Picalor

Multi-Channel Heat Balance Calorimetry on the Raspberry Pi

--> Incomplete - work-in-progress! <--

Thermal power (or heat flow) measurement of one segmented or multiple individual liquid-cooled or liquid-heated systems under the assumption that the enthalpy difference of the fluid entering and exiting each system per unit of time is equal to the energy dissipated or released by the system.

Quasi-isothermal condition can be achieved by using a sufficiently high flow rate. Accurate heat flow measurements under these conditions require very sensitive and robust differential temperature sensing.

This is implemented by the Picalor hardware using platinum resistive temperature sensors in a deflection-type bridge configuration connected to a multi-channel, high-precision delta-sigma ADC system.

When performing the measurement with fluid temperatures set nearly at environmental temperature level, convection and radiation heat loss can be made negligible e.g. for power loss measurements in electronics.

For applications in chemistry, the multi-channel hardware can be useful for Constant Flux Calorimetry or segmented Continuous Reaction Calorimters.

Supported hardware:

• Picalor OSHW Raspberry Pi add-on circuit board featuring:
  • 16-channel analog frontend for Pt 1000 sensors
  • 4x pulse-timing flow sensor inputs
  • 2x ADS1256 24-Bit 8-ch ADC
• Waveshare "High Precision AD/DA board"

Hardware:

• PCB Design Files: picalor_hardware
• Circuit Diagram (PDF)
• Circuit BOM (HTML)

Software Documentation (Generated):

• Picalor Core (server component)
• Picalor App (browser client)