Sinha leading study to improve low-temperature heat exchanger performance

Associate Professor Sanjiv Sinha is principal investigator on a two-year heat exchanger study. He is collaborating with fellow MechSE faculty Srinivasa Salapaka, Placid Ferreira, Chenhui Shao, and Nenad Miljkovic.

“The research seeks to answer the question of how best to combine inexpensive polymers with metals to obtain an economically viable heat exchanger that has better thermal and thermomechanical performance than existing hybrids,” Sinha said.

Polymers alone tend to be too low in thermal conductivity to be used effectively as material for heat exchangers. In contrast, the thermal conductivity of commonly used metals is magnitudes higher. For low-temperature waste heat recovery, a value in the middle of these extremes is needed.

In a 2008 analysis conducted for the Department of Energy, approximately 900 trillion BTU of heat below 230 degrees Celsius is lost as waste annually in the U.S. The team aims to develop a heat exchanger that will provide at least a 30% improvement in performance over competing composite plastic heat exchangers.

“In the past, research has looked into composites where polymers are seeded with metal particles to improve their thermal conductivity,” Sinha said. “This approach has flaws ranging from fundamental to practical.”  

One example he noted is that air pockets form around the particles in the seeded plastics due to a differential in thermal expansion between the two materials.

The project focuses on four core innovations: the use of a hybrid metal-polymer tape for the heat exchanger material, roll-to-roll manufacturing that allows for scalability, the implementation of anti-fouling coatings that increase lifespan by preventing corrosion and other aging, and continuous health monitoring through the use of sensors and controls systems.

Each faculty member on the team is leading aspects of the project especially relevant to one of the four innovations. Sinha is in charge of the thermal and thermomechanical aspects; Ferreira and Shao lead the manufacturing thrusts; Miljkovic leads research on anti-corrosion features in addition to thermal aspects; and Salapaka leads the controls and machine learning aspects.

The research project is one of 24 sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) and has a budget of $1M. The group began collaborating in April and is now in the process of testing several fabricated designs.