[en] A series of experiments have been performed in a vertical tube of 9.4 mm inner diameter using the Freon, HFC-134a as working fluid medium under the supercritical pressure range. Two kinds of experiments, i.e. steady-state and pressure transient, have been carried out. As for the steady-state heat transfer experiment, the mass flux was in the range between 600 and 2000 kg/m2s and the maximum heat flux was 160 kW/m2. The selected pressures were 4.1, 4.3 and 4.5 MPa which correspond to 1.01, 1.06 and 1.11 times the critical pressure, respectively. In the pressure transient experiments, the inlet pressures were varied from 3.8 to 4.5 MPa and vice versa in the pressure transient simulations. In this study, heat transfer correlation and criterion for the heat transfer deterioration are suggested under the supercritical pressures. And also heat transfer characteristics during the pressure transient are examined

[en] Ions produced by crossed-beam collisions of pulsed monoenergetic electrons and supersonic expansion molecules have been analysed by time-of-flight mass spectroscopy (TOF-MS) in order to determine the appearance potentials, absolute total, dissociative and parent ionization cross sections and nascent ion kinetic energy distributions. The electron impact study was conducted at incident electron energies up to 100 eV on the parent CH₂F₂ molecule (and Ar/CH₂F₂ mixtures), a fluoromethane where the CH₂F⁺ ion is produced at higher yields (1:18) than the parent molecule ion, CH₂F₂⁺. TOF-MS band profiles analysis has enabled us to determine the ions' nascent kinetic energy distributions, information that combined with the dissociative ionization appearance potentials, calculated molecular orbital energies and orbital bond characters, leads to improved identification of the electron impact dissociative channels. (author)

[en] To understand heat transfer mechanism from general character and make clear the difference caused by properties, experiments of heat transfer to water and Freon R134a flowing upward in vertical tubes were conducted on SWAMUP and SMOTH test facilities, respectively. The variations of heat transfer coefficients of water and Freon with dimensionless temperature are coincident in the case of normal heat transfer, heat transfer enhancement and heat transfer deterioration due to buoyancy force and acceleration effect. The HTC ratio decreases with the increase of dimensionless parameter π_B. The HTC ratio increases first and then decreases with the increase of dimensionless parameters π_A. The dimensionless parameters π_B and π_A show better relevance on the supercritical water and Freon experimental data, respectively. The investigation of the heat transfer behavior of supercritical water in the SCWRs by means of model fluid Freon R134a is proved reasonable and feasible because of the similarity dependence on dimensionless parameters. (authors)

[en] Initial energy audit has been conducted in the framework of energy saving program in PSTBM - BATAN, from the result of initial energy audit of electric energy consumption one month is worth 41.871.27 kWh. With the target of Energy Consumption Intensity of PSTBM Building obtained at 13.56 kWh/m², the achievement target of IKE is categorized as efficient (8.5 - 14 kWh/m²) pursuant to Regulation of Minister of Energy and Mineral Resources, 13 in 2012, and quite efficient (12.08 - 14.58 kWh/m²) based on IKE Criteria Standard building based on the Ministry of National Education Year 2004. The initial energy audit was conducted in February 2017 by collecting historical data and then conducting a direct energy audit on all buildings in PSTBM. After completion, the data obtained were analyzed and then it was concluded that 40 buildings consumed most electricity at 29,990.78 kWh/month or about 73 %, and 41 buildings consumed at least 586.85 kWh/month or about 1 %. Electrical cooling from air conditioners is 74 % of most sectors in total, it is necessary to modify the cooling room with the latest AC technology using R410 type freon gas. The recommendation of this initial energy audit program is to carry out a detailed energy audit that will produce energy saving recommendations electricity. (author)

[en] A novel method of measuring the rate of nucleation of superheated drops and also the lifetime of metastable superheated drops accurately has been developed. The lifetime of superheated drops of Freon-12 has been determined by measuring the time dependence of the volume of vapour formed due to spontaneous nucleation of the drops using a relative water manometer. The time dependence of the nucleated volume of vapour indicates the presence of two lifetimes of decay of superheated droplets by spontaneous nucleation

[en] Metal optics is actively used in IR optics, which makes it necessary to clean it from dust and other operational contaminants. This increases the life of these notably expensive products. Usually their mechanical wiping is excluded, since it leads to the appearance of scratches and other defects on the surface, markedly increasing the scattering of radiation. Methods for the selection of solvents have been analyzed and experiments have been carried out that make it possible to accept efficient their use in the purification of metal optics from contaminations. Contaminations have different physicochemical properties and are present, as a rule, together on the surface of metal optics (taking into account the corrosion properties of the latter). Solvent compositions based on azeotrope mixes with freon-114B2, having a solubility parameter (δ) corresponding or close to the solubility parameter (δ) of the main (by weight) contamination or a mixture of contaminants which are present on the optical surface, were used. (paper)

[en] Experiments on Critical Heat Flux (CHF) of Freon-12 have been carried out in the rectangular vertical channels with gap sizes of 1 mm, 2 mm, and 3 mm, respectively. Analysis of CHF data in the different channels shows that CHF decreases as the increase of pressure, and while the exit quality rises, CHF falls down quickly. Meanwhile, CHF goes up as the mass velocity increases when the exit quality is lower, and contrarily, when the exit quality is higher, the increase of mass velocity results in the decrease of CHF. According to the analysis results, a conclusion can be drawn that gap sizes almost have no effect on the CHF in rectangular channels with gaps from 1 mm to 3 mm under the same condition in the experiment. (authors)

[en] This paper presents experimental results on the effect of various operating parameters on the synthesis of gas hydrates by a method based on the self-organizing process of boiling-condensation of a hydrate-forming gas in the volume of water. A series of experimental studies were carried out under various conditions, and optimal conditions that affect the process of hydrate formation were determined. The influence of the water column height and the boiling intensity of the hydrate-forming gas on the hydrate formation process is estimated. Freon 134a was used as a hydrate-forming gas in the studies.

No abstract available

[en] Experimental results of spacer grid effect on the heat transfer under supercritical pressure conditions are investigated. The experiments are carried out in an electrically heated 19-rod bundle cooled with supercritical Freon R134a. Standard spacer grids with blockage ratio of 0.29 are equipped into the bundle. The local wall temperatures and heat transfer coefficients along the flow direction of the bundle are measured. An interpolation method to determine the fully developed Nusselt number at supercritical conditions is reported. The results indicate that the enhanced heat transfer is limited within 30 bundle diameters downstream of the spacer grids. A peak heat transfer enhancement is observed near the pseudo critical region, which cannot be captured by the subcritical correlations. Considering the maximum heat transfer enhancement as a function of dimensionless temperature ratio, an original approach for deriving the grid-enhanced heat transfer correlation for supercritical applications is presented and the corresponding correlation has been established.