1. CMS CO 2 Cooling Test Stand Capacity and Load Disruption Tests Simon Kwan Erik Voirin Simon Kwan, Erik Voirin1CMS CO2 Cooling Test Stand Test Results

2. Cooling System Temperature Control Cooling System uses three on/off condensing units and a trim heater to control temperature Simon Kwan, Erik Voirin2CMS CO2 Cooling Test Stand Test Results

3. Cooling System Heat Load Cooling System uses a fully variable 6000W Test heater to simulate detector heat load Simon Kwan, Erik Voirin3CMS CO2 Cooling Test Stand Test Results

4. Cooling System Temperature Control Trim Heater : 6000W resistance heater – Controlled by PID feedback loop – Controlling Process Variable is Storage Tank Temperature Storage Tank Temperature – Obtained from Pressure Transmitter Saturation Pressure to Temperature calculations done by PLC – Very fast response compared with RTD in heavy thermowell – Slightly Noisy, which was fixed by a digital filter in PLC Simon Kwan, Erik Voirin4CMS CO2 Cooling Test Stand Test Results

5. Tuning PID Loop and System Tests Control loop tuned for temperature stability – 2 Control scheme tests 1.Cooling Capacity Test – System tested for stability with high heat load. 2.Cooling Disruption Test – System tested for stability upon set point and load changes. Simon Kwan, Erik Voirin5CMS CO2 Cooling Test Stand Test Results

6. Cooling System Capacity Test Run Test Heater at 5000W for several hours – System remained stable at the temperature set point. – Temperature stayed within 0.05 o C of set point – Only needed to run a single condensing unit -20 o C temperature set point Condensing unit #3 ran solo during the capacity test System has cooling capacity to spare (or backup units) Simon Kwan, Erik Voirin6CMS CO2 Cooling Test Stand Test Results

7. Cooling System Disruption Tests Temperature set point change test – Showed maximum temperature overshoot of 0.4 o C (even on cool down from room temperature) Load change test – Simulates the turning on/off of some of the detectors electronics Simon Kwan, Erik Voirin7CMS CO2 Cooling Test Stand Test Results

8. Cooling System Disruption Tests Run test heater at a specific load, immediately apply increase (or decrease) load. – System remained stable within 0.2 o C of set point. – One temperature overshoot then back to set point in ~10 minutes – Overshoot appears somewhat proportional to load change: 0.1 o C error per 1000W load change Largest changes tested is 4000W  2000W  4000W Simon Kwan, Erik Voirin8CMS CO2 Cooling Test Stand Test Results

9. Some Load Step Change Data Simon Kwan, Erik Voirin9CMS CO2 Cooling Test Stand Test Results

10. Some Load Step Change Data Simon Kwan, Erik Voirin10CMS CO2 Cooling Test Stand Test Results

11. System Test Results Cooling system passed capacity and disruption tests. Next is testing micro-tube cooling loop performance – Test under steady state loads – Test at different flow rates / diff. pressures – Apply step changes in heat load to test for dynamic stability Simon Kwan, Erik Voirin11CMS CO2 Cooling Test Stand Test Results