SWEP offers solutions for compact heat transfer for low PUE and high-density data centers

SWEP offers evaporators with distribution systems that are optimized for a wide range of refrigerants and applications.

The below graphs give an indication of the suitable SWEP evaporator based on system chiller capacity for R134a and R410A

The capacity reach of SWEP BPHEs extends well into the Megawatt range, offering compact and cost-effective redundancy. 

• Free cooling capacity ranges based on Water and Ethylene Glycol (30%)
  • Water inlet 16°C (61°F)
  • Ethylene Glycol (30%) Inlet 13°C (55° F)
• For further information or selection help, please contact SWEP.

Data center cooling (short DCC) refers to the control of temperature inside a data center to give IT equipment optimal working temperature, for best efficiency and durability. Excessive heat can lead to significant stress that can lead to downtime, damage to critical components, and a shorter lifespan for equipment, which leads to increased capital expenditure. Not only that. Inefficient cooling systems can increase power costs significantly from an operational perspective.

• A traditional DCC approach deals with Computer Room Air Conditioner (CRAC) in
  order to keep the room and its IT racks fresh. Very similarly, Computer Room Air
  Handlers (CRAH) centralize the cooling water production for multiple units and/or
  rooms. Cooling water might be issued by an adiabatic cooling tower, a dry cooler,
  which counts as free-cooling, or with a dedicated chiller when the climate is too
  warm.
• Because air is a bad heat carrier, various improvements have been developed to
  increase cooling efficiency. Raised floor, hot aisle and/or cold aisle containment,
  and in-row up to In-rack cooling, have consistently decreased the losses.
• While CRAH units and cooling towers have become legacy, water usage has been growing year after year to become a challenge. Water is sprayed in the air to dissipate heat better than in a dry cooler. With growing water scarcity, Water Usage Effectiveness (WUE) is now an important factor for the data center industry.
• Liquid cooling is the most recent and advanced technology improvement and
  includes hybrid systems with integral coil or Rear Door Heat-Exchanger (RDHX), and Direct-to-Chip (DTC) while immersed systems offer the best possible Power Usage Efficiency (PUE) with highest energy density and unequaled WUE.

The cost of data center cooling depends on the type of data center, the Tier level, the location, design choices including cooling technology, etc. Total Cost of Ownership (TCO) and Return on Investment (ROI) are probably a better approach to get a full view on cost.

TCO comprises of three critical components:

1. CAPEX (Capital Expenditure) The initial investment which takes Tier level, expected lifetime and design choices into consideration – the cost to build.
2. OPEX (Operational Expenditure) Refers to the operating and maintenance costs and considerations like location and design choices, including PUE and cooling
   technology etc.
3. Energy costs: since water scarcity and climate warming increase as well as fossil energy stocks decrease, increased attention should be given to Leadership in Energy and Environmental Design (LEED) certification.

These considerations lead to a more holistic view and better evaluation of ROI and strategic choices.

Water Usage Effectiveness (short WUE) is a simple rating in l/kWh comparing the annual data center water consumption (in liters) with the IT equipment energy consumption (in kilowatt hours). Water usage includes cooling, regulating humidity and producing electricity onsite. Uptime Institute claims that a medium-sized data center (15 MW) uses as much water as 3 average-sized hospitals or more than two 18-holes golf courses* While the demand is growing for more data centers, WUE becomes crucial while water scarcity becomes more and more common. As a result, data centers must rely on more sustainable cooling methods. Ramping up on renewable energies (solar and wind) also allows data centers to indirectly curb their water consumption while lowering carbon emissions.

Power Usage Effectiveness (short PUE) is a metric for the energy-efficiency of data centers; specifically how much energy is used by the computing equipment, in contrast to cooling and other overhead that supports the equipment. PUE is also the inverse Data Center Infrastructure Efficiency (DCIE). An ideal PUE is 1.0. Anything that isn’t considered a computing device in a data center (e.g. lighting, cooling, etc.) falls into the category of facility energy consumption. Traditional data centers score PUE around 1,7-1,8 or more while aisle containment lowers PUE down to 1,2. Liquid cooling technologies allow down to 1,05-1,1.

A Coolant Distribution Unit (short CDU) is a system that enables smaller, more efficient and more precise liquid cooling in a data center, often integrating facility water. The CDU circulates the coolant in a closed-loop system on the secondary side (cooling application) and utilizes facility water on the primary side. (heat rejection) A CDU has a pump, reservoir, power supply, control board, and a brazed plate heat exchanger (BPHE) as the key components. Filters, flow meters, pressure transducers, and other devices are also used for managing the operation of the CDU optimally. In-Rack CDUs are designed to integrate into a server chassis and distribute coolant to a series of servers or heat sources. In-Rack CDU offer up to 60-80kW of cooling capacity. These can feature redundant pump design, dynamic condensation-free control, automatic coolant replenishing, a bypass loop for stand-by operation, and automatic leak detection.Freestanding In-Row CDUs are larger and designed to manage high heat loads across a series of server chassis in data center. These full liquid cooling systems distribute coolant in and out of server chassis and can integrate into existing facility cooling systems or be designed to be fully self-contained. In-Row CDU capacity ranges typically around 300 kW with models up to 700 kW.

Direct-to-chip cooling (short DTC) utilizes cold plates in contact with hot components and removes heat by running cooling fluid through the cold plates. Cooling fluids can be a refrigerant (Direct expansion DX or 2-phase systems) or chilled water (single phase) in direct feed or via CDU. Practically, liquid cooled systems often have one or more loops for each server. In the GPU server (Graphic Processing Unit), there are five loops, so one needs a CDU for the rack. DTC extends cooling to CPU (Core Processing Unit), GPU, RAM (Random Access Memory) and NIC (Network Interface Card) for High-frequency trading, Hyperscale Computing, Rendering and Gaming, Supercomputer, Telecommunications, etc.

Immersion systems involve submerging the hardware itself into a bath of non-conductive and non-flammable liquid. Both the fluid and the hardware are contained within a leak-proof case. The dielectric fluid absorbs heat far more efficiently than air and is circulated to a BPHE where heat is transferred to the chilled facility water.

In a 2-phase system, the dielectric liquid is evaporated to vapor phase, re-condensed into liquid phase on top of the casing. Heat is captured by fluid’s evaporation and dissipated into the condenser toward chilled facility water. Because latent heat (phase change) is far more important than sensible heat (temperature change), data center density can reach unequaled level. Also, temperature stability is over the top since phase change occurs at constant temperature. Finally, peak loads are shaved by the thermal mass that the dielectric fluid volume represents.

An alternative system makes the dielectric fluid circulate inside the racks where IT equipment is enclosed into leakproof casings. More likely in single phase, dielectric fluid actively absorbs heat and is then cooled again in the CDU. As such, immersion cooling is the best data center cooling method, encouraging future applications like High Power Computing (HPC), machine learning Artificial Intelligence (AI), Crypto Money mining, Big data analytic programs, Internet of Things (IoT) with 5G and cloud computing deployment, etc.

Not necessarily. There is a significant quantity of copper in direct contact with the dielectric coolant, which is likely non-corrosive. Hence, copper-free BPHEs is not a must. Printed circuit boards (short PCB) are used in nearly all electronic products. This medium is used to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with an artwork pattern of traces, planes and other features (similar to wires on a flat surface) etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate.

In Direct-to-Chip or DTC cooling, there is no direct contact between the electronics and the cooling fluid. It is crucial that the fluid is non-conductive in order to avoid perturbating the electronics operation and deionized water could be used. When reaching high purity and low electric conductivity (typically < 10 µS/cm), pure water becomes copper-corrosive.

When the DC uses evaporative or adiabatic cooling towers to reject heat, water is sprayed on the cooling air for better efficiency and resulting in a lower temperature than with a dry cooler. Unfortunately, in addition to water evaporation, salt concentration also increases to becoming fouling and corrosive. Water treatment then, becomes necessary, including water make-up for compensation, but associated operational cost rise. In order to limit this extra-cost, systems might be operated close to minimum water quality, which could result in copper-corrosive water. In these conditions, All-SS or copper-free BPHEs should be considered, but assessed case-by-case.