Understanding Sub and Supercritical Cryogenic Fluid Dynamics in Conditions Relevant to Novel Ultra Low Emission Engines

Gopal, Jaya Vignesh Madana; Tretola, Giovanni; Morgan, Rod; Sercey, Guillaume De; Atkins, Andrew; Vogiatzaki, Konstantina

doi:10.3390/en13123038

Cited by 18 publications

(9 citation statements)

References 26 publications

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“…Therefore, the contribution of sgs transport properties (like turbulent viscosity) on top of accurate, but small, molecular real-fluid transport properties appears questionable. Interestingly, in the study of Gopal et al [40], a two-fluid model with implicit LES assumption was successfully applied, using an interface compression method to deal with supercritical states, by making the interface term vanish above the critical pressure.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling of Transcritical and Supercritical Fuel Injections Using a Multi-Component Two-Phase Flow Model

et al. 2020

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In the present numerical study, implicit large eddy simulations (LES) of non-reacting multi-components mixing processes of cryogenic nitrogen and n-dodecane fuel injections under transcritical and supercritical conditions are carried out, using a modified reacting flow solver, originally available in the open source software OpenFOAM®. To this end, the Peng-Robinson (PR) cubic equation of state (EOS) is considered and the solver is modified to account for the real-fluid thermodynamics. At high pressure conditions, the variable transport properties such as dynamic viscosity and thermal conductivity are accurately computed using the Chung transport model. To deal with the multicomponent species mixing, molar averaged homogeneous classical mixing rules are used. For the velocity–pressure coupling, a PIMPLE based compressible algorithm is employed. For both cryogenic and non-cryogenic fuel injections, qualitative and quantitative analyses are performed, and the results show significant effects of the chamber pressure on the mixing processes and entrainment rates. The capability of the proposed numerical model to handle multicomponent species mixing with real-fluid thermophysical properties is demonstrated, in both supercritical and transcritical regimes.

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Section: Introductionmentioning

confidence: 99%

Numerical Modeling of Transcritical and Supercritical Fuel Injections Using a Multi-Component Two-Phase Flow Model

et al. 2020

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“…A schematic diagram of the concept RSCE accompanied with an entropy diagram is shown below in Figure 1. The second variant, Cryopower further increases the efficiency potential towards 60% by utilising liquid nitrogen (LN 2 ) as the compression stage coolant [5,25]. This has a twofold effect on both efficiency and emissions.…”

Section: Basic Principlesmentioning

confidence: 99%

“…LN 2 can be easily produced from excess renewable energy, providing a clean energy vector and store which utilises primarily cheap and easily recyclable elements. Isothermal compression using LN 2 will not be discussed further in this paper but is the subject of ongoing research [25,26]. Preliminary emissions results from the research combustion engine using air diluted with nitrogen are reported in past research [8], as well as detailed analysis of the RSCE thermodynamic cycle with isothermal compression [8,17,18], and will not be discussed or investigated in this piece of work.…”

Section: Basic Principlesmentioning

confidence: 99%

Starting to Unpick the Unique Air–Fuel Mixing Dynamics in the Recuperated Split Cycle Engine

et al. 2021

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In this work air fuel mixing and combustion dynamics in the recuperated split cycle engine (RSCE) are investigated through new theoretical analysis and complementary optical experiments of the flow field. First, a brief introduction to the basic working principles of the RSCE cycle will be presented, followed by recent test bed results relevant to pressure traces and soot emissions. These results prompted fundamental questioning of the air-fuel mixing and combustion dynamics taking place. Hypotheses of the mixing process are then presented, with differences to that of a conventional Diesel engine highlighted. Moreover, the links of the reduced emissions, air transfer processes and enhanced atomisation are explored. Initial experimental results and Schlieren images of the air flow through the poppet valves in a flow rig are reported. The Schlieren images display shockwave and Mach disk phenomena. Demonstrating supersonic air flow in the chamber is consistent with complementary CFD work. The results from the initial experiment alone are inconclusive to suggest which of the three suggested mixing mechanism hypotheses are dominating the air–fuel dynamics in the RSCE. However, one major conclusion of this work is the proof for the presence of shockwave phenomena which are atypical of conventional engines.

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“…A computational grid size of 150 mm was selected. Fluid properties were derived from the Peng-Robinson equation of state that comes with the Aspen software and is known to be accurate at cryogenic conditions [32]. A temperature-dependent heat capacity model based on a linear fit through the earlier reported experimental data was implemented.…”

Section: Modellingmentioning

confidence: 99%

The Modelling and Experimental Validation of a Cryogenic Packed Bed Regenerator for Liquid Air Energy Storage Applications

et al. 2020

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Electrical energy storage will play a key role in the transition to a low carbon energy network. Liquid air energy storage (LAES) is a thermal–mechanical energy storage technology that converts electricity to thermal energy. This energy is stored in three ways: as latent heat in a tank of liquid air, as warm sensible heat in a hot tank and as cold sensible heat in a packed bed regenerator (PBR), which is the focus of this paper. A PBR was selected because the temperature range (−196 °C to 10 °C) prohibits storage in liquid media, as most fluids will undergo a phase change over a near 200 °C temperature range. A change of phase in the storage media would result in exergy destruction and loss of efficiency of the LAES device. Gravel was selected as the storage media, as (a) many gravels are compatible with cryogenic temperatures and (b) the low cost of the material if it can be used with minimal pre-treatment. PBRs have been extensively studied and modelled such as the work by Schumann, described by Wilmott and later by White. However, these models have not been applied to and validated for a low temperature store using gravel. In the present research, a comprehensive modelling and experimental program was undertaken to produce a validated model of a low-temperature PBR. This included a study of the low-temperature properties of various candidate gravels, implementation of a modified Schumann model and validation using a laboratory scale packed bed regenerator. Two sizes of gravel at a range of flow rates were tested. Good agreement between the predicted and measured temperature fields in the PBR was achieved when a correlation factor was applied to account for short circuiting of the storage media through flow around the interface between the walls of the regenerator and storage media.

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Understanding Sub and Supercritical Cryogenic Fluid Dynamics in Conditions Relevant to Novel Ultra Low Emission Engines

Cited by 18 publications

References 26 publications

Numerical Modeling of Transcritical and Supercritical Fuel Injections Using a Multi-Component Two-Phase Flow Model

Numerical Modeling of Transcritical and Supercritical Fuel Injections Using a Multi-Component Two-Phase Flow Model

Starting to Unpick the Unique Air–Fuel Mixing Dynamics in the Recuperated Split Cycle Engine

The Modelling and Experimental Validation of a Cryogenic Packed Bed Regenerator for Liquid Air Energy Storage Applications

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