The flash tank cycle required significantly lower fin density for the indoor coil (480 fin/m instead of 709-752 fin/m for the economizer cycle) and slightly lower outdoor coil fin density (285 fin/m versus 289 to 356 fin/m for the economizer cycle) while meeting the design requirement for COP of 3.81 and capacity of 117.6 (60kBtu/hr).
In this optimization study, the compressor capacity multiplier for optimum design was 1.24 for the flash tank cycle and 1.3 for the economizer cycle. The outdoor fan flow rate multiplier varied between 0.65 and 0.9 for the different cycle configurations.
The flash tank cycle had a maximum COP of 2.02; 7% better than the 50% effective economizer cycle. The economizer cycle COP shows some dependence on the economizer effectiveness.
The lowest bin in this model is 30% of building load, because the cooling load associated with lesser loadings occurs only during that time of the year when an airside economizer cycle is available.
In facilities that employ a 100% air-side economizer cycle in mild weather, chillers may be turned off altogether during much of the IPLV's 25% bracket.
Typical energy savings from the refrigerant economizer cycle
range from 5% to 7%.
Whilst there may have been a case for trigeneration systems with traditional designs using absorption chillers for the base cooling load, extensive use of free cooling/ economizer cycles
means there is no longer a base refrigeration load.
Since supply-air temperatures for underfloor systems may be significantly higher, economizer cycles
using outdoor air only for building cooling can be extended, especially in areas with relatively mild temperatures and low-humidity climates.
Fan systems serving tenant floors were originally designed using the air-side economizer cycles
and were equipped with elaborate central air filtration systems.
Third, reduce other building loads through economizer cycles
, nighttime precooling, window film and shading, and increased exterior insulation.
This book covers many aspects of datacom facility energy efficiency, and includes chapters on the topics of environmental criteria, mechanical equipment and systems, economizer cycles
, airflow distribution, HVAC controls and energy management, electrical distribution equipment, datacom equipment efficiency, liquid cooling, total cost of ownership, and emerging technologies.