Case Study: Operational Saving – Correct Refrigerant Charging in Refrigeration Compressors
Energy efficiency in HVAC and refrigeration systems is critical for industries where utility costs form a large portion of operational expenses. One of the most overlooked factors affecting performance is correct refrigerant charging. This case study from XYZ Company demonstrates how optimizing refrigerant levels led to significant operational savings and improved system efficiency.
Background – Equipment and Industry
- Equipment: Refrigeration Compressors
- Industry/Sector: Chemical Manufacturing
- Location: XY region
- System Setup:
- 3 refrigeration compressors of 100 kW rated power each.
- Operated for a chilled water plant supplying cooling to chemical processes.
Problem Identified – High Specific Power Consumption
During an energy audit, the following issues were observed:
- Specific Power Consumption (SPC): 0.98 kW/TR (higher than expected).
- Suction Pressure: Only 30–40 psig (much lower than the recommended range).
- Impact: Reduced cooling capacity, higher energy usage, and unnecessary operation of all three compressors.
Practical Example: For an 8°C chilled water system, suction pressure should be 60–65 psig. At 37 psig, a 100 TR chiller delivered only 49 TR, wasting energy and reducing efficiency.
Corrective Measure – Refrigerant Charging
The audit recommended:
- Increase refrigerant charge to raise suction pressure to 60 psig.
- Result:
- Cooling capacity increased by 40%.
- Efficiency improved significantly.
- One compressor out of three was switched off permanently, reducing operating hours and maintenance costs.
Results – Energy Savings Achieved
- Power Saving: Approximately 30–35 kW (depending on load conditions).
- System Efficiency: Improved cooling performance with reduced compressor load.
- Operational Impact:
- Lower electricity bills.
- Reduced wear and tear on compressors.
- Extended equipment life.
Practical Example: By switching off one compressor, XYZ Company not only saved energy but also reduced maintenance costs, as fewer machines were running continuously.
Key Learning – Importance of Correct Refrigerant Charging
- Undercharging Issues:
- Sometimes done deliberately to reduce liquid carryover at low loads.
- Leads to reduced efficiency and higher specific power consumption.
- Correct Charging Benefits:
- Ensures optimal suction pressure.
- Maximizes cooling capacity.
- Reduces compressor energy consumption.
Conclusion
This case study highlights that correct refrigerant charging is a simple yet powerful measure to improve efficiency in refrigeration systems. By optimizing suction pressure, XYZ Company achieved 30+ kW power savings, improved cooling capacity by 40%, and reduced operational costs.
