Parameters Reference¶

Input Parameters (Read-Write)¶

Air Conditions¶

Parameter	Property Name	Default	Units	Description
Air Dry-Bulb Temperature	`Air Dry-Bulb Temperature`	298.15	K	Ambient air temperature
Air Wet-Bulb Temperature	`Air Wet-Bulb Temperature`	293.15	K	Ambient wet-bulb temperature
Air Relative Humidity	`Air Relative Humidity`	0.6	fraction	Alternative to wet-bulb (0 to 1)
Atmospheric Pressure	`Atmospheric Pressure`	101325	Pa	Local barometric pressure

Humidity Input

You can specify air humidity via either wet-bulb temperature or relative humidity. Select the input type in the editor. When using RH, the wet-bulb temperature is calculated internally and displayed read-only.

Tower Configuration¶

Parameter	Property Name	Default	Units	Description
Calculation Method	`Calculation Method`	0 (Poppe)	enum	0 = Poppe, 1 = Merkel
Calculation Mode	`Calculation Mode`	0 (Rating)	enum	0 = Rating, 1 = Design
L/G Ratio	`L/G Ratio`	1.0	dimensionless	Water-to-air mass flow ratio
KaV/L (Merkel Number)	`KaV/L (Merkel Number)`	1.5	dimensionless	Tower characteristic (Rating mode)
Desired Outlet Temperature	`Desired Outlet Temperature`	303.15	K	Target cold water temp (Design mode)

Fill Parameters¶

Parameter	Property Name	Default	Units	Description
Fill C1	`Fill C1`	0.9	—	Correlation coefficient
Fill C2	`Fill C2`	-0.55	—	Correlation exponent

Fill correlation: \( KaV/L = C_1 \times (L/G)^{C_2} \)

Water Balance¶

Parameter	Property Name	Default	Units	Description
Drift Loss %	`Drift Loss Percent`	0.1	%	Drift as % of circulation
Cycles of Concentration	`Cycles of Concentration`	5.0	—	For blowdown calculation

Fan¶

Parameter	Property Name	Default	Units	Description
Air Pressure Drop	`Air Pressure Drop`	200	Pa	Pressure drop across tower
Fan Efficiency	`Fan Efficiency`	0.75	fraction	Fan mechanical efficiency

Numerical¶

Parameter	Property Name	Default	Units	Description
Number of Increments	`Number of Increments`	50	—	Integration steps (Simpson/RK4)

Output Parameters (Read-Only)¶

Water Outlet¶

Parameter	Property Name	Units	Description
Water Outlet Temperature	`Water Outlet Temperature`	K	Cold water temperature
Cooling Range	`Cooling Range`	K	Tw,in - Tw,out
Approach	`Approach`	K	Tw,out - Twb
Tower Efficiency	`Tower Efficiency`	fraction	Range / (Range + Approach)
Heat Rejected	`Heat Rejected`	W	Total heat rejection

Air Outlet¶

Parameter	Property Name	Units	Description
Air Outlet Temperature	`Air Outlet Temperature`	K	Exhaust air temperature
Air Outlet Humidity Ratio	`Air Outlet Humidity Ratio`	kg/kg	Exhaust air moisture content
Air Outlet Relative Humidity	`Air Outlet Relative Humidity`	fraction	Exhaust air RH
Air Mass Flow Rate	`Air Mass Flow Rate`	kg/s	Dry air mass flow

Water Balance¶

Parameter	Property Name	Units	Description
Evaporation Rate	`Evaporation Rate`	kg/s	Water lost by evaporation
Drift Loss Rate	`Drift Loss Rate`	kg/s	Water lost as droplets
Blowdown Rate	`Blowdown Rate`	kg/s	Intentional water discharge
Makeup Water Rate	`Makeup Water Rate`	kg/s	Total water replacement

Performance¶

Parameter	Property Name	Units	Description
Calculated KaV/L	`Calculated KaV/L`	—	Merkel number (from calculation)
Fan Power	`Fan Power`	W	Fan energy consumption

Unit Conversions¶

All internal calculations use SI units (K, Pa, kg/s, W). The DWSIM editor automatically converts to/from the user's selected unit system using SharedClasses.SystemsOfUnits.Converter.

Quantity	SI Unit	Common Alternatives
Temperature	K	°C, °F, °R
Pressure	Pa	kPa, bar, atm, inHg, mmHg
Mass flow	kg/s	kg/h, lb/h, t/h
Power	W	kW, hp, BTU/h
Enthalpy	kJ/kg	BTU/lb, cal/g