# Heat Exchanger Sizing

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- **Type:** Skill
- **Install:** `agentstack add skill-jskherman-engg-skills-heat-exchanger-sizing`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [jskherman](https://agentstack.voostack.com/s/jskherman)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [jskherman](https://github.com/jskherman)
- **Source:** https://github.com/jskherman/engg-skills/tree/main/skills/heat-exchanger-sizing

## Install

```sh
agentstack add skill-jskherman-engg-skills-heat-exchanger-sizing
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Heat Exchanger Sizing (LMTD)

## Overview

LMTD-based duty and area calculation for a known overall heat transfer
coefficient U. Counter-current or co-current; multi-pass F-factor via the
`ht` library. Duty can be computed from terminal temperatures or supplied
explicitly.

## Prerequisites

1. `uv` available.

## When to Use

- Sizing a new exchanger when you have a defensible U value (vendor data,
  prior project) and terminal temperatures.
- Sanity-checking an existing exchanger for new conditions.

## Don't use for

- Bell-Delaware shell-side design with detailed baffle / bundle
  configuration.
- Rate-based two-phase boiling or condensation (use a vendor or
  specialized tool).
- Calculating U from first principles when h on either side is unknown
  (use `convective-heat-transfer-correlations` first).

## Utility Scripts

- `uv run scripts/size_heat_exchanger.py --hot-in-c 150 --hot-out-c 90 --cold-in-c 25 --cold-out-c 90 --arrangement counterflow --u-w-m2-k 500 --duty-w 1e6 --output /tmp/hx.json`

## Procedure

1. Define hot/cold inlet and outlet temperatures (°C for the bundled script).
2. Decide arrangement: counterflow (preferred), co-current, or
   multi-pass with F-factor.
3. Estimate U from either side's h (or vendor data); typical ranges:
   liquid-liquid 300-1000 W/m²K, liquid-gas 30-100, condensing steam
   2000-5000, boiling 1000-4000.
4. Provide duty from one stream's sensible heat (m × cp × ΔT) or pass
   the value if known.
5. Run the script. Inspect area; round up to the nearest commercial
   bundle size.
6. Cross-check by computing the other stream's duty and verifying the
   energy balance closes.

## Pitfalls

- Using bare LMTD without the F-factor for multi-pass exchangers.
- Picking U from a textbook table without flagging the fouling
  factor (overstates U).
- Forgetting that LMTD blows up to ±infinity when terminal differences
  approach zero (temperature pinch).
- Using sensible-heat duty for a two-phase service (latent heat
  dominates).
- Reporting required area without acknowledging the fouling allowance.
- Choosing LMTD when one stream is isothermal (condensing / boiling) and
  using F = 1 by default. Even for single-phase the F-factor is < 1 for
  multi-pass.
- Picking shell-and-tube as default; for liquid-liquid services with low
  fouling, a plate-and-frame is often smaller and cheaper.
- Treating the calculated area as final without vendor-validated TEMA
  layout and pressure-drop check.

## Fallback Strategies

- If `ht.LMTD` is unavailable, the script falls back to the direct LMTD
  formula and flags the substitution.
- If only one stream's enthalpy data is supplied, the script computes the
  matching cold/hot side from the energy balance, but only when
  arrangement allows it.

## Verification

- Run the listed script with representative inputs and an `--output` file when a deterministic calculation is available.
- Confirm the JSON result contains `ok: true`, expected units, and no unhandled warnings.
- Check result magnitudes against the stated assumptions, references, and a hand calculation or known operating range before reporting them.

## References

- `references/methods.md` — assumptions, formulas, and U ranges.
- TEMA standards (procure separately).
- Sinnott / Coulson & Richardson Vol 6 for U guidance.

## Anti-Patterns

- Reporting required area without specifying U and fouling factors.
- Using LMTD with widely different specific heats across the exchanger
  (Cp varies strongly with T).
- Sizing without checking the temperature pinch.

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [jskherman](https://github.com/jskherman)
- **Source:** [jskherman/engg-skills](https://github.com/jskherman/engg-skills)
- **License:** Apache-2.0

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-jskherman-engg-skills-heat-exchanger-sizing
- Seller: https://agentstack.voostack.com/s/jskherman
- Browse the marketplace: https://agentstack.voostack.com/browse

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