Dr. Srinivas Vanapalli

Srinivas Vanapalli is an expert on cryogenics

‘Although inconspicuous, cryogenics is the backbone of a number of processes that require rapid cooling and freezing capabilities, among them food and pharmaceutical processing, tissue fixation for molecular medicine, cold transportation, quenching of steel, getting rockets into space and so on.’ Srinivas Vanapalli, tenure track associate professor at the UT, leads the only academic cryogenic liquids research group in the Netherlands and works to make all of the above possible. ‘Cooling with small molecules such as liquid nitrogen and carbon dioxide is an environmentally sound alternative compared to conventional mechanical freezers. In addition, other potential advantages are its flexibility, smaller footprint and high throughput and yield. Despite this, a lack of physics-based models is hampering their adoption.’

My goal is to come up with a physics theory explaining the interaction in various thermodynamic states, in other words, what exactly happens when we ‘cool things.

‘We study heat and mass transfer phenomena at very low temperatures of −50 °C and below. Properties of materials are very different at such low temperatures,’ explains Vanapalli. ‘We try to understand the physical processes at these cryogenic temperatures and to investigate the mechanisms that play a role during the cooling of an object – during the transient state. There is very little scientific knowledge about these transient states at the moment, while it is crucial to understand how to cool things properly. If you cool an object too fast, it can shrink or expand and that could be catastrophic. Imagine if that happens in a liquid hydrogen tank in rockets, for example. The applications of ‘cooling’ are nearly countless. And that is precisely my goal: to do fundamental research with a strong focus on real-life applications.’

Although his work is often curiosity-driven, Vanapalli has a personal passion for technological innovation and he has contributed several inventions himself. ‘We developed a special gas-gap heat switch, which allows us to control heat flow when cooling an object. It is like a dimmer for a light lamp, in a way. This principle of heat switch is also applied in a tissue snap freezer. The snap freezer is able to quickly cool human tissue, which can therefore be immediately preserved and diagnosed. This allows a surgeon to diagnose the tumour and understand what causes the cancer. This is a necessary step toward personalized molecular medicine.’

The researcher’s ultimate goal is to come up with a physics theory explaining the interaction in various thermodynamic states, in other words, what exactly happens when we ‘cool things’. ‘I want to study different states of cryogenic liquids and understand the physics of heat transfer processes. Once we have this understanding, we can apply it in practice, for example for freezing biological materials. Cryogenic liquids are key in the physical fixation of biological matter such as cells and tissues. The importance of this was shown also by the 2017 Noble prize given to cryogenic electron microscopy. This technique allows us to visualize proteins in their functional natural environment, but it still has its challenges. My work could greatly benefit this field.’