Learn about Webel IT's new SysMLv2/MBSE Workshop Seminar course!

water

Webel: Psy/MPsy: Psychrometrics for Mathematica: Equation registry with variable/quantity markup

Webel: Psy/MPsy: Psychrometrics for Mathematica: A suffix '$wat$i' indicates water (liquid or vapour) flow TO (into) the humid air mixture. A suffix '$wat$o' indicates water (liquid or vapour) flow FROM (out of) the humid air mixture.

Webel: Psy/MPsy: Psychrometrics for Mathematica: A suffix '$sat' indicates a humid air mixture quantity at saturation (relative humidity = 1 or degree of saturation = 1).

Webel: Psy/MPsy: Psychrometrics for Mathematica: A suffix '$ha' indicates a HUMID air mixture variable, quantity, or function or a PER humid air mass quantity.

Webel: Psy/MPsy: Psychrometrics for Mathematica: A suffix '$a' indicates a DRY air component variable, quantity, or function. A suffix '$da' indicates a HUMID air mixture quantity PER dry air.

Webel: Psy/MPsy: Psychrometrics for Mathematica: A suffix '$wat' indicates a water-related variable, quantity, or function (note that 'w' is reserved for the humidity ratio).

Webel: Psy/MPsy: Psychrometrics for Mathematica: Variable/quantity registry and naming conventions, with symbol markup.

Webel: Psy/MPsy: Psychrometrics for Mathematica: The term 'steam' (indicated in variable names with a suffix '$s') is reserved for water vapour created through boiling.

Webel: Psy/MPsy: Psychrometrics for Mathematica: A suffix '$g' in a water-related variable name refers to water vapour (a special case of gas) or steam. A suffix '$f' refers to liquid (fluid) water. [Although a gas is a fluid.]

Psychrometrics: Calculations of the mass flow rate of the dry air component (assumed constant under steady state) from the ENTRY volumetric flow rate of the humid air mixture MUST use the INITIAL state variables!

Psychrometrics: The volumetric flow rate of a humid air mixture MAY change between a State1 and State2 (but the mass flow rate of dry air does not under steady state)! This is sometimes "glossed over" in some online calculators and less formal guides.

Psychrometrics links (references and online calculators)

Keywords

Keywords

This page collects some useful External links (see section below) for Psychrometrics (humid air physics).

Determine the total, sensible and latent cooling required cooling 20,000 cfm of air from a temperature of 90 F and a relative humidity of 60% to a temperature of 55 F and 100% relative humidity.

Source

CED Engineering course PDF: 'Air Conditioning Psychrometrics (A.Bhatia)'

Hot humid day 90°F and 90% RH. Condition the air to 70°F at about 50% RH. Chill the air to condense out enough moisture to dehumidify it: goal is air with absolute humidity not exceeding 0.008 lbs of moisture per pound of air. Show processes.

Source

CED Engineering course PDF: 'Air Conditioning Psychrometrics (A.Bhatia)'

How much moisture is added to 20 lb of air going from 50°F, 50% RH to 80°F, 60% RH?

Source

CED Engineering course PDF: 'Air Conditioning Psychrometrics (A.Bhatia)'

CED Engineering course PDF: 'Air Conditioning Psychrometrics (A.Bhatia)'

TRAIL: Air Conditioning Psychrometrics (vs CED Engineering course): Example results (only) in Mathematica and SysML using the Webel Psy package and MPsy class

Jump to first slide

Example 01: Values from 'tdb' and relative humidity 'r'

Sections

HVAC&R Zone

Keywords

Keywords

This zone presents some reference information on Heating, Ventilation, Air-Conditioning, and Refrigeration (HVAC&R), including some worked examples in Mathematica and SysML models.

When calibrated to ITS-90, where one must interpolate between the defining points of gallium and indium, the boiling point of VSMOW water is about 10 mK less, about 99.974 °C.

Source

Precise measurements show that the boiling point of VSMOW water under one standard atmosphere of pressure is actually 373.1339 K (99.9839 °C) when adhering strictly to the two-point definition of thermodynamic temperature.

Source

Fun fact: The normal boiling point of water isn't exactly 100 °C (at least not since 2019 when the definition of the Kelvin scale was changed to use the Boltzmann constant and decoupled from the triple point of water)

Webel vs SysPhS-1.1: Annex A.5: Humidifier: In EvaporationCalculation the specificHeat value 1.996 is off by a factor of about 2. It seems to have used the steam (gas) per gram value instead of the liquid water value per gram (or per mL volumetric) value.

The volumetric heat capacity can also be expressed as the specific heat capacity (heat capacity per unit of mass, in J/K/kg) times the density of the substance (in kg/L, or g/mL).

Source

The SI unit of volumetric heat capacity is joule per kelvin per cubic meter, J/K/m3 or J/(K·m3).

Source

Informally, it is the amount of energy that must be added, in the form of heat, to one unit of volume of the material in order to cause an increase of one unit in its temperature.

Source

The volumetric heat capacity of a material is the heat capacity of a sample of the substance divided by the volume of the sample.

Source

Isobaric volumetric heat capacity C(P,v) J⋅cm−3⋅K−1 of liquid Water at 100 °C = 4.2160

Source

Isobaric volumetric heat capacity C(P,v) J⋅cm−3⋅K−1 of liquid Water at 25 °C = 4.1796

Source

Webel vs SysPhS-1.1: Annex A.5: Humidifier: Dimensional analysis of VaporPressureCalculationConstraint implies each 1 mL of water is equated with EXACTLY 1 g of produced vapor.

Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that "vapor" is a volume rate corresponding to the rate of consumption OF HEATED LIQUID WATER (from a tank) used to create the vapor.

Annex A.5: Humidifier (with Units)

TRAIL: SysPhS-1.1 Annex A examples in MagicDraw/Cameo SysML vs Modelica (Wolfram SystemsModeler)

Slides in this section

If you want to navigate the entire section including the additional explanatory text click on the title link of the first slide to view the full slide page, then use the next links to move through the slide pages. If you just want to view the slide images only in sequence, click on any slide to view it larger in a viewer, then click again to move through each slide in this tutorial trail section.

Figure 64: Total humidifier system example (MOCKUP)

Figure 65: Internal structure of the total humidifier system - black box vs details

REFERENCE: A.5 Humidifier: Webel: ValueTypes and Units

REFERENCE: A.5 Humidifier: Webel: Block overview

BDD & IBD: HumidifierSystem

BDD & IBD: HumidifiedRoom

BDD & PD: VolumeConversion

BDD & PD: SaturationVaporPressure

BDD & IBD: RelativeHumidity

BDD & PD: RelativeHumidityCalculation

BDD & PD: HumidityBalance

BDD & PD: VaporPressureCalculation

BDD & PD: PercentageConversion

BDD & IBD: Humidifier

BDD & PD: WaterTank

BDD & STM: UsageScenario

BDD & STM: Control

BDD & STM: HeaterControl

BDD & IBD: VaporGenerationPlant

BDD & PD: Radiation

BDD & PD: VaporGenerationPlantCalculation

BDD & IBD: Heating

BDD & PD: TemperatureIncrease

BDD & PD: HeatingCalculation

BDD & IBD: Evaporation

BDD & PD: EvaporationCalculation

BDD & PD: EvaporationCalculation2

Export to Modelica and execution of the SysML/SysPhS block HumidifierSystem_S1

A.5 Humidifier: Scenario block overview BDDs: 96 to 102

A.5 Humidifier: Value property defaults table

Continuous ... It is independent from UML streaming, see clause 11.3.2.8. A streaming parameter may or may not apply to continuous flow, and a continuous flow may or may not apply to streaming parameters.

Source

OMG Systems Modeling Language (SysML) 1.6

Continuous rate is a special case of rate of flow (see Rate) where the increment of time between items approaches zero. It is intended to represent continuous flows that may correspond to water flowing through a pipe, a time continuous signal, or ...

Source

OMG Systems Modeling Language (SysML) 1.6

Subscribe to water

We are Australia's Systems Modeling Language (SysML^®) and Model-Based Systems Engineering (MBSE) specialists!

Catch our SysMLv2/MBSE course Early Bird Deal 50% off all courses fully pre-paid by 31st Mar 2026!

Save 30% off Live Online SysML/MBSE web sessions for individuals before 31st Mar 2026!

SysMLv1 slide set PDFs now available for purchase!

Home of the Webel Parsing Analysis recipe for Model-Based Systems Engineering with SysML^®

Visit our Client showcase