CAREL solutions for indirect evaporative cooling in data centres
CAREL offers a wide range of solutions for cooling units in data centres that exploit the principle of indirect evaporative cooling (IEC).
The CAREL Group product portfolio features high-efficiency technologies developed over many years of experience in this sector, technologies that have been adopted in this specific application to ensure significant energy savings.
Alongside the traditional range of controllers and displays, the brains of the system, the CAREL Group also offers the Recuperator B Blue air-to-air heat exchanger, the true heart of the system. Synergy with the KEC atomiser means evaporative cooling can be applied exactly where it is most needed, just like in the human circulatory system.
A vast series of accessories, ranging from sensors, to electronic expansion valves and BLDC compressor drivers, complete the flexible and modular offering for developing different variants of these units.
Integrated control solutions
KEC is an evaporative cooler that atomises water using a pump and a highly-flexible nozzle distribution system that can be adapted to the layout of different units. The pump features variable-speed operation driven by an inverter, and is managed by a controller (available on a separate module for installation flexibility) that optimises the supply of water; the distribution rack is extremely flexible, so as to adapt to the layout of different IEC units; the distribution nozzles can be equipped with special deflectors that increase air turbulence for better distribution of the water droplets across the air stream.
All of this makes it possible to exploit the specific advantages of atomisation systems, in particular when compared to so-called “wetted media”, such as the possibility of evaporation in contact with the surface of the heat exchanger.
Comparison between atomisation systems and wetted media
The graph below shows a comparison between the evaporative effect in the air only (also obtainable with wetted media) and the possibility of wetting the heat exchanger surface, with the same air saturation, using an atomisation system: the improvement is 25% in the worst-case scenario.
Here are other advantages:
Better absorption efficiency due to the smaller droplets;
Better temperature control with the Variable-frequency Pump and the faster response allowed by reduced inertia;
Reduced pressure drops means a lower TCO due to a lower fan power consumption;
Reduced maintenance, as no need to be replaced periodically like wet pad and also can guarantee absence of bacteria proliferation;
Direct contacting evaporative cooling by wetting the surface of the heat exchanger, can improve the efficiency.
Heat exchanger
B Blue is an aluminium air-to-air heat exchanger with a special coating designed for this specific application. It optimises heat exchange and enhances the evaporative effect due to surface wetting; all of this together with perfect tightness (tested on every single product) and extreme reliability over time ensured by resistance to corrosion.
Benefits of the B-Blue coating
Research projects conducted together with the Politecnico di Milano have shown that spraying water droplets onto the heat exchanger (B) increases cooling capacity by 20% compared to traditional adiabatic systems such as wetted media, which are limited to saturating the air (A). The water sprayed onto the heat exchanger continues to evaporate, extending the cooling effect in the entire air flow crossing the heat exchanger. The most common corrosion protection is GOLD epoxy coating: replacing this with the innovative B Blue coating brings considerable advantages. Indeed, B Blue has hydrophilic properties, and therefore allows better distribution of the droplets across the surface, giving increased wettability and consequently a further 15% increase in efficiency (C). Finally, the corrosion-protection primer guarantees product reliability.
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