Kota is examining two fundamental interactions: the flow and the thermal interaction of the liquid propellants with the surface of the tubing through which they flow in the heat exchanger.
To improve performance, Kota and his team are tailoring engineered surfaces, such as dimpled surfaces, like that on a golf ball only much smaller, and innovatively textured wavy surfaces, that will optimize the flow.
"This is the first time that anyone has looked at such wavy channels for this purpose," Kota said.
"We have multiple ways to modify the surface topology," Kota said. "One way is through conventional machining, like milling or drilling."
The other method is to use chemical modification of surfaces.
"On the microscale we can modify the surfaces using chemicals or micro-fabrication techniques performed in a clean room, and can fundamentally alter the way these surfaces interact with different fluids," Kota said.
For example, chemical treatments produce thousands of nanostructures on the surface of copper, in this case, making the surface that is water-phobic or hydrophobic: water slides on the surface. The surface structure is inspired by the lotus leaf, a naturally occurring hydrophobic surface.
"This reduces the drag of the fluid or the friction of the fluid as it flows through the pipes. When the drag goes down it saves a lot in the pumping power, which means less electricity consumption," Kota said.
"It is significant that we are applying this technology to the surface of copper, which is good for heat transfer. We could do this on Teflon or some polymer surfaces that are naturally water repellant, but these materials are not good for heat transfer. The challenge is realizing these surfaces with adequate robustness on materials that have good heat transfer properties. Copper is one of the best thermal conductors."
Based on preliminary analysis, Kota's research has found that, under certain operating conditions, cryogenic heat exchangers being pursued could be at least one-third of the size of the current state-of-the-art, with more than 10-15 percent improvement in thermal performance.
Kota and Hyde are working with students at NMSU to optimize flow and heat transfer of cryogenic fluids through the proposed textured channels in addition to identifying a cost-effective manufacturing solution. Along with
"This is really, really exciting, because we have fluid flowing through pipes in innumerable applications - from drug delivery in medicine, thermal management of defense and automotive electronics, to cooling supercomputing data centers in which we have thousands of computing servers generating large amounts of heat, and we have power generation systems involving heat exchangers and a lot of piping and tubing for transfer of fluids," Kota said.
"The driving force is energy. Basically what we're trying to do is improve energy efficiency by lowering the electrical costs of pumping and improving thermal transfer using engineered surfaces and bio-inspired designs. If we can improve energy efficiency from the thermal-fluid perspective, we can actually see a lot of reduction of the carbon footprint as a result of power generation by burning of fossil fuels. It could also make renewable power generation economical."
TNS 30TagarumaMar-130829-4469916 30TagarumaMar
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