Final Design

Overview

CAD of final Chill Puck assembly

Photo of prototype Chill Puck assembly, with hair dryer to emulate heated wind tunnel

The final Chill Puck deliverable includes two subassemblies. The first is a lightweight silicon coupon holder with an embedded thermocouple routed to a bluetooth communicator, for a substrate stand assembly without any moving parts.

The first subassembly, consisting of the coupon stand and Bluetooth-enabled thermocouple sensing suite

The second is an air delivery assembly consisting of a vortex tube and a motorized pressure regulator controlled via a closed-loop PD feedback system designed to control the cooling airflow to maintain a constant coupon temperature. 

The Second subassembly, consisting of a pressure-controlled vortex tube and a custom duct

Performance

To achieve temperature control of the silicon coupon substrate, the temperature is read from the embedded thermocouple, digitally transmitted to the vortex tube control system, and the cooling airflow is adjusted accordingly. Cold air from the vortex tube is injected into the heated airflow to the underside of the coupon substrate, providing the cooling necessary to maintain setpoint temperatures. Below is a sample dataset demonstrating the Chill Puck's ability to match a variety of setpoint temperatures to a fantastic degree of accuracy.

Data from Chill Puck temperature range and controller tracking test

The Chill Puck was also designed to be capable of collecting data for testing periods of an hour or more, and the final design was capable of maintaining a coupon temperature for an hour without any issues.

Data from Chill Puck hour-long test period