Fig. 1. Schematic diagrams of system. (a) Radiative cooling principle; (b) power measurement principle and system

Fig. 2. Schematic diagrams of 3D modeling structure and measurement position structure. (a) Device structure; (b) measurement component position structure

Fig. 3. Circuit system block diagram

Fig. 4. System hardware composition diagram. (a) Physical connection diagram; (b) PT100 platinum resistance; (c) DS18B20 digital temperature sensor; (d) PTC heater; (e) LCD screen

Fig. 5. Error test of temperature sensor. (a) Open space testing environment; (b) sealed space testing environment

Fig. 6. Temperature sensor test after calibration

Fig. 7. System step response. (a) Step response; (b) fit curve

Fig. 8. Temperature regulation results. (a) Black paint (2022-05-31); (b) PVDF film (2022-06-01)

Fig. 9. Fuzzy PID control simulation model

Fig. 10. Response curves of different controller. (a) K=1.4,T=344; (b) K=2.4,T=396

Fig. 11. Diagram of open environment measurement device

Fig. 12. PVDF film structure and spectrogram. (a) Macroscopic appearance; (b) surface topography; (c) reflectance; (d) emissivity

Fig. 13. Outdoor environment temperature measurement by using PVDF film

Fig. 14. Cooling power measurement by using PVDF film