Selection scope and sizing decision
Useful for: Buyers preparing complete inputs for a refrigeration supplier selection
Cooling capacity changes with evaporating and ambient conditions. A nominal model rating may therefore be unsuitable for direct comparison unless the test conditions match the project.
Oversizing is not a substitute for correct airflow, sealing or operation, while undersizing can lead to long recovery and uncontrolled temperature. The calculation should expose each assumption for review.
Sizing inputs
Supply these values before a model, body size or working rating is selected:
- 01Internal and external body dimensions
- 02Insulation material, thickness and thermal data
- 03Required box and worst ambient temperatures
- 04Cargo mass, starting temperature and pull-down responsibility
- 05Door sizes, openings and route pattern
- 06Airflow, power, defrost and monitoring requirements
From sizing inputs to model approval
Size from the operating requirement, test the complete configuration and retain the project records that control the final selection.
- 01Define the target duty
Truck refrigeration unit sizing
- 02Quantify sizing inputs
Internal and external body dimensions; Insulation material, thickness and thermal data
- 03Test the complete vehicle
Transmission and Infiltration must both pass.
- 04Approve the selected rating
Approved body and operating brief; Supplier heat-load calculation with assumptions
Selection and sizing matrix
Use every row to test the proposed size. A nominal value is not sufficient when payload, geometry or operating limits conflict.
Scroll horizontally to view all columns.
| Decision factor | What to choose or check | Limit or condition |
|---|---|---|
| Transmission | Calculate heat through body surfaces and thermal bridges. | Nominal panel thickness alone is incomplete. |
| Infiltration | Model doors, seals and opening duration. | Urban multi-drop duty can dominate the load. |
| Product load | State starting temperature and any pull-down requirement. | Holding pre-cooled cargo differs from cooling warm cargo. |
| Capacity basis | Compare unit output at project box and ambient conditions. | Headline ratings at different conditions are not comparable. |
Applied calculation
Sum heat-load components at the project condition The unit is compared with a documented total load, not selected from body volume or a headline model rating.
- 01Base design load4.6 kW
2.1 + 1.4 + 0.8 + 0.3 - 02Explained marginSupplier defines and explains
4.6 kW + documented uncertainty or recovery allowance - 03Capacity comparisonMust pass
Unit capacity at project box and ambient conditions ≥ design load
Decision: The example base load is 4.6 kW. It is not a unit selection until the supplier verifies every input, margin and capacity condition.
Evidence boundary: Illustrative heat-load components only. Use controlled thermal data, route conditions and refrigeration manufacturer performance tables.
Selection evidence checklist
Ask for evidence that is traceable to the selected model, configuration, vehicle or project scope. A record from another project is context, not verification.
- Approved body and operating brief
- Supplier heat-load calculation with assumptions
- Capacity data at project conditions
- Installation, commissioning and airflow verification
Selection and sizing traps
Sizing from cubic volume only
Better selection method: Calculate all material heat-load components.
Comparing nominal unit model numbers
Better selection method: Compare capacity at the same box and ambient conditions.
Adding an unexplained safety factor
Better selection method: State the uncertainty or operational reason for the margin.
Limitations
- This page does not perform the final heat-load calculation.
- Thermal properties and unit capacity data must come from controlled supplier documents.
- Do not approve a unit without a matched body, operating brief and capacity basis.
Evidence scope and technical basis
Each source is limited to what it can support. This makes the evidence chain readable to buyers, search engines and AI systems without turning a general source into a project claim.
Supports: Controls the project-input, quotation, approval and inspection workflow described in this guide.
Does not establish: It does not replace the signed quotation, approved specification, selected OEM documents or unit-linked project records.
Supports: Provides public checklists and worksheets; the signed project documents remain controlling.
Does not establish: It does not replace the signed quotation, approved specification, selected OEM documents or unit-linked project records.
Supports: Defines the relevant product family and published configuration boundaries. Project-specific ratings require the selected OEM documents.
Does not establish: It does not replace the signed quotation, approved specification, selected OEM documents or unit-linked project records.
Supports: Primary public guidance supporting preconditioning, airflow, door-seal and loading checks. Cargo-owner and destination requirements remain controlling.
Does not establish: It is authority, jurisdiction or subject specific and does not approve the selected vehicle for another destination or project.