Outcome
Let a user select an architecture, observe a stable baseline, inject one bounded fault, trace propagation, and state an appropriate investigation sequence.
Product requirements · liquid-cooling controls simulator
CDU Mini-BMS
A verifiable product contract for the five CDU architectures, thirteen signal tiles, six coherent scenarios, P&ID interaction and operator-learning workflow in cdu-mini-bms.html. The cockpit is an engineering simulator, not a live controller or approved cause-and-effect matrix.
01 Purpose & problem
Liquid-cooling operators must correlate a plant symptom with its physical path and dependent signals. A static P&ID explains topology; a point list shows values. This cockpit combines them without implying field connectivity.
Product truth
Every displayed value is attributable to a type baseline, scenario delta or labelled derived formula. Simulation, limitations and source basis stay visible.
02 Users & decisions
| Persona | Decision supported | Primary evidence | Success |
|---|---|---|---|
| Critical-facility operator | Identify the first safe investigation path. | Alarm banner, affected tiles, P&ID state. | Names cause, consequence and next inspection. |
| Liquid-cooling engineer | Compare placement/capacity architectures. | Type selector, capacity, flow, temperature and pressure basis. | Separates architecture inputs from dynamic readings. |
| Commissioning engineer | Turn behavior into deterministic checks. | Signal mapping, scenarios, pause/step and reset. | Reproduces every AC without private knowledge. |
| Learner | Understand CDU fault propagation. | Guided walkthrough and Manual formulas. | Explains why multiple readings move together. |
03 Scope & non-goals
In scope
- In-rack, in-row, sidecar, L2L end-of-row and L2A baselines.
- Thirteen instrument/state tiles and linked P&ID bubbles.
- Normal, leak, pump failure, filter clog, hot-water and low-flow scenarios.
- Trend drill-down, guided walkthrough, pause, step, speed and reset.
Non-goals
- No BACnet/Modbus/PLC connection or write-back.
- No pump curve, hydraulic network, fluid-property or HX sizing solver.
- No vendor alarm set-points or safety trip authority.
- No historian, acknowledgement, work order or audit trail.
04 Functional requirements
| ID | Requirement | Deterministic check |
|---|---|---|
| FR-01 | Expose five CDU type selectors. | Each selection changes caption and all authored type baselines together. |
| FR-02 | Expose six scenario selectors. | Exactly one has aria-pressed=true; Normal is reset state. |
| FR-03 | Declare the cockpit as simulated. | Visible copy and machine-readable data mode agree. |
| FR-04 | Render facility and technology loops on one P&ID. | HX, pumps, filter, manifold, racks and sensor tags remain labelled. |
| FR-05 | Bind thirteen tiles to stable tag IDs. | Tile label, unit, reference band and value are present. |
| FR-06 | Derive total flow from specific flow and capacity. | FT-01Σ equals LPM/kW × kW within display rounding. |
| FR-07 | Derive return temperature from supply plus ΔT. | TT-02 arithmetic matches the Manual. |
| FR-08 | Evaluate every numeric tile against its declared band. | NORMAL/WARN/ALARM text accompanies color. |
| FR-09 | Let explicit scenario state override a conflicting numeric band. | Leak and filter states latch on their dedicated tiles. |
| FR-10 | Set overall state to the worst active tile severity. | ALARM outranks WARN, which outranks NORMAL. |
| FR-11 | Show coherent leak propagation. | Leak active, level/pressure/flow fall together. |
| FR-12 | Show coherent pump-failure propagation. | Pump A stops, N+1 is lost, flow and dP fall. |
| FR-13 | Show coherent filter-clog propagation. | Filter and loop dP rise while flow falls and ΔT rises. |
| FR-14 | Show hot facility-water propagation. | Supply temperature and HX approach rise together. |
| FR-15 | Show low-flow propagation. | Flow/dP fall while ΔT rises. |
| FR-16 | Open a trend from a tile or P&ID tag. | Current, min/avg/max, samples, unit, band and source are readable. |
| FR-17 | Provide a guided cause-to-response walkthrough. | Steps identify cause, signal propagation, consequence and response. |
| FR-18 | Provide pause, single-step, speed and reset controls. | Controls affect simulation time only; type/scenario basis stays stable. |
| FR-19 | Support keyboard operation and Escape close. | Selectors, bubbles, tiles and overlays operate without a pointer. |
| FR-20 | Preserve site theme, mobile nav, cookie and explanation services. | Shared scripts load with no non-asset console error. |
| FR-21 | Link the cockpit, PRD and Manual bidirectionally. | Public URLs resolve and labels are explicit. |
05 Data model & telemetry points
Ranges are simulator presentation bands, not commissioned alarms.
| Point | Meaning | Unit / band | State semantics | Source binding |
|---|---|---|---|---|
| FT-01 | Specific secondary flow | LPM/kW · 1.0–1.5 | Low/high band state. | TYPES.flow + SCEN.flow |
| FT-01Σ | Total secondary flow | LPM | Derived display. | FT-01 × capacity |
| TT-01 | Supply temperature | °C · 17–45 | Band state. | TYPES.supply + SCEN.supply |
| TT-02 | Return temperature | °C | Derived display. | TT-01 + ΔT-01 |
| ΔT-01 | Loop temperature rise | K · 8–12 | Band state. | TYPES.dT + SCEN.dT |
| PDT-02 | Secondary-loop differential pressure | bar · 0.5–3.0 | Low/high band state. | TYPES.dP + SCEN.dP |
| PT-01 | System pressure | bar · 2–6 | Low band under leak. | TYPES.sysP + SCEN.sysP |
| LT-01 | Reservoir level | % · 45–70 | Low band under leak. | 56 + scenario level delta |
| P-01 | Duty/standby pumps | state | N+1 / N, no standby. | Scenario pump flags |
| PDT-01 | Filter condition | state / dP | CLEAN / CLOG. | Scenario filter flag |
| LSH-01 | Leak detection | DRY / LEAK | LEAK is ALARM. | Scenario leak flag |
| TT-Δ | HX approach | K · 3–7 or n/a | High under hot facility water. | Type architecture + scenario |
| AT-01 | Chemistry summary | PG25 state | Static simulated state. | Authored cockpit constant |
06 Calculation & state rules
totalFlow_LPM = specificFlow_LPM_per_kW × capacity_kWreturnTemperature_C = supplyTemperature_C + deltaT_KExample In-Row Normal: 1.30 × 300 = 390 LPM; 32 + 11 = 43°C.
display = typeBaseline + scenarioDelta + bounded sinusoidoverall = max(tileSeverity), where ALARM > WARN > NORMALFull calculation basis and worked examples: CDU Mini-BMS Manual.
07 UX, state & accessibility
Operating sequence
- Select architecture.
- Confirm Normal baseline.
- Correlate tile and P&ID.
- Inject one scenario.
- Read worst-state banner.
- Walk cause to response.
- Reset.
Required states
- Selected controls expose
aria-pressed. - Color always has text/state equivalent.
- Focus is visible; controls meet 44 px target.
- Reduced motion disables non-essential animation.
- At 375 px no page-level horizontal scroll occurs.
08 Acceptance criteria
| ID | Given / when / then | Evidence |
|---|---|---|
| AC-01 | Given each type, when selected, then capacity, supply, ΔT, specific flow, dP and pressure equal the authored type object. | Automated five-type matrix. |
| AC-02 | Given Normal, when the type is In-Row, then total flow is 390 LPM and return is 43°C before bounded display variation. | Unit assertion. |
| AC-03 | Given Leak, then LSH-01 alarms and LT-01/PT-01/FT-01 move in the declared direction. | Scenario snapshot. |
| AC-04 | Given Pump A fail, then duty state and redundancy loss agree. | Scenario snapshot. |
| AC-05 | Given Filter clog, then flow falls while dP/ΔT rise and overall is ALARM. | Scenario snapshot. |
| AC-06 | Given Hot facility water, then TT-01 and TT-Δ rise without changing type capacity. | Scenario snapshot. |
| AC-07 | Given Low flow, then FT-01/PDT-02 fall and ΔT rises. | Scenario snapshot. |
| AC-08 | Given L2A, then HX approach reports n/a. | Type snapshot. |
| AC-09 | Given any tile, keyboard activation opens a labelled trend and Escape closes it. | Browser E2E. |
| AC-10 | Given a fault, walkthrough steps preserve cause → propagation → consequence → response order. | Browser E2E/text contract. |
| AC-11 | Given pause/step/reset, state transitions are deterministic and do not mutate type inputs. | Browser E2E. |
| AC-12 | Given dark/light and 375/1440 px, no critical accessibility issue, console error or horizontal overflow occurs. | Axe/layout screenshots. |
| AC-13 | Given cockpit/PRD/Manual links, all resolve as public HTTP 200 pages. | Link audit. |
09 Non-functional & security requirements
Reliability & performance
- Repeated reloads yield identical engineering inputs.
- Animation work pauses when the page is not visible where practical.
- Core text/formulas remain useful without animation.
- No external operational dependency is required.
Security & privacy
- No credentials, write endpoint or user-entered HTML.
- No production tag/value or personal telemetry is collected.
- Shared cookie control remains active.
- Errors do not expose filesystem or internal service details.
10 Provenance & verification map
| Evidence | Authority | Use | Required verification |
|---|---|---|---|
cdu-mini-bms.html | Current implementation | TYPES, SCEN, TILES, interactions. | Static contract + browser flow. |
| CDU Mini-BMS Manual | Project engineering basis | Equations, examples, tag mapping, limitations. | Formula/source preservation test. |
| CDU Checklist and Selection Guide | Existing RZ reference | Placement, chemistry and maintenance context. | Human technical review. |
| Vendor manuals / approved SOO | Site authority | Real limits, trips and response. | Required before field use. |
11 Risks, dependencies & release gate
Known risks
- Users may mistake smooth animation for live telemetry.
- Illustrative bands may be copied as site set-points.
- Specific-flow input can be mistaken for a hydraulic solution.
- L2A heat rejection may be read as fully modelled.
Release gate
- All FRs and ACs map to executable or visual evidence.
- Simulation and limitations remain visible.
- Exact cockpit diff contains only PRD/Manual links.
- PRD, Manual, hubs, search, sitemap and
llms.txtagree. - Dark, light, mobile, keyboard and console gates pass.
Dependency: any transition to a live BMS requires a new frozen contract covering protocols, authentication, authorization, freshness, write safety, approved set-points and site cause/effect.