1. TRACI V3 Sheffield & Milano Commissioning Status
Norbert Borek
University of Technology Cracow, Poland

2. TRACI - Sheffield Problem with minimum achievable temperature:
cannot achieve evaporation temperature less than about -30oC
Minimum reached evaporation temperature: -28ºC

3. Issue with compressor TRACI - Sheffield
When chiller high pressure side valve is closed (located before expansion vale) pressure should fall. Compressor should behave like a vacuum pump. However pressure stays constant around absolute 0.9 bar. It is a clear indication that compressor itself is damaged. Actually we are in discussion with chiller supplier about new compressor.
Manual valve on the high pressure side
EH204, TT204
EH205, TT205
Compressor SC21CL R404A/R507 Danfoss

4. TRACI - Milano Problem identification:
Traci filled with CO2 for operation.
To be able to compare correctly the current TRACI pump performance curves with previous pump of M Pumps tested at CERN, we have replaced the local box bypass valve from L series to 31 series valve.
The results showed bizarre behavior of the chiller.
Temperature was permanently too high.
Curves should go up, not fall. It proves that the chiller is too warm
Local box with 31 valve series
Improved and installed new insulation custom made plate dedicated for M Pump type

5. Proposed solution TRACI - Milano
We’ have identify chiller expansion valve misbehavior.
Because of above and previous problem of TRACI Milano we have decided to make one working chiller out of two (Sheffield and Milano)
We have exchanged piping section including HX & expansion valve between TRACI Milano and TRACI Sheffield.
Extra designed part with expansion valve
Pump out the refrigerant from chiller
Manual leakage measurement

6. TRACI - Milano Leakage measurements results
Recorder
Curves are stabilised. The chiller is tight. We can mount the unit to the Traci !

7. TRACI - Milano Assembly repaired chiller
We are currently on the stage of assembling. After refilling the refrigerant, chiller should work fine !

8. Summary TRACI - Sheffield TRACI - Milano Next steps
Problem with minimum achievable temperature.
Recognized issue with compressor.
Waiting for respond from supplier of new compressor.
TRACI - Milano
Problem with warm chiller (R404a temperate was permanently too high).
Exchanged piping section including HX & expansion valve between TRACI Milano and TRACI Sheffield.
Leakage measurements prove that the chiller is tight.
The chiller unit is currently mounted.
Next steps
Restart the commissioning tests for both models TRACI V3