3.4 Sensor Subsystem
To see which sensors and electronics used in semester 1 click here
3.4.1 Purpose of the Sensing Subsystem
The sensing subsystem was used to measure operating parameters, support system monitoring, enable water circulation control, and provide data for performance evaluation of the small-scale CSP system.
3.4.2 Sensing elements
The project mainly used an irradiance sensor to measure solar input and temperature sensors to monitor the receiver, pipes, and TES temperatures. Additional components in the sensing and control subsystem included a humidity sensor for rain detection, a wind sensor for environmental monitoring, an ESP32 as the sensor controller, a Raspberry Pi as the multitask server and data-processing unit, and a MOSFET as a timed on-off switching component.
3.4.3 Data Acquisition and Processing Components
Data acquisition and processing components such as the Raspberry Pi, ESP32, thermocouple data loggers.
3.4.4 Basis for Component Selection
ESP32-DEVKITC-32UE: Selected as a low-cost and compact sensor controller for data acquisition. Compared with common alternatives such as Arduino or non-wireless microcontrollers, it offers built-in wireless connectivity, allowing continuous data transmission to brokers or online databases with simpler integration.
Raspberry Pi 5: Used as the central processing and logging unit. Compared with lighter microcontrollers, it provides stronger computing capability, multitasking, and offline data storage, making it suitable for coordinating multiple sensing components and supporting the ESP32 within the overall sensing system.
Apogee SP-420 pyranometer: The SP-420 provides direct USB output and simple data logging when connected to Pi 5, making it easy to integrate into the prototype. also IPX7 rated for outdoor measurement.
6-Channel Omega: Selected for its SD-card data logging capability and small probe size, this thermometer was the most suitable option for measuring temperature inside the small copper tubes of the receiver.
IRLB8743 MOSFET: Although other relay or switching components are possible, the system only requires a simple on-off switch controlled by the Raspberry Pi 5. A power MOSFET was therefore selected as a suitable switching component for the 24 V DC pump.
3.4.5 Sensor Placement and Measurement Points
For outdoor test. the controlling sensing components are inside electric boxes, preventing rain from coming in and continuously measure.