Wet Bulb - Johnson Controls - Metasys - LIT-12011147 - Software Application - Controller Configuration Tool - 13.1

Controller Tool Help

Brand
Johnson Controls
Metasys
Product name
Controller Configuration Tool
Document type
User Guide
Document number
LIT-12011147
Version
13.1
Revision date
2019-12-04
Language
English

The Wet Bulb logic block calculates the wet bulb temperature of air given dry bulb temperature and either relative humidity or dew point temperature as configured by the Setup attribute found in the Details dialog box of the block. This block calculates the saturation temperature, which is a very close approximation to the thermodynamic wet bulb temperature. The following table describes the inputs and outputs of the Wet Bulb logic block.

Table 1. Wet Bulb Block Inputs and Outputs

Name

Data Type

Exposed for Connection by Default

Description

Default Value

Inputs

Dew Point Temperature

Float

No

Indicates the dew point temperature of air, which is the temperature at which moisture condenses out of the air. If the Setup property is DP, this input represents the air dew point temperature that is used to calculate Enthalpy. If the Setup property is RH, this input is ignored.

14 °C,

57 °F

Dry Bulb Temperature

Float

Yes

Indicates the temperature of air as measured with a simple thermometer.

25 °C, 77 °F

Elevation

Float

No

Indicates the distance above or below sea level. Below sea level is represented with a negative value.

0 ft, 0 m

Relative Humidity

Float

No

Indicates the relative humidity of air. If the Setup property is RH, this input represents the air relative humidity that is used to calculate the wet bulb temperature. If the Setup property is DP, this input is ignored.

50%

Range: 0-100%

Outputs

Wet Bulb Temperature 1

Float

Yes

Indicates the wet bulb temperature. The wet bulb temperature is the adiabatic saturation temperature defined as the temperature at which water, by evaporating into air, brings the air to saturation at the same temperature.

18 °C,

64.4 °F

Properties

Setup

Enum

N/A

Indicates if the relative humidity or dew point temperature is used as the second independent variable to calculate wet bulb temperature.

RH

Unit Set

Enum

N/A

Indicates the units of measurement used by the block.

SI, IP

1 This input or output is the Default Element of the block.