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Sunday, February 9, 2025

Boosting Thermal Conductivity with Nanofluids as New Working Fluids, and Turbulators: New Research


     Heat exchange is a key function in many processes and industries that use heating and cooling. Optimizing the efficiency of heat exchange is a key goal in many processes. Better thermal conductivity increases heat transfer efficiency, resulting in lower costs and lower energy use.

     Nanofluids, or nanoparticles, are composed of nano-sized particles. Turbulators are usually made of stainless steel and are made up of small metal baffles or coiled wire. There are many different kinds of turbulators suited for different applications. The combination of nanofluids and turbulators has the potential to increase thermal conductivity significantly, which could make thermal energy storage and discharge more efficient. More broadly, better thermal conductivity can significantly improve electric heating and cooling, saving money and emissions by lowering energy use. The use of novel working fluids can also lead to efficiency increases. Heat exchange efficiency can also be improved for solar collection applications.

     A collaboration of researchers from the UAE, the UK, Saudi Arabia, Greece, and Malaysia set out to define the challenges and opportunities for the emerging methods of optimizing heat exchange via new working nanofluids and turbulators. Their work was explained in a 2025 article in the journal Applied Thermal Engineering. While the researchers are optimistic about the future implications there are still problems to be solved before the commercialization of the technique, explaining that it:

“…requires careful consideration of potential drawbacks, such as increased nanoparticle deposition, which may reduce system efficiency. This holistic approach considers economic, environmental, and social factors, ensuring compliance with global sustainability benchmarks and contributing to energy system sustainability research."







They note the opportunities and challenges:

"The future energy systems are going to be designed based on the principles of efficiency and the usage of new materials. Some of the major challenges in research involve developing new materials and combinations to achieve cost reductions and enhancement of heat transfer using turbulators and special fluids.”

They note that in addition to basic heating and cooling this research can be beneficial in automotive and aerospace engineering, where the control of heat, or thermal management, is very important. Design considerations are very important to success.

"Moreover, applying heat transfer enhancement techniques can lead to a higher pressure drop in the flow, which increases the unit's operational cost, especially in the cases with turbulators. However, the proper design of the enhanced units can minimize the increase in the pumping work demand, and finally, the overall designs can effectively enhance the global system performance."

They explain that the research needs to be tested, presumably in pilots, to get to the development stage, from lab to field, from theory to practice. They note the potential for improvement in aeronautical and automotive heating and cooling, which can improve fuel economy. The tech can also be used in heat pumps and refrigeration. They indicate that there is great potential in the agri-food industry.

    

 

Turbulators

     An August 2022 paper in Sustainable Energy Technologies and Assessments compared different types of turbulators in heat transfer efficiency. They found that roughness geometry on the heat transfer surface of the collector plate is a very good way to improve the heat transport rate through a solar air heater duct.

Roughness elements like multi v-fashion ribs with gaps, multi arc-fashion ribs with gaps, discrete multiple arc-fashion ribs, and conical ring turbulator with jet-impingement are found to have maximum heat transfer ratio compared to the base model in the respective parametric range. A mathematical model with 90% porous serpentine-wavy wire mesh on a collector plate was found to have thermal efficiency and an effective efficiency of 80% and 74%, respectively. The three-sided ribbed SAHD is far superior (40–48% increase in efficiency) to that of single-sided SAHD. Maximum effective efficiency of 80.12% was observed for a parallel-pass double duct with inclined ribs.”

     Turbulators promote turbulence or turbulent flow of fluids that pass within them. Heat transfer enhancement techniques include active and passive methods. Turbulators are a passive method that involves modifying the heat transfer surface of the system. They increase turbulent flow via the creation of eddies and vortices. Different types of turbulators, or turbulence promoter configurations are shown below.







Source: Turbulence Promoters for Heat Transfer Enhancement. Jorge C Melo Gonzalez and Martin Picon Nunez. Progress in Petrochemical Science. March 27, 2018. Petrochemical Industry in India: Determinants, Challenges and Opportunities

 

     The paper in Applied Thermal Engineering explored the scientific literature regarding turbulator and heat transfer optimization, looking at different turbulator designs. They noted the issues with pressure drops mentioned above, explaining that there can be tradeoffs between

“…enhancement in thermal performance and operational challenges related to increased pressure drops, where more energy has to be put into a system in order to overcome such pressure drops.”

 

Nanofluids

    According to the paper in Applied Thermal Engineering:

The nanofluids are novel working fluids with improved thermal properties that are used in energy applications to increase the thermal conductivity in the flow and lead to higher heat transfer rates.”

The authors summarize the different research results showing efficiency improvements from using different nanofluids. One was a “photovoltaic-driven nanofluid-assisted thermoelectric air conditioning unit.” They also note some as-of-yet unresolved challenges:

Research on nanofluids in various energy systems, such as PV-NTEAC, has shown promising energy savings and improvements in various varied performance metrics. However, long-term stability analysis, environmental impact, and nanofluid lifecycle costs remain unconsidered.”

 

Nanofluids and Turbulators in Combination and Future Research, Including Machine Learning and AI-enhanced Research

     Regarding the combination of turbulators and nanofluids used in combination, the researchers cited recent research:

Combining nanofluids with turbulators can lead to a global optimal design because two different thermal enhancement techniques are applied in parallel. Aissa et al. [30] used nanofluids and turbulators to improve solar thermal collectors. The researchers found that combining these two strategies boosts solar collector thermal efficiency. However, further research requires further research on nanofluid stability with turbulators, greater pumping power, and long-term operating concerns. The review stresses the need for more experiments to determine the efficacy and viability of this integrated method in solar energy applications.”

     TechXplore notes that they emphasize the potential for machine learning and AI to optimize the combined use of new working nanofluids and turbulators.

They also urge scientists to introduce machine learning in their research to optimize their technologies and devices using nanofluids and turbulators. This approach "leverages AI and machine learning to tune a system to the most optimal configuration for business. It greatly reduces experimentation and accelerates the dissemination of technologies."

     Phase change materials (PCM) and their nanoparticle combinations look promising in future thermal applications. The paper authors reviewed many other studies including one that utilized deep learning for thermal system management.

     As noted, they see AI and machine learning as key to optimizing heat transfer efficiency. They note the power of AI to save time on experimental setup and to decrease computational costs while designing and simulating energy systems. They also emphasize the importance of considering long-term stability in these nanofluid-turbulator combinations. The authors propose the following use cases:

•  Improved aeronautical and automotive cooling systems: Nanofluids can be used to enhance the heat transfer inside car cooling systems. This will provide improved performance and better fuel economy for automobiles. Specific case studies can be done on this.

•  Industrial heat exchangers: These turbulators can be applied in pilot projects to determine their energy consumption in such industries; the pilot projects should focus on chemical processing and on HVAC systems in large commercial buildings.

•  Renewable systems shall research new and imaginative materials to be utilized as heat transfer fluids in solar thermal collectors and systems to extract heat from geothermal sources. These systems could have some real-world applications. The efficiency gains can be tested with prototypes or pilot installations to determine if problems arise in these solutions when scaled up to larger sizes.

•  Machine Learning for Optimization: It leverages AI and machine learning to tune a system to the most optimal configuration for business. It greatly reduces experimentation and accelerates the dissemination of technologies.

    

References:

 

Nanofluids and turbulators have potential to boost renewable energy and slash dependence on fossil fuels. Science X staff. TechXplore. January 6, 2025. Nanofluids and turbulators have potential to boost renewable energy and slash dependence on fossil fuels

Nanofluids, turbulators, and novel working fluids for heat transfer processes and energy applications: Current status and prospective. Zafar Said, Evangelos Bellos, Hafiz Muhammad Ali, Saidur Rahman, and Christos Tzivanidis. Applied Thermal Engineering. Volume 258, Part A, 1 January 2025, 124478. Nanofluids, turbulators, and novel working fluids for heat transfer processes and energy applications: Current status and prospective - ScienceDirect

Implementation of hybrid rib-turbulators on the thermal performance of solar air heater duct: A collective review. Mahanand, Yadaba ; Senapati, Jnana Ranjan. Sustainable Energy Technologies and Assessments, Volume 52, id.102345. August 2022. Implementation of hybrid rib-turbulators on the thermal performance of solar air heater duct: A collective review - Astrophysics Data System

Turbulence Promoters for Heat Transfer Enhancement. Jorge C Melo Gonzalez and Martin Picon Nunez. Progress in Petrochemical Science. March 27, 2018. Petrochemical Industry in India: Determinants, Challenges and Opportunities

 

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