Papers by Keyword: Reference Temperature

Abstract: Energy labeling of buildings is accepted and used in all European countries. Depending on the yearly specific primary energy consumption the energy quality of a building is expressed using a country specific method. Consequently primary energy is the basis of building energy class. Primary energy is obtained using different country specific transformation factors for gas, electricity, wood, biomass etc. However different quantities of warm water and steam can have the same energy content. Calculating the exergy content of used energy a better classification of buildings can be achieved. This paper presents a method to analyze residential buildings from exergy point of view. It was found a transformation factor between energy and exergy: 0.075.

Abstract: In this paper, viscous effects on hypersonic vehicle are investigated. Firstly, viscous aerodynamic is modeled based on reference temperature method, and viscous aerodynamic lift, drag and pitching moment are calculated by the model. And then, aerodynamic forces and elastic deformation are analyzed by comparing with viscous effects on/off. In final, considering the thermal choking condition, longitudinal velocity and attitude boundary values are discussed.

Abstract: In this paper, a new phenomenological and empirically based constitutive model was proposed to change the temperature term in the original Johnson-Cook constitutive model. The new model can be used to describe or predict the stress-strain relation of the metals deformed over a wide range of temperatures even though the current temperatures are lower than the reference temperature. Based on the impact compression data obtained by split Hopkins pressure bar (SHPB) apparatus about one hot-extrudedMg-10Gd-2Y-0.5Zr alloy, the material constants in the new model can be experimentally determined using isothermal and adiabatic stress-strain curves at different strain rates and temperatures. Good agreement is obtained between the predicted and the experimental flowcurves for the hot-extrudedMg-10Gd-2Y-0.5Zr alloy at both quasi-static and dynamic loadings under a wide range of temperatures ever though the current temperatures are lower than the reference temperature.

Abstract: ASTM A106/B is commonly used for pressure piping in alumina refineries. Due to the problem of caustic cracking in alumina refineries, piping must be stress relieved after welding, usually through a post-weld heat treatment (PWHT) process at a temperature of 635°C. However, multiple PWHT procedures tend to degrade the mechanical properties of steel and design standards have set limits on the length of time PWHT can be carried out before steel should be replaced. In this study, the effect of PWHT time on the properties of A106/B parent metal was examined, with particular emphasis on the effect on toughness. PWHT was carried out for 1, 8 and 40 hours and the results were compared with those for as-received material. Impact transition temperature and room-temperature tensile results were determined using standard tests. The reference temperature, To, was determined using ASTM E1921 with arc-shaped tension specimens. The results showed that the ductile-to-brittle transition temperature increased significantly as PWHT time increased and the implications of this to a fracture mechanics analysis of plant operations are discussed.

Abstract: The advancement of proper methodology to determination of VVER reactor pressure vessel (RPV) materials transition behaviour has been followed. The project included selection of proper specimen geometries (standard 10x10x55 mm, sub-size 3x4x27 mm and 5x5x27.5 mm Charpy-V samples) and impact as well as dynamic fracture toughness testing. All the fundamental criterions have been applied to consider an applicability of small-sized specimens to Cr-Mo-V and Cr-Ni-Mo-V steel radiation embrittlement studies. Selected specimen geometries have been found to be fully valid for impact and dynamic fracture data and capable for prediction of standard specimen behaviour from the small specimens. Within testing of irradiated materials, it has been found not fully validity of all the compared transition temperatures.

Abstract: Charpy transition temperature TCVN and reference temperature To for 10Ni3CrMoV steel were determined using two different experimental techniques such as Charpy V-notch impact test technique and reference temperature To test technique. It was found that two methods provided different test results. The median master curve with upper and lower tolerance bounds was got from the test. The upper tolerance bound is often used for material design and application. At the same time the TCVN and To results were discussed for two kinds of heat treatment which are QT(Quenching and Temper) and QLT(Quenching, anneal and temper). JC (med ) K values calculated were 101 and 105MPam1/2 for the QT and QLT steels, respectively. These indicated that the QLT steels have the higher JC (med ) K , the lower reference temperature and lower energy (or fracture appearance) transition temperature(ETT50 or FATT50) than the QT steels. This was mainly related with the different microstructures of two kinds of heat treatment.