Cat Lab · Preliminary thermal engineering
From a heat requirement to an inspectable exchanger calculation.
CAT LAB · SINGLE-PHASE THERMAL SCREENING
Heat Exchanger
Size the conductance for a target duty, or rate a supplied UA. Inspect both outlet temperatures, terminal approaches, and the property basis.
Equal-capacity synthetic example loaded. Review its assumptions, then calculate.
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Working case: Synthetic equal-capacity example
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1 · Define the case
Two steady, nonreacting streams with constant Cp. No boiling, condensation, ambient heat loss, or pass correction is modeled.
2 · Specify the streams
Use source-marked properties for the intended temperature range.
3 · Set the thermal requirement
Overall heat-transfer conductance, not a heat-transfer coefficient. Zero UA represents no heat transfer.
Optional area estimate and U basis
A supplied U is required for area. Missing or invalid U must not remove independent duty and outlet results.
Use a reference, measurement, or explicit screening assumption. No U is inferred from the fluid.
For example, outside tube area. The calculated area uses this same basis.
Record fouling treatment, property assumptions, and unresolved limitations. Fouling is not predicted here.
Synthetic equal-capacity example
Draft · calculation not run
| Input / source | Original entry | Unit / state |
|---|---|---|
| Calculation mode | rating | |
| Arrangement | counterflow | |
| Hot stream phase | liquid | |
| Cold stream phase | liquid | |
| Hot mass flow | 1 | kg/s |
| Cold mass flow | 1 | kg/s |
| Hot specific heat capacity | 1 | kJ/(kg·K) |
| Cold specific heat capacity | 1 | kJ/(kg·K) |
| Hot inlet temperature | 100 | °C |
| Cold inlet temperature | 20 | °C |
| Target heat duty | 40 | kW · inactive in this mode |
| Supplied UA | 1 | kW/K |
| Supplied overall coefficient U | 500 | W/(m²·K) |
| Hot Cp minimum temperature | Not supplied | °C |
| Hot Cp maximum temperature | Not supplied | °C |
| Cold Cp minimum temperature | Not supplied | °C |
| Cold Cp maximum temperature | Not supplied | °C |
| Hot Cp source | Synthetic constant-Cp assumption for an analytical example; no real fluid property claim. | |
| Cold Cp source | Synthetic constant-Cp assumption for an analytical example; no real fluid property claim. | |
| U source | Synthetic U assumption, not an equipment correlation. | |
| U area basis | Declared demonstration heat-transfer surface | |
| U convention | design | |
| Assumptions and fouling notes | Illustrative arithmetic only. Phase and Cp temperature applicability are not established. No fouling calculation is included. |
Draft · calculation not run
Review the two streams and the selected sizing or rating input, then choose Calculate. A saved or imported answer is not current calculation evidence.
The equal-capacity synthetic example uses two 1 kW/K streams at 100 °C and 20 °C. In counterflow with UA = 1 kW/K, the analytical reference is 40 kW, two 60 °C outlets, and 2 m² for the stated U. These are demonstration values, not measurements.
Model scope and assumptions
- Two nonreacting streams remain in their declared single phases throughout the exchanger.
- Steady state; constant mass-specific heat capacities and constant overall conductance; no ambient heat loss or shaft work.
- Only ideal parallel flow and counterflow are supported. No pass correction, boiling, condensation, or maldistribution model.
- U is supplied with its source, area basis, and clean/design convention; no film coefficient or fouling prediction is made.
- Pressure loss, mechanical design, material compatibility, controls, and equipment qualification are outside this model.
This result supports preliminary thermal screening. It does not establish mechanical design, pressure rating, procurement readiness, or experimentally validated equipment performance.
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