Hi Gary,

Thank you so much for your great question!

The term “cold combustion” is not precise. Instead, we should call it “low-temperature combustion” (LTC) because the temperatures are lower than those in ordinary engines, but it can still be hot. LTC is a collection of different strategies, such as Homogeneous Charge Compression Ignition (HCCI) and Premixed Charge Compression Ignition (PCCI), that promise higher efficiency and reduced emissions with lower temperatures as a common factor. ( Lower combustion temperatures alter the chemistry of NOx and/or soot formation, Nitrogen oxides (NOx) is a common term for the nitrogen oxides N2O, NO, N2O3, NO2, and NO3 formed during the combustion of fuel and an essential component of air pollution). However, controlling ignition timing and heat release rate (HRR) are primary challenges before LTC technology can be implemented commercially.
Each strategy works in a very different way. For example, HCCI, developed in the second half of the twenty century, was one of the early diesel combustion concepts that differed from the conventional diesel process. The goal of HCCI was to achieve as homogeneous a mixture of air and fuel as possible before ignition—much the same way as in a conventional spark ignition engine. This can be done either by injecting fuel into the intake port or directly into the cylinder and allowing sufficient time between injection and ignition to allow complete mixing of air and fuel. In both cases, as well said by Mr. Careaga, no spark or other forced ignition is used. It is done only by the chemical reactions in the mix, and here is when my research work could be significant.
To simulate any molecular system dynamics, including chemical reactions, we have to know the interaction or forces, or in consequence, the potential energy surface (PES), which is related to the force. Nowadays, we have software(like Molpro) that can calculate points of the PES with great accuracy, but they are costly in time and computational resources. For example, calculating hundreds of these points could take hours or even days; however, simulations need thousands of them, making this approach extremely inefficient. My research has led me to build robust software that, from a set of points, can build the whole long-range part(When the molecules are far away from each other) of the PES for any molecular system in the order of the dataset accuracy. For a large number of systems, when the temperature, pressure, and energy are within a specific range, the long range of the PES is the most critical part, so accuracy here is crucial. For example, the systems that take part in low-temperature combustion. But they are not the only case. For instance, in Atmospheric Chemistry, to study complex processes like Ozone formation, or in Astro-Chemistry, to comprehend the formation and distribution of some compounds in a comet.

It is a concise introduction, but I highly recommend the book listed below, which contains a more extended and detailed description of low-temperature combustion technology.

Singh, A.P., Agarwal, A.K. (2018). Low-Temperature Combustion: An Advanced Technology for Internal Combustion Engines. In: Srivastava, D., Agarwal, A., Datta, A., Maurya, R. (eds) Advances in Internal Combustion Engine Research. Energy, Environment, and Sustainability. Springer, Singapore. https://doi.org/10.1007/978-981-10-7575-9_2

Hi Gary. Great question. From what I can glean from Google, cold combustion is the term used to describe the generation of electrical energy by the reaction of H2 and O2 in fuel cells. It is “cold” combustion because there is no spark involved, just the chemical reaction. We’ll see if we can find a more detailed explanation.

Thanks,
Andrew Careaga