Fundamento
Absolute and gauge pressure
Absolute pressure is measured from vacuum; gauge pressure takes the local atmosphere as its reference.
\(P_{abs}=P_{atm}+P_{man}\)
ThermoLab · Chapters 1 and 2
Pressure, temperature and general energy balance
Converts units, solves fluid columns and closes energy balances with traceable signs.
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Engineering results
NOT RUNDetailed calculation reportEquations · substitution · verification
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Engineering directory
13 linked modules on a single calculation base
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01
Appendices A-1 to A-28Universal property interpolator
→02Chapters 1 and 2Pressure, temperature and general energy balance
→03Chapter 3Pure substances and equations of state
→04Chapter 4Energy integrals for closed systems
→05Chapter 5Control volumes and the first law
→06Chapters 6 and 7Second law, Carnot and entropy
→07Chapter 8Exergy, destruction and second-law efficiency
→08Chapter 9Gas power cycles
→09Chapter 10Rankine steam power cycles
→10Chapter 11Refrigeration cycles
→11Chapters 12 and 13Gas mixtures and psychrometrics
→12Chapters 14 and 15Combustion and adiabatic flame temperature
→13Chapters 16 and 17Chemical equilibrium and compressible flow
→Engineering framework
Theory, equations and conditions of use
Pressure changes with the weight of the fluid column, and total energy changes with the transfers that cross the system boundary.
Fundamento
Hydrostatic relation
For constant density and gravity, the vertical difference integrates directly.
\(\Delta P=\rho g h\)
Fundamento
Balance general
Energy is conserved by recording inflows and outflows under a consistent sign convention.
\(\Delta E_{system}=E_{in}-E_{out}\)
Base documentalÇengel & Boles, 7th edition · SI appendices A-1 to A-28
USCS conversionA-1E to A-27E, via exact factors from the SI base
AlcancePreliminary design, teaching and independent verification
Engineering FAQ
Preguntas frecuentes
Can I enter a negative height?+
Yes. The sign indicates rising or falling relative to the reference point.
When does density change?+
In tall gas columns, or where temperature varies widely, ρ(z) must be integrated.
Is atmospheric pressure always 101.325 kPa?+
No; it depends on altitude and weather. That value is the standard atmosphere.