Energy optimisation project

Trane CGAM Chiller Performance Analysis

Air-cooled Trane CGAM

On March 16, 2016, Emerging Energy Solutions tested one of two air cooled Trane CGAM chillers located on building 2 at ViaSat’s corporate campus in Carlsbad, CA. with a ClimaCheck onsite system. The timeframe of the evaluation period was from 10:15am to 11:50am with an ambient temperature of 80°F.

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Decreased operating costs

Removed problems

Executive Summary

On March 16, 2016, Emerging Energy Solutions tested one of two air cooled Trane CGAM chillers located on building 2 at ViaSat’s corporate campus in Carlsbad, CA. with a ClimaCheck onsite system. The timeframe of the evaluation period was from 10:15am to 11:50am with an ambient temperature of 80°F.

The test indicated that circuit B had a problem with high condensing pressure which caused an excess consumption in energy of 35% for this circuit. Additionally, it was noted that there was a possibility of refrigerant leaking backwards into through stand still compressors. The conclusion was that there was a
problem with the condenser that was supported not by one input of data but three inputs – pressure, temperature and power.

On July 26, 2016 EMCOR had conducted their PM on this machine and reported there was not a problem with charge or a problem with refrigerant migrating back to the stand still compressors. This was a concern to us as it suggested our collected data was incorrect. To avoid any arguments or disagreements, it was agreed to go back to Viasat and retest the chiller in question.

On October 6, 2016, Emerging Energy Solutions reconnected to the same chiller. The timeframe of the evaluation period from 12:50pm to 1:50pm with an ambient temperature of 75 F. The lead chiller technician from EMCOR was present to assist in the test. Once the test had begun it was clear that the previous
symptoms were no longer present. After the first 30 minutes, each circuit ran independently for approximately 30 minutes. Circuit B was operating much better and identical to Circuit A. After running each circuit independently, the system ran at normal operation. Again, circuit B was running almost identical to
Circuit A. The problem was clearly rectified and no longer an issue.

It should be noted that it is now known that EMCOR had a service call on June 2, 2016. Per the paperwork the technician had found a contactor and fuses to the condenser were blown. It is not noted in the paperwork which circuit that was affected but our assumption is Circuit B since this was our problem circuit. In this case the impact of the reduced airflow over the condenser has created the same symptoms as an over charge with high condensing and high sub cool.
Assuming that this system works 24/7 at loads near the measured 45Kw (more than 50% utilization of capacity) and assuming equal distribution of load between circuits A and B, the difference in annual operating cost as measured in March until condenser fan was fixed in June, the result is approximately $ 1,500 and the compressors would have worked near their limit with increased wear as a result.

Read the full report here. 

Project details

Tests done by: Sean McCaffery, Emerging Energy Solutions
Report published by: Klas Berglof
Unit: Trane CGAM

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