Curve Tab
Speed <X> Ref. Rated Clg Capacity
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Default: 38 tons
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Typical Range: N/A
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Min Max: 0 < X < 100,000,000,000,000
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Units: Btuh; kW; MBh; tons; W
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This field specifies the total, full load gross cooling capacity (sensible plus latent) of the DX coil at rated conditions (air entering the cooling coil at 26.7 °C DB/19.4 °C WB, air entering the outdoor condenser coil at 35 °C DB/23.9 °C WB, and a cooling coil air flow rate defined by the rated air flow rate field) for speed <X> operation. Capacity should be gross (i.e., the effect of supply air fan heat is not accounted for).
Speed <X> Ref. Rated Airflow
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Default: 0 cfm
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Typical Range: N/A
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Min Max: 0.01 < X < 100,000,000,000,000
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Units: ACH; cfm; L/s; m3/hr; m3/s
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This field defines the airflow rate across the cooling coil at rated conditions for Speed <X> operation. The gross rated total cooling capacity, gross rated SHR and gross rated COP should be performance information for the unit with air entering the cooling coil at 26.7 °C DB/19.4 °C WB, air entering the outdoor condenser coil at 35 °C DB/23.9 °C WB, and the rated air volume flow rate defined here.
Speed <X> Ref. Rated Condenser Flow (For Evaporatively Cooled Condenser)
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Default: 0 cfm
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Typical Range: N/A
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Min Max: 0.01 < X < 100,000,000,000,000
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Units: ACH; cfm; L/s; m3/hr; m3/s
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This field specifies the air volume flow rate entering the evaporative condenser coil if an evaporatively cooled condenser has been selected. This value is used to calculate the amount of water used to evaporatively cool the condenser inlet air. This field is not used when Condenser Type = Air Cooled.
Speed <X> Ref. Rated Sensible Heat Ratio
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Default: 1
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Typical Range: N/A
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Min Max: 0 < X < 1
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Units: N/A
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This field defines sensible heat transfer ratio (SHR = gross sensible cooling capacity divided by gross total cooling capacity) of the cooling coil at rated conditions for speed <X> operation at rated conditions (air entering the cooling coil at 26.7 °C DB/19.4 °C WB, air entering the outdoor condenser coil at 35 °C DB/23.9 °C WB, and a cooling coil air flow rate defined by the Ref. Rated Airflow field). Both the sensible and total cooling capacities used to define the Rated SHR should be gross (i.e., the effect of supply air fan heat is not accounted for).
Speed <X> Ref. Rated Energy Rate
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Default: 3 COP
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Typical Range: N/A
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Min Max: 0.11 < X < 1,000,000,000
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Units: COP; EER; kW/kW; kW/MBh; kW/ton; MBh/ton; therms/(ton-hr)
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This field defines the efficiency of the cooling coil at rated conditions for speed <X> operation (ratio of gross total cooling capacity to electrical power input). The input power includes power for the compressor(s), condenser fan and accessories, but does not include the supply air fan. The gross Reference Rated Energy Rate should not account for the supply air fan.
Speed <X> Bypass Airflow
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Default: 0%
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Typical Range: 0 to 100%
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Min Max: -100,000,000,000,000 < X < 100,000,000,000,000
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Units: %
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This field specifies the fraction of the Rated Air Volume Flow Rate which bypasses the active cooling coil for the performance mode. The remaining portion of the flow should be between 300 to 450 cfm/ton (0.00004027 m3/s and .00006041 m3/s per watt) of Reference Rated Cooling Capacity for this performance mode. For DOAS applications the remaining portion of Rated Air Volume Flow Rate should be between 125 to 250 cfm/ton (0.00001677 m3/s and 0.00003355 m3/s per watt) of Reference Rated Cooling Capacity. This is used to model face-split coils on multi-stage units or bypass dampers. If total flow rate varies during simulation, the same fraction is always bypassed. For a multi-stage face-split coil in which stage 1 is 60% of total capacity, this field would be set to 40% for the Stage 1 performance and set to 0% for the Stage 1+2 performance. For a DX system which activates a bypass damper for improved dehumidification, this field would be set to 0% for normal mode performance and set to something greater than 0% for enhanced dehumidification mode performance.
Speed <X> Evap PreClg Pad Effectiveness (For Evaporatively Cooled Condenser)
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Default: 1
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Typical Range: N/A
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Min Max: 0 < X < 10
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Units: N/A
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This field specifies the effectiveness of the evaporative condenser, which is used to determine the temperature of the air entering the outdoor condenser coil as follows:
T cond inlet = (T wb, o) + (1 − EvapCondEffectiveness) (T db, o − T wb, o)
where
Tcondinlet = the temperature of the air entering the condenser coil
Twb,o = the wet-bulb temperature of the outdoor air
Tdb,o = the dry-bulb temperature of the outdoor air
The resulting condenser inlet air temperature is used by the Capacity Curve (function of temperature) and the Ambient Relief Curve (function of temperature). This field is not used when Condenser Type = Air Cooled. To specify an air-cooled condenser, simply specify AirCooled in the Condenser Type field. In this case, the Capacity Curve (function of temperature) and the Ambient Relief Curve (function of temperature) input fields for the equipment should reference performance curves that are a function of outdoor dry-bulb temperature.
If attempting to model an evaporatively-cooled condenser and performance curves are available that are a function of the wet-bulb temperature of air entering the condenser coil, then specify Condenser Type = EvaporativelyCooled and the evaporative condenser effectiveness value should be entered as 1.0. In this case, the Capacity Curve (function of temperature) and the Ambient Relief Curve (function of temperature) input fields for the equipment should reference performance curves that are a function of the wet-bulb temperature of air entering the condenser coil.
If attempting to model an air-cooled condenser that has evaporative media placed in front of it to cool the air entering the condenser coil, then the user should specify Condenser Type = EvaporativelyCooled. The appropriate evaporative effectiveness for the media should also be entered. In this case, the Capacity Curve (function of temperature) and the Ambient Relief Curve (function of temperature) input fields for the equipment should reference performance curves that are a function of outdoor dry-bulb temperature. Be aware that the evaporative media will significantly reduce the dry-bulb temperature of the air entering the condenser coil, so the Capacity and Ambient Relief Curves must be valid for the expected range of dry-bulb temperatures that will be entering the condenser coil.