Dr. Reza Azizian, a research scientist at ATS and an expert on nanofluids, will speak about nanofluid technology as part of a PSMA webinar on Thursday, Oct. 6. (Josh Perry/Advanced Thermal Solutions, Inc.)
On Thursday, Oct. 6, Dr. Reza Azizian, a research scientist at Advanced Thermal Solutions, Inc. (ATS), a leading-edge engineering and manufacturing company focused on the thermal management of electronics, and an expert on nanofluid technology, nano-engineered surfaces, fluid dynamics, heat transfer and two-phase flow, will present “Nanofluids for Electric Cooling” as part of a webinar sponsored by the Power Sources Manufacturers Association (PSMA).
Dr. Azizian will join a panel of experts to discuss the enhanced heat transfer properties of nanofluids and their potential for the thermal management of compact, liquid-cooled electronics. Dr. Azizian will present an overview of the current stage of nanofluids technology, state-of-the-art research into nanofluid thermos-physical properties, convective heat transfer, and boiling heat transfer.
Prior to the webinar, Dr. Azizian sat down with the Josh Perry, Marketing Communications Specialist at ATS, to speak about his career, his interest in nanofluids technology, and the upcoming webinar.
JP: Thank you for sitting down with us. We want to highlight the work that the engineers are doing here at ATS, so I appreciate you taking a few minutes out of your schedule for this Q&A. I saw on your bio that you got your doctorate in Australia, is that where you’re from?
RA: Thanks for having me! No, originally I am from Iran and I did my undergraduate there; then I moved to Turkey and did my Master’s in Turkey. After that I moved to Australia and I did my Ph.D. in Australia. And then I ended up in Boston and did my post-doc at MIT.
JP: How did you end up at MIT?
RA: There is a very famous professor at MIT who was working on heat transfer in nanofluids back then. I invited him to Australia. He came and visited our facility in Australia and gave a talk and then he became interested in my research. Then he invited me over and during my Ph.D. I came to MIT as a visiting student and I was here for a year and then I went back to finish my Ph.D. and came back as a post-doc.
JP: How did you end up joining the team at ATS?
RA: It was four years ago as a visiting student. I have a very good friend in Australia and I was always interested in high technology, heat transfer, electronic cooling, and then he sent me the link to the ATS website and said, ‘Hey Reza, while you’re in Boston, you might want to visit this company.’ I thought, wow this is cool. I went through the website to see what ATS does and saw some fascinating projects done by ATS. So, I emailed Dr. Kaveh Azar and he responded to one of my emails and then that’s how we got in touch and then I visited the ATS facility, and coincidentally when I went back to MIT and I was talking to my supervisor and I said, ‘Oh, I went and visited this company and they’re doing a great job.’ He said, ‘Oh, the name is very familiar.’ We realized that when he graduated, something like 16 years ago, he applied here for a job and got a job offer but he got a position at MIT so now he’s a professor there. I kept my contact with Kaveh and then I went back to Australia and finished my Ph.D. After I came back to the U.S. as a post-doc, I invited them to MIT to come and visit our laboratory. So, we stayed in touch.
That’s how I came to know ATS and I realized that they are doing a great job in electric cooling and I was always interested because in electronic cooling there is no limit basically. Electronic equipment is becoming smaller and smaller every day and the only limit is thermal, at least at the moment. The only barrier is thermal issue for the advancement of electronic cooling and that’s why basically all of the funding from the Department of Defense, NASA, etc., it’s all on cooling. Because again, at this stage with all of these nanotechnologies and manufacturing capabilities, they don’t have any barrier to make things smaller except thermal. It’s a very interesting area of research and, you know, when you’re at the university you do cutting-edge research, which is cool, but it’s always nicer to do the research and then build something and use your knowledge in a more applicable way.
JP: Many of the people who read this will probably know, but what are nanofluids?
RA: Nanofluid is the term that you use when you disperse metal or metal oxide nanoparticles, which with the dimensions of 109 m, which is like .000000001 meter…very tiny, and you disperse these in your base fluid, whatever it is – could be water, oil, anything – and because they are tiny they are going to stay dispersed and at the same time because they are metal or metal oxide their thermal conductivity is going to be much higher than your base fluid. In simple language, thermal conductivity means the ability of the material to transfer heat. So, for example, for water the thermal conductivity is .6 W/mK, but for copper it’s like 400 W/mK, so you can assume that by mixing these two, again because the particles are tiny you will still have your liquid, which can easily flow, but at the same time it has higher thermal conductivity compared to the base fluid that you have.
The nanofluid term comes into play because of the heat transfer limitations that you normally have. In very general terms, there are two ways that you can increase the rate of heat transfer. One of them is increasing the surface area and the other is to increase the flow rate. Increasing the surface area, you are normally limited by the space that you have, right, and also increasing the flow rate you should use a bigger pump for example, to have a higher flow rate, which these are all costly. The only option left is if you can play with your working fluid and see how you can improve that and one of the ways you can improve that is by dispersing these nanoparticles to increase the overall thermal conductivity of your working fluid.
JP: How did you get interested in nanofluids? How did that become the focus of your studies and work?
RA: I’ve been working on nanofluids for the past 10 years. I came to know nanofluids during my Master’s and it was for my final-year project. I was looking for something cool and, even back then, nanotechnology was everywhere and then I was looking for something in the area of nanotechnology and heat transfer. I remember, my supervisor didn’t know much and he was like, ‘If you’re going to do this then you’re going to be on your own. I can’t help you much.’ It was funny, I went to the Internet to look up nanofluids and the first thing that came up was the name of this professor at MIT that I was working with during my post-doc. Back then, I remember I was sitting in my office and his name came up and I was telling my office mate, ‘This guy is cool. I’m going to go and work with him one day.’ And he laughed at me like, ‘Oh from here you’re going to go and work with him at MIT? Such a dream.’ And I’m here now.
JP: Obviously there is quite a bit more known about them now, how much has the subject matter changed in the 10 years that you’ve been studying nanofluids?
RA: The good thing is that now there are companies that are actually making nanofluids with very good stability – the particles don’t settle, they stay stable for a long time – and they commercialized a couple of nanofluids that are available now. They even use them in car engines, in the radiators, to increase the rate of cooling. They use it for CPU cooling. Next month, I’m going to go to Europe, there’s an event for the European Union, and they’re trying to basically commercialize nanofluids by 2020. They’re trying to see what are the barriers. The field’s improved a lot. The whole term of nanofluid was invented in 1999, so it’s only 17-18 years. So, it’s a fairly new area of research and seeing this technology commercialized now…the progress was quite fast.
JP: What will you be talking about in the PSMA webinar taking place on Thursday, Oct. 6?
RA: I’m going to be talking about nanofluids in general. What are nanofluids, basically, and what are the applications of nanofluids, in particular, in electronic cooling and high-powered electronics, which is the interest to PSMA. Then I’m going to give a brief explanation about the thermo-physical properties of the nanofluids followed by how they behave under laminar and turbulent flow conditions or even boiling for immersed cooling of electronics. And then I will conclude my talk by [explaining] what is the state-of-the-art and what are the future directions we expect nanofluids are heading to.
JP: Why do you think this is an important topic? Why do you think nanofluids are important as we go forward in the world of electronics cooling?
RA: These tiny particles, you add them to your working fluid and you don’t add much to the pumping power that you’re going to use because they are tiny, but at the same time you see 15-20 percent enhancement (depending on the nanoparticles and working fluid combination) in the heat transfer coefficient without changing any hardware. So, it has a very good potential and, again, this is only for single-phase heat transfer. In the case of immerse cooling of high-powered electronics, which boiling is the main heat transfer mechanism, we were able to see 200-250 percent enhancement in the value of critical heat flux by just changing the working fluid to nanofluid. It’s a very convenient way of doing it.
JP: Do you see nanofluids as the future of the industry? Do you see this is where electronics cooling is heading?
RA: I have to highlight that there are still problems with using nanofluids. This is why there is still research going on in this area. Stability is a big issue. You can use definitely some form of surfactant, which is a polymer that covers these particles’ surfaces and that keeps them dispersed. But in general if you don’t have that these particles, because they are tiny, they are under constant Brownian motion and when they become close to each other they stick to each other and then they agglomerate and they settle. So, there are still some issues that different research groups are trying to address but definitely it’s an area that I think is very useful for electronic cooling.
JP: Is research still going on here at ATS? Are you still really involved in the research and trying to find more applications for it?
RA: Yeah, yeah…we are always trying to push more towards using nanofluids. And hopefully we’ll see more in the future.
If you are interested in the PSMA webinar on Oct. 6, contact power@psma.com no later than Oct. 4. For more information about Advanced Thermal Solutions, Inc., its thermal management products, testing equipment, and consulting services, visit www.qats.com.