Energy Optimization by Correcting Low Refrigerant Charge
Overview
A large U.S. cold-storage distribution facility operating a centrally controlled ammonia refrigeration plant used the SiteSense platform to better understand system performance and monitor electrical consumption. Continuous monitoring revealed rising electricity consumption, unusual compressor operation, and deviations from expected refrigeration performance. Digital twin analytics identified patterns consistent with a low refrigerant charge, leading to corrective action and significant cost savings.
Energy Challenges
SiteSense digital twin analytics detected abnormal compressor loading that did not align with expected refrigeration demand. The models flagged a mismatch between energy consumption and predicted evaporator performance. Additional symptoms included fluctuating suction pressure and temperature instability.
Root Cause Diagnosis: Low Refrigerant Charge
Investigation revealed a loss of liquid seal on the evaporator feed trees, allowing vapor to recirculate through the system. Instead of absorbing heat and providing refrigeration, the compressors were recompressing vapor, increasing energy use while reducing cooling capacity.
Corrective Actions Implemented
Recharged refrigerant to proper operating levels
Verified vessel feed operation and control setpoints
Verified suction and liquid feeds across evaporators
Results: Clear & Rapid Performance Improvement
After correcting the refrigerant charge, overall electricity consumption decreased by nearly 20%, resulting in more than $22,000 in savings within a single month.
Daily energy usage declined by 7,743 kWh (-35.8%)
Peak demand reduced by 173 kW (-14.6%)
Average daily energy costs dropped by $1,176 (-31.4%)
Power demand decreased from 901.3 kW to 578.6 kW
Daily refrigeration costs decreased from $3,753/day to $2,575/day
Key Takeaway
The SiteSense digital twin monitoring platform identified a hidden low refrigerant charge and reduced energy costs by approximately $1,200 per day while improving overall system performance and reliability.
