www . refrigerationandaircon . co . za RACA Journal I September 2024 41
Professionals who care
By Michael Young , Pr . Eng .
MICHAEL YOUNG
Michael Young is a trainer , coach and a pre-sales engineer in the HVAC industry . He graduated from the University of the Witwatersrand in the field of Mechanical Engineering ( B . Sc Mech Eng ) in 2008 and qualified as a Professional Engineer ( Pr . Eng ) in 2013 . Michael is passionate about promoting knowledge and helping other young engineers grow within the industry through his training workshops and coaching sessions .
BEST PRACTICES FOR OPTIMISING AIRFLOW IN DATA CENTRES : ENHANCING EFFICIENCY AND RELIABILITY
Airflow is extremely important inside a data centre - it is the medium that cools the central processing unit ( CPU ) chip in IT equipment .
The challenge is that we can experience server failure not because there ' s insufficient cooling but because there ' s insufficient airflow that is being delivered to certain servers . When this occurs , some servers may not receive an adequate amount of cold air which results in a temperature rise of the CPU and the server will shut down . The opposite can also occur where excessive airflow results in higher energy consumption of the cooling unit .
Ensuring optimal and sufficient airflow in a data centre has emerged as a critical factor in maintaining the efficiency and reliability of IT equipment . Today , HVAC engineers are developing innovative strategies to tackle airflow challenges , thereby
preventing potential server disruptions and optimising energy consumption from the cooling unit .
So how do we now accomplish this ? Inside a computer room air conditioning ( CRAC ) unit are multiple different types of airflow control strategies and today , we are going to discuss two general methods that are used by some suppliers :
• One prominent method involves utilising the pressure difference between the raised floor and the data centre environment to control the speed of the fans . This approach makes use of a pressure differential measurement device that monitors the air pressure difference under the raised floor and outside the cooling unit . By comparing these measurements against a predefined pressure difference set point , the system will dynamically adjust the fan speed . If the sensor measures a high-pressure difference value , it indicates that over-pressurisation is occurring and there is excessive airflow . The onboard controller within the cooling unit immediately reduces the fan speed , thereby reducing the airflow into the raised floor and electrical consumption of the unit . Conversely , if pressure difference readings are below the set point , the unit recognises that there is insufficient air under the raised floor and a signal is sent to increase the fan speed .
• A second approach is the use of remote temperature sensors that are strategically placed throughout the data centre . These sensors continuously monitor temperature variations and relay this data to the cooling unit ’ s controller via an advanced communication protocol like Modbus . Once this data is received from the controller , it can adjust the speed of the fans according to either the highest temperature sensor reading or the average
“ By fine-tuning airflow based on real-time data and feedback , data centre operators can achieve significant improvements in energy efficiency .”
www . refrigerationandaircon . co . za RACA Journal I September 2024 41