Fluidtool DocsCoolProp Wiki
A practical thermodynamics and refrigerants primer for HVAC and automotive use cases.
Short, practical notes to help you interpret results from FluidTool. These pages are educational and do not replace codes, standards, manufacturer guidance, or local regulations.
For humid-air topics, pair these notes with the Humid Air Calculator when you want to compute real states after reading the concept pages.
P-h Diagram
How to read a pressure-enthalpy chart: dome, quality, isolines, and cycle intuition.
Superheat & Subcooling
ΔTsh and ΔTsc definitions, how they relate to saturation, and measurement pitfalls.
Two-phase quality (Q)
How vapor quality works on the saturation line and why PT can be ambiguous there.
Saturation pressure vs temperature
Psat(T) and Tsat(P), superheat/subcooling intuition, and common pitfalls.
Refrigerant PT chart
Organized refrigerant-specific PT chart primers and guidance on choosing the right chart for your system.
Psychrometric Chart
Learn how to read a moist air chart, then apply those ideas in the Humid Air Calculator.
Dew Point
Understand dew point, then use the Humid Air Calculator to check condensation risk and RH relationships.
Wet-bulb temperature (Twb)
Understand Twb, then use the Humid Air Calculator to derive RH, dew point, and enthalpy.
RH vs Humidity Ratio (W)
Learn why RH and W behave differently, then compare both in the Humid Air Calculator.
Mixing Outdoor Air & Return Air
Learn why mixed air is solved with W and h, then use the Humid Air Calculator to compute OA/RA endpoint states.
Refrigerant and HVAC references
Subcooling
A focused reference for subcooling, saturation temperature, and liquid-line checks.
Bubble/dew and temperature glide
How blends use bubble and dew points, plus why glide matters for PT readings.
Zeotropic vs azeotropic refrigerants
Compare blend behavior, glide, fractionation risk, and practical charging implications.
Critical Point
Understand critical temperature, critical pressure, and why supercritical states behave differently.
Gauge vs absolute pressure
Convert between gauge and absolute pressure before using PT tables or property tools.
GWP and ODP
Read refrigerant environmental metrics and connect them to replacement decisions.
CO2 transcritical cycle
Why CO2 systems can run above the critical point and how gas coolers differ from condensers.
Specific humidity vs humidity ratio
Separate two common moisture ratios before comparing psychrometric calculations.
Car AC pressure chart
Practical pressure-reading context for automotive AC checks and PT chart interpretation.
R134a vs R1234yf
Compare common automotive refrigerants, pressure behavior, and retrofit caveats.
R410A vs R32
Compare HVAC refrigerant replacements, pressure levels, and safety considerations.
Tool entry points
P-h Diagram and Properties Calculator
Calculate state points, read refrigerant properties, and connect the concepts above to a live P-h diagram.
Saturation Pressure Temperature Table
Compare Psat/Tsat trends, inspect liquid and vapor properties, and export CSV tables.
Humid Air Calculator and Psychrometric Chart
Compute RH, dew point, wet-bulb temperature, humidity ratio, enthalpy, and chart points.
Vapor Compression Cycle Calculator
Model a refrigeration cycle, estimate COP, and inspect the cycle on a P-h diagram.