A team of researchers from Nagoya University in Japan has achieved a remarkable breakthrough by developing a loop heat pipe (LHP) with the ability to transport up to 10 kW of heat without any reliance on electricity. This extraordinary heat transport capability represents the largest in the world.
The team’s innovative LHP is poised to revolutionize energy efficiency and play a pivotal role in achieving carbon neutrality across various sectors, including industrial waste heat recovery, solar heat utilization, electric vehicle (EV) thermal management, and data center cooling. The groundbreaking findings have been published in the prestigious International Journal of Heat and Mass Transfer.
This exceptional LHP has surpassed the performance of its predecessors through significant enhancements in the evaporator structure. These advancements have resulted in an 18% reduction in size, a remarkable 1.6 times increase in heat transport capability, and a fourfold improvement in heat transfer efficiency compared to the previous LHP developed by Nagoya University.
LHPs have already found applications in manned space flights, electric vehicles, meteorological satellites, and home electronic appliances, and this latest advancement promises to elevate their impact even further.
“This LHP is unprecedented in transporting such a large amount of heat without electricity, achieving the world’s largest non-electric heat transport,” said Professor Hosei Nagano, a senior researcher involved in the project. “This eliminates the need for the electricity previously consumed by conventional mechanical pumps, allowing for near-perpetual heat transport without electricity.”
The increasing demand for energy-efficient cooling methods in the EV industry is driving companies to seek innovative solutions to minimize their carbon footprint. One such solution is the adoption of Loop Heat Pipes (LHPs), which not only provide effective cooling for EVs but also reduce their reliance on electrical power.
“For electric vehicles, maintaining the inverter temperature is crucial for optimal performance,” explained Shawn Somers-Neal, a graduate student involved in the project. “Traditional cooling methods for inverters require energy, but our LHP maintains temperature without electricity. This leads to an increase in efficiency while being able to handle the high heat loads required in industry.”
In an LHP, a working fluid and a porous wick work in tandem to efficiently transport heat over long distances. By utilizing capillary action, the wick draws the working fluid to the surface, allowing it to absorb heat and transform into vapor when applied to the evaporator. The vapor then moves to the condenser, where it releases heat and condenses back into liquid, completing the cooling cycle.
To optimize the performance of LHPs, a group focused on enhancing the wick section by making it thinner, longer, and wider while preserving its high-quality porous properties. They also improved heat transport capabilities by narrowing the escape channels for vapor from the evaporator and adding extra channels on the sides, effectively increasing the total number of channels. This innovation promises to elevate the efficiency and environmental sustainability of cooling systems in the EV industry.
“The uniqueness of the loop heat pipe (LHP) is the shape, quality, and size of the wick and the overall performance of the LHP. Usually, when making larger wicks, the quality decreases, but the quality of this wick is similar to that of smaller wicks,” explains Professor Nagano. “The wick has cores that help reduce the thickness, leading to less pressure drop and lower operating temperatures.”
The recently developed LHP has shown an extraordinary heat transfer efficiency, surpassing existing LHPs by more than four times during testing. Its innovative design enabled it to transport waste heat over a distance of 2.5 meters without power, using the capillary force generated by the wick. This achievement marks a significant breakthrough in non-power heat transport.
“This pioneering LHP technology is expected to revolutionize energy conservation and carbon neutrality across multiple fields, including factory waste heat recovery, solar heat utilization, electric vehicle heat management, and data center cooling,” Somers-Neal said. “The effective saving of factory waste heat marks a significant step towards sustainable energy solutions.”
Journal reference:
- Shawn Somers-Neal, Tatsuki Tomita, Noriyuki Watanabe, Ai Ueno, Hosei Nagano. Experimental investigation of a 10 kW-class flat-type loop heat pipe for waste heat recovery. International Journal of Heat and Mass Transfer, 2024; DOI: 10.1016/j.ijheatmasstransfer.2024.125865