This simulator models a closed chilled-water plant — chiller evaporator, compressor, centrifugal pump, two-way coil control valve, building cooling coil, supply/return headers and an expansion vessel — as a coupled hydraulic and thermal balance. Set the building's sensible load, pump speed, coil valve opening, chiller supply setpoint, available capacity and COP, then watch flow, pump head, supply/return temperature, coil duty and chiller electrical input respond, including what happens when the pump or chiller is lost.
• Equipment laboratory tab: a real-time 3D cutaway of the plant 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 (chiller evaporator shell, chiller compressor assembly, centrifugal circulating pump, two-way coil control valve, building cooling coil, chilled-water supply header, warm-water return header, expansion vessel, plant control panel) 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 plant, fail the pump or the chiller directly, and adjust building sensible load (20–220 kW), pump speed ratio (0.2–1.2×), coil valve opening (0.1–1 fraction), chiller supply setpoint (4–12°C), available chiller capacity (40–200 kW), chiller COP (2–7 kW/kW), and toggle pump and chiller availability. • Curves & measurements tab: a room-and-loop-temperatures chart, a heat-carried-and-removed chart, the model's governing equations, a model-boundaries note, and snapshot measurements for water mass flow, pump differential pressure, supply water, return water, building coil duty and chiller electricity. • Experiments tab: guided experiments (normal plant, throttle the coil valve, chiller unavailable, pump unavailable) 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 finding the hydraulic operating point, reading supply and return separately, tracking stored heat, and testing loss of a dependency, a knowledge-check quiz with reset, and a scope/references note linking to DOE process-cooling and HVAC guidance.
A centrifugal pump circulates water around a closed loop between a chiller evaporator and a building cooling coil. The pump's differential pressure falls with increasing flow while the system's flow resistance (set mainly by the coil control valve) rises with flow squared, so the actual operating flow is the intersection of the pump curve and the system curve: Δppump = 60·N² − 0.6·ṁ² (kPa) meets Δpsystem = (0.4/valve²)·ṁ².
The building coil transfers room heat to the circulating water with a finite UA of 8 kW/K: Qcoil = Cwater·(Troom − Twater)·[1 − exp(−UA/Cwater)]. The chiller is modeled as a capacity-limited, setpoint-seeking removal of heat from the loop, with electrical input computed from the selected COP: Wchiller = Qchiller/COP. The loop itself has a lumped thermal capacity of 2800 kJ/K and accumulates or sheds heat according to Cloop·dTwater/dt = Qcoil + Wpump − Qchiller — note that pump work itself adds a small amount of heat to the loop, which is why the loop-storage verification check must account for it explicitly.
In the throttle-the-valve experiment, closing the coil valve raises system resistance, which lowers the pump/system intersection flow and increases the water temperature rise per unit of heat transferred (since the same coil duty is carried by less water). In the chiller-unavailable experiment, the building coil keeps absorbing room heat with no removal path, so loop water temperature climbs over simulated time — this is the stored-heat imbalance the model is built to expose. In the pump-unavailable experiment, both circulating flow and forced coil heat transfer drop to zero immediately, since a healthy chiller cannot move heat through a stopped pump.
The Run model checks button exercises the eight built-in checks from the shared verification suite for this simulator: losing the pump zeroes flow and coil duty, throttling the valve reduces flow, higher pump speed increases flow, the coil water-side energy balance closes (Q = ṁ·cp·ΔT), losing the chiller warms the loop, the chiller stays within its available capacity limit even under excess demand, COP correctly maps heat removal to electrical input, and loop thermal storage closes including the pump's own heat contribution. These confirm the implemented hydraulic and thermal relationships are self-consistent rather than certifying a specific manufacturer's plant selection.
It models a closed chilled-water plant with a centrifugal pump and system curve intersection for flow, a finite-UA (8 kW/K) building coil, and a capacity-limited chiller with a settable COP, on a lumped 2800 kJ/K loop and 600 kJ/K room thermal capacity. Refrigerant dynamics, the cooling tower side, pipe transit time and expansion-vessel pressure dynamics are excluded.
Flow is set by the intersection of the pump curve, Δppump = 60·N² − 0.6·ṁ² (kPa) at pump speed ratio N, and the system resistance curve, Δpsystem = (0.4/valve²)·ṁ² set by the coil control valve opening — the same graphical method used to find a real pump's operating point against its system curve.
Losing the pump immediately zeroes circulating flow and forced coil heat transfer, since a healthy chiller cannot move heat through a stopped pump. Losing the chiller leaves the building coil absorbing room heat with no removal path, so loop water temperature climbs over simulated time — both behaviors are directly testable in the guided experiments and the built-in checks.
The Run model checks button verifies independent invariants in the implemented plant model — such as the coil water-side energy balance closing, the chiller respecting its capacity limit, COP correctly relating heat removal to electrical input, and loop thermal storage closing including pump heat — using fresh, independent model instances that do not disturb your current trial.