# Evaluating the Energy-Saving Potential of Solar Dedicated Ventilation Systems Based on ADRC
## 4 Experimental System  
The experimental system, shown in Figure 4, was designed to calculate and analyze the energy-saving features of the proposed solar dedicated ventilation system. This experimental system involves a variable speed fan, a heat insulation duct, a reheating system that can get thermal energy from the solar thermal system, and a DX coil with its cooling and dehumidification system, which has an electronic expansion valve, condenser, and inverter compressor. This cooling and dehumidification system is driven by 1.5 kW electrical power. The variable speed fan is located at the inlet side of the duct to control the air flow rate. All the equipment gets its electrical power supply from the photovoltaic system. The cooling output is controlled by the setting conditions of the indoor chamber by adjusting the electric control valve of the solar thermal system, the electronic expansion valve, and the inverter compressor. This experimental system is an approximate adiabatic system to minimize heat loss. A series of thermal insulation materials is used for the ductwork and experimental equipment. There are two nearly adiabatic spaces in this test rig. One simulates the outdoor conditions and the other simulates indoor conditions, as shown in Figure 4. Two sets of heat generators and moisture generators were applied to realize the variable space load conditions for both the indoor and outdoor conditions through sensible heat and latent heat changes. As the heat generator and moisture generator run by themselves, the sensible heat ratio (SHR) can be adjusted to simulate a wider range of operating conditions. The air handling unit (AHU) was applied to supply a cooling load for this system to meet the thermal energy balance. The power of the heat generator is 0-10 kW and the power of the moisture generator is 0-5 kW, which are adjusted by the ADRC. Test instruments were used in this experiment. The wet-bulb and dry-bulb temperatures were measured by using thermocouples and the airflow rate was measured by an air flow meter. Moreover, all the equipment was connected with the power meter to measure how much electrical power is supplied by the photovoltaic system. The major instruments are thermocouples, which measure  
Figure 4: The experimental system. the wet-bulb and dry-bulb temperatures within a range from -50 to 100 \({}^{\circ}\)C with an accuracy of \(\pm\) (0.05% \(\mathrm{rdg}+0.5\)\({}^{\circ}\)C); an air flow meter, which measures the airflow rate within a range from 0 to 10 m\({}^{3}\)/s with an accuracy of \(\pm\)1%; and a power meter, which measures all the electrical power within a range from 0 to 60 A. The data loggers connect with all the meters to save the experimental data. The system should maintain a thermal energy balance state all the time. A schematic figure of data collection is shown in Figure 5 and the photo of experimental environment is shown in Figure 6 respectively. As climatic conditions in this paper refer to summer in most parts of China and subtropical areas in southern China, the common dry-bulb temperature almost falls in the range 20 to 35 \({}^{\circ}\)C and relative humidity almost falls in the range 35% to 90%. It is necessary to keep the dry-bulb temperature and relative humidity values appropriate for the hot and humid conditions to gain the relevant accurate data in these experiments. Therefore, the test process should satisfy the indoor (setting conditions: 22 \({}^{\circ}\)C and 50%) and outdoor (range: 25 to 35 \({}^{\circ}\)C at 5 \({}^{\circ}\)C interval for temperature, 50% to 80% at 10% interval for relative humidity, and 0.1 to 0.3 m\({}^{3}\)/s at 0.05 m\({}^{3}\)/s interval for airflow rate) thermal conditions, which are similar to the actual environments in these experiments. The data were collected  
Figure 5: Schematic diagram of data collection. Figure 6: Photo of experimental environment. after the experimental system reaches steady-state equilibrium, which takes more than a half-hour for each experiment.