A Dive into Erythritol Slurry and Its Potential for Waste Heat Recovery
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Scientists study the effect of density difference on the rheological behavior of erythritol slurry
Energy efficiency is crucial for sustainability, yet vast amounts of low-temperature waste heat remain unused in industrial processes. Now, researchers from Japan have investigated erythritol slurry as a promising heat transfer medium for thermal storage and transport. By analyzing its flow behavior and non-Newtonian properties, they developed a predictive equation for its rheological characteristics. Their findings could help guide the design of industrial waste heat recovery systems, advancing energy efficiency and carbon neutrality.
Image title: Grayscale map of the average power-law index with particle Reynolds number and solid fraction
Image caption: This image depicts the relationship between these three important properties, which together determine the rheological behavior of erythritol slurry. Understanding the correlation between them could lead to more efficient waste heat transport and storage systems, contributing to more efficient industrial processes.
Image credit: Shunsuke Abe of Shinshu University
License type: CC-BY 4.0
Image link: https://www.sciencedirect.com/science/article/pii/S0894177725000238?via%3Dihub
Usage restrictions: Credit must be given to the creator.
Energy efficiency is one of the most important pillars of our global sustainability goals. Simply put, one of the most straightforward and effective ways of minimizing carbon emissions is making the most out of every unit of energy produced and consumed. One severely underutilized resource is factory waste heat, especially in the low-temperature range(<230℃).
Many researchers around the world are exploring ways of making use of such waste heat as thermal energy, either by directly repurposing it in industrial operations or converting it into other useful forms, such as residential heating. Of course, the first step would be to get this waste heat where it needs to be, which requires a latent heat storage and transport system. Over the past few decades, interest in using phase change material (PCM) slurries for this purpose has steadily increased. PCM materials exchange a lot of heat when they undergo a phase transition, making them promising for managing waste heat.
Against this backdrop, a research team led by Project Assistant Professor Shunsuke Abe from Shinshu University, Japan, has focused on erythritol slurry as a promising heat transfer medium. In their latest study, which was published online in Experimental Thermal and Fluid Science on February 06, 2025, they investigated the rheological properties of this sugar alcohol-based mixture, hoping to gain new insights and pave the way to more efficient thermal storage and transport. The study was co-authored by Mr. Hikaru Ebihara, a graduate student, and Associate Professor Tatsunori Asaoka, both from Shinshu University.
More specifically, the researchers sought to analyze how density differences between the dispersed erythritol particles and carrier fluid (erythritol aqueous solution) influenced the slurry’s flow pattern, and rheological behavior. To achieve this, they conducted a series of experiments under laminar flow conditions in a horizontal circular tube, systematically measuring pressure drop and flow rate while adjusting the solid fraction and the density difference between dispersed erythritol particles and the carrier fluid (erythritol aqueous solution).
Worth noting, erythritol slurry exhibits non-Newtonian behavior, meaning its viscosity changes depending on flow conditions. The team observed that, at higher solid fractions and lower carrier concentrations, the non-Newtonian characteristics of the slurry became more pronounced, exhibiting a greater decrease in viscosity the higher the flow rate. On the other hand, at lower solid fractions, carrier concentration had little effect on this property.
To better characterize this behavior, the researchers analyzed the slurry’s particle Reynolds number, a value that describes how solid particles interact with the surrounding fluid based on slurry velocity, density difference, carrier fluid viscosity, and particle size. Their results indicated that the particle Reynolds number, along with solid fraction, plays a key role in predicting non-Newtonian effects. This allowed them to develop a correlation between these parameters and the power-law index, which quantifies the degree of non-Newtonian behavior. “This finding provides a new approach for predicting the transport properties of this and other PCM slurries, which would be essential in the design of energy-efficient thermal transport systems,” notes Dr. Abe.
The implications of this study are many, as understanding the rheological properties of PCM slurries could lead to various sustainability-oriented applications. One example is waste heat recovery in factories and power plants, where erythritol slurry can be used to capture and efficiently transport unused low- to medium-temperature waste heat. This addresses a significant energy loss point in manufacturing and power generation.
Hot water supply and HVAC systems in residential and commercial buildings represent another promising area of application. “Thermal storage systems utilizing PCM slurries can store heat during off-peak hours and release it when needed, effectively balancing energy loads, improving efficiency, and reducing peak power demand—a critical factor in grid stability,” explains Dr. Abe.
Additionally, PCM slurries could be used in cogeneration systems, also known as combined heat and power (CHP). These systems generate both electricity and useful heat from a single energy source, significantly improving efficiency compared to conventional power generation methods. By integrating PCM slurries, these systems would be able to store excess heat and release it when needed, optimizing waste heat utilization, and making cogeneration a more cost-effective solution.
Through insight and innovation, this study will serve as a stepping stone towards a carbon-neutral future, one where we make the most out of available energy in its many forms.
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Title of original paper: |
Effect of carrier concentration on rheological behavior of high density PCM slurry |
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Experimental Thermal and Fluid Science |
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