The Danfoss ADAP-KOOL system is a modular refrigeration control platform for managing compressor packs and condensers in commercial and industrial refrigeration applications. It covers the full spectrum from small cold rooms to large supermarket transcritical CO2 systems. The platform includes multiple controller models matched to application size and complexity, all sharing a common MODBUS communication backbone for integration with the AK-SM 800 series system manager.

Controller Models

• AK-PC 781: Transcritical CO2 capacity controller with heat recovery. Manages up to 4 compressors with variable-speed and single-step mixing via Best Fit logic. Controls both MT suction and high-pressure stages with gas cooler and heat reclaim functions for hot tap water and space heating.
• AK-PC 651: Mid-size pack controller for up to 10 compressors and 15 combined compressor/condenser steps. Supports Digital Scroll, Copeland Stream (4/6-cylinder), Bitzer CRII unloaders, plus variable-speed drives. Configurable analogue and digital I/O with 4 analogue outputs for speed control.
• AK-PC 551: Compact DIN-rail pack controller for up to 8 compressors across 2 suction groups with common condenser. Suction pressure optimisation, intelligent cycling and run-hour balancing. IP20, 10-module width.

Energy Optimisation

All ADAP-KOOL controllers include multiple energy-saving strategies: adaptive suction pressure optimisation that floats the setpoint based on actual load, floating condensing pressure referenced to outdoor ambient temperature, night-time noise reduction via fan capacity limiting, and heat recovery integration that boosts condensing pressure to capture waste heat for space heating or hot water. These strategies typically deliver 15–30% energy savings compared to fixed-setpoint control.

Safety and Diagnostics

Each controller provides comprehensive safety monitoring: minimum and maximum suction pressure with immediate cut-out on low limit, maximum condensing pressure with stepped compressor shedding before trip, high discharge gas temperature protection, individual compressor safety circuits, and sensor failure fallback modes that maintain operation at a configurable fixed capacity. All alarms and events are logged and communicated via MODBUS to the system manager for remote monitoring.

Technical Specifications