STUDY ON HEAT TRANSFER IN THE BWR CORE DURING LOCA: HEAT TRANSFER TO FALLING FILM AT HIGH PRESSURE AND HIGH TEMPERATURE

1982 ◽  
Author(s):  
Shinichi Morooka ◽  
N. Inai ◽  
Toshimi Tobimatsu
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
High Temperature ◽  
Falling Film

Experimental investigation of wall heat transfer due to spray combustion in a high-pressure/high-temperature vessel

2021 ◽  
pp. 146808742110072
Author(s):  
Karri Keskinen ◽  
Walter Vera-Tudela ◽  
Yuri M Wright ◽  
Konstantinos Boulouchos
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
High Pressure ◽  
High Temperature ◽  
High Speed ◽  
Transfer Problem ◽  
Wall Heat Transfer ◽  
Gas Temperature ◽  
Reference Case ◽  
High Pressure High Temperature

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.

Comparison of 3D Unsteady Transient Conjugate Heat Transfer Analysis on a High Pressure Cooled Turbine Stage With Experimental Data

2017 ◽  
Author(s):  
Jong-Shang Liu ◽  
Mark C. Morris ◽  
Malak F. Malak ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Flux ◽  
High Pressure ◽  
High Temperature ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Turbine Rotor ◽  
Turbine Stage ◽  
Cooling Flow

In order to have higher power to weight ratio and higher efficiency gas turbine engines, turbine inlet temperatures continue to rise. State-of-the-art turbine inlet temperatures now exceed the turbine rotor material capability. Accordingly, one of the best methods to protect turbine airfoil surfaces is to use film cooling on the airfoil external surfaces. In general, sizable amounts of expensive cooling flow delivered from the core compressor are used to cool the high temperature surfaces. That sizable cooling flow, on the order of 20% of the compressor core flow, adversely impacts the overall engine performance and hence the engine power density. With better understanding of the cooling flow and accurate prediction of the heat transfer distribution on airfoil surfaces, heat transfer designers can have a more efficient design to reduce the cooling flow needed for high temperature components and improve turbine efficiency. This in turn lowers the overall specific fuel consumption (SFC) for the engine. Accurate prediction of rotor metal temperature is also critical for calculations of cyclic thermal stress, oxidation, and component life. The utilization of three-dimensional computational fluid dynamics (3D CFD) codes for turbomachinery aerodynamic design and analysis is now a routine practice in the gas turbine industry. The accurate heat-transfer and metal-temperature prediction capability of any CFD code, however, remains challenging. This difficulty is primarily due to the complex flow environment of the high-pressure turbine, which features high speed rotating flow, coupling of internal and external unsteady flows, and film-cooled, heat transfer enhancement schemes. In this study, conjugate heat transfer (CHT) simulations are performed on a high-pressure cooled turbine stage, and the heat flux results at mid span are compared to experimental data obtained at The Ohio State University Gas Turbine Laboratory (OSUGTL). Due to the large difference in time scales between fluid and solid, the fluid domain is simulated as steady state while the solid domain is simulated as transient in CHT simulation. This paper compares the unsteady and transient results of the heat flux on a high-pressure cooled turbine rotor with measurements obtained at OSUGTL.

Design of High Temperature and High Pressure Petroleum Bullets Performance Test Device

2012 ◽  
Vol 580 ◽  
pp. 346-349
Author(s):  
Xiao Qing Li ◽  
Ren Qiang Liu ◽  
Da Zhong Hua ◽  
Xiao Yan Liu
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
High Temperature ◽  
Performance Test ◽  
Convection Heat Transfer ◽  
Local Area ◽  
Temperature Fields ◽  
Test Time ◽  
Test Device ◽  
High Pressure Reaction

A high temperature and high pressure reaction autoclave for petroleum bullets performance test is designed in this paper. Heat transfer in both vertical and horizontal reaction autoclave structure is analyzed and calculated. Considering system heat loss, heating power of these two kinds of devices is calculated in different test time. Meanwhile, temperature fields in these two kinds of autoclave are simulated. According to the comparison result, the authors come to the conclusion that temperature field in vertical reaction autoclave is uniform and can meet design demand with a temperature difference less than ±5°C. Horizontal reaction autoclave in which there are small eddies in air interlayer cannot meet demand because eddies enhance the convection heat transfer in local area. Based on this conclusion, a reasonable reaction autoclave structure can be designed.

scholarly journals Numerical Simulation and Design of a High-Temperature, High-Pressure Fluid Transport Pipe

2020 ◽  
Vol 10 (17) ◽  
pp. 5890
Author(s):  
Jiyoung Yoon ◽  
Junkyu Park ◽  
Jinhyoung Park
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
High Pressure ◽  
High Temperature ◽  
Low Temperature ◽  
Fluid Transport ◽  
Projectile Velocity ◽  
Gas Leakage ◽  
And Performance ◽  
High Temperature High Pressure

When designing a hand caliber with a high-temperature, high-pressure internal fluid transport pipe, reliability, safe use, and performance must be considered. Reliability refers to the stress caused by thermo-mechanical load; safe use refers to the low-temperature burns that might occur upon contact, and high-temperature burns caused by gas leakage occurring in the cylinder gap; and performance refers to projectile velocity. In this study, numerical simulation methods for heat transfer, structure analysis, and gas leakage are proposed so that solutions can be designed to account for the above three criteria. Furthermore, a hand-caliber design guide is presented. For heat transfer and structural analysis, mesh size, the transient convective heat transfer coefficient, and boundary conditions are described. Regarding gas leakage, methods reflecting projectile motion and determination of the molecular weight of the propellant are described. As a result, a designed hand caliber will have a high reliability, because the thermo-mechanical stress is lower than the yield stress. There will be little risk of low-temperature burns, but there will be a high temperature-burn risk, owing to gas leakage in the cylinder gap. The larger the cylinder-gap size, the greater the gas leakage and the smaller projectile velocity. The presented numerical simulation method can be applied to evaluate various aspects of other structures that require high-temperature, high-pressure fluid-transport pipes.

Study on Nickel Ferrite Formation by Using a Simple Method to Simulate Heat Transfer Surface

2007 ◽  
Vol 124-126 ◽  
pp. 1565-1568 ◽  
Author(s):  
Jei Won Yeon ◽  
Kwang Soon Choi ◽  
Yongju Jung ◽  
Selvaraj Rengaraj ◽  
Yeong Keong Ha ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
High Temperature ◽  
Nickel Ferrite ◽  
Energy Difference ◽  
Heat Transfer Surface ◽  
Simple Method ◽  
Ft Ir ◽  
Thermodynamic Relationship ◽  
Relationship Of

The condition of a heat transfer surface with boiling is composed of three environmental components; high temperature, high pressure and water vapor. In general an autoclave or a high temperature loop system is used for maintaining the required condition. The thermodynamic relationship of chemical reactions states that the free energy difference (ΔG) is clearly dependent on the reaction temperature and independent of the reaction pressure if the reaction has no volume change: (∂ΔG/∂P)T = ΔV ~ 0. Based on the above relationship, the high-pressure term was removed from the environmental components of the heat transfer surface. A vacuum quartz capsule with a moisturized metal oxide powder was used to study the formation of nickel ferrite. The feasibility of this simplified method to simulate a heat transfer surface was confirmed by an analysis of the FT-IR spectra and XRD pattern during the transformation of a nickel and iron mixed oxide into nickel ferrite.

scholarly journals Heat Transfer Characteristics of Biomass Slurry under High Pressure and High Temperature

2011 ◽  
Vol 90 (9) ◽  
pp. 874-880 ◽  
Author(s):  
Takashi NOGUCHI ◽  
Yoji NODA ◽  
Yoshihiko YAMASAKI ◽  
Shuhei INOUE ◽  
Yoshifumi KAWAI ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
High Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

scholarly journals Formation of Soot in Oxygen-Enriched Turbulent Propane Flames at the Technical Scale

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 191
Author(s):  
Rikard Edland ◽  
Thomas Allgurén ◽  
Fredrik Normann ◽  
Klas Andersson
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
High Temperature ◽  
Oxygen Concentration ◽  
Soot Formation ◽  
Atmospheric Conditions ◽  
Total Flow ◽  
Total Flow Rate ◽  
Partial Pressures ◽  
Combustion Processes

Soot is an important component for heat transfer in combustion processes. However, it is also a harmful pollutant for humans, and strict emissions legislation motivates research on how to control soot formation and release. The formation of soot is known to be triggered by high temperature and high pressure during combustion, and it is also strongly influenced by the local stoichiometry. The current study investigates how the formation of soot is affected by increasing the oxygen concentration in the oxidizer, since this affects both the temperature profile and partial pressures of reactants. The oxygen-to-fuel ratio is kept constant, i.e., the total flow rate of the oxidizer decreases with increasing oxygen concentration. Propane is combusted (80 kWth) while applying oxygen-enriched air, and in-flame measurements of the temperature and gas concentrations are performed and combined with available soot measurements. The results show that increasing the oxygen concentration in the oxidizer from 21% to 27% slightly increases soot formation, due to higher temperatures or the lower momentum of the oxidizer. At 30% oxygen, however, soot formation increases by orders of magnitude. Detailed reaction modeling is performed and the increase in soot formation is captured by the model. Both the soot inception rates and surface growth rates are significantly increased by the changes in combustion conditions, with the increase in soot inception being the most important. Under atmospheric conditions, there is a distinct threshold for soot formation at around 1200 °C for equivalence ratios >3. The increase in temperature, and the slower mixing that results from the lower momentum of the oxidizer, have the potential to push the combustion conditions over this threshold when the oxygen concentration is increased.

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