "I/O Device Configuration" item in the navigation menu; expand the category "Intelligent Module" and select the appropriate device manufacturer, here "ADVANTECH"; select the appropriate device model, here "ADAM5000-E"; define the device parameters in the "I/O Device Definition" dialog box. 2.2 Create and Connect to a Real-Time Database: Locate the database configuration in the navigator and begin creating the monitoring system's database. The temperature, pressure points collected in the system, along with calculated specific enthalpy values, valve openings, inverter frequencies, etc., must all be stored in the database. When creating the database, first create new points according to point types, set their parameters, and then establish a mapping relationship between the created points and point parameters and a specific data item detected by the I/O device. Once this relationship is established, a data link is established between the points and point parameters in the database and the data source from the I/O device. 2.3 The human-machine interface of the system consists of a main data acquisition screen, a control and alarm window, a trend curve window, a data report window, a real-time pressure-enthalpy chart, and a historical data pressure-enthalpy chart. (1) Main data acquisition screen The main data acquisition screen displays the temperature, pressure, and specific enthalpy obtained from the acquisition panel in real time and in the trend curve. See Figure 2. (2) Control and alarm window The control and alarm window includes the on/off control of the frequency converter, solenoid valve, chilled water pump, and cooling water pump. The set values ​​of the frequency converter (30Hz-100Hz), electronic expansion valve (0%-100%), chilled water and cooling water temperature (0℃-50℃), chilled water and cooling water electric heater (0%-100%), and chilled water and cooling water flow meter (0L/M-40L/M). Alarm software (3) Operation window The system operation window displays the operation screen of the entire system, as shown in Figure 4. The screen can display the temperature, pressure and other parameter values ​​of each measurement point in real time, and simulate the operation status of the refrigerant flow, chilled water circulation system, cooling water circulation system, electronic expansion valve and compressor in the control process in the form of animation. (4) Trend curve window The real-time curve window displays the real-time change trend curve of temperature and pressure at the collection point. Through this curve, the dynamic change trend of the system under various operating conditions can be observed in a vivid way. The trend curve can display any real-time or historical data curve of any measurement point, and can scale the time axis (X axis) and parameter measurement range (Y axis). It can display data from 1 minute to 12 hours and scale the Y axis from 1 to 8 times. And can zoom in on any part of the curve. (5) Data report window In this window, you can view the real-time data report of the system, or query historical data records and generate historical data reports according to the conditions. You can also edit and print as needed. It can be exported to EXCEL spreadsheet for data analysis. (6) Pressure-Enthalpy Chart Window This window is an innovation of this platform. First, the configuration software fits the saturated liquid line and saturated gas line of the refrigerant, and displays the collected pressure and specific enthalpy values ​​on the pressure-enthalpy chart, which greatly facilitates experimental analysis and research. The real-time pressure-enthalpy chart displays the collected pressure value and the calculated specific enthalpy value on the pressure-enthalpy principle diagram in real time. The historical pressure-enthalpy chart can display up to 8 different operating condition cycle curves at the same time. As shown in Figure 5. 3. Conclusion This paper was formed during the project development process. After the system was put into operation, the effect was good and stable. Continuous operation shows that the system design is reasonable, the investment cost is low, the development cycle is short, the operation is stable, it reduces the labor intensity of the staff, and improves the accuracy of data acquisition. It is a new idea for the design of experimental measurement and control system and has high practical and promotional value. References: [1]. Comparative analysis of regulation technology of variable capacity central air conditioning system; Lin Li, Pei Xiuying; Refrigeration and Air Conditioning, No. 5, 2007, p15-p18; [2]. Variable capacity regulation technology - the future path of refrigeration and air conditioning system; Copeland Corperation; Heating and Refrigeration, June 2003, p122-p123; [3]. Research on regulation characteristics of variable frequency air conditioning system; Shao Shuangquan, Shi Wenxing, Li Xianting, Yan Qisen; Refrigeration and Air Conditioning; No. 1, 2001, p17-p20; [4]. Analysis of the advantages of refrigeration device using variable frequency technology; Shi Yideng, Tian Huaizhang, Chen Linhui, Liang Junjie, Wu Zhihui; Refrigeration and Air Conditioning, Vol. 4, No. 5, October 2004, p59-p62; [5]. Research progress and application prospect of household small central air conditioning; Cai Weidong, Liu Guiping, Li Bin; Refrigeration, Vol. 22, No. 4, December 2003, p31-p35; [6]. Focecontrol 6.0 Graphical Interface Development Manual; Beijing Sanwei Focecontrol Technology Co., Ltd.; [7]. Focecontrol User Manual; Beijing Sanwei Focecontrol Technology Co., Ltd.; [8]. Application of "Focecontrol" in Rubber Powder Production Monitoring System; Wang Dayong, Zhang Xiaodong, Li Huagui, Li Wenhua; Microcomputer Information, Vol. 20, No. 10, 2004, pp. 14-15; [9]. Development of Central Air Conditioning Automatic Control System Based on Configuration Software; Yang Shaohui, Shi Ling; Automation and Instrumentation; No. 3, 2008, pp. 64-66;