# Research on Real-Time Control Strategy for HVAC Systems in University Libraries
## 3 Experimental Cases
### Device Model and Objective Function
#### 3.2.4 Collection of Equipment Data  
To gather data for the experimental research, a communication card was installed on the frequency converter of the unit to facilitate communication between the frequency converter and the upper computer system. The communication card can collect various data during the operation of the frequency converter, including the input voltage and current, output voltage and current, power, temperature, and other parameters. These data can be used to evaluate the operating status of the refrigeration unit, detect anomalies in a timely manner, and make the necessary adjustments. In the HVAC system, sensors are utilized to collect information, such as temperature and humidity, which are then transmitted to the control system. This collected information serves two purposes: it can provide feedback for control adjustment within the HVAC system while also enabling energy consumption calculations based on these data. Some of the devices used are listed in Table 2. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Name** & **Brand** & **Type** & **Range and Accuracy** \\ \hline Data collector & Qingdao Hantai & DAQ4090A &
\begin{tabular}{c} Basic DCV accuracy of 0.003\%, scan rate up to \\ 450 channels/second \\ \end{tabular} \\  & & & Temperature measurement accuracy is \(\pm 1\)\({}^{\circ}\)C. The measurement accuracy of voltage and current is \(\pm 1\)\%. Measurement accuracy of pressure and flow rate is \(\pm 1\)\%. \\ Industrial intelligent gateway & Huachen Zhitong & HINET & Support Ethernet, serial port, CAN port, 10 port and other devices access and Ethernet, 2G/3G/4G \\  & & & full network access. Embedded a variety of industrial protocols, support more than 99\% of PLC and most industrial equipment access. Temperature measurement accuracy is \(\pm 1\)\({}^{\circ}\)C. Measuring range is 0 to 50 \({}^{\circ}\)C. Temperature measurement accuracy is \(\pm 1\)\({}^{\circ}\)C. Measuring range is 0 to 50 \({}^{\circ}\)C. \\ Humidity sensor & Amphenol & Telaire RH & Measurement range is 5 to 95\% RH. \\  & & & Accuracy \(\pm 5\)\% RH \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Device information. The original plan was to test the energy-saving effect of the system from 18 June to 22 June, in accordance with the national standard GB/T 31349-2014 [34] \"Technical requirements of measurement and verification of energy savings--Central air conditioning system\" using the similar day comparison method. However, owing to sudden equipment  
\begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Data** & \begin{tabular}{c} **Mean Outdoor** \\ **Temperature** \\ **(\({}^{\circ}\)C)** \\ \end{tabular}  & \begin{tabular}{c} **Operation** \\ **Mode** \\ \end{tabular}  & \begin{tabular}{c} **1\# Chiller** \\ **(kWh)** \\ \end{tabular}  & \begin{tabular}{c} **2\# Chiller** \\ **(kWh)** \\ \end{tabular}  & \begin{tabular}{c} **1\# Chilled** \\ **Water Pump** \\ **(kWh)** \\ \end{tabular}  & \ \begin{tabular}{c} **2\# Chilled** \\ **Water Pump** \\ **(kWh)** \\ \end{tabular}  & \begin{tabular}{c} **3\# Chilled** \\ **Water Pump** \\ **(kWh)** \\ \end{tabular}