# HX-02B visible pre-run packet

**Benchmark:** Zhang et al. (2022), open-access prototype PCHE.

**Status:** `FROZEN_FOR_HUMAN_REVIEW; LUNA_NOT_STARTED`

This packet contains only pre-analysis information. Experimental outlet temperatures, heat duties, overall-U result, author comparisons, wall-temperature results and conclusions are sealed.

## Physical problem

Two-stream PCHE prototype: hot sodium on one plate family and high-pressure supercritical CO₂ on alternating plates. The bounded objective is to reconstruct inlet/outlet temperatures, two-side heat-duty balance and overall U at a declared operating point. Pressure drop and wall-material/FEA truth are not scored in this revision.

## Geometry

- core envelope: 110 mm × 273 mm × 224 mm;
- sodium channels: circular, 4 mm diameter, 6 mm spacing, 40 channels per sodium plate, 3 mm plate thickness;
- CO₂ channels: semicircular, 1.5 mm diameter, 2.5 mm spacing, 26 channels per CO₂ plate, 1.5 mm plate thickness;
- alternating arrangement: one sodium plate to two CO₂ plates.

## Operating envelope

- sodium: 0.17–0.30 kg/s, 0.1–0.2 MPa, 490–520 °C inlet;
- CO₂: 0.21–0.24 kg/s, 15/18/20 MPa, 310–340 °C inlet;
- 18 steady-state groups are described; one rated point may be selected before reveal.

## Measurement definitions

Flow meters measure each stream; pressure sensors are at exchanger inlet/outlet; inlet/outlet thermocouples have stated ±0.5 °C accuracy; wall-temperature thermocouples are arranged along the flow direction. Any unresolved manifold idealization must be declared.

## Known unknowns

Wall material identity/properties and a complete machine-readable 18-point table are not supplied here. Pressure-drop outputs are not selected. No author CFD model, fitted correlation, result figure, conclusion or preferred design is visible.