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

Lead Research Organisation: University of Brighton
Department Name: Sch of Computing, Engineering & Maths


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.

Planned Impact

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.
Description -Flash boiling can occur when cryogenic fluids are injected into the reaction chamber that is initially at low pressure. The dynamics of this process will determine the spray breakup that will then drastically affect the mixing of fuel and oxidizer, the reliability of the ignition and the subsequent combustion process. A multiphase solver with interface capturing is developed to perform direct numerical simulations (DNS) of the primary breakup
of the liquid oxygen jet that is driven by homogeneous nucleation, growth, coalescence and bursting of vapour bubbles in the
superheated liquid.

- Considering the main breakup patterns and droplet formation mechanisms for a range of conditions, we have proceeded to an
evaluation of the effectiveness of the volume of fluid (VoF) with continuum surface stress (CSS) method to capture the breakup of
thin lamellae formed at high Weber numbers. A grid refinement study shows convergence of the mass averaged droplet size
towards a droplet diameter. The order of magnitude of the resulting diameter can be estimated based thermodynamic conditions

- A resolution criterion for DNS is established such that the artificial droplets related to the mesh size areinsignificant in terms of mass and area compared to the real droplet size distribution, and a resolution criterion could thus be established.

- We have performed a comprehensive study on how various equations of state perform for the conditions relevant to Split Cycle. It was found that none of the existen models performs accurately

- We have developed a methodology to represent numerically real fluid thermodynamics of cryogenic fluids at various temperatures and pressures.

- We have investigated the effect of initial turbulent fluctuations on the cryogenic jet dynamics and we found a similar behavior of conventional jets
Exploitation Route The current finding relevant to the grid resolution requirements for performing DNS of flash evaporation can help the modellers reduce the time of computations since a priori selection criteria can be established instead of lengthy "trial and error " rans.

The results relevant ot existent equations of state and the new model we have developed have been presented in one conference paper and will also be included in an upcoming paper in energies
Sectors Aerospace, Defence and Marine,Energy,Transport

Title Cryogenic jet dynamics at conditions relevant to Split Cycle 
Description We have created a database that includes information of the the dynamics of cryogenic LN2 at various pressures environments (5MPa-17MPa) that correspond to the compression pressures present at the Split Cycle 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact Part of the work that resulted from the on going collaboration with Ricardo in terms of the development of Cryopower 
Title Direct Numerical Simulaitons of Flash Evaporaiton 
Description Currently a new data base is under development (in collaboration with the University of Stuttgart) that records the behavior of bubble expansion and merging under various Weber numbers in order to shed light to flashing atomisation processes taking place at cryogenic fluids. 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? No  
Impact Although the data base in not currently published this will happen soon and will benefit modellers in deriving more accurate sub-grid-scale models to model bubble dynamics. 
Description Collaboration with Ricardo Lrd on the development of split cycle 
Organisation Ricardo UK Ltd
Country United Kingdom 
Sector Private 
PI Contribution Through this project as well as previous projects we have developed a strong collaboration with Ricardo Ltd. Ricardo is currently benefiting from this collaboration from the development of fundamental knowledge and models from our group that shed light to the complex fluid interactions taking place at the compression and combustion chamber of the the split cycle engine currently under development within the CryoPower project Ricardo has undertaken
Collaborator Contribution Ricardo is offering a) Access to the extensive experimental data base of the CryoPoewer project that help us validate our numerical models b) Access to VECTIS (the Ricardo commercial code) c) Access to the Ricardo technical library of Riccardo Innovation. d) technical advise in terms of the the operating conditions and challenges arising in the split cycle engine.
Impact Although the collaboration within this project is at its initial steps a paper has been published (F. Khalid, S. Harvey, R. Morgan, K. Vogiatzaki, A. Atkins, D. Mason, M. Heikal, Towards zero emission engines through the adoption of combustion lead engine design realised through a split cycle topology, will appear at the Proceedings of the Conference on Thermo-and Fluid Dynamic Processes in Direct Injection Engines (THIESEL) 2018 )
Start Year 2019
Description Collaboration with the University of Stuttgart 
Organisation University of Stuttgart
Country Germany 
Sector Academic/University 
PI Contribution An important component of this project is the collaboration of a leading German university (Stuttgart). The Stuttgart Group currently is performing pioneering work in collaboration with DLR in the field of cryogenic fuels for space propulsion. The work is mostly focusing on DNS methodologies. We explore how these data can be used in order to derive sub-grid scale models for the LES methodology we are working on. The work of the two groups is complimentary and can lead to better numerical tools for modelling cryogenic fluids In February 2020 Mr Giovanni Tretola (the post doc working on the project) and myself perforemd a visit to Stuttgart team to work on the code we co-develop for flash boiling. We have helped them understand better the prcinciples of a new model we have developed (S-?) that they will use in their code.
Collaborator Contribution The group in Stuttgart during the last 5 years (http://www.itv.uni-stuttgart.de) has been working intensively on the better understanding of cryogenic fuel injection for space propulsion applications which can help us diversify the applicability of our research currently mostly focusing on hybrid engines and power generation systems. The have offered us access to the detailed DNS data set they have developed in order to use them as SGS models in our LES framework. As mentioned above in February 2020 Mr Giovanni Tretola (the post doc working on the project) and myself performed a visit to Stuttgart team and they shared their experience with us in terms of the modelling of the temperature equation in OpenFoam when non constant fluid properties are considered. Their experience has helped us a lot in a follow up publication we currently prepare for energies
Impact We are currently in the process of developing together a new modelling framewrok to shed light to the mechanisms of flash evaporation in cryogenic fluids.
Start Year 2018
Title Real fluid Thermodynamics Modelling 
Description We have developed withn OpenFoam (OpenSource) a new method to model the real fluid thermodynamics of cryogenic fluids at a range of temperatures and pressures based on polynomial fitting of NIST data base. Some initial results are presented in 2. M.Jaya Vignesh, S. Harvey A. Atkins, P. Atkins1, G. De Sercey, M.Heikal, R. Morgan,, K. Vogiatzaki, Use of cryogenic fluids for zero toxic emission hybrid engines, IMechE, Internal Combustion Engines and Powertrain Systems for Future Transport Conference, 2019. One more paper (currently invited for publicaiton at Energies) is under preparation 
Type Of Technology Software 
Year Produced 2020 
Open Source License? Yes  
Impact This will enable us to further develop the new tool that we plan to create relevant to cryogenic jet dynamics especially for the modelling of the jet at sueprcritical conditions 
Description Invited Talk at BP 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact I gave a talk entitled "An overview of the modelling capabilities of multi-phase flows at the University of Brighton" November 2018 at BP, UK. The focus of the talk was to demonstrate the tools that have been developed within my group and explore the possibilities for potential new collaborations. My talk attracted their interest and we are currently in discussions for a follow up project relevant to gasoline injection dynamics.
Year(s) Of Engagement Activity 2018
Description Invited Talk at Caterpillar 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Industry/Business
Results and Impact I gave a talk entitled " Complex flows modelling capabilities: Droplets, Sprays • Microfluidics, Combustion" October 2018 at Cterpillar UK in front of people from the R&D department in UK but in US as well (through skype). The focus of the talk was to demonstrate the tools that have been developed within my group and explore the possibilities for potential new collaborations
Year(s) Of Engagement Activity 2018
Description Talk: Developing numerical models for sub and supercritical cryogenic fluid dynamics 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Other audiences
Results and Impact I performed a talk for the UK Fluid Network with the SIG of Sprays (Sprays in engineering applications: modelling and experimental studies ) relevant to the recent progress on cryogenics field. The uadience was colleagues as well some industrial representatives. Discussions I had afterwords indicated that the talk motivated other people to consider how they use cryogenics at their research as well as we identified areas of future collaboration.
Year(s) Of Engagement Activity 2020
Description University of Brighton Open Days 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact I participate regularly at the Open Days of our University with interactive talks relevant to Flight Simulators. I do equipment demonstration allowing the students to try our simulators (Plane and Flying Oculus platform) while I explain them the basic Fluid and Programming knowledge they need in order to build such simulators. I also discuss with them the basics of aeronautical gas turbines and how our research in sprays can help manufacturers improve fuel efficiency and safety. This gives me the opportunity to reach a wide audience and promote the understanding of parents and future students regarding the subject area of aeronautical engineering from the perspective of multiphase flows.

The feedback we got after these Open Days was that the students seemed very enthusiastic learning about the research activities of my group (as well as other groups)
Year(s) Of Engagement Activity 2017,2018