This simulator heats or cools a sealed, fixed-mass water charge beneath an ideal constant-pressure piston at atmospheric pressure. Watch sensible heating raise temperature, a boiling plateau hold temperature constant while liquid converts to vapor, and condensation return that same latent heat as the piston reverses.
• A real-time 3D cutaway workbench (a sealed vessel, a movable constant-pressure piston, a liquid/vapor charge shown with a schematic phase-fraction fill level, and a heater/cooler boundary) with home view, focus-selected-part, auto-rotate, expand, show/hide outer shell and hide-labels scene tools. • Experiment controls: net heat rate (positive to boil, negative to condense) and initial phase-fraction sliders, plus pause/resume, single-step and 60 s-step buttons, six playback speeds, and restart/start/stop/reverse-heat actions. • A Curves & measurements analysis tab with two live charts (sensible and latent enthalpy; heat supplied and vapor mass), the underlying sensible-heat and latent-heat equations, and snapshot readouts (temperature, vapor mass fraction, accumulated heat, and enthalpy change). • An Experiments tab with four guided fixtures (heating liquid water to the boiling plateau, condensing a wet vapor charge, a thermal hold mid-plateau, and a dryout boundary at fully dry saturated vapor) and a Model verification bench with a timestamped event log and copyable trial report. • A Learn & assess tab with four guided lessons, a knowledge-check quiz with reset, and a written model-scope statement linking to a phase-change reference.
Below and above the boiling plateau, added heat is sensible — it raises the water's temperature according to its specific heat capacity, following Q = mcΔT. Once the charge reaches saturation temperature, however, added heat becomes latent: it changes the fraction of liquid converted to vapor at constant temperature, following Q = mL where L is the latent heat of vaporization (approximately 2256 kJ/kg for water at atmospheric pressure). This is why the temperature-vs-time chart shows a flat plateau precisely where the phase-fraction chart shows the most dramatic change.
Condensation is the same process running in reverse: as heat is removed from a vapor charge, the vapor releases its latent heat and converts back to liquid at the same constant saturation temperature, demonstrated directly in the condense-a-wet-vapor-charge experiment.
Because the piston is free to move at constant pressure, the system does boundary work as vapor (which occupies far more volume than liquid at the same mass) forms and expands — though the visual expansion shown is schematic rather than to true volumetric scale. The thermal-hold experiment demonstrates that heating can be paused mid-plateau, holding the phase fraction constant until heating resumes, while the dryout-boundary experiment shows the simulation's crisp stopping point once the charge reaches fully dry saturated vapor at the low-temperature bound.
This is an equilibrium, fixed-mass water model under an ideal constant-pressure piston at 101.325 kPa, using approximately constant liquid specific heat and a fixed latent heat of 2256 kJ/kg. Vessel heat capacity, heat losses to the environment, nucleation behavior, boiling crisis (critical heat flux), pressure dynamics and superheat are all omitted — the prescribed net heat rate accounts for all heat transfer directly. Enthalpy is advanced exactly for a constant heat input and stops exactly at 20 °C liquid or dry saturated vapor. The Reverse Heat control preserves the current state and accumulated heat rather than resetting the trial. The simulation runs for up to one simulated hour.
During the phase change, added heat is latent heat — it goes into converting liquid to vapor rather than raising temperature. Only once the charge is fully vaporized (or, in reverse, fully condensed) does further heat addition or removal resume changing the temperature.
Sensible heat changes temperature according to Q = mcΔT and occurs before boiling starts or after the charge is fully vapor. Latent heat changes the liquid-to-vapor phase fraction at constant temperature according to Q = mL, and occurs only while both phases coexist at the saturation temperature.
Yes, for the same mass converted. The model uses the same latent heat value (2256 kJ/kg) in both directions, so condensing back to liquid releases exactly the heat that was absorbed during boiling — demonstrated in the condense-a-wet-vapor-charge experiment.
No. It is an idealized equilibrium model of a fixed-mass water charge at constant pressure, and explicitly omits nucleation behavior, boiling crisis (critical heat flux), vessel heat losses and pressure dynamics — it tracks only the sensible/latent energy balance and resulting phase fraction.