Overcoming the Limitations of Current Cooling Technology in the Energy Market
Futuristic energy conversion technologies are limited by the parasitic energy losses from their outdated thermal management solutions, like single phase liquid cooling. The demand for highly efficient conversion technologies requires more effective cooling technology in the energy market.
Typical renewable technology – such as solar, wind, and hydro power – require thermal management with each conversion step AND within the energy storage device itself. Non-renewable technologies – such as oil and natural gas – require thermal management in large variable frequency drive devices. And clean technologies – such as micro-nuclear reactors, require effective heat transfer mechanisms to harvest the energy from the reactor core in a safe manner.
Advanced Cooling Technologies (ACT) has been working to support the growing need for effective energy conversion solutions by developing innovative passive, active, and sub-ambient hybrid cooling technologies that work within each of these unique applications.
Two-Phase Technology for Energy Applications
Passive two-phase technologies, like heat pipes and loop thermosyphons are ideal heat transfer mechanisms that work to pull heat from hot components. The technology utilizes the latent heat of vaporization which is the thermal energy required to convert a liquid to its vapor. The latent heat of vaporization is significantly higher than the specific heat of a molecule – which is the amount of thermal energy required to increase the temperature one-degree Celsius. By leveraging the latent heat of vaporization, the passive two-phase technique removes large amounts of thermal energy with less fluid than typical single-phase solutions. A heat pipe essentially becomes a super conductor of heat (but remember, it is not conduction, it is the latent heat of vaporization).
By encapsulating the working fluid inside a sealed environment and pulling vacuum, the fluid exists in both the liquid and vapor phase, and able to provide highly efficient heat transfer from its freeze point to its critical point (or whenever the envelope cannot contain the pressure). By adjusting the fluid, you can leverage the passive two-phase technology for a wide range of temperatures and applications, below are select examples related to the industry:
- Electronics Cooling: Water (Best for high heat flux and adverse gravity orientations)
- Power Electronics: Refrigerants (di-electric, loop thermosyphon/thermosyphon applications)
- Microreactors: Liquid Metal (High temperature capability > 500 C)
Pumped Two-Phase (P2P) technology, while like single-phase in system components, is designed to meet the heat generating component at a fluid’s saturation level. The technology leverages the same latent heat of vaporization as the passive heat pipe with the addition of a pump. As the fluid interacts with the component at saturation the working fluid vaporizes and removes the unwanted heat at a desired set point. During vaporization the fluid does not rise in temperature thus creating isothermality across the evaporator.
The pump drives the vapor and fluid flow, allowing the technology to operate in any orientation, but the pump does not drive heat removal. The pump is therefore relatively small as it only has to create a directional flow, when compared to single phase solutions. In some cases, the size and power consumption of the pump can be reduced by 85%. The pump driven two-phase technology is designed with dielectric or ‘waterless’ fluids that offer high latent heat capacity. This means that the system can remove heat directly from the hot component without the fear of leak damage. The system to component level engineering with this technology can significantly optimize the design:
- Cold Plates (Evaporators): Flow paths and channel sizing can enhance heat flux capabilities and lower thermal resistance.
- Manifolding: In many cases, parallel flow cold plates can allow for modular design and provide isothermality and common performance across many components nearby and/or physically separated in the system.
- Balance of Plant: Proper sizing and packaging of pump(s), accumulator, condenser(s), etc. play a large role in meeting project size and/or environmental constraints
- Controls: Enabling smart control systems to monitor system performance and adjust flow for various ambient and/or heat load conditions can enhance performance and limit energy consumption.
Hybrid Thermal Management Technology
Passive and active two-phase systems offer high efficiency above ambient cooling, meaning the components will always operate at some temperature above ambient air. However, in some energy applications it is critical for the thermal management solution to provide sub-ambient levels. System integrators typically turn to inefficient COTS vapor compression systems in these cases, dramatically increasing energy consumption required for the thermal management system. For this reason, ACT has developed an innovative hybrid technology that combines P2P cooling with vapor compression: the Vaphtek™ ECU. By engineering the two technologies together, the user can operate the cooling system with a compressor when the ambient temperature is high and P2P when the ambient temperature is low. For applications in the energy industry reducing the unnecessary energy consumption of the compressor is critical for an efficient solution.
The demand for efficient energy conversion technologies is driving the need for advanced thermal management solutions. As both renewable and non-renewable energy systems evolve, the limitations of current cooling technologies become increasingly apparent. Advanced Cooling Technologies (ACT) has responded to this challenge by developing innovative solutions such as passive and Pumped Two-Phase (P2P) systems, as well as hybrid technologies that combine P2P with Vapor Compression Systems. These advancements not only enhance the thermal management capabilities of various energy applications but also reduce energy consumption, paving the way for a more sustainable and efficient energy future.