Unveiling the injection dynamics of cryogenic energy carriers for zero-emission high-efficiency systems

The project aims to create new fundamental knowledge and advanced numerical tools regarding the atomisation, heating and evaporation characteristics of liquefied gases, in order to significantly advance the technology required to efficiently control cryogenic injection. Liquid gases such as air, nitrogen or natural gas can serve as cost-effective energy vectors within power production units as well as transport "fuels" with zero emissions. For example, energy coming from renewables can be used in order to "cool" air or nitrogen, up to the point that they become liquids. Follow up injection of these liquids to a higher temperature environment causes rapid re-gasification and a 700-fold expansion in volume, which can drive a turbine or piston engine even without combustion. Most importantly, because of the low boiling point of cryogenic liquids, low-grade or ambient heat can be used as a heat source, which otherwise is wasted. A better understanding and control of the injection dynamics of the cryogenic fluids could boost the efficiency of hybrid combustion systems to 60% (Ricardo's Cryopowder split-cycle engine), and achieve zero emissions when used for work generation through isothermal expansion without the need of combustion (Dearman Engine and Libertine Free Piston Engine). Recently, there has been an increased interest towards cryogenic technologies, however this has been focused mostly on the liquefaction processes (such as the £6m EPSRC grant to the Birmingham Centre for Cryogenic Energy Storage). Within the suggested project the attention is shifted towords the injection process of the cryogenics in real life industrial applications. Dr Vogiatzaki with the support from two leading UK companies in the field of innovative energy system solutions (Ricardo Ltd and Libertine Ltd) aspires to provide new knowledge and robust modelling tools to unlock the dynamics of cryogenic energy carrier's atomisation and heat transfer dynamics.

The social, environmental and economic importance of maximising energy efficiency and minimising emissions from the use of cryogenic energy carriers in the power generation and transportation fields is significant.

- Impact on UK energy sector in terms of cheap and clean energy: If cryogenic energy carriers are efficiently integrated into modern energy systems, they can help speed up the transformation of the energy infrastructure from a centralised system to a flexible decentralised dynamic system. Liquid nitrogen is already produced in various local units for use in food processing, fire suppression etc and currently gets wasted. In the UK alone there is spare liquid nitrogen production capacity to fuel a third of the urban bus fleet, as diesel-liquid air 'heat hybrids'. Liquid air is not yet produced in large scale, however liquid nitrogen, can store off-peak low or zero carbon electricity, which can then be used to displace high-carbon coal or gas in electricity generation at local units, as well as to replace polluting petrol and diesel in vehicles. New liquefiers could be integrated with renewable energy generation such as wind to produce effectively zero carbon liquid energy carriers from excess energy.

Using the RCUK Typology, this project has also impact in the three more general fields outlined below:

- Commercialisation & Exploitation: This project will take an innovative modelling approach to unveil the mechanism of the transition of sub to super-critical injection of cryogenic fluids, pushing forward towards novel, energy efficient future engines. While seeking to unlock the physics of a very complex fluid dynamics problem at a fundamental research level, the proposal has been formulated to also address the current needs of the automotive and power generation industry. The code to be developed aims to model realistic pressure and temperature scenarios, currently unsatisfactorily modelled by existing methodologies. Two leading companies in the field, Ricardo UK and Libertine Ltd UK, as well as an innovative company in the field of linear machines for power a motion, have indicated through their communication with the Principal Investigator (PI) the various ways in which this project could impact their design and manufacturing process.

- Healthcare: Away from the automotive and energy sector, this proposal has the potential for a wider impact in various other fields that cryogenic sprays are involved in, especially healthcare since it is expected that some of the results will be directly applicable to the modelling for the development of medical sprays for use to treat skin related medical conditions, for example.

- The Environment and sustainability: Environmental sustainability and improving social welfare are key development areas for the UK in particular the effects of air quality on health and social well-being. A large number of deaths are currently linked to air pollution according to the World Health Organisation. Moreover, pollution and environmental degradation is negatively affecting people's overall quality of life. Considering that by some estimates, the total number of vehicles worldwide could reach 2.5 billion by 2050, there is a pressing need for zero emission transportation and power generation systems. This project aims to make a significant contribution to the design of a new generation of computational tools resulting in a technology with the potential to provide clean energy systems

- Evidence based policy making & influencing public policies: Pushing the technology frontiers in terms of engine
manufacturing indirectly affects the way that policies are made. If the technology is available that allows minimum emissions then a greater pressure can be put to industries to reduce their emissions.