Mobile Machinery and Thermal Management: What Challenges Does the Design Involve?

1. Refrigerant Choices Redefine the Design Foundation

The tightening EU F-gas Regulation and the expanding PFAS restrictions under REACH are permanently reshaping the refrigerant landscape. HFC and HFO solutions are no longer viable long-term strategies.

Natural refrigerants such as propane (R290), carbon dioxide (R744), and ammonia (R717) are becoming increasingly central — including in battery thermal management for mobile machinery. In addition, R1234yf (tetrafluoropropene) has a low GWP value, similar to natural refrigerants.

However, each comes with specific design implications:

• CO₂ (R744) involves high operating pressures and requires structural dimensioning accordingly.
• Propane (R290) demands fire safety considerations already at the layout design stage.
• Ammonia (R717) requires industrial-grade leak detection and safety systems.
• R1234yf may be subject to restrictions depending on how the upcoming PFAS regulation is interpreted.

Refrigerant selection affects the entire machine architecture — not just the cooling unit. For this reason, thermal management must be integrated into overall machine design from the beginning, not treated as a standalone component.

Read our article on natural refrigerants

2. Placement and Space Constraints

Space inside mobile machinery is limited and weight matters.

From a thermal management perspective, the following must be considered:

• Battery capacity
• Structural constraints
• Serviceability
• Airflow
• Load and charging cycles
• Ambient temperature
• Target battery temperature range

Too often, the cooling system is forced into an already finalized machine layout. This can result in compromises in airflow, serviceability, and performance.

A distributed architecture is often an effective solution. Components such as compressors, heat exchangers, pumps, and control units are positioned throughout the machine. This approach:

• Optimizes space utilization
• Eliminates the need to charge the refrigerant circuit during machine assembly.
• Enables customer-specific design.
• Improves weight distribution
• Enhances protection against impacts and dust
• Simplifies maintenance

3. Operating Voltages and Heat Generation

The transition from internal combustion engines to fully electric machinery also increases operating voltage levels. Where conventional vehicles operated at 12V or 24V, fully electric machines now operate at 400–900 VDC.

Heat must be managed across multiple systems:

• Battery
• Power Electronics
• Electric motor
• Fast charging system
• Cabin

In high-voltage systems, the challenge is often “a large amount of heat in a short time,” whereas in low-voltage systems it was more about “continuous excess heat.”

4. Managing Thermal Loads Throughout the Product Lifecycle

As batteries age:

• Heat generation increases
• Tolerance to high temperatures decreases
• Response to charging loads changes
• Capacity declines
• Charging capability and speed decrease

Battery cooling requirements evolve over time. If thermal management is designed solely for a new battery, the system may be undersized within a few years.

Design must therefore account for:

• Capacity margins — cooling must be dimensioned for aged battery performance
• Adaptive control systems
• Changes in usage patterns
• Correct dimensioning of the refrigeration system and avoiding oversizing are essential. Peak loads can be managed through system design features other than simply increasing nominal capacity.

Lifecycle thinking is an essential part of responsible machine design.

5. Environmental Conditions

Mobile machinery operates in demanding environments:

• -40 °C winter conditions
• +45 °C summer heat
• Dusty mining environments
• Saltwater exposure in ports
• Continuous vibration and mechanical stress
• Humid conditions

Thermal management systems must withstand:

• Corrosion
• Mechanical impacts
• Dust and contamination
• Large temperature fluctuations
• Continuous vibration

Environmental durability is a fundamental starting point in thermal management system design.