constants.h

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#pragma once
 
namespace physics {
 
inline constexpr double kPi = 3.14159265358979323846;
 
} // namespace physics
 
namespace physics::si {
 
inline constexpr double kStefanBoltzmann = 5.670374419e-8;
 
inline constexpr double kWaterDensityBase = 1000.0;
 
inline constexpr double kSpecificHeatWater = 4.1796;
 
} // namespace physics::si
 
namespace physics::imperial {}
 
namespace physics::us {
 
inline constexpr double kOrificeAreaFactor = 1300.0;
 
inline constexpr double kAtmosphericPressurePsi = 14.7;
 
inline constexpr double kWaterBoilingPointF = 212.0;
 
inline constexpr double kSpecificHeatWaterVapor = 0.481;
 
inline constexpr double kWaterEvaporation = 970.0;
 
inline constexpr double kStefanBoltzmann = 1.713441e-9;
 
inline constexpr double kStandardGasTemperatureR = 520.0;
 
inline constexpr double kAmbientTemperatureF = 60.0;
 
inline constexpr double kSpecificHeatAirBase = 0.017828518;
 
inline constexpr double kSpecificHeatAirCoeff = 0.000002556;
 
inline constexpr double kAirCorrectionBase = -1.078913827;
 
constexpr double kWaterDensity = 8.335;
 
inline constexpr double kAirSensibleHeatFactor = 1.08;
 
inline constexpr double kWaterSensibleHeatFactor = 500.0;
 
inline constexpr double kGravityFtPerSec2 = 32.174;
 
inline constexpr double kStandardGravityApprox = 32.2;
 
inline constexpr double kSpecificGasConstantAir = 53.34;
 
inline constexpr double kGammaAir = 1.4;
 
} // namespace physics::us
 
namespace physics::conversions {
 
inline constexpr double kBtuPerLbFToKJPerKgK = 4.1868;
 
inline constexpr double fahrenheitToKelvin(double fahrenheit) { return ((fahrenheit - 32.0) / 1.8) + 273.15; }
 
inline constexpr double psigToMPa(const double psig) {
    return (psig + physics::us::kAtmosphericPressurePsi) * 0.00689476;
}
 
inline constexpr double kM3PerKgToFt3PerLb = 16.0185;
 
inline constexpr double kFt3ToIn3 = 1728;
 
inline constexpr double kKJPerKgToBtuPerLb = 0.429923;
 
inline constexpr double kWaterSurfacePressure = 14.6;
 
inline constexpr double kFahrenheitToRankineOffset = 459.67;
 
inline constexpr double kHoursPerDay = 24.0;
 
inline constexpr double kMinutesPerHour = 60.0;
 
inline constexpr double kSecondsPerMinute = 60.0;
 
inline constexpr double kIn2PerFt2 = 144.0;
 
inline constexpr double kKilowattToBtuPerHour = 3412.136247820839;
 
inline constexpr double kKgPerM3ToLbPerGal = 0.0083454;
 
constexpr double fahrenheitToRankine(double fahrenheit) { return fahrenheit + kFahrenheitToRankineOffset; }
 
constexpr double fahrenheitToCelsius(double fahrenheit) { return (fahrenheit - 32.0) / 1.8; }
 
inline constexpr double kMMBtuToBtu = 1'000'000.0;
 
inline constexpr double kLbPerFt3ToKgPerM3 = 16.018463;
 
inline constexpr double kBhpToKw = 0.746;
 
constexpr double kBtuPerTonRefrigeration = 12000.0;
 
constexpr double mmbtuPerHrToKW(double mmbtu_per_hr) { return mmbtu_per_hr * 293.07107; }
 
constexpr double kWToMMBtuPerHr(double kw) { return kw * 0.003412142; }
 
} // namespace physics::conversions