Match capacity to heat load – and save energy
One of the largest cost factors in the industrial refrigeration system lifecycle is energy. In many refrigeration applications, capacity exceeds heat load due to seasonal variations, product loading, occupancy variations, and electrical appliances that cause power loss. Modern, dedicated AC drives, such as Danfoss Drives’ range of VLT® drives, provide the ideal means to continually adjust the equipment capacity to the actual heat load and process needs. The benefits are significantly lower energy consumption and lower operation and maintenance costs.
Intelligent compressor and condenser/evaporator fan control are essential in any optimized refrigeration system. You can typically achieve 10–25% savings on energy consumption by applying Danfoss AC drives to optimize the capacity control of refrigeration compressors, condensers and evaporators. By creating stability while balancing the capacity to the actual load, the system-wide coefficient of performance (COP) improves providing significant energy savings.
Screw compressors controlled by an AC drive typically use 15% less energy than traditional screw compressors with slide valve control only. Optimized start/stop cycles reduce wear and tear on the compressor.
Drive-controlled reciprocating and scroll compressors have higher COP at part loads. VLT® drives are particularly suitable for controlling scroll compressors.
Cascade control optimizes energy savings and reduces lifecycle costs
Cascade configuration produces the optimal interaction between an application and an AC drive under partial loading. The base load is handled by a single application, such as a compressor, controlled by a drive. When heat load rises, the drive starts up additional compressors one at a time. This ensures the applications work at their optimum efficiency point, and the drive maintains maximum energy efficiency throughout the system.
Well-planned cascade control also ensures minimal wear on the individual applications. By rotating mains-powered compressors, for example, maintenance managers can ensure each ends up with a similar number of operating hours and an equal wear level. This increases the lifetime of the applications and extends service intervals reducing lifecycle costs.
Danfoss Drives’ advanced Multi-zone pack controller ensures effective cascading and control of up to six compressor packs. This minimizes energy consumption, avoids too frequent staging and de-staging, stabilizes pressures and temperatures, and reduces compressor wear and tear. Similarly, the Pump Cascade Controller distributes running hours evenly across all pumps to keep wear and tear on individual pumps to a minimum.
Commissioning is fast and easy utilizing the Danfoss Drives display panel that uses common refrigeration terms rather than computer language. The wizard guides the user through the necessary settings. Ease of programming makes installers and service technicians more comfortable and confident, makes their jobs easier and quicker, reduces human errors and improves employee productivity.