Thermal Management Solutions from APW President Systems

… the story so far In the beginning power dissipation levels in Cabinets were low ………………. With the advent of rack mount servers, the power dissipations increased ……….. Now, with use of 1U Servers becoming widespread, these levels are set to cross. Floor space in Data Centres is expensive. The trend is to pack as many servers in one cabinet as possible But conventional cooling methods are inadequate when the “ceiling” is reached typically 300-600 watts typically 1000-2000 watts 6 KW in a 42U cabinet! $ 20,000.00/sq.ft 3.6 KW in a cabinet

So what do we do? We start with the basics! Fundamentals of Heat Transfer…. revisited What happens inside Electronic Equipment What happens inside Cabinets containing electronic equipment Typical arrangements in Datacentres and Computer rooms Introducing the CoolRack from President – and how it works The CoolRack – a real life solution What the CoolRack solution will do for you A summary of benefits More COOLING options from President

General Cooling Methods At todays power levels radiation and conduction methods are inadequate. Heat has to be “convected” away by moving fresh air past the heat-emitting devices All electrical components and devices emit heat. At low energy levels radiation is a good enough way to dissipate this heat At higher dissipation levels, radiation alone will not suffice and heat has to be conducted away by using heatsinks 1 2 3

Current Trends Individual fans for critical devices Power Dissipation Todays high performance Rack-Mount Servers consume as much as 300 Watts of power in a 1U high format. This power is dissipated as heat within the cabinet 1U Server 2U Server 3U Server A 1U Server uncovered Current Trends Power Dissipation Packing Density DC fans to evacuate the heat Individual fans for critical devices Prevention of hot spots forming due to still air

Internal view showing devices with heat sinks for conduction and DC fans set up to create strong air currents from the front of the equipment towards the rear.

In general, professional grade equipment have adequate cooling provisions designed into them so that they are able perform normally to their published specifications given the required ambient conditions……. provided those required ambient conditions are maintained unimpaired. Equipment stacked inside a Cabinet encounter a very different environment from the free- standing equipment in an air-conditioned room.

Conventional cooling methods for computer equipment in cabinets … generally adopted arrangements Light thermal loads When heat dissipation is 300 watts or less, no special arrangements for airflow are needed. The metal skin of the cabinet provides sufficient heat transfer through radiation.

Exhaust fans cause cabinet air to flow to the top The warmed up air flows out from the top after collecting heat from the equipment inside Moderate thermal loads Air is drawn into the cabinets through vents at the sides Note: This arrangement works fine as long as cabinets are not placed side-by-side, as this will prevent airflow into the cabinets When heat loads are between 300 – 600 watts conventional arrangements for dissipating the heat by means of air convection are adequate.

Heavy thermal loads In the case of rack-mounted Servers that have their air intakes in the front, or rows of cabinets placed side-by-side, air flow MUST be from the front to the rear of the cabinets When the heat load inside cabinets with rack- mounted Servers exceeds 1000 watts, then strong airflow has to be set up in the front-to-back direction. But these conventional methods have limitations

The type of arrangements for cooling of equipment inside cabinets just seen is the conventional approach. These worked fine till now when heat loads were fairly light. But these methods have severe limitations in todays situation. Conventional cooling methods are 30 years old Conventional designs compromise equipment reliability Conventional cooling systems are expensive to build Conventional design is expensive to operate here’s why……….

In many Computer Centres it is common to have the AC Inlet and Return ducts running along the top of the room. This results in airflow patterns that are far from ideal for the equipment inside the Cabinets. Incoming air at 16-18 C Return air temp.is 25-28 C at best Inlet air will take the line of least resistance.A large proportion will flow into the return duct Air exiting the cabinets Will be at 27-30 C Air flowing down is diluted by the room air.Temp.will rise to 22-25 C by the time it is drawn in at the bottom of the cabinets

The newer computer facilities may have both false ceilings and raised plenums with the inlet AC ducts below the raised floors while the return air ducts are above. This leads to more effective equipment cooling Air temp at top of will be 20-23 C Most incoming air still flows into the room.Its temp.rises to 20-23 C Inlet air at 16-18 C Is drawn into the Cabinets at the bottom Air inflow at 16-18 C

Same room showing cabinets positioned over the AC inlet Return air ducts Incoming air at 16-18 deg. C

Airflow patterns and temperatures in a typical Computer centre “Delta T” is 10 deg typically

Possibilities with the “CoolRack” arrangement A “ Delta T” of as much as 20 deg is possible

How does the CoolRack concept work ? Conventional Datacentre set-up With a delta T of 10-11 degC and 3.6 kilowatts power dissipation Airflow required = 569 CFM With the CoolRack set-up And a delta T of 20 degC, with 3.6 kilowatts power dissipation Airflow required = 284 CFM Thus the CoolRack method uses half the airflow ! Half the airflow means a 50% reduction in Air Handling capacity Each AC unit transfers twice as much heat energy Reducing the airflow by half means 50% fewer fans motors

The CoolRack approach reduces the cost to cool a data centre by 14% In a typical data centre, fan energy accounts for 28% of the total cooling plant energy The CoolRack approach reduces the cost to cool a data centre by 14% It also reduces the initial investment outlays because ….. Half as many AC units are needed, and associated ducting Reduced cooling plant size (due to less fan motor heat) Reduced emergency power requirements Leading to a net saving on initial investments of 5% or more

Introducing the CoolRack --- a configured solution for your thermal problems

CoolRack – an internal view

Presidents CoolRack A side view showing the Internal airflow paths

Same views - but showing airflow arrangements

9 Slides giving the efficiencies and savings to be gained from the Cool Rack approach and other quantitative data

11 Summary of benefits

Presidents CoolRack - the reality

Inside the CoolRack: Accessories include vertical Cable Managers and an AC Power Channel with high- reliability universal IEC Sockets. Note also the provisions for Cable entry

Here’s what has been happening 39 Servers in 42U of Cabinet space!

Fans shown mounted directly on the Rear Door so as to create a front-to- back air flow

Benefits of the CoolRack solution Ability to house more Servers in a Cabinet ……. Upto 42 in a 42U cabinet Equipment runs cooler- therefore more reliability…… MTBF is increased Optimal use of the AC plant capacity …………… less capacity needed Initial costs for Air Conditioning plant reduced …… upto 7% savings Running costs for electrical energy reduced ………. upto 14%

What will the CoolRack do for you ? Provide the means for utilizing your air conditioning capacity more efficiently More efficient use of AC capacity means that you need use less cooling power Net Result Increased MTBF Savings in investment and operating costs