Why is thermal management important in defense vehicles?
Thermal management is critically important in defense vehicles because heat generated by propulsion systems, power electronics, communication equipment, and onboard computing may need to be controlled to keep equipment within its specified operating conditions and support crew operational effectiveness. In military environments, thermal management systems may be required to operate reliably under demanding conditions where system availability is critical. The sections below address the most common technical questions around why temperature control in military vehicles can require different engineering considerations from conventional commercial applications.
What happens when thermal management fails in a defense vehicle?
When thermal management fails in a defense vehicle, the consequences can extend beyond equipment damage. Electronics may overheat, derate, or shut down, while excessive cabin temperatures can place additional thermal strain on the crew. Depending on the affected system and mission, these effects can reduce operational capability.
Defense applications can place particularly high demands on system availability across the vehicle’s defined operating environment, which may extend from arctic cold to temperatures above 50 degrees Celsius. Reliability, fault tolerance, and, where required by the vehicle architecture, redundancy therefore need to be considered according to the project’s operational requirements. Cooling system failures can also affect multiple functions where systems share power or thermal-management resources.
Which systems inside a defense vehicle generate the most heat?
Heat-generating systems in a defense vehicle can include the propulsion drivetrain, power electronics, communication and radar equipment, onboard computing infrastructure, and, in electrified platforms, the battery and motor inverter systems. Their thermal loads vary significantly depending on the vehicle architecture, equipment configuration, and operating profile, and may require separate or coordinated thermal management solutions.
Modern armored vehicles can carry substantial electronic payloads. Situational awareness systems, encrypted communications, electronic warfare modules, and sensor arrays can contribute to the vehicle’s overall thermal load. In electrified military vehicles, the battery thermal management system adds another layer of complexity, as lithium-ion cells must be kept within temperature limits defined by the battery design, chemistry, operating conditions, and manufacturer requirements. The combination of crew, electronics, propulsion, and other thermal loads must therefore be considered when sizing HVAC and other thermal management systems.
How does thermal management differ in military vehicles versus commercial ones?
Thermal management in military vehicles can differ from conventional commercial applications in operating conditions, environmental and mechanical requirements, integration constraints, and required system availability. Military vehicles may need to operate across wide climatic and terrain conditions and according to program-specific requirements.
Military thermal management systems may be subject to defense requirements covering vibration, electromagnetic compatibility, shock, climatic conditions, and other environmental factors. Vehicles requiring collective protection may also integrate CBRN filtration with the air-management system. Space constraints inside armored hulls can be severe, meaning every component must be precisely sized and positioned. Materials and components must be selected according to the expected exposure to factors such as dust, moisture, corrosion, vibration, and temperature. Depending on the application, an existing product may be used directly, an established product platform can be adapted, or a fully customized system may be required.
How does temperature affect electronics and crew performance in combat conditions?
Temperature can affect both electronics reliability and human performance. Electronic components have specified operating temperature ranges, and operation outside these limits can lead to derating, reduced reliability, protective shutdowns, or component damage. Significant thermal stress can also affect crew physical and cognitive performance, although the severity depends on factors such as temperature, exposure duration, workload, hydration, acclimatization, and the task being performed.
On the electronics side, processors, power modules, and communication hardware all have defined thermal operating limits and protection strategies. Excessive temperatures can therefore affect the performance or availability of temperature-sensitive equipment. For the crew, research in occupational physiology shows that sufficiently severe heat stress can negatively affect performance, with the magnitude of the effect depending strongly on the type of task and exposure conditions. Effective cabin climate control is therefore an important contributor to crew conditions and operational effectiveness in demanding environments.
What are CBRN filtration systems and why are they part of vehicle thermal management?
CBRN filtration systems are collective protection systems designed to reduce exposure to specified airborne chemical, biological, and radiological contaminants. Where collective CBRN protection is required, filtration and HVAC need to be coordinated as part of the vehicle’s overall air-management architecture.
In an overpressure-based protection system, filtered outside air is supplied to the protected compartment to maintain a specified positive pressure. This helps reduce the ingress of untreated outside air through uncontrolled leakage paths while the protected space and system are operating as intended. The filtration process introduces airflow resistance that the ventilation system must account for, and incoming filtered air may also require thermal conditioning. The exact relationship between the CBRN filtration, HVAC, ventilation, controls, and pressure-management functions depends on the vehicle’s protection concept and project requirements.
How is thermal management designed for electrified military vehicles?
Thermal management for electrified military vehicles may need to address several thermal loads, including batteries, power electronics, electric motors, and the crew cabin. These functions may use separate or partially integrated thermal circuits depending on the vehicle architecture.
Battery thermal management systems for military applications must be designed according to the battery system’s specified operating temperature range, mission profile, ambient conditions, and charging requirements. These requirements are not necessarily the same for every battery chemistry or vehicle application. In cold conditions, battery heating or pre-conditioning may be required to achieve the required charging or power performance. In hot conditions, sufficient heat removal is needed to keep the battery within its specified operating limits. Battery safety, including management of thermal runaway risk, depends on the design of the complete battery system and cannot be ensured by the cooling system alone. Power electronics may also require dedicated thermal management, such as liquid cooling, depending on their heat loads and system architecture.
Lumikko has developed battery thermal management systems for demanding mobile machinery, including work with Sandvik on battery cooling and heating for mining machines. This experience addresses several thermal-management challenges that can also be relevant in other demanding mobile applications, such as wide ambient temperature ranges, high thermal loads, vibration, and constrained installation space. Lumikko’s Sandvik case describes significant battery and power-electronics heat loads particularly during charging and high-load operation. Find the right solution for you among Lumikko’s defense and electrification product range, engineered and manufactured at the Seinäjoki factory in Finland.
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