Digi CRAC-CRAH™ Data Center AC Units
Digi controllers are plug and play controllers. Computer room air conditioning is often provided by either direct expansion units or water-cooled air handling units. The DX units are called CRAC units. The water-cooled units are called CRAH units. The CRAC units are the best option for small to medium data centers. However, the CRAC units require more maintenance and consume more energy. The CRAH units are the best options for large dada centers. The CRAH units are often equipped with variable speed fan control. However, the decoupled latent and sensible load control can further improve the data energy efficiency significantly. Based on the specific data center applications, Digi Controllers are named:
- Digi-CRAC™ for CRAC units
- Digi-CRAH™ for CRAH units
- Integrates with the existing management system of the CRAC/H unit
- Automatic emergency bypass system
- Demand response functionality
- Soft start/stop for the fans and compressors
- Easy installation inside existing CRAC/H units or on the wall
The Digi-CRAC/H™ can be applied to CRAC/H units with the following specifications:
- Size: 3-30 tons
- Brands: Lieber / Stultz / APC / ETC
- Units with multiple fans and compressors
- Water, glycol or air cooled condensors
- DX coil evaporator
- Scroll or reciprocating compressor
- Power: 200V-240V/3ph/50Hz,60Hz/380V-480V/3ph/50Hz,60Hz
- Reduces the PUE (Performance Usage Effectiveness) rating to 1.5
- Improves system energy efficiency by 30-40% (2,000-3000 kWh/ton-yr)
- Reduces thermal stress on mission critical equipment
- Reduces peak electrical demand by up to 50% (0.3-0.6kW/ton)
- Runs at 80% speed at peak times with a 30% savings due to reduced compressor lift
- Soft start/stop functionality extends the lifespan of the fans and compressor
- The Digi-CRAH™ created a fan power savings of 60-70%
Data Center – Beijing, China
System Information
- Space temperature requirement of 18-26° C
- Three (3) 25-ton DX units with two compressors
Digi-CRAC™
- M&V for baseline mode (2 wee pre-period)
- M&V for energy efficiency mode (2 week post period)
- Installed return air registers and return air duct work for Lab Room #3
- Improved the reliability and stability of the HVAC system
- Reduced maintenance costs and prolonged the equipment life
Energy savings: CRAC 1 (38.3%) | CRAC 2 (39.7%)
Project simple payback: 1.8-2.1 years
- What is Digi-Crac™? Digi-CRAC/H™ is an aftermarket innovation for data center air conditioning units and air handler units
- What are the benefits of using a Digi-CRAC/H™?Energy savings of up to 30% or more for a DX unit and up to 60% savings for chilled water units
- What does the Digi-CRAC/H™ do?The Digi-CRAC/H™ matches the dynamic nature of the cooling loads of a data center with capacity modulation
- Can the Digi-CRAC/H™ be installed in any data center?Yes, the Digi-CRAC™ can be installed in any data center
- What is the communication protocol that comes with the Digi-CRAC™?The Modbus RTU RS485 communication protocol
- How does the Digi-CRAC/H™ save energy?A typical annual data center load is between 40% to 80% of the design cooling capacity. If the compressor lift is reduced and the system runs at lower speeds, the capacity of the existing heat exchanger is expanded. This increased capacity results in a 20% to 30% compressor energy savings. Following the cube rule of the fan law for power vs. speed, running a CRAC unit at a speed of 80% results in a fan power savings of 50%.