Hao Zhao: Overcoming Obstacles and Catalyzing Combustion

Hao Zhao likes to say that life starts with a blank canvas—it is up to us to make it colorful. Today, Hao’s canvas has vibrant colors, beautiful lines, and rich shapes. But the path to painting a masterpiece demands years of hard work.

“My road to growth was never smooth,” says Hao who is a PhD Candidate in Mechanical & Aerospace Engineering at Princeton. “When I look back, persistence is a distinct feature of mine—it is the reason I have always been able to overcome hardship.”

As a child, Hao was shy and struggled to speak. He describes himself as feeling like an “alien among a group of lively children.” In junior school, Hao realized if he wanted a better life he had to tackle problems head on.

He pushed himself to the frontlines—participating in debates and acting as an emcee. Hao carried a pen in his mouth to train his facial muscles and read professional articles to develop a sense of good language. The sweat paid off, he says. Today, Hao speaks naturally and confidently in front of thousands of researchers at conferences.

Throughout his schooling, Hao showed a strong aptitude for math and science. As a student in China, college admissions depended on a single entrance exam. Unfortunately, Hao had a lot of mental pressure and did not perform well in the exam. As a result, the nation’s top college rejected him.

“You only have one chance and, if you fail, your future suffers. The news was like thunder in a clear sky. I felt lost for several years after that,” explains Hao who helps mentor students in similar situations today.

“I carry this experience deep in my heart and never feel regret about it,” says Hao who ended up attending Southeast University. “What matters in life is the process not the outcome. Even if I had the chance to experience it all over again, I would follow it this way.”


As a major in thermal energy and power engineering, Hao was eager to leave the classroom and start tinkering around in the lab. Southeast University had limited research opportunities for undergraduate students so once again Hao found a way to create his own opportunity.

He applied to the National Central University of Taiwan as an exchange student and found a lab to work in. His first project was to design a game with an 8051 microcomputer.

“I have never been so inspired to contribute to academic research. Having the opportunity to communicate with top academic professors and researchers broadened and provoked my thoughts. I found pleasure in learning once again. I would spend 15-hour days in the lab to figure out a solution to a problem,” recalls Hao.

The experience showed Hao that international study was the right path and soon after he was accepted to graduate school at Columbia University. At graduation, the students elected him the “Most Influenced Graduate of Southeast University.” Hao felt humbled by the award and was inspired to start a motivational organization to help other struggling university students. 

“Everyone was surprised by my uncommon experience from the worst to the best,” he jokes.“I said at the award ceremony that anyone could be a genius and get somewhere if you never give up on yourself.”

Hao thinks about that journey to self-realization, and the obstacles he was able to overcome, everyday when he walks around the Princeton campus. As a research assistant in Professor Yiguang Ju’s Combustion Lab, his work focuses on combustion chemistry, including experiments in complex systems, kinetic modeling, and diagnostics techniques. In particular, he is interested in understanding low-temperature chemistry and high-pressure systems. Ultimately, Hao hopes these insights will help engineers design more efficient and sustainable engines. 

“With concerns about limited fossil fuel resources, pollution, and global warming, it is important that we keep studying new alternative fuels and combustion systems that have the ability to enhance efficiency and reduce emissions,” says Hao who studied Earth and Environmental Engineering at Columbia.

One of the greatest hurdles in designing greener engines is that chemistry kinetics is still poorly understood at low temperatures and high pressures. New techniques—which offer slightly lower temperatures—have been developed to control emissions in traditional combustion engines. But novel ideas are still lacking for large-molecule fuels and dual fuel blends.

Hao is developing more accurate kinetic models that utilize these new fuels and extended combustion conditions. For example, from 2014 to 2016, Hao designed a laminar flow reactor and a jet-stirred reactor system with the molecular-beam mass spectrometry technique to investigate the effect of ozone and NOx on ignition kinetics of potential fuel sources, like dimethyl ether and n-pentane. 

“Low temperature chemistry is essential for fundamental combustion studies on engine knocking, ignition delay time of engines, and fire safety in space,” explains Hao. “The experiments showed that the presence of ozone dramatically enhances the low-temperature oxidation of dimethyl ether, while NOx plays a complicated role in fuel oxidation.”

“Hao is a very smart and hard working student,” says Yiguang Ju, PhD, Robert Porter Patterson Professor at Princeton. “He has a strong research drive and is always ready to help others. His work on ozone and NOx sensitized low temperature chemistry provides new insights in low carbon combustion and emission control for advanced engines.”

Hao has also been involved in studying high-pressure systems. Combustion techniques that operate at super high pressures (100-200 atm) attract a lot of attention for potential usage in future aircraft engines and gas turbines. However, Hao notes, there is nearly no experimental study of combustion chemistry at these supercritical conditions.

“My goal is to be the first researcher in the combustion community to build a jet-stirred reactor at this critically high pressure,” says Hao. “This will allow us to study chemistry kinetics of different fuels—including methane, fossil fuel surrogate, and jet fuel—at supercritical conditions. This valuable data can later inform current and future engine design effectively. In my PhD career, I have to keep challenging myself and building new designs to contribute to the engineering community.”

While Hao’s master painting is still yet to be completed, his experience has shown him that you can truly paint your own life. Hao says he feels fortunate that his canvas is colorful.

~Carolyn Sayre