Following Subteam Lead CoDR on January 21st, we are trying to figure out :
Multi-Junction Probe Extensions: Is it possible to design a probe with multiple lateral extensions (similar to a "T" shape) with junctions attached at those points? We want to measure temperature at various radii throughout the tank rather than just at the center. Goal is to get a nice temperature gradient.
Compression Fitting Alternatives: Since the tank will be rotating, we need to ensure the cabling doesn’t tangle. Is there a specific adapter or slip-ring compatible fitting that allows the assembly to rotate with the tank while keeping the cable from tangling or liquid from leaking?
Also, this is a better explanation for the DAQ system of the thermocouplers:
The process begins with a Multipoint Thermocouple Probe. A thermocouple is a sensor made of two different metal wires joined at one end.
Thermal Gradient: This is simply the difference in temperature between the tip of the probe and the electronics it is plugged into.
Multiple Junctions: These are the specific spots where the metal wires meet. When these junctions are exposed to heat, they generate a tiny amount of electricity.
μV-Level Signal: The electricity generated is measured in microvolts (μV). This is an extremely small amount of power—so small that it is very easy for electrical "noise" from other devices to ruin the signal.
The signal must travel from the heat source to the circuit board without being corrupted.
Thermocouple Extension Cable: This cable is made of the exact same metals as the probe. If you used regular copper wire here, you would create a new, accidental "junction" that would give you a wrong temperature reading.
Twisted Pair & Shielded: The wires are twisted together and wrapped in a metal foil (shield). This prevents electromagnetic interference from outside sources from "leaking" into the tiny μV signal.
Differential Analog Domain: This means the system looks at the difference in voltage between the two wires rather than the voltage of just one. This helps cancel out any errors that affect both wires equally.
Now the tiny electricity reaches the DAQ (Data Acquisition) PCB. This is a circuit board that houses a specialized chip called the MAX31856.
Thermocouple-to-Digital Converter: This chip is the translator. It takes the tiny analog voltage and turns it into a digital number.
CJC (Cold-Junction Compensation): Because thermocouples only measure the difference between the tip and the board, the chip has to measure its own temperature (the "Cold Junction") and add that to the calculation to get the actual temperature of the probe tip.
Linearization: The relationship between heat and voltage in metal is slightly curved, not a straight line. The chip uses math to "straighten" this data so the temperature is accurate.
The data is now a clean digital number, but it needs to be sent to the main brain of the device.
Digital SPI Interface: This is a set of four wires used for high-speed communication between chips. It tells the converter exactly when to send its data.
Payload MCU (Microcontroller Unit): This is the "computer" or brain of the system.
Timestamping & Packetization: The computer records exactly when the temperature was taken (timestamping) and bundles that data into a small digital "envelope" (packetization) so it can be saved or sent to a screen.
Sources:
Serial Peripheral Interface (SPI) Guide (SparkFun): A standard reference for how the "Master" (the MCU) and the "Peripheral" (the MAX31856) stay in sync using a shared clock.