Time-Dependent Analysis of the Regenerative Engine Cycle

Proceedings of the Institution of Mechanical Engineers, Part D:

Cypris

2014

An innovative engine concept with fuel injection and combustion in a three-dimensional porous combustion reactor allows realization of very clean and efficient combustion. In this paper the combustion process as realized in a free-volume combustion chamber and in porous combustion reactors was analysed under diesel-engine-like conditions. A special combustion chamber allows simulations of engine conditions corresponding to the moment when diesel injection begins (the initial conditions). There are characteristic features (modes) of a heat release process that was defined in a two-dimensional and three-dimensional field of the initial pressure and temperature. The characteristic modes of the heat release process in a free-volume chamber were analysed and compared with the process occurring in highly porous three-dimensional combustion reactors. These combustion modes depend on the reactor parameters, especially on its heat capacity, pore structure and density. The combustion in the reactor occurs at a reduced temperature; however, a qualitative similarity of the heat release process to that in a free-volume combustion chamber was proven. Furthermore, a limitation of the reaction rate at high initial temperatures and pressures was recognized in the case of porous reactors. This indicates the applicability of this combustion technology to internal-combustion engines even at high loads and has the favourable effect of a lower combustion noise

Section: Resultsmentioning

confidence: 99%

Characteristics of the heat release in three-dimensional, highly porous reactors under engine-like conditions in comparison with free diesel injection conditions

Proceedings of the Institution of Mechanical Engineers, Part D:

Cypris

2014

“…In the latter case, heat recuperation in a solid phase of the porous structure performs automatically, as the structure has contact with hot burned gases. Different aspects of heat recuperation in a porous structure applied to thermal engines are described in [16][17][18][19][20][21][22][23][24][25]. From the point of view of the application of porous reactors to in-cylinder engine processes (e.g., fuel distribution and vaporization, mixing, ignition, combustion, and heat recuperation), there are a number of requirements on structures and material properties [13].…”

Section: Characterization Of Highly Porous Reactorsmentioning

confidence: 99%

Characteristics of Flameless Combustion in 3D Highly Porous Reactors under Diesel Injection Conditions

Cypris

2013

Journal of Combustion

The heat release process in a free volume combustion chamber and in porous reactors has been analyzed under Diesel engine-like conditions. The process has been investigated in a wide range of initial pressures and temperatures simulating engine conditions at the moment when fuel injection starts. The resulting pressure history in both porous reactors and in free volumes significantly depends on the initial pressure and temperature. At lower initial temperatures, the process in porous reactors is accelerated. Combustion in a porous reactor is characterized by heat accumulation in the solid phase of the porous structure and results in reduced pressure peaks and lowered combustion temperature. This depends on reactor heat capacity, pore density, specific surface area, pore structure, and heat transport properties. Characteristic modes of a heat release process in a two-dimensional field of initial pressure and temperature have been selected. There are three characteristic regions represented by a single- and multistep oxidation process (with two or three slopes in the reaction curve) and characteristic delay time distribution has been selected in five characteristic ranges. There is a clear qualitative similarity of characteristic modes of the heat release process in a free volume and in porous reactors. A quantitative influence of porous reactor features (heat capacity, pore density, pore structure, specific surface area, and fuel distribution in the reactor volume) has been clearly indicated.

“…Ruiz [152][153][154][155][156] described a Stirling cycle which can be approximated in an internal combustion engine by means of regeneration of internal heat. Computational results showed that the IC Stirling cycle offers a significantly better thermal efficiency over a conventional IC engine if some effects, such as the tendency for the cylinder air to "hide" inside the regenerator, are overcome.…”

Section: Engine Concept With a Catalytic Component: Pm Reactor With Cmentioning

confidence: 99%

Potential of Porous-Media Combustion Technology as Applied to Internal Combustion Engines

Journal of Thermodynamics

2010

The paper summarizes the knowledge concerning porous media combustion techniques as applied in engines. One of most important reasons of this review is to introduce this still not well known technology to researchers doing with internal combustion engine processes, thermal engines, reactor thermodynamics, combustion, and material science. The paper gives an overview of possible applications of a highly porous open cell structures to in-cylinder processes. This application means utilization of unique features of porous media for supporting engine processes, especially fuel distribution in space, vaporization, mixing with air, heat recuperation, ignition and combustion. There are three ways for applying porous medium technology to engines: support of individual processes, support of homogeneous combustion process (catalytic and non-catalytic) with temperature control, and utilization of the porous structure as a heat capacitor only. In the first type of application, the porous structure may be utilized for fuel vaporization and improved fuel distribution in space making the mixture more homogeneous in the combustion chamber. Extension of these processes to mixture formation and ignition inside a combustion reactor allows the realization of a homogeneous and a nearly zero emissions level combustion characterized by a homogeneous temperature field at reduced temperature level.