Jan Mary Baloyo is a PhD student in the University’s School of Engineering:
“My PhD project is funded by the Centre for Global Eco-innovation and Versarien Plc. It aims to develop the Lost Carbonate Sintering (LCS) process for manufacturing porous metals with novel structures for optimum heat exchange performance.
The LCS process was invented in the University of Liverpool by Dr. Yuyuan Zhao in 2004, and is used to produce porous metals with customisable structural properties.
One big problem encountered in the advancement of technologies is that they use more energy and hence generate a lot of heat in a small area or volume. With the application of Moore’s law in the electronics industry, even smaller yet more powerful devices are sought after.
This results in systems overheating or reduction in the system’s efficiency. As a consequence, the demand for effective cooling techniques for thermal management (i.e. more efficient heat exchangers) has increased dramatically over the recent years.
Porous metals like that produced by the Lost Carbonate Sintering (LCS) process are effective thermal management solutions due to their high surface area, superior thermodynamic characteristics and good mechanical properties. LCS porous metals have the ability to transport large amount of heat over a small volume, which makes them the ideal materials for heat transfer.
Prior to my project, the research on LCS porous metals had been mainly focused on their mechanical properties. Although some exploratory work was done on the thermal properties of LCS porous metals, it was confined to homogeneous porous structures. The uniqueness of my project lies in the development of complex porous metal structures to achieve maximum heat exchange performance.
The two areas my project focuses on are the fluid permeability and heat transfer of the LCS porous metals. To maximise their heat exchange performance for use in thermal management applications, we aim to develop LCS porous metals with exceptionally high heat transfer rate allied with high fluid permeability. The high permeability of the LCS porous metals mean that less power is required to pump a cooling fluid through the LCS porous metal; hence less energy (electricity) is used. However, permeability is often sacrificed to maintain a good thermal conductivity. My project hypothesises that by changing the structure of the porous metal, both high heat transfer rate and high permeability can be achieved.
Several structures of LCS porous metals have been studied so far in my project, and the experimental results are very promising. For homogeneous LCS structures, optimum heat transfer performance was observed at 60% sample porosity. At this optimum point, heat transfer by conduction and convection is maximised. Different trends in heat transfer performance were observed in samples with novel, hybrid structures.
The results have shown that the sample orientation and the distribution of porosity within the sample greatly affect the heat transfer performance. A three-fold increase in the heat transfer performance was observed when open channels were introduced within the LCS porous structure, in comparison to its homogeneous counterpart. A five-fold increase in heat transfer performance was achieved by having a bilayer structure. These results not only prove the hypothesis, but also verify the flexibility of the LCS process in producing customisable porous metal structures.
LCS porous metals have proven to be an eco-innovative solution. Porous metals produced by the LCS process contain 60% less material content than competing thermal management technologies. They can be re-used and recycled. Additionally, LCS porous metals have potentials in waste-heat recovery applications, which can reduce energy consumption.
My research project has opened a lot of opportunities for me. With the project being industry-led, I had a chance to work with Versarien Plc (company commercialising LCS porous metals) and gain industrial experience, which many PhDs do not have. Also, with the additional supervision of the CGE, I was able to view my project in a new light. I have learnt that nowadays, producing innovative products is not enough. The environmental impacts of these products have to also be carefully thought through.
The next step for my project is to understand the structure-thermal property relationship. This involves modelling the fluid permeability and heat transfer as a function of the structural parameters of the LCS porous metals.
I must say that the time I spent on my project has gone very quickly and I wish that I have more time to do more research. Now that I have fully realised the potentials of the LCS process, I foresee more industrial applications for it.”