This simulator models a single-pass concentric-tube counterflow heat exchanger carrying two water streams. Adjust inlet temperatures, mass flow rates, fouling and a cold-side bypass fraction, then check outlet temperatures, heat duty and energy conservation across the core.
• A real-time 3D cutaway workbench (hot and cold inlet headers, a concentric-tube counterflow core, a cold-side bypass line, and mixed cold outlet manifold) with home view, focus-selected-part, auto-rotate, expand, show/hide outer shell and hide-labels scene tools. • Experiment controls: hot inlet temperature, cold inlet temperature, hot mass flow rate, cold mass flow rate, fouling factor and cold-side bypass fraction sliders, plus pause/resume, single-step and 60 s-step buttons, six playback speeds for the flow animation, and restart/animate/stop actions. • A Curves & measurements analysis tab with two live charts (duty versus clean UA; bypass and mixed outlet temperature), the underlying effectiveness-NTU and UA-fouling equations, and snapshot readouts (heat duty, hot and cold outlet temperatures, mixed cold outlet temperature, and an energy-balance check). • An Experiments tab with four guided fixtures (verifying the energy balance, equal capacity rates on both streams, a fouled exchanger with reduced conductance, and bypass dilution of the cold outlet) 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 heat-exchanger reference.
Heat moves from the hot stream to the cold stream through the separating tube wall, governed by the exchanger's overall conductance UA and the local temperature difference between the two streams. Because both streams have a capacity rate (mass flow rate times specific heat), the stream with the smaller capacity rate experiences the larger temperature change for a given heat duty — a relationship the equal-capacity-rates experiment makes explicit by putting both streams on equal footing.
The energy-balance experiment confirms that heat lost by the hot stream equals heat gained by the cold stream (before any bypass mixing), a direct check of conservation of energy in the steady model.
Fouling accumulates a layer of scale or deposit on the heat-transfer surface, adding thermal resistance and reducing the effective UA — the fouled-exchanger experiment shows outlet temperatures degrading compared with the clean baseline at the same flows. The cold-side bypass diverts a fraction of the cold stream around the exchanger core entirely; that diverted fraction mixes back in afterward, diluting the mixed cold outlet temperature even though the core-exit temperature of the treated portion is unchanged — demonstrated in the bypass-dilution experiment.
This is a steady single-pass concentric-tube counterflow model using water with constant specific heat, prescribed UA and mass flows, with no heat loss to the environment, axial conduction along the tube, pressure drop or phase-change behavior. UA and the fouling factor are lumped parameters, and the physical geometry shown is representative rather than dimensioned. Controls recompute steady conditions immediately — this is not a transient startup calculation, and running or pausing only animates the flow visualization. The core temperature chart and outlet readouts recompute instantly on every control change; animation pauses automatically after one simulated hour.
This exchanger is configured as a single-pass concentric-tube counterflow unit, meaning the hot and cold streams flow in opposite directions through the shared tube wall. This arrangement generally sustains a more uniform temperature difference along the exchanger's length than a parallel-flow arrangement with the same UA — a comparison explored in the companion Counterflow vs. Parallel Flow simulator.
Fouling deposits an insulating scale or film layer on the heat-transfer surface, which adds thermal resistance and lowers the effective overall conductance (UA). With the same flow rates and inlet temperatures, a fouled exchanger delivers less heat duty and produces outlet temperatures closer to the inlet conditions than a clean exchanger would.
The bypass fraction of the cold stream skips the exchanger core entirely and rejoins the treated portion afterward. Because the bypassed fluid never exchanges heat, mixing it back in dilutes the final mixed cold outlet temperature toward the original cold inlet temperature, even though the treated portion's core-exit temperature is unaffected.
No. The model is a steady, lumped-UA representation focused on the energy balance and temperature outcomes; it does not include pressure-drop calculations, axial conduction along the tube wall, or any transient startup dynamics — outlet conditions recompute immediately whenever a control changes.