Heat Transfer Characteristic of Thermal Barrier Coated Piston Crown for a Compressed Natural Gas Direct Injection Engine

2014 ◽  
Vol 663 ◽  
pp. 304-310
Author(s):  
Ahmad Jalaludin Helmisyah ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali

Compressed natural gas with direct injection (CNGDI) engine produces high temperature and pressure ultimately leading to high thermal stress. The piston crown material fails to withstand high temperature and operate ineffectively due to improper heat transfer. By insulating the surface namely; thermal barrier coating (TBC) such as ceramic based yttria partially stabilised zirconia (YPSZ), heat transfer to the piston might be reduced and lead to improvement of piston durability. Hence, in this research, YPSZ/NiCrAl coating was utilised to differentiate with the uncoated piston crowns in terms of the ability to reduce thermal stresses to the piston using finite element method and burner rig test. Several samples of AC8A aluminium alloy piston crowns were coated with bonding element of NiCrAl and ZrO2-7.5Y2O3namely the YPSZ as the top coat by using air-plasma spraying technique and were assessed by burner rig test. The results exhibited the durability of the YPSZ/NiCrAl coating could withstand the test and the heat flux for the YPSZ/NiCrAl-coated piston crown was about 98% reduction compared to the uncoated piston crown. Also, the lower the gradient value of the heat flux, the higher the heat resistance.

2011 ◽  
Vol 52-54 ◽  
pp. 1830-1835 ◽  
Author(s):  
A.J. Helmisyah ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali

The top land of a piston normally known as the piston crown is an engine part that is continuously exposed to extreme temperature and pressure during combustion. For a compression ratio level, the compressed natural gas with a direct injection system (CNGDI) typically uses a range of compression ratio between gasoline and diesel engines, producing extremely high temperature and pressure which lead to high thermal stresses. Consequently, the piston crown is exposed to direct combustion due to the vertical movement of the piston, leading to various possible damages of thermal stresses. In contrast to a petrol fuelled internal combustion engine, natural gas combustion creates a dry condition in the combustion chamber, inducing cooling difficulties in the engine. Without good heat transfer, the piston crown materials will soon fail to withstand high temperature and operate effectively. Alternatively, any sort of insulation inside the combustion chamber such as applying ceramic coatings may protect the piston crown surface and affect the overall combustion process, as well as improving the engine performance and the exhaust emissions. By reducing the heat loss of a cylinder bore, a higher thermal efficiency of an engine can also be improved by applying a surface thermal insulation, namely; thermal barrier coating (TBC). Thus, in this study, a ceramic based TBC, yttria partially stabilised zirconia (YPSZ) coating was used to compare with conventional tin coated (Na2SnO3) and uncoated piston crown in terms of heat concentration. Moreover, a set of average value of combustion temperature of a CNGDI engine was selected. Detailed analyses using a finite element analysis (FEA) technique was utilised in order to determine the location of hotspots via distribution profiles of temperature. It was noted that the maximum heat flux of the uncoated piston crown was much higher than that of tin coated and YPSZ coated piston crown. Heat flux value reached about 62% of decrement due to lower conductivity levels of piston crown.


2013 ◽  
Vol 393 ◽  
pp. 281-286 ◽  
Author(s):  
Helmisyah Ahmad Jalaludin ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
Bulan Abdullah ◽  
Nik Rosli Abdullah

Due to high temperature and less proper heat transfer, the material of piston crown in an engine of compressed natural gas with a direct injection system (CNGDI) may lead to high thermal stresses and fails to withstand high temperature and operate effectively. By insulating with thermal barrier coating (TBC) such as ceramic-based yttria partially stabilised zirconia (YPSZ), heat transfer to the piston might be reduced and lead to improvement of piston durability. Hence, in this research, YPSZ coating was utilised to differentiate with the uncoated piston crowns in terms of the ability to reduce thermal penetration to the piston. A detailed finite element analysis (FEA) was carried out to determine the location of hotspots via profiles distribution of thermal. In short, it was observed that hotspots were mainly concentrated at the piston bowls rim. The heat flux for the YPSZ/NiCrAl-coated from FEA exhibited about 98% reduction compared to the uncoated piston crown.


2013 ◽  
Vol 68 ◽  
pp. 505-511 ◽  
Author(s):  
Helmisyah Ahmad Jalaludin ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali ◽  
Bulan Abdullah ◽  
Nik Rosli Abdullah

2017 ◽  
Vol 9 (1) ◽  
pp. 47 ◽  
Author(s):  
Balbheem Kamanna ◽  
Bibin Jose ◽  
Ajay Shamrao Shedage ◽  
Sagar Ganpat Ambekar ◽  
Rajesh Somnath Shinde ◽  
...  

The piston is considered as most important part of I.C engine. High temperature produced in an I.C engine may contribute to high thermal stresses. Without appropriate heat transfer mechanism, the piston crown would operate ineffectively which reduce life cycle of piston and hence mechanical efficiency of engine. The literature survey shows that ideal piston consumes heat produced by burnt gases resulting in decrease of Engine overall Efficiency. In this project work an attempt is made to redesign piston crown using TBC on piston surface and to study its Performance. A 150 cc engine is considered and TBC material with different thickness is coated on the piston. 3D modeling of the piston geometry is done 3D designing software Solidworks2015. Finite Element analysis is used to calculate temperature and heat flux distribution on piston crown. The result shows TBC as a coating on piston crown surface reduces the heat transfer rate within the piston and that will results in increase of engine efficiency. Results also show that temperature and heat flux decreases with increase in coating thickness of YSZ.


Author(s):  
Subhash Chander ◽  
Gurpreet Singh

An experimental study has been conducted to investigate the effect of helical vane swirler geometry on heat transfer characteristics for compressed natural gas (CNG)/air swirling flame impinging on a flat surface. Effects of helical vane swirler geometric parameters like, length of helical insert (25 mm, 45 mm and 65 mm), depth of groove on the helical insert (2.5 mm, 3.5 mm and 4.5 mm) and number of helical vanes (8, 10 and 12), on heat transfer characteristics have been studied. All the inserts were having fixed helical vane angle of 45°. Also, the burner exit diameter was kept constant (d = 20 mm). Experiments were conducted at different dimensionless separation distances (6, 4, 3 and 2) for fixed values of Reynolds number (6000) and equivalence ratio (1.3). Significant variation in the heat flux profiles has been observed for different swirler inserts till the radial hump in heat flux. After the radial hump, almost in all cases, the heat flux lines merged together. These variations in the heat flux profiles were due to different level of swirling intensities produced by different swirlers at fixed value of the helical vane swirler angle. It was observed that the heating was comparatively more uniform at larger separation distances (H/d = 6). It has been concluded that defining swirl intensity only with the helical vane swirler angle would be incorrect for such type of swirlers. Other geometric parameters of the swirler like, number of vanes, length of the swirler and the depth of the groove should also be included in swirl intensity definition.


2021 ◽  
pp. 146808742110072
Author(s):  
Karri Keskinen ◽  
Walter Vera-Tudela ◽  
Yuri M Wright ◽  
Konstantinos Boulouchos

Combustion chamber wall heat transfer is a major contributor to efficiency losses in diesel engines. In this context, thermal swing materials (adapting to the surrounding gas temperature) have been pinpointed as a promising mitigative solution. In this study, experiments are carried out in a high-pressure/high-temperature vessel to (a) characterise the wall heat transfer process ensuing from wall impingement of a combusting fuel spray, and (b) evaluate insulative improvements provided by a coating that promotes thermal swing. The baseline experimental condition resembles that of Spray A from the Engine Combustion Network, while additional variations are generated by modifying the ambient temperature as well as the injection pressure and duration. Wall heat transfer and wall temperature measurements are time-resolved and accompanied by concurrent high-speed imaging of natural luminosity. An investigation with an uncoated wall is carried out with several sensor locations around the stagnation point, elucidating sensor-to-sensor variability and setup symmetry. Surface heat flux follows three phases: (i) an initial peak, (ii) a slightly lower plateau dependent on the injection duration, and (iii) a slow decline. In addition to the uncoated reference case, the investigation involves a coating made of porous zirconia, an established thermal swing material. With a coated setup, the projection of surface quantities (heat flux and temperature) from the immersed measurement location requires additional numerical analysis of conjugate heat transfer. Starting from the traces measured beneath the coating, the surface quantities are obtained by solving a one-dimensional inverse heat transfer problem. The present measurements are complemented by CFD simulations supplemented with recent rough-wall models. The surface roughness of the coated specimen is indicated to have a significant impact on the wall heat flux, offsetting the expected benefit from the thermal swing material.


Energy ◽  
2020 ◽  
Vol 197 ◽  
pp. 117173 ◽  
Author(s):  
Jeongwoo Lee ◽  
Cheolwoong Park ◽  
Jongwon Bae ◽  
Yongrae Kim ◽  
Sunyoup Lee ◽  
...  

Author(s):  
Stewart Xu Cheng ◽  
James S. Wallace

Glow plugs are a possible ignition source for direct injected natural gas engines. This ignition assistance application is much different than the cold start assist function for which most glow plugs have been designed. In the cold start application, the glow plug is simply heating the air in the cylinder. In the cycle-by-cycle ignition assist application, the glow plug needs to achieve high surface temperatures at specific times in the engine cycle to provide a localized source of ignition. Whereas a simple lumped heat capacitance model is a satisfactory representation of the glow plug for the air heating situation, a much more complex situation exists for hot surface ignition. Simple measurements and theoretical analysis show that the thickness of the heat penetration layer is small within the time scale of the ignition preparation period (1–2 ms). The experiments and analysis were used to develop a discretized representation of the glow plug domain. A simplified heat transfer model, incorporating both convection and radiation losses, was developed for the discretized representation to compute heat transfer to and from the surrounding gas. A scheme for coupling the glow plug model to the surrounding gas computational domain in the KIVA-3V engine simulation code was also developed. The glow plug model successfully simulates the natural gas ignition process for a direct-injection natural gas engine. As well, it can provide detailed information on the local glow plug surface temperature distribution, which can aid in the design of more reliable glow plugs.


Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1784
Author(s):  
Jiangyu Hu ◽  
Ning Wang ◽  
Jin Zhou ◽  
Yu Pan

Thermal protection is still one of the key challenges for successful scramjet operations. In this study, the three-dimensional coupled heat transfer between high-temperature gas and regenerative cooling panel with kerosene of supercritical pressure flowing in the cooling channels was numerically investigated to reveal the fundamental characteristics of regenerative cooling as well as its influencing factors. The SST k-ω turbulence model with low-Reynolds-number correction provided by the pressure-based solver of Fluent 19.2 is adopted for simulation. It was found that the heat flux of the gas heated surface is in the order of 106 W/m2, and it declines along the flow direction of gas due to the development of boundary layer. Compared with cocurrent flow, the temperature peak of the gas heated surface in counter flow is much higher. The temperature and heat flux of the gas heated surface both rises with the static pressure and total temperature of gas. The heat flux of the gas heated surface increases with the mass flow rate of kerosene, and it hardly changes with the pressure of kerosene. Results herein could help to understand the real heat transfer process of regenerative cooling and guide the design of thermal protection systems.


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