This is equipment that pre-cools the outside air that is brought into the building. It may be used with any type of cooling system that brings in outside air. This equipment is not applicable for the baseline building.
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Evaporative Cooling Type |
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Applicability |
Systems with evaporative pre-cooling |
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Definition |
The type of evaporative pre-cooler, including:
An integrated pre-cooler can operate together with the compression or CHW cooling. A non-integrated pre-cooler will shut down the evaporative cooling whenever it is unable to provide 100% of the cooling required. In all cases, the evaporative pre-cooler must be modeled with 100% of the outside air routed through the pre-cooler. |
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Units |
None |
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Input Restrictions |
As designed |
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Baseline Rules |
Not applicable |
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Direct Stage Effectiveness |
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Applicability |
Systems with evaporative pre-cooling |
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Definition |
The effectiveness of the direct stage of an evaporative cooling system. Effectiveness is defined as follows: (Equation 3.7.5.3-1) $$DirectEFF=\frac{T_{db}-T_{direct}}{T_{db}-T_{wb}}$$ Where
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Units |
Numeric |
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Input Restrictions |
As designed |
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Baseline Rules |
Not applicable |
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Indirect Stage Effectiveness |
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Applicability |
Systems with evaporative pre-cooling |
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Definition |
The effectiveness of the indirect stage of an evaporative cooling system. Effectiveness is defined as follows: (Equation 3.7.5.3-2) $$IndEFF=\frac{T_{db}-T_{ind}}{T_{db}-T_{wb}}$$ where
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Units |
Numeric, a value between zero and one |
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Input Restrictions |
As designed |
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Baseline Rules |
Not applicable |
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Evaporative Cooling Performance Curves |
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Applicability |
Systems with evaporative cooling |
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Definition |
A curve that varies the evaporative cooling effectiveness as a function of primary air stream airflow. The default curves are given as follows: (Equation 3.7.5.3-3) $$PLR=\frac{CFM_{operating}}{CFM_{design}}$$ $$EFF\_FFLOW=a+b\cdot PLR+ c \cdot PLR^{2}$$ where
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Units |
Data structure |
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Input Restrictions |
User may input curves or use default curves. If defaults are overridden, the software must indicate that supporting documentation is required on the output forms. |
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Baseline Rules |
Not appliable |
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Auxiliary Evaporative Cooling Power |
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Applicability |
Systems with evaporative cooling |
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Definition |
The auxiliary energy of the indirect evaporative cooler fan, and the pumps for both direct and indirect stages |
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Units |
kW or kW/cfm |
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Input Restrictions |
As designed |
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Baseline Rules |
Not applicable |
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Evaporative Cooling Scavenger Air Source |
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Applicability |
Systems with evaporative cooling |
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Definition |
The source of scavenger air for an indirect section of an evaporative cooler. Options include:
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Units |
List (see above) |
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Input Restrictions |
As designed |
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Baseline Rules |
Not applicable |
This is equipment that pre-cools the outside air that is brought into the building. It may be used with any type of cooling system that brings in outside air. This equipment is not applicable for the baseline building. The analyst must be careful to input evaporative cooler and outside air controls, as allowed by the software that reasonably reflect anticipated operation as indicated in sequences of operation, and review the simulation outputs, particularly zone or return air relative humidity, to ensure that the simulated sensible cooling from the evaporative cooler is realistic.
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Evaporative Cooling Type |
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Applicability |
Systems with evaporative pre-cooling |
|
Definition |
The type of evaporative pre-cooler, including:
An integrated pre-cooler can operate together with the compression or CHW cooling. A non-integrated pre-cooler will shut down the evaporative cooling whenever it is unable to provide 100% of the cooling required. In all cases, the evaporative pre-cooler must be modeled with 100% of the outside air routed through the pre-cooler. |
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Units |
None |
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Input Restrictions |
As designed |
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Baseline Building |
Not applicable |
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Evaporative Cooling System Capacity |
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Applicability |
Systems with evaporative cooling |
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Definition |
The total sensible cooling capacity of the evaporative cooling system at design outdoor dry-bulb conditions. This value may be derived from other inputs of supply fan design air rated capacity (5.7.3), direct stage effectiveness, indirect stage effectiveness, and design outdoor conditions. |
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Units |
None |
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Input Restrictions |
Not applicable. This is a derived input. If there are excessive UMLH in any zone served by the evaporative cooling system, a supplementary DX cooling unit must be defined by the user. See Section 3.7.5.2 of this document for descriptors related to DX cooling units. |
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Baseline Building |
Not applicable |
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Direct Stage Effectiveness |
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Applicability |
Systems with evaporative pre-cooling |
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Definition |
The effectiveness of the direct stage of an evaporative cooling system. Effectiveness is defined as follows:
Where: DirectEFF = The direct stage effectiveness Tdb = The entering air dry-bulb temperature Twb = The entering air wet-bulb temperature Tdirect = The direct stage leaving dry-bulb temperature |
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Units |
Numeric (0 <= eff <=1) |
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Input Restrictions |
As designed |
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Baseline Building |
Not applicable |
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Indirect Stage Effectiveness |
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Applicability |
Systems with evaporative pre-cooling |
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Definition |
The effectiveness of the indirect stage of an evaporative cooling system. Effectiveness is defined as follows:
Where: IndEFF = The indirect stage effectiveness Tdb = The entering air dry-bulb temperature of the supply air Twb = The entering air wet-bulb temperature of the “scavenger air” Tind = The supply air leaving dry-bulb temperature |
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Units |
Numeric (0 <= eff <=1) |
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Input Restrictions |
As designed |
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Baseline Building |
Not applicable |
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Evaporative Cooling Performance Curves |
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Applicability |
Systems with evaporative cooling |
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Definition |
A curve that varies the evaporative cooling effectiveness as a function of primary air stream airflow. The default curves are given as follows:
Where: PLR = Part load ratio of airflow based on design airflow EFF-FFLOW = A multiplier on the evaporative cooler effectiveness to account for variations in part load CFMoperating = Operating primary air stream airflow (cfm) CFMdesign = Design primary air stream airflow (cfm) Table 71. Part Load Curve Coefficients – Evaporative Cooler Effectiveness
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Units |
Data structure |
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Input Restrictions |
User may input curves or use default curves. If defaults are overridden, the software must indicate that supporting documentation is required on the output forms. |
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Baseline Building |
Not used |
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Auxiliary Evaporative Cooling Power |
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Applicability |
Systems with evaporative cooling |
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Definition |
The auxiliary energy of the indirect evaporative cooler fan, and the pumps for both direct and indirect stages |
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Units |
Watts |
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Input Restrictions |
As designed |
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Baseline Building |
Not applicable |
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Evaporative Cooling Scavenger Air Source |
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Applicability |
Systems with evaporative cooling |
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Definition |
The source of scavenger air for an indirect section of an evaporative cooler. Options include:
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Units |
List (see above) |
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Input Restrictions |
As designed |
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Baseline Building |
Not applicable |