This simulator places two separate, matched plate-channel exchangers side by side — one counterflow, one parallel-flow — with identical prescribed UA and identical inlet conditions on both streams. Watch both temperature profiles along the channel length and discover why counterflow delivers more heat transfer than parallel flow at the same surface conductance.
• A real-time 3D workbench (two independent plate-channel exchanger rigs, one wired counterflow and one parallel-flow, with hot and cold stream inlets/outlets on each) with home view, focus-selected-part, auto-rotate, expand, show/hide outer shell and hide-labels scene tools. • Experiment controls: shared hot inlet temperature, shared cold inlet temperature, hot capacity rate, cold capacity rate and shared UA 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 (heat duty versus UA; effectiveness versus NTU) comparing both arrangements directly, the underlying effectiveness-NTU equations for each flow arrangement, and snapshot readouts (duty, outlet temperatures and effectiveness for both the counterflow and parallel-flow rigs). • An Experiments tab with four guided fixtures (a matched reference case, an outlet-temperature-crossing condition, disabling thermal contact entirely, and unequal stream capacity rates) 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-arrangement reference.
In parallel flow, both streams enter at the same end and their temperature difference is largest at the inlet but shrinks continuously along the channel, ultimately limiting how close the outlet temperatures can approach each other. In counterflow, the streams move in opposite directions, which distributes the driving temperature difference more evenly along the entire length — this is the core lesson the matched-reference experiment sets up as a controlled baseline before changing anything else.
A subtlety the outlet-temperature-crossing experiment reveals: in counterflow, the cold stream's outlet temperature can actually exceed the hot stream's outlet temperature, something that is thermodynamically impossible in parallel flow. This is 'outlet crossing,' and it happens without violating any local temperature difference — it is not the same as the two streams' temperatures crossing at any single point along the channel.
Because heat duty and outlet temperature change depend on each stream's capacity rate (mass flow rate times specific heat), the unequal-capacity-rates experiment shows that the stream with the smaller capacity rate always experiences the larger temperature swing — a direct consequence of following capacity rates rather than flow rate or UA alone. The no-thermal-contact experiment sets UA effectively to zero, confirming that with no heat transfer path, both streams pass through completely unchanged, which serves as a sanity check on the model.
Both rigs are independent steady-state, single-pass plate-channel exchangers with identical prescribed UA and water capacity rates, using constant specific heat with no phase change, external heat loss, axial conduction, pressure drop, fouling or transient warm-up. Channel colors represent the model's computed temperature rather than a literal fluid color, and the flow animation is purely illustrative — time does not change the steady-state temperatures shown. Parameter edits reset the animation, and the trial ends automatically after one simulated hour.
Counterflow's opposing stream directions distribute the temperature driving force more evenly along the entire exchanger length, rather than concentrating it at one end and letting it shrink toward the other — which lets a counterflow exchanger achieve a higher effectiveness than an equivalent parallel-flow exchanger with the same UA and capacity rates.
In counterflow, yes — this 'outlet temperature crossing' is thermodynamically possible and demonstrated directly in one of the simulator's guided experiments. In parallel flow, it cannot happen, since both streams start at the same end and the cold stream can never exceed the hot stream's local temperature anywhere along the channel.
No — outlet crossing refers only to the final outlet values. It does not imply the two streams' local temperatures cross at some point along the channel length; the local temperature difference remains physically consistent (hot always at or above cold) throughout the exchanger.
The stream with the smaller capacity rate (mass flow rate times specific heat) always undergoes the larger temperature change for the same heat duty — shown directly in the unequal-capacity-rates experiment, which is why capacity rate matters more than raw flow rate alone.