Welcome to our FAQ-section
We have collected the most common questions and answers about brazed plate heat exchangers.
The brazed plate heat exchanger maximizes the most efficient transfer of energy
SWEP has pioneered the development of the gasket-free brazed plate heat exchanger which has several clear advantages over the gasket plate to frame heat exchanger. The brazed plate heat exchanger maximizes the most efficient transfer of energy, with 95% of its content.
The life cycle cost for a brazed plate heat exchanger over a period of 15-20 years can often be halved compared with gasket-plate solutions, which are built on a frame, require much more material and are thereby less efficient (the additional material does not provide additional heat exchange capability).
SWEP Software Package
Our unique and world-leading software SWEP Software Package has been developed for advanced heat exchange calculations. The software handles single-phase, condenser, evaporator, cascade calculations, two-stage applications and more. Input your data and SWEP Software Package immediately presents the product concept that best meets your needs.
A brazed plate heat exchanger is normally self-cleaning thanks to highly turbulent flows. In applications with a high risk of fouling or scaling due to unsuitable conditions such as questionable water quality and high temperatures (scaling), chemical cleaning may be necessary to maintain efficiency.
In such cases Cleaning in Place (CIP) is suitable, a convenient way of cleansing the interior surfaces of closed systems.
The mediums come into close proximity inside the brazed plate heat exchanger, on either side of the corrugated plate without mixing, and energy is transferred from one side to the other as they flow side by side.
A traditional data center cooling approach
A traditional data center cooling 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.
Various improvements have been developed
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.
Water usage has been growing year after year
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.
Depends on the type of data center
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:
- CAPEX (Capital Expenditure) The initial investment which takes Tier level, expected lifetime and design choices into consideration – the cost to build.
- OPEX (Operational Expenditure) Refers to the operating and maintenance costs and considerations like location and design choices, including PUE and cooling
- 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.
Copper-free brazed plate heat exchangers is not a must
There is a significant quantity of copper in direct contact with the dielectric coolant, which is likely non-corrosive. Hence, copper-free brazed plate heat exchangers 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.
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.
Involve submerging the hardware
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 brazed plate heat exchanger 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.
All-SS or copper-free brazed plate heat exchangers should be considered
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 brazed plate heat exchangers should be considered, but assessed case-by-case.
Heat exchangers that take latent heat from a saturated vapour at a constant temperature
Condensers in the context of brazed plate heat exchangers are heat exchangers that take latent heat from a saturated vapour at a constant temperature to convert the vapour to a liquid. For most cases in brazed plate heat exchangers this is in applications such as refrigeration or air-conditioning where heat is taken from a refrigerant and given to a fluid such as water to be expelled into the atmosphere via cooling towers.
A brazed plate heat exchanger uses a secondary fluid, such as water, which is at a lower temperature than the refrigerant vapour. Latent heat of the vapour is transferred to the secondary fluid as sensible heat and hence converts the refrigerant to a liquid without changing its temperature.
Condensers can last 15 years
If correctly designed, installed and maintained, a brazed plate heat exchanger condenser can last typically 15 years. This is dependent on on no excessive thermal stresses that can be imparted by the compressor, and that water quality is of a standard that does not lead to fouling or corrosion.
Freezing may occur when operating a refrigeration or heat pump cycle in reverse or running in de-frost mode. Design provisions can be made to stop the freezing from occurring.