CHILLERS FANS
Turbocor chillers provide low energy consumption, low maintenance, and excellent comfort for building occupants. They also off er exceptional longevity and high effi ciency, especially at partial loads.
Advanced fan motors – Electronically commutated (EC) fan motors combine AC and DC voltages bringing the best of both worlds. The motor runs on a DC voltage, but with a single phase 230VAC or three phase 400VAC supply. The motor incorporates voltage transformation within the motor. A perfect illustration of how technology develops over time can be found at the world-renowned National Physical Laboratory (NPL) building complex, the pioneering centre of excellence in measurement science in West London. Here, upgrading chillers with the latest high effi ciency heat exchangers has resulted in impressive savings. Klima-Therm has supplied, installed, and commissioned 16 chillers at NPL since 2012 to serve the HVAC requirements of plant pods.
The chillers – which feature Turbocor compressors, EC condenser fan motors, fl ooded refrigerant to water evaporators, and microchannel condenser coils – were state-of-the-art when fi rst fi tted. However, the installation location deep inside the plant pods and strict acoustic requirements near the pods meant that the machines were compromised by the restricted airfl ow into and away from them. This compromised their operational reliability on the warmest days when they were most in demand. In 2019, a new type of condenser was introduced by Klima- Therm partner Althermo. This comprised a microchannel coil (as already in use on the machines), but the condenser was formed into a cylinder. The new confi guration increases the heat
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exchange area by 40% inside the same footprint, which has led to higher effi ciency, more capacity, and lower noise, smaller footprint. The confi guration of these coils allowed for the entire condensing section of the existing chillers to be removed from inside the plant pods, below the primary pod steelwork, along with all of their associated ductwork, with the attenuation above that steelwork also being removed. The new condensers were installed onto that primary steelwork, where the attenuators used to be, putting them into essentially open air and removing all of the air movement restrictions that had previously limited chiller performance. For the NPL condenser upgrade project, the extra coil surface
area and coil shape allowed two problems in particular to be solved: The extra coil surface area allowed for a lower air volume to
be moved through the coils to achieve the same heat rejection, which meant that the condensers did not need external attenuation, which meant they could sit in open air at the very top of the pods.
The cylindrical coil shape marries well with the air movement patterns caused by the rotating EC condenser fans such that the air movement across the coil face is at much lower velocity and is more laminar than with the traditional rectangular, fl at coils. This means that very little pollen or debris is drawn into the coil face.
On top of this, the chiller replacement project has seen up to 400kW of cooling output from machines that had previously been restricted to around 330kW cooling duty. In addition, even at the higher capacities, chiller effi ciency has increased by around 20%.
www.acr-news.com • August 2024 17
On top of this, the chiller replacement project has seen up to 400kW of cooling output from machines that had previously been
restricted to around 330kW
cooling duty.
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