scholarly journals Performance enhancement of a diesel engine with a rotating injector – a numerical study

2021 ◽  
Author(s):  
Chandrasekar P ◽  
◽  
Natteri M Sudharsan ◽  
Keyword(s):  
Performance Enhancement ◽  
Volume Fraction ◽  
Numerical Study ◽  
Engine Performance ◽  
Combustion Characteristics ◽  
Contour Plot ◽  
Static Case ◽  
Spray Structure ◽  
Lower Heat ◽  
Rotating Injector

Improving engine performance is a constant challenge and various methodologies have been adopted by researcher’s world over. In this work, the dispersion characteristics of a rotating injector is studied by varying the umbrella angle (UA) followed by its combustion characteristics and comparing it to a static 3 – hole injector. The present numerical study is bench marked with the experimental data obtained from open literature for a 2 – hole injector with various umbrella angles. The volume fraction of the dispersed fuel along with its spray structure in relation to spray width is compared. This is done by processing the numerical contour plot using LabView image processing utility with appropriate calibration. From this study the 130 degree UA injector configuration was found to be effective when compared with 70. The combustion characteristics is now studied for this injector. It is found that the rotating injector has better dispersion and lowers NOx by 14 % when compared to a static injector with a very marginal loss in thermal efficiency. The rotary system has a lower heat release but a wider spread in comparison to a static case. This helps in marginally reducing the in-cylinder temperature and pressure lower NOx.

Numerical Study of the Combustion Characteristics of a Diesel Micro Pilot Ignited DI Gasoline Engine With Turbocharging and Cooled EGR

2013 ◽  
Author(s):  
Yuhua (York) Zhu ◽  
Nameer Salman ◽  
Kevin Freeman ◽  
Ronald Reese ◽  
Zihan Wang ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Numerical Study ◽  
Direct Injection ◽  
Engine Performance ◽  
Combustion Characteristics ◽  
Significant Fraction ◽  
Combustion Stability ◽  
Ignition Source ◽  
Lean Burn ◽  
Load Range

Advanced technologies combining turbocharging, downsizing, direct injection, and cooled EGR are being intensively investigated in order to significantly improve the fuel economy of spark-ignition (SI) gasoline engines. To avoid the occurrence of knock and to improve the thermal efficiency, a significant fraction of EGR is often used. Due to the significant fraction of EGR, the ignition source needs to be enhanced to ensure high combustion stability. In addition to advanced spark-based solutions, diesel micro-pilot (DMP) technology has been proposed in recent years where the diesel fuel replaces the spark-plug as the ignition source. This paper studies the combustion characteristics of a diesel micro pilot ignited gasoline engine, employing direct injection of gasoline and diesel as well as turbocharging and cooled EGR. A multi-dimensional CFD code with a chemical kinetic calculation capability was extensively validated across the engine speed and load range in a previous study [1]. This paper explores the influence of a number of parameters on DMP combustion behavior, including: diesel pilot mass fraction, start of injection (SOI), DMP injection strategy, as well as EGR rate, air/fuel ratio, and DI gasoline/air mixture inhomogeneity. Besides, the comparison of DMP ignited combustion with traditional spark ignited combustion is also made in terms of EGR tolerance, lean burn limit, and DI gasoline air mixture inhomogeneity. Finally, numerical simulations aimed at optimizing both gasoline and diesel injection parameters, as well as EGR rate in order to enhance the engine performance in the DMP combustion mode, are discussed.

scholarly journals Numerical Study of Shell and Tube Heat Exchanger Performance Enhancement Using Nanofluids and Baffling Technique

2021 ◽  
Vol 80 (2) ◽  
pp. 42-55
Author(s):  
Lahcene Bellahcene ◽  
Djamel Sahel ◽  
Aissa Yousfi
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Performance Enhancement ◽  
Volume Fraction ◽  
Numerical Study ◽  
Fluid Flows ◽  
Physical Parameters ◽  
Minimum Entropy ◽  
Tube Heat Exchanger ◽  
Maximum Improvement

The aim of this work is to investigate the forced convective heat transfer phenomena and fluid flows of water-based Al2O3 nanofluids in the baffled shell and tubes heat exchanger (STHE). Water as a hot fluid flows in the side of the tubes, and Al2O3 nanofluids as cooling fluid flow in the shell side. Numerical investigations have been carried out based on the continuity, momentum, and energy equations which are solved by using the finite element method with the help of the COMSOL 5.4 CFD software. The obtained results were presented by average Nusselt number, streamlines, isotherms, and various physical parameters which are a volumetric fraction of nanoparticles (1%? Cv ?3%). The results are found that the heat transfer increases with the rise of inlet velocity and volume fraction. In addition, the presence of baffles inside tubular heat exchangers can create a better mixture of fluids which is augmenting heat transfer execution. The choice of these parameters is important to get the maximum improvement of heat transfer with minimum entropy consumption.

Thermal-Hydraulic Performance Enhancement by the Combination of Rectangular Winglet Pair and V-Shaped Dimples

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Inderjot Kaur ◽  
Prashant Singh ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Performance Enhancement ◽  
Numerical Study ◽  
Hydraulic Performance ◽  
Channel Height ◽  
Transfer Enhancement ◽  
Spacing Variation ◽  
Lower Heat

Abstract This paper presents numerical study on heat transfer enhancement due to the combination of rectangular winglet pair with V-dimples in an array-type arrangement. Array of rectangular winglet pairs results in heat transfer enhancement, however, at a cost of significant pressure drop, resulting in reduced thermal-hydraulic performance (THP). On the other hand, dimples are associated with lower heat transfer enhancement levels at relatively lower pumping power penalty. To this end, a combination of rectangular winglet pair and V-shaped dimples has been studied in this paper, where the arrangements were intended to achieve enhanced thermal-hydraulic performance. Three different configurations, namely, rectangular winglet pair, rectangular winglet pair with one V-dimple between two consecutive winglets, and rectangular winglet pair with two V-dimples packed in a pitch, are studied here. The variation of heat transfer enhancement, pressure drop gain, and THP with respect to winglet-to-winglet (S) spacing variation for rectangular winglet pair and rectangular winglet pair with one V-dimple configuration is presented at a Reynolds number of 25,000. The THP of the rectangular winglet pair configuration decreases up to S/H equal to 2.5 and then increases (H: channel height). For rectangular winglet pair with one V-dimple, three values of winglet-to-dimple (P) spacings are analyzed. For fixed S/H, the highest P/H configuration provided highest heat transfer enhancement and THP. Among the three configurations studied, rectangular winglet pair with two V-dimples resulted in the highest thermal-hydraulic performance.

scholarly journals Numerical Study on an Interface Compression Method for the Volume of Fluid Approach

Fluids ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 80
Author(s):  
Yuria Okagaki ◽  
Taisuke Yonomoto ◽  
Masahiro Ishigaki ◽  
Yoshiyasu Hirose
Keyword(s):  
Linear Theory ◽  
Volume Fraction ◽  
Numerical Study ◽  
Volume Of Fluid ◽  
Interfacial Wave ◽  
Validation Process ◽  
Two Phase ◽  
Numerical Diffusion ◽  
Mesh Resolution ◽  
Water Reactors

Many thermohydraulic issues about the safety of light water reactors are related to complicated two-phase flow phenomena. In these phenomena, computational fluid dynamics (CFD) analysis using the volume of fluid (VOF) method causes numerical diffusion generated by the first-order upwind scheme used in the convection term of the volume fraction equation. Thus, in this study, we focused on an interface compression (IC) method for such a VOF approach; this technique prevents numerical diffusion issues and maintains boundedness and conservation with negative diffusion. First, on a sufficiently high mesh resolution and without the IC method, the validation process was considered by comparing the amplitude growth of the interfacial wave between a two-dimensional gas sheet and a quiescent liquid using the linear theory. The disturbance growth rates were consistent with the linear theory, and the validation process was considered appropriate. Then, this validation process confirmed the effects of the IC method on numerical diffusion, and we derived the optimum value of the IC coefficient, which is the parameter that controls the numerical diffusion.

Numerical study for the combustion characteristics of Orimulsion fuel in a small-scale combustor

2005 ◽  
Vol 25 (17-18) ◽  
pp. 2998-3012 ◽  
Author(s):  
Hey-Suk Kim ◽  
Mi-Soo Shin ◽  
Dong-Soon Jang ◽  
Young-Chan Choi ◽  
Jae-Goo Lee
Keyword(s):  
Numerical Study ◽  
Combustion Characteristics ◽  
Small Scale

Analysis of Engine Performance and Combustion Characteristics of Diesel and Biodiesel blends in a Compression Ignition Engine

2016 ◽  
Author(s):  
Henrique Dornelles ◽  
Jácson Antolini ◽  
Rafael Sari ◽  
Macklini Dalla Nora ◽  
Paulo Romeu Machado ◽  
...  
Keyword(s):  
Engine Performance ◽  
Combustion Characteristics ◽  
Compression Ignition ◽  
Compression Ignition Engine ◽  
Biodiesel Blends

A Parametric Numerical Study of Radiative Transfer in Thermotropic Materials

2013 ◽  
Author(s):  
Adam C. Gladen ◽  
Susan C. Mantell ◽  
Jane H. Davidson
Keyword(s):  
Particle Size ◽  
Radiative Transfer ◽  
Optical Thickness ◽  
Parametric Study ◽  
Volume Fraction ◽  
Numerical Study ◽  
Anisotropic Scattering ◽  
Index Of Refraction ◽  
Spherical Particles ◽  
Size Parameter

A thermotropic material is modeled as an absorbing, thin slab containing anisotropic scattering, monodisperse, spherical particles. Monte Carlo ray tracing is used to solve the governing equation of radiative transfer. Predicted results are validated by comparison to the measured normal-hemispherical reflectance and transmittance of samples with various volume fraction and relative index of refraction. A parametric study elucidates the effects of particle size parameter, scattering albedo, and optical thickness on the normal-hemispherical transmittance, reflectance, and absorptance. The results are interpreted for a thermotropic material used for overheat protection of a polymer solar absorber. For the preferred particle size parameter of 2, the optical thickness should be less than 0.3 to ensure high transmittance in the clear state. To significantly reduce the transmittance and increase the reflectance in the translucent state, the optical thickness should be greater than 2.5 and the scattering albedo should be greater than 0.995. For optical thickness greater than 5, the reflectance is asymptotic and any further reduction in transmittance is through increased absorptance. A case study is used to illustrate how the parametric study can be used to guide the design of thermotropic materials. Low molecular weighted polyethylene in poly(methyl methacrylate) is identified as a potential thermotropic material. For this material and a particle radius of 200 nm, it is determined that the volume fraction and thickness should equal 10% and 1 mm, respectively.

Sign in / Sign up

Export Citation Format

Share Document