Ignition of a solid with a heat flux considering thermal stresses

1991 ◽  
Vol 27 (5) ◽  
pp. 539-550
Author(s):  
A. G. Knyazeva
Keyword(s):  
Heat Flux ◽  
Thermal Stresses

Thermo-Fluid-Stress-Deformation Analysis of Two-Layer Microchannels for Cooling Chips With Hot Spots

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Abas Abdoli ◽  
George S. Dulikravich ◽  
Genesis Vasquez ◽  
Siavash Rastkar
Keyword(s):  
Heat Flux ◽  
Thermal Stresses ◽  
Hot Spot ◽  
Heat Removal ◽  
High Heat ◽  
Heat Transfer Analysis ◽  
Deformation Analysis ◽  
High Heat Flux ◽  
Cooling Design ◽  
Microchannel Cooling

Two-layer single phase flow microchannels were studied for cooling of electronic chips with a hot spot. A chip with 2.45 × 2.45 mm footprint and a hot spot of 0.5 × 0.5 mm in its center was studied in this research. Two different cases were simulated in which heat fluxes of 1500 W cm−2 and 2000 W cm−2 were applied at the hot spot. Heat flux of 1000 W cm−2 was applied on the rest of the chip. Each microchannel layer had 20 channels with an aspect ratio of 4:1. Direction of the second microchannel layer was rotated 90 deg with respect to the first layer. Fully three-dimensional (3D) conjugate heat transfer analysis was performed to study the heat removal capacity of the proposed two-layer microchannel cooling design for high heat flux chips. In the next step, a linear stress analysis was performed to investigate the effects of thermal stresses applied to the microchannel cooling design due to variations of temperature field. Results showed that two-layer microchannel configuration was capable of removing heat from high heat flux chips with a hot spot.

Heat Flux Distribution Over a Solar Central Receiver Using an Aiming Strategy Based on a Conventional Closed Control Loop

2017 ◽  
Author(s):  
Jesús García ◽  
Yen Chean Soo Too ◽  
Ricardo Vasquez Padilla ◽  
Rodrigo Barraza Vicencio ◽  
Andrew Beath ◽  
...  
Keyword(s):  
Heat Flux ◽  
Flux Distribution ◽  
Thermal Stresses ◽  
Control Strategies ◽  
Multiple Input Multiple Output ◽  
Control Loop ◽  
Heat Flux Distribution ◽  
Input Multiple Output ◽  
Solar Receiver ◽  
Solar Field

Solar thermal towers are a maturing technology that have the potential to supply a significant part of energy requirements of the future. One of the issues that needs careful attention is the heat flux distribution over the central receiver’s surface. It is imperative to maintain receiver’s thermal stresses below the material limits. Therefore, an adequate aiming strategy for each mirror is crucial. Due to the large number of mirrors present in a solar field, most aiming strategies work using a data base that establishes an aiming point for each mirror depending on the relative position of the sun and heat flux models. This paper proposes a multiple-input multiple-output (MIMO) closed control loop based on a methodology that allows using conventional control strategies such as those based on Proportional Integral Derivative (PID) controllers. Results indicate that even this basic control loop can successfully distribute heat flux on the solar receiver.

Thermal Barrier Coating on IC Engine Piston to Improve Engine Efficiency

2017 ◽  
Vol 9 (1) ◽  
pp. 47 ◽  
Author(s):  
Balbheem Kamanna ◽  
Bibin Jose ◽  
Ajay Shamrao Shedage ◽  
Sagar Ganpat Ambekar ◽  
Rajesh Somnath Shinde ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Thermal Stresses ◽  
Mechanical Efficiency ◽  
Project Work ◽  
Element Analysis ◽  
Ic Engine ◽  
Engine Efficiency ◽  
Piston Crown ◽  
Barrier Coating

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.

The Effect of Disc Radius on Heat Flux and Temperature Distribution in Friction Clutches

2012 ◽  
Vol 505 ◽  
pp. 154-164 ◽  
Author(s):  
Oday Ibraheem Abdullah ◽  
Josef Schlattmann
Keyword(s):  
Heat Flux ◽  
Numerical Calculation ◽  
Thermal Stresses ◽  
Outer Radius ◽  
Accurate Estimation ◽  
Friction Materials ◽  
Machine Element ◽  
Friction Clutch ◽  
Proper Design ◽  
Friction Surfaces

Friction clutch is an important machine element, which transmits the torque from the engine to the gearbox. Hence, an accurate estimation of the heat flux and temperatures on the friction surfaces is essential for proper design of the clutch to avoid failure due to thermal stresses. The dimensionless radius ratio (R=inner disc radius/outer disc radius) is the main key quantifying the quantities of heat flux and temperature on friction materials of clutch. Furthermore, the effect of (R) on the axial force, inner and outer radius, peripheral velocity and torque is investigated as well. The MATLAB and ANSYS have been used to perform the numerical calculation in this paper.

scholarly journals An External Circular Crack in an Infinite Solid Under Axisymmetric Heat Flux Loading in the Framework of Fractional Thermoelasticity

Entropy ◽  
2021 ◽  
Vol 24 (1) ◽  
pp. 70
Author(s):  
Yuriy Povstenko ◽  
Tamara Kyrylych ◽  
Bożena Woźna-Szcześniak ◽  
Renata Kawa ◽  
Andrzej Yatsko
Keyword(s):  
Heat Flux ◽  
Thermal Stresses ◽  
Time Derivative ◽  
Circular Crack ◽  
Constant Heat Flux ◽  
Circular Ring ◽  
Different Types ◽  
External Circular Crack ◽  
Fractional Heat Conduction ◽  
Real Solid

In a real solid there are different types of defects. During sudden cooling, near cracks, there can appear high thermal stresses. In this paper, the time-fractional heat conduction equation is studied in an infinite space with an external circular crack with the interior radius R in the case of axial symmetry. The surfaces of a crack are exposed to the constant heat flux loading in a circular ring R<r<ρ. The stress intensity factor is calculated as a function of the order of time-derivative, time, and the size of a circular ring and is presented graphically.

Effect of Thermal Barrier Coating on Piston Crown for Compressed Natural Gas with Direct Injection Engine

2011 ◽  
Vol 52-54 ◽  
pp. 1830-1835 ◽  
Author(s):  
A.J. Helmisyah ◽  
Shahrir Abdullah ◽  
Mariyam Jameelah Ghazali
Keyword(s):  
Heat Flux ◽  
High Temperature ◽  
Natural Gas ◽  
Thermal Stresses ◽  
Direct Injection ◽  
Thermal Barrier ◽  
Compressed Natural Gas ◽  
Piston Crown ◽  
Barrier Coating ◽  
Temperature And Pressure

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.

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