# Heat exchanger first-pass review

Project / revision:  
Reviewer / date:  
Decision and acceptance criteria:  
Flow arrangement and area basis:  

## Inputs and sources

| Quantity | Hot side | Cold side | Unit / source |
| --- | ---: | ---: | --- |
| Mass flow |  |  | kg/s |
| Inlet temperature |  |  | °C |
| Outlet temperature |  |  | °C |
| Heat capacity or inlet/outlet enthalpy |  |  | J/(kg·K) or J/kg |
| Design pressure / allowable pressure drop |  |  | Pa |

## Checks

- Hot-side heat loss, Q_hot = ṁ_hot × (h_in − h_out):
- Cold-side heat gain, Q_cold = ṁ_cold × (h_out − h_in):
- Balance difference, (Q_hot − Q_cold) / average(Q_hot, Q_cold):
- Counterflow ΔT1 = T_hot,in − T_cold,out:
- Counterflow ΔT2 = T_hot,out − T_cold,in:
- ΔT_lm = (ΔT1 − ΔT2) / ln(ΔT1 / ΔT2); if equal, use that value:
- UA = Q / ΔT_lm, using a justified heat duty:
- Min approach, flow arrangement correction, and off-design limits:
- Pressure drop and fouling allowance:

Use enthalpy differences for phase change or strongly varying heat capacity. This simple LMTD check assumes known end states and an appropriate flow arrangement; multipass and crossflow designs need a correction or a different method. Define U against the same area basis used for A. Record any ambient heat loss and measurement uncertainty.

Evidence / unresolved questions:  
Decision / next test:  

The Workflow Stack · https://theworkflowstack.com/guides/heat-exchanger-check