This simulator models a counterflow, induced-draft cooling tower — spray distribution, fill, fan, drift eliminators, basin, makeup and blowdown — as an evaporative-effectiveness heat and water balance. Set hot-water inlet temperature, entering-air wet bulb, circulating water flow, fan speed, fill fouling and concentration-cycles target, then watch leaving water temperature, range, approach, heat rejection, makeup water and fan power respond in real time.
• Equipment laboratory tab: a real-time 3D cutaway of the tower with Home view, Focus selected part, Show full enclosure / cutaway toggle, Exploded view, Auto rotate, Expand and Hide/show labels camera controls, a clickable, numbered component list (hot-water distribution and nozzles, corrugated fill pack, induced-draft fan and motor, drift eliminators, cold-water collection basin, air-inlet louvers and casing, makeup valve and float, blowdown branch, cooled-water outlet) with a callout describing each part, live stat readouts, a running commentary of what is happening, and an experiment-controls panel to pause/step the simulation (0.1 s or 1 s advances, four playback speeds from 10× slow motion to 1 minute per second), start/stop the equipment, and adjust hot-water inlet (28–45°C), entering-air wet bulb (10–30°C), circulating water flow (5–40 kg/s), tower fan speed (0–1.2×), fill conductance loss (0–0.85 fraction) and concentration-cycles target (2–8×). • Curves & measurements tab: a leaving-temperature-and-approach chart, an evaporation-and-makeup chart, the model's governing equations, a model-boundaries note, and snapshot measurements for leaving water, tower range, wet-bulb approach, heat rejection, makeup water and fan electrical input. • Experiments tab: guided experiments (design-weather comparison, humid weather, fouled fill, higher concentration cycles) that apply a preset and predict what you should observe, a Run model checks button that runs the built-in verification suite against independent fresh models without disturbing your current trial, and a timestamped event log with a Prepare trial report button that assembles a copyable text report of settings, measurements and event times. • Learn & assess tab: lesson content on spreading water over the fill, comparing range and approach, accounting for water losses, and trading fan power against performance, a knowledge-check quiz with reset, and a scope/references note linking to DOE cooling-tower guidance.
Warm condenser water is sprayed over a corrugated fill pack while an induced-draft fan pulls ambient air upward through it in counterflow. Water evaporates into the moving air stream, carrying away latent heat and cooling the remaining water toward the entering air's wet-bulb temperature — the theoretical thermodynamic limit a tower can approach but never reach.
In this model, leaving water temperature is computed from an effectiveness relation: Tcold = Twb + (Thot − Twb)·exp[−UAeff/(ṁw·cp)], where the nominal fill conductance (UA = 75 kW/K) is scaled by the fan-speed ratio raised to the 0.7 power and reduced by fill fouling. Range is hot-water inlet minus leaving water; approach is leaving water minus wet bulb. About 80% of the rejected heat is assigned to evaporation using a latent heat of vaporization of 2440 kJ/kg, drift is fixed at 0.002% of circulation, and blowdown is sized from the target concentration cycles so makeup replaces evaporation, drift and blowdown together.
Watch how range and approach move independently: increasing fan speed narrows the approach (closer to wet bulb) because effective UA rises with airflow, while fouling widens the approach at fixed air and water settings by degrading fill conductance. If hot water arrives already below wet bulb, the cooling-only model leaves it unchanged, since a tower cannot cool water below the wet-bulb reference in this scope. Raising the concentration-cycles target reduces required blowdown and makeup in the steady mass balance, though real water chemistry and scaling limits are outside the model.
The Run model checks button exercises the eight built-in checks from the shared verification suite for this simulator: leaving water never drops below wet bulb, higher wet bulb raises leaving water, fan speed improves approach, fouling reduces heat rejection, the tower water energy balance closes (heat = ṁ·cp·range), higher concentration cycles reduce blowdown, makeup equals evaporation plus blowdown plus drift, and fan power follows the cube law (half fan speed gives one-eighth power). These confirm the implemented physics is self-consistent rather than validating any specific manufacturer's tower selection.
It models a counterflow, induced-draft cooling tower using an effectiveness (NTU-style) heat-transfer relation with a nominal fill conductance of 75 kW/K, scaled by fan speed and fouling, plus a steady evaporation/drift/blowdown water balance. It is a teaching effectiveness relation, not a full Merkel calculation or a rated tower selection.
Range is the hot-water inlet temperature minus the leaving (cold) water temperature — how much the tower cooled the water. Approach is the leaving water temperature minus the entering-air wet-bulb temperature — how close the tower got to the thermodynamic limit set by ambient humidity.
Faster fan speed increases the effective fill conductance (scaled by the fan ratio to the 0.7 power), narrowing the approach, but fan electrical power follows an approximate cube law with speed, so a small speed increase costs disproportionately more power — the built-in check confirms half speed gives one-eighth power.
The Run model checks button verifies independent invariants in the implemented model — such as leaving water never cooling below wet bulb, the tower water energy balance closing, and the fan cube law — using fresh, independent model instances that do not disturb your current trial.