New Liquid Cooling Plate Design Enhances Battery Thermal Management
In the rapidly evolving world of electric vehicles (EVs), where performance, safety, and efficiency are paramount, researchers continue to push the boundaries of battery thermal management systems (BTMS). As ambient temperatures rise and consumers demand longer driving ranges and faster charging, the challenge of maintaining optimal battery operating conditions has become increasingly complex. A recent breakthrough in cooling technology, detailed in a study published in Energy Conservation, presents a novel composite liquid cooling plate design that significantly improves thermal regulation in high-temperature environments. Developed by Liu Jiaxin and Wang Changhong from the School of Materials and Energy at Guangdong University of Technology, this innovative solution combines non-uniform flow channels with phase change materials (PCM) to achieve superior heat dissipation while minimizing energy consumption.
The research, featured in the October 2024 issue of Energy Conservation, addresses one of the most pressing issues in modern EV design: how to efficiently manage the heat generated by lithium-ion battery packs during high-rate discharge cycles. Under aggressive usage conditions—such as fast charging, rapid acceleration, or operation in hot climates—batteries can quickly exceed their ideal temperature range of 25–45 °C. Excessive heat not only degrades battery life but also increases the risk of thermal runaway, a dangerous condition that can lead to fires or explosions. Moreover, uneven temperature distribution across the battery module, where differences exceed 5 °C, can cause imbalanced cell aging and reduced overall system efficiency.
Traditional cooling methods have long faced limitations. Active air cooling, while simple and low-cost, struggles to provide sufficient heat removal under high thermal loads. Liquid cooling systems, though more effective, often require high flow rates and powerful pumps, leading to increased parasitic energy losses. Passive systems using phase change materials offer excellent thermal buffering due to their high latent heat capacity, but once the PCM is fully melted, its ability to absorb additional heat diminishes unless the stored thermal energy is actively dissipated. Recognizing these shortcomings, Liu and Wang proposed a hybrid approach that leverages the strengths of both active and passive cooling strategies.
Their solution centers on a newly designed composite liquid cooling plate featuring non-uniform channel geometry. Unlike conventional liquid cold plates that use evenly spaced, uniform-width channels, this new design gradually tapers the channel width from the inlet to the outlet. Specifically, the researchers tested two configurations—one with channels narrowing progressively (designated as Structure A), and another with widening channels (Structure B)—while keeping the total cross-sectional area constant. This architectural innovation was aimed at addressing a common flaw in multi-channel cooling systems: flow maldistribution. In standard parallel-channel layouts, coolant tends to favor paths of least resistance, often resulting in uneven flow and suboptimal heat transfer in certain regions of the plate.
Through extensive numerical simulations using Ansys Fluent 2022R1, the team analyzed the fluid dynamics and thermal performance of each configuration under various operating conditions. The results were striking. At low inlet velocities—specifically below 0.08 m/s—Structure A showed little advantage over uniform-channel designs. However, as flow velocity increased beyond this threshold, the tapered channel design demonstrated a clear superiority in both maximum temperature reduction and temperature uniformity across the battery pack. When the inlet velocity reached 0.16 m/s, the non-uniform channel system managed to keep the temperature difference within the battery module under 5 °C, meeting the critical safety benchmark. In contrast, the traditional uniform-channel design required a higher flow rate of 0.2 m/s to achieve the same level of thermal uniformity.
This improvement is attributed to the enhanced flow distribution achieved by the narrowing channel profile. By increasing flow resistance progressively along the path, the design promotes a more balanced distribution of coolant across all channels, preventing localized hotspots and ensuring consistent heat extraction throughout the module. Importantly, this optimization came with minimal additional pressure drop. At 0.16 m/s, the pressure loss in Structure A was only 5.51 Pa higher than that of the uniform design—a negligible increase considering the significant gains in thermal performance. This means that the pump power required to circulate the coolant remains relatively low, contributing to overall system energy efficiency.
Building upon this structural advancement, the researchers took the concept a step further by integrating phase change material into the cooling plate. The composite design embeds PCM—specifically selected for its phase change temperature range of 38–40 °C and a latent heat capacity of 160,000 J/kg—within the spaces between the cooling channels. This hybrid configuration allows the system to simultaneously benefit from convective heat transfer (via liquid cooling) and latent heat absorption (via PCM phase transition). The combination creates a dual-mode thermal regulation mechanism: during initial operation, the PCM absorbs excess heat as it melts, stabilizing the battery temperature; meanwhile, the flowing coolant continuously removes heat from the system, preventing the PCM from reaching full saturation.
The synergy between these two cooling mechanisms proved particularly effective under low-flow conditions. When the inlet velocity was set to 0.12 m/s, the composite system reduced the battery’s maximum temperature to 41.27 °C and the inter-cell temperature difference to 4.84 °C—improvements of 0.23 °C and 0.17 °C, respectively, compared to a non-PCM baseline using the same Structure A plate. More importantly, the composite design achieved these results without requiring higher pump speeds, thereby reducing parasitic energy consumption. This makes the system especially suitable for urban driving cycles or stop-and-go traffic, where frequent thermal transients occur but sustained high cooling power is unnecessary.
One of the most insightful aspects of the study was the investigation into the impact of inlet coolant temperature on system performance. Intuitively, one might assume that colder coolant would always yield better cooling. However, the researchers found a trade-off between peak temperature control and thermal uniformity. Lower inlet temperatures—such as 30 °C or 31 °C—did indeed reduce the maximum battery temperature, but they also led to larger temperature gradients within the module. This occurs because the coolant absorbs heat progressively as it flows through the channels, becoming warmer toward the outlet. As a result, cells near the inlet experience cooler conditions, while those near the outlet remain relatively hotter, creating a longitudinal temperature imbalance.
Conversely, when the inlet water temperature was raised closer to the initial battery temperature—around 33–34 °C—the thermal gradient across the module decreased significantly. At 34 °C, the temperature difference dropped to 4.97 °C, just under the 5 °C safety threshold, while the maximum temperature was still maintained at a safe 40.48 °C. This finding has important practical implications: instead of expending extra energy to chill the coolant below ambient temperature, vehicle manufacturers can operate the cooling system with coolant pre-warmed to near-battery temperature, achieving both energy savings and improved thermal uniformity.
The choice of 34 °C as the optimal inlet temperature also aligns well with real-world operating conditions. In many climates, especially during summer months, ambient temperatures often exceed 30 °C. Cooling the liquid below this point would require additional refrigeration, increasing the load on the vehicle’s HVAC system and reducing overall efficiency. By operating the BTMS with coolant slightly above ambient, the system avoids unnecessary energy expenditure while still maintaining safe and stable battery temperatures.
From a materials perspective, the use of PCM offers additional benefits beyond thermal regulation. Phase change materials typically have lower density than metals, meaning that replacing portions of the aluminum cooling plate with PCM reduces the overall weight of the thermal management system. In an industry where every kilogram counts toward range and performance, this weight reduction can contribute to improved vehicle efficiency. Furthermore, the selected PCM exhibits shape-stable properties during phase transition, preventing leakage and ensuring long-term reliability even under mechanical vibration and thermal cycling.
The simulation model used in the study was rigorously validated against experimental data. Using a 4C discharge rate at an ambient temperature of 35 °C, the researchers compared simulated surface temperature profiles with real-world measurements obtained via thermocouples connected to an Agilent temperature logger. The close agreement between the two datasets—showing a maximum deviation of only about 1 °C—confirmed the accuracy and reliability of the numerical model. This validation step is crucial for establishing confidence in the simulation results, particularly when proposing new designs for real-world implementation.
The computational domain was carefully constructed to balance accuracy and efficiency. By leveraging the symmetry of the battery module, the team modeled only half of a single cell and its adjacent cooling plate, significantly reducing computational load without sacrificing fidelity. Key assumptions included uniform internal heat generation within the battery, incompressible and steady-state coolant flow, negligible contact resistance between materials, and constant thermophysical properties for the PCM. While these simplifications are common in engineering simulations, they do impose certain limitations. For instance, real-world batteries may exhibit non-uniform heat generation due to internal resistance variations, and PCM properties such as thermal conductivity can vary with temperature. Future work could explore transient phase change behavior and temperature-dependent material properties for even greater realism.
Despite these limitations, the findings of this study offer valuable insights for automotive engineers and battery system designers. The integration of non-uniform channel geometry with PCM represents a significant step forward in the development of energy-efficient, high-performance thermal management solutions. Unlike previous approaches that focused solely on enhancing heat transfer through structural modifications or material selection, this work demonstrates the power of a holistic, systems-level design philosophy.
The implications extend beyond passenger EVs. High-performance applications such as electric buses, commercial trucks, and energy storage systems—where thermal loads are even more intense—could greatly benefit from this technology. In grid-scale battery installations, where thousands of cells must be maintained within a narrow temperature window, the ability to reduce pump power while improving thermal uniformity could translate into substantial operational cost savings over the system’s lifetime.
Moreover, the principles uncovered in this research may inspire further innovations in other areas of thermal engineering. The concept of flow redistribution through geometric design could be applied to heat exchangers in HVAC systems, microchannel coolers in electronics, or even in fuel cell stacks. The successful coupling of active and passive cooling mechanisms also opens new avenues for hybrid thermal management in aerospace, robotics, and portable electronics.
As the global transition to electrified transportation accelerates, advancements like this underscore the importance of continued investment in fundamental research. While much attention is given to battery chemistry and energy density, equally critical are the supporting systems that ensure safe and efficient operation. Thermal management, though often overlooked, plays a foundational role in determining the lifespan, reliability, and safety of every electric vehicle on the road.
The work of Liu Jiaxin and Wang Changhong exemplifies how thoughtful engineering and rigorous simulation can lead to practical, scalable solutions. Their composite liquid cooling plate not only meets current industry standards for thermal performance but does so in a way that prioritizes energy conservation and system efficiency. As automakers strive to meet increasingly stringent emissions regulations and consumer expectations, innovations like this will be essential in shaping the next generation of sustainable mobility.
In conclusion, the study published in Energy Conservation presents a compelling case for rethinking traditional liquid cooling plate design. By combining tapered flow channels with phase change materials and optimizing operating parameters such as inlet velocity and temperature, the researchers have developed a system that achieves excellent thermal control with minimal energy input. When operated at an inlet flow rate of 0.12 m/s and an inlet temperature of 34 °C, the composite cooling plate maintains the battery’s maximum temperature at 40.48 °C and the temperature difference at 4.96 °C—well within safe operating limits. This balance of performance and efficiency marks a significant advancement in battery thermal management technology.
Liu Jiaxin, Wang Changhong, School of Materials and Energy, Guangdong University of Technology, Energy Conservation, doi:10.3969/j.issn.1004-7948.2024.10.001