scholarly journals Renormalization of QED Near Decoupling Temperature

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Samina S. Masood
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Weak Interactions ◽  
Renormalization Constant ◽  
Heating System ◽  
Electron Mass ◽  
Effective Parameters ◽  
Background Contribution ◽  
First Order ◽  
The Difference

We study the effective parameters of QED near decoupling temperatures and show that the QED perturbative series is convergent, at temperatures below the decoupling temperature. The renormalization constant of QED acquires different values if a system cools down from a hotter system to the electron mass temperature or heats up from a cooler system to the same temperature. At T = m, the first order contribution to the electron self-mass, δm/m is 0.0076 for a heating system and 0.0115 for a cooling system and the difference between two values is equal to 1/3 of the low temperature value and 1/2 of the high temperature value around T~m. This difference is a measure of hot fermion background at high temperatures. With the increase in release of more fermions at hotter temperatures, the fermion background contribution dominates and weak interactions have to be incorporated to understand the background effects.

Development of High-Accuracy Simulation Test Technology for Hot Stamping

2021 ◽  
Vol 1016 ◽  
pp. 1430-1435
Author(s):  
Akito Suzuki ◽  
Yasushi Fujii ◽  
Tatsumi Kimura ◽  
Masaki Kawano ◽  
Toru Inazumi
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Hot Stamping ◽  
Sheet Steel ◽  
Heating System ◽  
High Accuracy ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Testing System ◽  
Hybrid Heating

A new high temperature testing system was developed to evaluate high temperature deformation behavior in hot stamping process with high accuracy using a hybrid heating system consist of direct resistance heating and high-frequency induction heating. The uniform temperature distribution was achieved in the sheet steel tensile test specimen. The typical hot stamping thermal history was successfully simulated with the combination of the hybrid heating system and the gas cooling system. The strain distribution in high temperature deformation was confirmed to be uniform in the parallel portion of the specimen and the developed testing system may contribute to improving the accuracy in hot stamping CAE analysis.

The Heating System of Agricultural Facilities Using Excess Heat Power Transformers

2020 ◽  
Vol 67 (1) ◽  
pp. 42-47
Author(s):  
Anatoliy I. Sopov ◽  
Aleksandr V. Vinogradov
Keyword(s):  
System Design ◽  
Heat Supply ◽  
Cooling System ◽  
Power Transformer ◽  
Electric Heating ◽  
Heating System ◽  
Power Transformers ◽  
Large Power ◽  
Excess Heat ◽  
Power Centers

In power transformers, energy losses in the form of heat are about 2 percent of their rated power, and in transformers of large power centers reach hundreds of kilowatts. Heat is dissipated into the environment and heats the street air. Therefore, there is a need to consume this thermal energy as a source of heat supply to nearby facilities. (Research purpose) To develop methods and means of using excess heat of power transformers with improvement of their cooling system design. (Materials and methods) The authors applied following methods: analysis, synthesis, comparison, monographic, mathematical and others. They analyzed various methods for consuming excess heat from power transformers. They identified suitable heat supply sources among power transformers and potential heat consumers. The authors studied the reasons for the formation of excess heat in power transformers and found ways to conserve this heat to increase the efficiency of its selection. (Results and discussion) The authors developed an improved power transformer cooling system design to combine the functions of voltage transformation and electric heating. They conducted experiments to verify the effectiveness of decisions made. A feasibility study was carried out on the implementation of the developed system using the example of the TMG-1000/10/0.4 power transformer. (Conclusions) The authors got a new way to use the excess heat of power transformers to heat the AIC facilities. It was determined that the improved design of the power transformer and its cooling system using the developed solutions made it possible to maximize the amount of heat taken off without quality loss of voltage transformation.

scholarly journals Technology Pathways and Economic Analysis for Transforming High Temperature to Low Temperature District Heating Systems

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3218
Author(s):  
Pedro Durán ◽  
Herena Torio ◽  
Patrik Schönfeldt ◽  
Peter Klement ◽  
Benedikt Hanke ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Renewable Energy ◽  
High Temperature ◽  
Low Temperature ◽  
Economic Analysis ◽  
District Heating ◽  
Heating System ◽  
District Heating System ◽  
Heating Systems ◽  
District Heating Systems

There are 1454 district heating systems in Germany. Most of them are fossil based and with high temperature levels, which is neither efficient nor sustainable and needs to be changed for reaching the 2050 climate goals. In this paper, we present a case study for transforming a high to low temperature district heating system which is more suitable for renewable energy supply. With the Carnot Toolbox, a dynamic model of a potential district heating system is simulated and then transformed to a low temperature supply. A sensitivity analysis is carried out to see the system performance in case space constrains restrict the transformation. Finally, an economic comparison is performed. Results show that it is technically possible to perform the transformation until a very low temperature system. The use of decentralized renewable sources, decentralized heat storage tanks and the placement of a heat pump on each building are the key points to achieve the transformation. Regarding the sensitivity analysis, the transformation is worth doing until the seasonal storage and solar collector field sizes are reduced to 60% and 80% of their values in the reference case, respectively. The economic analysis shows, however, that it is hard for highly efficient low temperature renewable based heat networks to compete with district heating systems based on a centralized fossile CHP solution. Thus, though the presented transformation is technically possible, there is a strong need to change existing economic schemes and policies for fostering a stronger promotion of renewable energy policies in the heat sector.

Combined Experimental and CFD Study of a HP Blade Multi-Pass Cooling System

2009 ◽  
Author(s):  
D. Jackson ◽  
P. Ireland ◽  
B. Cheong
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Detailed Comparison ◽  
Bulk Temperature ◽  
Internal Cooling ◽  
3 Dimensional ◽  
Turbine Cooling ◽  
Cooling Hole ◽  
The Difference

Progress in the computing power available for CFD predictions now means that full geometry, 3 dimensional predictions are now routinely used in internal cooling system design. This paper reports recent work at Rolls-Royce which has compared the flow and htc predictions in a modern HP turbine cooling system to experiments. The triple pass cooling system includes film cooling vents and inclined ribs. The high resolution heat transfer experiments show that different cooling performance features are predicted with different levels of fidelity by the CFD. The research also revealed the sensitivity of the prediction to accurate modelling of the film cooling hole discharge coefficients and a detailed comparison of the authors’ computer predictions to data available in the literature is reported. Mixed bulk temperature is frequently used in the determination of heat transfer coefficient from experimental data. The current CFD data is used to compare the mixed bulk temperature to the duct centreline temperature. The latter is measured experimentally and the effect of the difference between mixed bulk and centreline temperature is considered in detail.

Design of cooling system for inspection manipulator and analysis based on experiment

2016 ◽  
Vol 43 (2) ◽  
pp. 231-240 ◽  
Author(s):  
Tan Chen ◽  
Wei-jun Zhang ◽  
Jian-jun Yuan ◽  
Liang Du ◽  
Ze-yu Zhou
Keyword(s):  
High Temperature ◽  
Cooling System ◽  
Insulation Material ◽  
Water Cooling ◽  
Content Type ◽  
Cooling Method ◽  
Temperature Experiment ◽  
Gas Cooling ◽  
Loop Feedback ◽  
Electrical Components

Purpose – This paper aims to present a different cooling method (water cooling) to protect all the mechanical/electrical components for Tokamak in-vessel inspection manipulator. The method is demonstrated effective through high temperature experiment, which provides an economical and robust approach for manipulators to work normally under high temperature. Design/methodology/approach – The design of cooling system uses spiral copper tube structure, which is versatile for all types of key components of manipulator, including motors, encoders, drives and vision systems. Besides, temperature sensors are set at different positions of the manipulator to display temperature data to construct a close-loop feedback control system with cooling components. Findings – The cooling system for the whole inspection manipulator working under high temperature is effective. Using insulation material such as rubber foam as component coating can significantly reduce the environmental heat transferred to cooling system. Originality/value – Compared with nitrogen gas cooling applied in robotic protection design, although it is of less interest in prior research, water cooling method proves to be effective and economical through our high temperature experiment. This paper also presents an energetic analysis method to probe into the global process of water cooling and to evaluate the cooling system.

High Temperature Creep Behavior of Austenitic Fe-Ni-Cr Alloy

2013 ◽  
Vol 686 ◽  
pp. 170-179 ◽  
Author(s):  
Esah Hamzah ◽  
Maureen Mudang ◽  
Ang Khwang Jenq ◽  
Muhammad Adil Khattak
Keyword(s):  
High Temperature ◽  
Detrimental Effect ◽  
Creep Damage ◽  
Transgranular Fracture ◽  
Creep Fracture ◽  
Secondary Stage ◽  
Tertiary Stage ◽  
The Difference ◽  
Temperature Test ◽  
Section Form

Creep damage investigation was carried out in Fe-Ni-Cr alloy at 800°C, 900°C, and 983°C using rectangular section form of specimen. In all the tests conducted on this material, some creep curves showed primary stage, secondary stage and tertiary stage. The creep fracture shows ductile transgranular fracture where separation occurred at the dendrites carbide interface suggesting that the detrimental effect of creep was compounded by precipitation of carbides at matrix. The presence of cavities may be due to the difference in thermal expansion characteristics of the austenite and carbide during high temperature test. Coarsening of carbides lead to cavities formation within the dendrite and carbide interface and form cavities linkage due to formation of crack and finally cause creep fracture. Increase in creep temperature it will lead to increase in creep rate. The fracture modes of creep samples were investigated to predict the failure mode.

scholarly journals Equations of viscous flow of silicate liquids with different approaches for universality of high temperature viscosity limit

2014 ◽  
Vol 8 (2) ◽  
pp. 59-68
Author(s):  
Ana Kozmidis-Petrovic
Keyword(s):  
High Temperature ◽  
Viscous Flow ◽  
Temperature Limit ◽  
High Temperature Limit ◽  
Viscosity Parameter ◽  
General Rules ◽  
Viscosity Limit ◽  
Dependent Parameter ◽  
Silicate Liquids ◽  
The Difference

The Vogel-Fulcher-Tammann (VFT), Avramov and Milchev (AM) as well as Mauro, Yue, Ellison, Gupta and Allan (MYEGA) functions of viscous flow are analysed when the compositionally independent high temperature viscosity limit is introduced instead of the compositionally dependent parameter ??. Two different approaches are adopted. In the first approach, it is assumed that each model should have its own (average) hightemperature viscosity parameter ??. In that case, ?? is different for each of these three models. In the second approach, it is assumed that the high-temperature viscosity is a truly universal value, independent of the model. In this case, the parameter ?? would be the same and would have the same value: log ?? = ?1.93 dPa?s for all three models. 3D diagrams can successfully predict the difference in behaviour of viscous functions when average or universal high temperature limit is applied in calculations. The values of the AM functions depend, to a greater extent, on whether the average or the universal value for ?? is used which is not the case with the VFT model. Our tests and values of standard error of estimate (SEE) show that there are no general rules whether the average or universal high temperature viscosity limit should be applied to get the best agreement with the experimental functions.

scholarly journals Performance evaluation of sub ground passive cooling system with Ecotech software simulation (Case study: Pasio Christi Church at Cibunut, Kuningan, West Java)

2021 ◽  
Vol 878 (1) ◽  
pp. 012006
Author(s):  
I Musdinar ◽  
R A Ardli
Keyword(s):  
Performance Evaluation ◽  
Cooling System ◽  
Passive Cooling ◽  
West Java ◽  
Tropical Regions ◽  
Software Simulation ◽  
Church Building ◽  
The Difference ◽  
Passive Cooling System ◽  
The Church

Abstract The church in Cibunut, Kuningan, West Java has implemented a sub ground passive cooling system in its renovated building in 2018. This sub ground passive cooling system has not been widely applied in tropical regions, however the church is trying to implement it. This system is supported by making air wells and flowing cold air through distribution pipes into the room. Because not many people have implemented this system, performance evaluation through an ecotect software simulation is used to determine the success of the system in cooling the room. The research was carried out with the following steps: (i) Data collection in the form of CAD drawings of Cibunut Church building, (ii) Simulation using ecotect software, and (iii) Analysis of simulation results with thermal comfort standards in the tropics. The results of this study are conclusions from the results of simulations and analyzes, as an illustration in applying of the sub ground passive cooling system. This research helps illustrate the difference between buildings that have not applied sub ground passive cooling and buildings that have applied sub ground passive cooling.

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