Air-based freecooling uses low-temperature ambient air as a cooling medium for chilled water systems, thus providing significant opportunities to generate energy savings. The more time the chilled water system can operate in the freecooling mode, the greater the energy efficiency it can deliver.
Usage of microchannel technology in freecooling applications leads to a significant increase of freecooling time. An excellent example of this is the new range of freecooling chillers with microchannel water coils developed by Kaltra (will be available for order in Q4 2016). With 12/18°C chilled water temperatures, Lightstream Freecool chillers operate in full freecooling mode at ambient temperatures up to +6.5°C, while the leading competitors use mechanical cooling in addition to free cooling to top-up chiller capacity at the same conditions (full freecooling is available for fin-and-tube based chillers when ambient temperature falls below +2.5°C). Such an increase in freecooling time translates to electrical power savings of about 250,000kWh per 1000kW of cooling capacity per year in Central European climate zone.
Lightstream Freecool chillers are extremely compact: due to superior heat transfer efficiency and low airside resistance of microchannel heat exchangers, required airflow has been increased by 25% (compared to chillers equipped with fin-and-tube coils), thus decreasing the quantity of fans and overall chiller length.
New freecooling chillers are equipped with automatic coil cleaning system which determines the need for cleaning by reading from air differential pressure transmitters. The coil cleaning procedure starts when the pressure difference rises above a set point. The automatic heat exchanger cleaning technique allows for maintenance to be performed without shutting down the chiller and dismantling, thus reducing the system downtime incurred with a manual cleaning method.
Until now, microchannel heat exchangers have been predominantly used in automotive industry and as the condensers in HVAC applications. A number of issues, including non-uniform cooling medium distribution and condensate shedding problems do not allow microchannel coils to be used in evaporator applications. With the advanced technology developed by Alcoil, microchannel evaporators have become a reality for water and direct expansion applications.
Besides the heat transfer efficiency, microchannel water coils have a number of benefits compared with fin-and-tube heat exchangers:
Low airside pressure drops leading to significant power savings on chiller fans
Low waterside pressure drops
Reduced water content
Smaller coil face area and coil thickness
Reduced unit weight
Kaltra is a provider of innovative cooling technologies and advanced cooling products for mission-critical applications, such as data centers, cleanrooms, contaminant-free areas, processing plants, and other facilities where reliability and energy efficiency are key factors. Kaltra’s cooling equipment range includes precision cooling systems, air cooled and water cooled chillers, evaporative cooling solutions, dry coolers, and condensers.
For more information on Kaltra and its products call +49 911 715-32021
or visit www.kaltra.de