Experimental Investigations of Effective Thermal Conductivity of the Selected Examples of Steel Porous Charge

In many cases of heat treatment of steel products, the heated charge has a porous structure. The examples of such charges include bundles of long steel components e.g., bars. The basic thermal property of the charge in this form is effective thermal conductivity kef. This paper presents the results of experimental examinations of effective thermal conductivity of the porous charge, which is composed from various types of steel long components. Due to the specific nature of the samples, a special measurement stand was constructed based on the design of a guarded hot plate apparatus. The measurements were performed for sixteen different samples across a temperature range of 70–640 °C. The porosity of the samples, depending on the type of components used, ranged from 0.03 to 0.85. Depending on these factors, the effective thermal conductivity ranged from 1.75 to 8.19 W·m−1·K−1. This accounts for 0.03 to 0.25 of the value of thermal conductivity of the solid phase of the charge, which in the described cases was low-carbon steel. It was found that the effective thermal conductivity rises linearly with temperature. The intensity of this increase and the value of coefficient kef depend on the transverse dimension of the components that form the charge. The results may represent the basis for the validation of various models of effective thermal conductivity with respect to the evaluation of thermal properties of the porous charge.

The reactor research and test facility

The paper describes an overview of the history of development and the current state of JSC “SSC RF-IPPE” reactor research and test facility designed for assembly, research and full-scale life energy tests of space nuclear power plants with a thermionic reactor. The leading specialists involved in development and operation of this facility are represented. The most significant technological interfaces and upgrade operations carried out in the recent years are discussed. The authors consider the use of an oil-free pumping system as part of this facility during degassing and life testing. Proposed are up-to-date engineering solutions for development of the automated special measurement system designed to record NPP performance, including volt-ampere characteristics together with thermophysical and nuclear physical parameters of a ground prototype of the space nuclear power plant. Key words: reactor research and test facility, thermionic reactor, life energy tests, oil-free pumping system, automated special measurement system, volt-ampere characteristics.

State primary measurement standard of ultrasound power unit in water GET 169-2019

Results of works on improvement of the state primary special measurement standard of ultrasound power unit in water GET 169-2005 are given. As a result of the inclusion of two new reference ultrasound power meters in the standard, the frequency and dynamic ranges of reproduction and transmission of the power unit to lower-level measuring instruments were expanded using absorbing targets for measuring the radiation effect of the ultrasonic wave and the absorbed ultrasonic energy. That is very important for metrological support of modern high-tech medical ultrasound equipment, including focused high-intensity ultrasound beams for the treatment of cancer. The automation of the measurement process used in the updated standard has reduced significantly the complexity of verification procedures increasing the accuracy of measurements.

The concept of measurement of calorific value of gaseous fuels

The issue of measuring and determining the calorific value of fuels is related to thermodynamic analysis of the effects of the combustion process aimed at determining the amount of heat transferred to the environment. Currently, there are several methods for determining the calorific value of fuels and their methodology is related to the type of fuel being analyzed. These methods are quite complicated and require the use of specialized measuring equipment. The energy demand of modern civilization along with the need to protect the natural environment prompts the search for new ways to generate energy directed at sources other than conventional fossil fuels. Technologies related to the use of biogas, synthesis gas obtained in biomass or waste gasification processes are being introduced. The use of these fuels in industrial processes of generating heat and electricity requires caloric stability of the fuel. The caloric stability of the fuel is necessary to ensure the stability of thermal energy conversion processes that translate directly into the set values of generated electricity using electric machines. One way to assess the energy quality of a fuel is to measure its calorific value. There are several methods for determining the calorific value of a fuel, but they all require special measurement conditions. The article presents the author’s concept of a calorimeter dedicated to the analysis of the calorific value of gaseous fuels.

Target simulation for UHF RFID DoA estimation systems

In this work a new method for the evaluation of UHF RFID Direction of Arrival (DoA) estimation systems is developed and demonstrated. Instead of simulating the system performance or manually measuring it in realistic or ideal environments, a method for the evaluation of DoA systems using received signals produced by a target simulator is proposed. The simulator generates the signals for each channel of the DoA estimator by attenuating and phase shifting the signals of an UHF RFID chip to replicate the signal propagation conditions for a chosen tag distance and arrival angle. This combines the advantages of the simulative approach and real world evaluation: it is fast, reproducible and doesn't require special measurement environments. To facilitate this method, plane and spherical wave signal models for the simulation of RFID targets are derived, multichannel phase-shifting and attenuation hardware for the simulation of such signals is presented and a demonstrative evaluation of a RFID DoA estimation system is performed, replicating evaluation scenarios in non reflective and multipath environments.

Temperature and moisture distribution in a highway in south-eastern Kazakhstan

The matters of investigation for water thermal regime of pavement and subgrade structures of the highways are especially important as the moisture and temperature distribution in pavement and subgrade layers impact greatly on their deformation and strength indicators. Experimental results, which can be obtained by special measurement devices, are primary ones for establishing of peculiarities and regularities for distribution and migration of heat and moisture in the mentioned structural elements of the highways. Special measurement devices are required to obtain such experimental data. The paper shows the results for analysis of temperature and moisture variation in points of pavement and subgrade of “Almaty-Bishkek” highway. Temperature measurement has been performed by set of special sensors. Regular temperature and moisture measurement have been performed for the period from September 18, 2015 to June 2, 2016. Regularities for temperature regime variation in points of pavement for 24 hours are coordinated with air temperature variations. Amplitude of vibration for temperature is decreased with the depth increase. Moisture in subgrade points is gradually decreased with the reduction of daily average air temperature.