Icon class icon_class far fa-sticky-note icon_class_computed far fa-sticky-note Note kind ASSERTION Policy level STRONG Specification keywords SysPhS-1.1 SysMLv1.x keywords Unit ValueType ValueType::unit Keywords SysPhS dimensional analysis vapour steam water One reason for his conclusion is: Webel vs SysPhS-1.1: Annex A.5: Assume the conversion value property names 'WaterTank::litpSec2mLitpHr' and 'EvaporationCalculation2::litPSec2mLitPHour' stand for 'litres per second to millilitres per hour' It also leads directly through dimensional analysis to the following conclusions: Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that "energy" is a rate (equivalent to a power). Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that "radiation" is a rate (equivalent to a power). Relates to 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 & IBD: VaporGenerationPlant BDD & IBD: Evaporation BDD & PD: EvaporationCalculation2 Related notes Related notes (backlinks) [ASSERTION]{SUGGESTED} Webel vs SysPhS-1.1: Annex A.5: Assume the conversion value property names 'WaterTank::litpSec2mLitpHr' and 'EvaporationCalculation2::litPSec2mLitPHour' stand for 'litres per second to millilitres per hour' [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: The restriction of "vapor" to the range 0..1 in EvaporationCalculation2 seems completely arbitrary, it is NOT a ratio! [ASSERTION] 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. [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: Dimensional analysis of TemperatureIncrease and EvaporationCalculation implies the 'specificHeat' is a volumetric heat capacity, not a specific heat capacity (heat capacity per unit of mass). [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is NOT assumed that the specification example is completely realistic (but an attempt is made to indeed interpret it as realistic using dimensional analysis and quantity magnitude checks). [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that "waterVolume" in TemperatureIncreaseConstraint is a rate litres per second (L/s), so it is named 'waterVolumeRate' in the Webel trail version. [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: In the Webel version it will be tentatively assumed we are in fact dealing with a large humidified space like an office building NOT a single "humidified room" - despite the block name HumidifiedRoom in the spec [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: If the WaterTank::tankVolume 50,000 is measured in litres (L) the VaporPressureCalculation::volume within the HumidifiedRoom can't possibly be 25000.0 litre (L), it has to be 25000.0 (m^3), which is NOT a "room" [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that 'HumidityBalance::volume = 25,000' and 'VaporPressureCalculation::volume = 25,000' are the same fixed SpaceVolume in cubic metres (m^3). [ISSUE] 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. [ISSUE] Webel vs SysPhS-1.1: Annex A.5: Humidifier: Dimensional analysis of VaporPressureCalculationConstraint implies the output is a pressure rate, which makes no sense as consumed by RelativeHumidityCalculation and is inconsistent with the rest of the system. [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: Dimensional analysis of HumidityBalanceConstraint implies constraint parameter 'airExRate' in {change=((humidity-envH)*(volume*airExRate))} is per-volume, assuming that 'volume' is a fixed Volume. [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: Dimensional analysis of RelativeHumidityCalculationConstraint implies constraint parameter 'change' in {der(x)=((press/satVap)-change)/c2} is a unitless relative humidity, given that 'c2' is a Time. [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that "radiation" is a rate (equivalent to a power). [ASSERTION] Webel vs SysPhS-1.1: Annex A.5: Humidifier: It is assumed that "energy" is a rate (equivalent to a power). Related snippets (extracts) Visit also SysPhS-1.1 Visit also (backlinks) Flags
