RRefrigDNA
LACI / TECHNICAL REVIEWREV C · TRL 4
Concept rendering of RefrigDNA SenseNode installed on refrigeration piping

THE EVIDENCE LAYER FOR DISCONNECTED REFRIGERATION ASSETS

Know the asset.
See the signal.
Prove the response.

RefrigDNA binds non-invasive equipment signals, technician judgment, and compliance documentation into one audit-ready asset history.

Enter the Field Node ↓What exists today
CLAIM BOUNDARY

Rev C indicates leak-risk for technician review. It is not certified life-safety detection and does not autonomously declare a leak.

HARDWAREClamp-on multisignal node
IDENTITYQR / NFC asset passport
EVIDENCEHash-linked event record
OUTPUTOwner + audit packet
CONCEPT RENDERING · PROPOSED INDUSTRIAL DESIGN
✓

INTERACTION ACCEPTANCE MATRIX

Nineteen requirements. Nineteen things the board can test.

Every card states the interaction and jumps directly to the working component. This is the proof index for the complete diligence room.

02

EXECUTIVE ENGINEERING SESSION

Three hours. Six decisions. No hand-waving.

This room is designed to extract every technical, product and commercial decision required to turn Rev C into a field-validated system.

00:00–00:2001

Claim & boundary

What the system does, does not do, and what must be true for the wedge to hold.

DECISION 01 · CLAIM
00:20–01:0002

Hardware & sensing physics

Mechanical coupling, sensor selection, analog front end, power, placement and environmental envelope.

DECISION 02 · REV D
01:00–01:3503

Firmware, data & security

Sampling, feature extraction, evidence chain, device identity, transport, tenancy and APIs.

DECISION 03 · ARCHITECTURE
01:35–02:0504

Compliance & application

Rule provenance, workflow states, exception handling, technician UX and owner exports.

DECISION 04 · PRODUCT
02:05–02:3505

Validation & manufacturing

DOE, ground truth, performance metrics, DFM, test fixtures, unit cost and certification path.

DECISION 05 · PILOT
02:35–03:0006

Risk, resources & 90 days

Owners, gates, kill criteria, budget and one undeniable customer loop.

DECISION 06 · FUND
ROOM STANDARDEvery assertion resolves to a measurement, artifact, owner, test, or explicit assumption.Every open issue receives a closure criterion.Every feature must earn power, BOM, latency, security and workflow cost.
03

SYSTEM ARCHITECTURE

One signal path. Every claim traceable.

The architecture is intentionally narrow: sense an operational condition, preserve context, request human judgment, and produce evidence an owner can export.

01REV C

Sense

Pipe temperature · vibration · 38–42 kHz acoustic energy · ambient T/RH · optional pressure

→
02FIRMWARE

Gate

Run-state prevents idle acoustic noise from being interpreted as leak-risk evidence.

→
03CALIBRATE

Screen

Bounded 0–1 heuristic. A watch state prompts technician review; it does not declare a leak.

→
04PROTOTYPE

Bind

Timestamped reading + asset identity + prior hash become one append-only evidence event.

→
05TARGET

Route

BLE/Wi-Fi → MQTT/TLS target → asset passport → owner dashboard → audit packet.

Concept command center showing portfolio, sensor, evidence and audit views
PORTFOLIO CONTROL PLANE

Asset state, sensor traces, action history and documentation converge without erasing the underlying evidence.

INTERACTIVE PRODUCT VISION
04

SENSOR / MODULE HARDWARE

A field node designed around context—not a magic sensor.

Off-the-shelf components reduce early technical risk. The engineering advantage is in placement, gating, evidence design, calibration and workflow.

Exploded concept rendering of SenseNode enclosure and electronicsEXPLODED CONCEPT · NOT MANUFACTURING CAD
CH0 Specified

Pipe temperature

TI TMP117 · I²C · 0x48

Establishes thermal trend and supports contextual diagnosis.

ENVELOPE116 × 68 × 42.5 mm
PIPE RANGEØ 6.35–28.6 mm
INTERFACEWi-Fi 2.4 + BLE 5
COMPUTEESP32-S3
POWER TARGETUSB-C / DC · battery option
INTERACTIVE ENGINEERING DIGITAL TWIN
TRUE 3D / WEBGLorbit · zoom · pan · raycast select
MODULE 01

Upper enclosure + service boss

Rev C governing envelope 116 × 68 × 42.5 mm, 3 mm prototype wall, 6 mm corner radius. USB-C and 1/4-inch SAE service-boss positions remain CAD assumptions pending PCB freeze.

Material
FDM PLA/PETG fit check; production TBD
Risk
Ingress · thermal path · boss collision
PARAMETRIC REV C DIMENSION LAB

Governing uploaded parameters—not guessed marketing dimensions.

PAD THICKNESS1.50 mm
DERIVED BORE Ø25.23 mm
ENCLOSURE116 × 68 × 42.5 mm
PRINT CLEARANCE0.30 mm
REV C SIGNAL / NET MAPGPIO PROPOSED · CONFIRM IN EE CAPTURE
TRACE SELECTED / 00Pipe contact → TMP117 conversion → I²C frame → quality flag → event channel CH0Confirm thermal interface and self-heating error
SELECTED COMPONENT

TMP117 pipe-temperature channel

Interface
I²C 0x48
Placement
sprung contact against pipe
Scientific issue
thermal contact resistance + response lag
Promotion test
reference thermometry across pipe sizes
ENGINEERING SOURCE VAULT

Governing artifacts supplied for this review. Open or download the exact source.

SCADOpenSCAD parametric body↗PYFreeCAD STL-export macro↗TXTCAD + print recipe↗MDPCB net / pinout specification↗CSVMaster prototype BOM↗INOFirmware entry point↗CPPSensor acquisition scaffold↗CPPEvidence-chain scaffold↗
05

SENSING PHYSICS + DETECTION METHODOLOGY

Screen first. Diagnose second. Escalate with evidence.

Rev C uses an intentionally conservative heuristic. The model is a calibration target, not a finished scientific claim.

RUN-STATE GATE
running = RMSvibration ≥ 0.05 g

If the compressor is not running, the current firmware returns zero acoustic leak-risk.

REV C SCREEN
risk = clamp(Eultra, 0, 1)

Normalized ultrasonic energy is interpreted only inside the run-state gate.

WATCH STATE
running ∧ risk ≥ 0.70

WATCH requests review. It is not a leak diagnosis, alarm certification or automatic compliance determination.

01

Assumption

Ultrasonic band energy contains a useful screening signal after mechanical and environmental noise controls.

02

Required test

Collect labeled baseline, known-condition and nuisance-condition data across asset classes and operating modes.

03

Promotion gate

Freeze thresholds only after sensitivity, specificity, false-positive rate and repeatability are measured.

ACOUSTIC PATH

Source → pipe wall → silicone pad → microphone AFE

Coupling loss, pipe diameter, wall thickness, refrigerant state, background machinery and clamp preload all alter transfer response. Rev D requires a characterized transfer function and installation repeatability specification.

H(f) = Ysensor(f) / Xsource(f)
THERMODYNAMIC CONTEXT

Temperature and pressure are contextual—not direct charge measurements.

Raw pressure cannot be interpreted without refrigerant identity, line side, operating state, saturation relationship, superheat/subcooling context and ambient/load conditions.

T_sat = f(P, refrigerant)
FEATURE PIPELINE

Window → detrend → band energy → baseline delta → persistence

The production candidate should retain raw windows for validation, compute device-side features for bandwidth, and version every feature extractor so historical decisions remain reproducible.

Eband = Σ |FFT(x)[f₁:f₂]|²
06

EMBEDDED SYSTEMS / FIRMWARE

From GPIO to defensible event—every state explicit.

The current scaffold proves the pipeline shape. The production firmware needs deterministic acquisition, health telemetry, secure identity, offline resilience and remotely verifiable versions.

DEVICE STATE MACHINE
STATE 02

Baseline is a controlled procedure

  • ✓ Confirm placement, line identity and pipe diameter
  • ✓ Capture idle and running windows
  • ✓ Estimate noise floor and channel variance
  • ✓ Reject commissioning if health limits fail
NON-NEGOTIABLEWatchdogMonotonic sequenceSigned OTARollbackHealth events
CURRENT REV C / PSEUDOCODE TRACESCAFFOLD
reading = acquire_channels()
running = vibration_rms >= 0.05g
risk = running ? clamp(ultrasonic_energy, 0, 1) : 0
state = (running && risk >= threshold) ? WATCH : NORMAL
event = append(reading, risk, state, previous_hash)
// TODO: calibrated features, durable storage, signed event, TLS publish
07

DATA MODEL / API CONTRACTS

The proprietary software begins with an immutable semantic model.

Signals, interpretations, actions and regulatory conclusions must be separate objects. Otherwise the system cannot be audited, recalculated or trusted.

event_idUUIDv7
device_idstring
asset_idUUID
captured_atRFC3339 + trusted-time status
sequenceuint64 monotonic
channelsraw + units + quality
featuresextractor version + values
screenstate + model/threshold version
provenancefirmware · hardware · calibration
integrityprevious hash · signature
API / CANONICAL RESPONSE
POST /v1/assets/{id}/events
Idempotency-Key: dev-042:184430

{
  "sequence": 184430,
  "state": "WATCH",
  "quality": {"clock":"trusted","channels":5},
  "model_version": "screen-0.1.0",
  "signature": "ed25519:…"
}
Immutable raw event≠Derived feature≠Screening interpretation≠Compliance evaluation≠Human action
08

EVIDENCE CHAIN

A reading is not proof until its context survives.

Each event preserves the measured state, the prior event reference and the human disposition needed to explain what happened next.

RDNA-FW-0.1.0 / HW REV CSERIAL EVIDENCE MODE
12:04:00pipe 7.8°Cvib 0.082gultra 0.31P 228psiNORMAL
12:05:00pipe 8.1°Cvib 0.091gultra 0.74P 226psiWATCH
PREVIOUS HASH0x7A91D30B→CURRENT HASH0xB41C2E90

Illustrative interface data. Current code prints FNV-linked records to serial; flash/SD persistence, cryptographic signing and secure MQTT publishing remain implementation work.

01Asset-bound timestamp
02Raw channel values
03Derived screen state
04Technician disposition
05Exportable owner record
09

COMPLIANCE-RULE ENGINE

Rules change. The evidence should not disappear with them.

RefrigDNA separates immutable source records from versioned rule interpretation, allowing an owner to reconstruct why a task, deadline or packet was produced.

INPUT

Asset profile

Jurisdiction · refrigerant · charge · equipment class · owner policy · service history

VERSIONED LOGIC

Rule evaluation

Applicability → threshold → event window → required action → due date → required evidence

OUTPUT

Actionable record

Alert · work order · technician attestation · repair evidence · owner report · audit export

EXAMPLE / TRACE VIEWVERIFY BEFORE PRODUCTION

Why did this asset enter review?

Signal
Persistent WATCH condition during run-state
Rule set
Customer policy / v0.3
Evaluation
3 qualified events inside 24 hours
Action
Technician review requested
Evidence
5 readings + asset profile + event hashes

Regulatory applicability and deadlines must be validated against current EPA, CARB and jurisdiction-specific requirements before deployment.

INTERACTIVE RULE PROVENANCE TRACE

Select each stage to prove how an outcome can be reproduced.

TRACE STAGE 1

Typed facts, never free-text guesses

Asset snapshot includes refrigerant identity, charge, equipment class, jurisdiction, event history and confidence/source for each fact.

asset_snapshot sha256:… / facts[12] / confidence visible
10

APPLICATION + PLATFORM ARCHITECTURE

Four products. One domain model. Zero duplicated truth.

Technician, owner, auditor and internal operations experiences are projections of the same asset and evidence graph—not disconnected applications.

REFRIGDNA DOMAIN CORE

Asset graph + evidence ledger + workflow engine + rules engine

IdentityEventsTasksDocumentsRulesPermissions
SELECTED RESPONSIBILITYField truth creation: authenticated install, channel health, diagnostic evidence and technician disposition.MOBILE / TECH APP
WORKFLOW STATE CONTRACT0OBSERVED1QUALIFIED2REVIEW_REQUESTED3TECH_ACCEPTED4DIAGNOSED5REPAIR_PLANNED6REPAIRED7VERIFIED8CLOSED9REOPENED
11

LIVE VALIDATION WORKBENCH

Move the inputs. Expose the claim.

This simulator makes the current Rev C decision boundary visible. It is an engineering discussion tool—not field performance evidence.

RUN-STATEQUALIFIEDSCREEN RESULTWATCH
SCREEN FUNCTION / CURRENT SCAFFOLDNOT CALIBRATED
RISK SCORE0.74
if vibration_rms < 0.05g:
    risk = 0.00
else:
    risk = clamp(ultrasonic_energy, 0, 1)
state = WATCH if risk >= 0.70 else NORMAL
FACTORLEVELS / STRATARESPONSEACCEPTANCE ANALYSIS
DOE FACTOR 1

Prevent a model that only works on one machine

Block by compressor technology, refrigerant family, nominal charge, line side and asset age. Report confidence intervals within strata—not only pooled accuracy.

SensitivityTP / (TP + FN)
SpecificityTN / (TN + FP)
PrecisionTP / (TP + FP)
FARfalse watches / asset-day
Latencycondition → qualified event
Repeatabilityinstaller × asset variance
12

DFM / SUPPLY CHAIN / UNIT ECONOMICS

A prototype becomes a product when every part earns its place.

Rev C is a parametric, printable fit-check platform. Rev D must close electrical, mechanical, test, assembly and certification architecture together.

Compute + radioESP32-S3 module$8–15Single module; provision per-device identity
Core sensingTMP117 + ADXL355 + SHT4x$55–95ADXL355 dominates cost; validate lower-cost alternative
Acoustic AFEmic + filter + ADC path$8–25Custom AFE required; characterize 38–42 kHz response
Pressure tier0–600 psi transducer + adapter$25–80Optional service tier; safety and field connection cost
Enclosure + clampFDM prototype → molded/machined$18–65Pipe adapters, preload control, ingress and thermal design
Power + interconnectbuck/LDO · protection · connectors$12–30Industrial supply range and reverse/transient protection
Assembly + testfixture · calibration · serialization$20–55Design-for-test points and automated end-of-line record
INTERACTIVE EARLY COST ENVELOPE$234–366

Illustrative sensitivity model—not a supplier quote. Move volume to expose assumptions and required sourcing work.

Dominant cost risk
engineering modules + manual assembly/test
DFM decision
retain modular pilot architecture
Commercial test
value per avoided manual inspection / completed evidence packet
DFMEA PRIORITYFAILURE MODEEFFECTDESIGN CONTROLVERIFICATION
P0Clamp loosens / coupling changesSilent signal driftPreload feature + tamper/installation checkthermal cycle + vibration + installer R&R
P0Water/condensation ingressCorrosion / false readings / safetyvent strategy + gasket + conformal coatingIP target test + condensation cycle
P0AFE saturates in plant noiseMissed/false screengain strategy + clipping telemetrynuisance matrix + dynamic range test
P1Clock or sequence discontinuityEvidence chronology compromisedtrusted-time status + monotonic counterpower-cycle/offline/fault injection
P1Credential extractionFleet impersonationsecure element + per-device keysthreat model + penetration test
P1OTA failureDevice unavailable / inconsistent fleetA/B image + signed manifest + rollbackpower-loss update test
13

PROTOTYPE / MVP READINESS

The difference between designed, demonstrated and validated.

Technical credibility comes from making readiness legible. This is the current evidence boundary.

FILTER EVIDENCE BOUNDARY

Exists now

08 ITEMS
  • ✓Parametric OpenSCAD clamp body + jaw
  • ✓FreeCAD STL-export macro
  • ✓Rev C mechanical envelope and pipe range
  • ✓Component-level BOM and pinout/net specification
  • ✓ESP32-S3 firmware scaffold
  • ✓Run-state-gated screen logic
  • ✓Hash-linked serial evidence record
  • ✓Passport, dashboard and audit UX prototypes

Specified / ready to build

06 ITEMS
  • ✓Sensor module selection and channel map
  • ✓USB-C / DC power architecture
  • ✓Wi-Fi/BLE and MQTT/TLS target
  • ✓QR/NFC asset identity
  • ✓FDM fit-check recipe
  • ✓Pilot kit and installation workflow

Must be proven

08 ITEMS
  • ✓Routed PCB and electrical bring-up
  • ✓Real driver integration and calibrated ADC
  • ✓Battery life under duty cycle
  • ✓Environmental and mechanical durability
  • ✓Secure persistent event storage
  • ✓Labeled validation dataset
  • ✓Sensitivity / specificity / repeatability
  • ✓Applicable certifications and production enclosure
Concept rendering of SenseNode clamped to copper pipe
INSTALLATION CONCEPT

Clamp. Bind. Baseline. Verify.

  1. Confirm pipe size and safe placement.
  2. Install silicone interface and clamp without penetrating the line.
  3. Scan QR/NFC to bind asset identity and technician.
  4. Capture commissioning baseline across operating states.
  5. Verify telemetry, time, channel health and owner export.
FIELD METHOD REQUIRES PILOT VALIDATION
14

CYBERSECURITY · DATA · ENGINEERING RISK

Known unknowns, converted into controlled work.

No security theater. No certification theater. Each open risk has an explicit control and closure test.

RISKWHY IT MATTERSCONTROL / CLOSURE TEST
01Signal discriminationPlant rooms are acoustically and mechanically noisy.Labeled nuisance matrix; baseline normalization; cross-signal persistence; blinded test set.
02Sensor couplingClamp force, pipe size and pad condition alter readings.Installation torque/fit method; reference coupon; repeatability test across installers.
03Evidence integrityFNV chaining is tamper-evident scaffolding, not production cryptography.Device identity, secure element, signed events, trusted time and verification service.
04Transport securityCredentials and telemetry cross customer networks.Per-device credentials, TLS, rotation, least privilege, offline queue and revocation test.
05Tenant/data ownershipOperational records may be commercially sensitive.Customer ownership terms, tenant isolation, RBAC, audit logs, retention/export/deletion controls.
06Regulatory interpretationRules and applicability can change.Versioned sources, effective dates, legal/technical review and reproducible evaluation trace.
07A2L / hazardous locationDevice placement and refrigerant class affect safety requirements.Installation envelope, ignition-source assessment and certification pathway before production use.
INTERACTIVE SECURITY + DATA-OWNERSHIP THREAT MODEL
THREAT DOMAIN 1

A counterfeit or cloned node submits trusted-looking events

Control
Per-device asymmetric identity in secure element; claim and revocation lifecycle
Verification
clone/replay/revocation test
Data right
Device identity belongs to fleet trust domain
15

DEVELOPMENT ROADMAP

Ninety days to one undeniable loop.

The objective is not more screens. It is traceable evidence that the device, workflow and customer value survive contact with a real asset.

DAY 0–30

Instrument

Freeze pilot claim and test protocol. Print clamp variants. Complete bench wiring, drivers, channel-health checks, secure local storage and raw-data export.

GATERepeatable readings on a controlled rig
DAY 31–60

Calibrate

Capture baseline, seeded/known-condition and nuisance data. Label with refrigeration technician review. Quantify false positives and revise installation control.

GATELocked evaluation dataset + threshold rationale
DAY 61–90

Prove

Run one customer pilot from installation through owner packet. Measure alert usefulness, technician time, documentation completion and willingness to pay.

GATEOne customer loop with signed evidence
TECHNICAL ACCEPTANCE THESIS

RefrigDNA becomes fundable when a real customer can point to one asset and say: “This record helped us see the condition, route the work, and prove what we did.”

16

REVIEWER Q&A MODE

Interrogate the claim before the room does.

The hardest technical questions are part of the product—not hidden in an appendix.

ANSWER / 01

Does RefrigDNA detect refrigerant leaks?

Rev C is an evidence and leak-risk screening system—not a certified automatic leak detector. It combines contextual signals to identify a condition worth technician review. The product claim expands only after calibration and applicable certification.

REVIEW STANDARDDirect answerClaim boundaryEvidence gapClosure test