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[en] The contribution under consideration reports on a gamma denitometric measurement of gas concentrations in a vertical heated tube bundle which is flowed around by a fluid. Two measurement positions, two flow rates of the circulating fluid, two subcooling values and eleven heat fluxes were selected for the measurement. The authors of this contribution describe the test facility, measurement methodology, results and their interpretation. The measurement uncertainty is described in detail.
[en] The purpose of this study was to investigate the effect of long-term aging on the thermal stability and chemical structure of seven different ILs so as to explore their suitability for use as a heat transfer fluid. This was accomplished by heating the ILs for 15 weeks at 200 °C in an oxidizing environment and performing subsequent analyses on the aged chemicals
[en] The Korea Atomic Energy Research Institute (KAERI) has developed key technologies in preparation of the 'nuclear hydrogen demonstration and development plant' since 2006. In particular, this paper focuses on the experimental research related to high temperature gas loops and a passive cooling test facility. A nitrogen gas loop was constructed in 2007. The design features and test scope are explained using some results obtained from the validation test for the design concept of a process heat exchanger. In the next step, a helium experimental loop was introduced, which was built for verifying bench-scale prototypes of key components in a very high temperature gas-cooled reactor (VHTR). Another test facility for verifying the passive cooling capability of VHTR was designed at the 1/4 scale and the construction started in 2013. The design features and related experimental studies are described in detail. (author)
[en] The work presented here concerns the measurement of heat transfer in a cryogenic tank with several configurations. The experimental test incorporates the conductive heat in the neck, the convection heat transfers between the inner wall of the neck and the ascending vapor resulting from boiling, and the radiation heat transfers between the external envelope and the tank through a vacuum of 10-8 mm Hg. An experimental prototype was produced in collaboration with the nuclear center of Orsay in France according to a didactic design, which takes into account the Wexler effect and the importance of the radiation compared to the conduction-convection heat transfer. The addition of a screen radiative ventilated with variable position on the neck (which can effectively replace several tens of floating screens), in order to find the optimal position, which minimizes the radiation flux, is presented in this paper
[en] The interface between the Next Generation Nuclear Plant (NGNP) and the hydrogen-generating process plant will contain an intermediate loop that will transport heat from the NGNP to the process plant. Seven possible configurations for the NGNP primary coolant system and the intermediate heat transport loop were identified. Both helium and liquid salts are being considered as the working fluid in the intermediate heat transport loop. A method was developed to perform thermal-hydraulic evaluations of the different configurations and coolants. The evaluations will determine which configurations and coolants are the most promising from a thermal-hydraulic point of view and which, if any, do not appear to be feasible at the current time. Results of the evaluations will be presented in a subsequent report
[en] The thermal conductivity of traditional heat transfer fluids is inherently low. Metals or metal oxide in ultra-fine form have orders of magnitudes higher thermal conductivity of those of fluids. So it is a need to understand the fundamental behavior of the metals or metal oxides nanoparticles in base fluids. ZnO is a semiconductor but has a wide range of application. In this study the thermal conductivity and viscosity will be discussed in details with experimental and theoretical models. The application of ZnO based nanofluids will be very much useful in nuclear fusion
[en] Compared to the pure refrigerants, the zeotropic refrigerant mixtures have the obvious temperature glide during phase change. Therefore, the Lorenz cycle can be approached with this special attribute. By analysing the heat transfer in the counter flow heat exchanger, a new evaluation method for zeotropic refrigerant mixtures based on the variance of the temperature difference between the refrigerant and heat transfer fluid (HTF) is proposed in this paper. For approaching to the Lorenz cycle and perfect glide matching, the zeotropic mixture which has smaller variance in the heat exchanger should be chosen in the refrigeration cycle. The variance of temperature difference is affected by two factors which are the temperature difference between the inlet and outlet of HTF and the linear relationship between the refrigerant temperature and enthalpy, respectively. The smallest variance of the zeotropic refrigerant can be obtained by setting the temperature difference of HTF to be the optimal temperature difference.
[en] A design study was conducted to evaluate the cost-effectiveness of solar thermal power generation in a 50 kWe power plant that could be used in a remote location. The system combines a solar collector-thermal storage system utilizing a heat transfer fluid and a simple Rankine cycle power generator utilizing R123 refrigerant. Evacuated tube solar collectors heat mineral oil and supply it to a thermal storage tank. A mineral oil to refrigerant heat exchanger generates superheated refrigerant vapor, which drives a radial turbogenerator. Supplemental natural gas firing maintains a constant thermal storage temperature irregardless of solar conditions enabling the system to produce a constant 50 kWe output. A simulation was carried out to predict the performance of the system in the hottest summer day and the coldest winter day for southern California solar conditions. A rigorous economic analysis was conducted. The system offers advantages over advanced solar thermal power plants by implementing simple fixed evacuated tube collectors, which are less prone to damage in harsh desert environment. Also, backed up by fossil fuel power generation, it is possible to obtain continued operation even during low insolation sky conditions and at night, a feature that stand-alone PV systems do not offer. (author)
[en] It has been proposed to introduce a new parameter into the practice of the heat calculation and testing of the flat-plate solar water-heating collectors (FSWHCs)—the coefficient of heat transfer from the light-absorbing panel (LAP) to the heat transfer fluid in its internal heat-exchange channels (HECs) reduced to the unit area of the frontal surface of their cases. The mechanism of the formation of this parameter is studied, the design expression is derived, and a practical example of the calculation to define its value is performed. The structures of the flowing LAPs of a sheet-piped thin parallelepiped form are selected as the objects of the investigation. The reliability of the results of the investigations is proved by comparing the values of the specific (relative to the area unit of the frontal surface of the case) heating efficiency of the collector obtained based on the various formulas.
[en] The free convective MHD flow of a non-Newtonian electrically conducting fluid past an infinite vertical porous plate in the presence of constant suction and heat absorbing sinks has been discussed. To obtain the solutions for the velocity and temperature fields, mean skin-friction and mean rate of heat transfer the multi-parameter perturbation approximation is used. Expressions for dimensionless velocity, temperature, mean skin-friction and mean rate of heat transfer at the plate have been obtained and numerically worked out for different values of parameters involved in the solution. The mean skin-friction and mean rate of heat transfer have been presented numerically and the dimensionless velocity and dimensionless temperature have been presented graphically for various values of non-Newtonian parameters. (author)