[en] Regenerated air (reverse Brayton) cycle has unique potentials in heat pump applications compared to conventional vapor-compression cycles. To better understand the regenerated air heat pump cycle characteristics, a thermodynamic model with new equivalent parameters was developed in this paper. Equivalent temperature ratio and equivalent isentropic efficiency of expander were introduced to represent the effect of regenerator, which made the regenerated air cycle in the same mathematical expressions as the basic air cycle and created an easy way to prove some important features that regenerated air cycle inherits from the basic one. Moreover, we proved in theory that the regenerator does not always improve the air cycle efficiency. Larger temperature ratio and lower effectiveness of regenerator could make the regenerated air cycle even worse than the basic air cycle. Lastly, we found that only under certain conditions the cycle could get remarkable benefits from a well-sized regenerator. These results would enable further study of the regenerated air cycle from a different perspective. - Highlights: • A thermodynamic model for regenerated air heat pump cycle was developed. • Equivalent temperature ratio and equivalent expander efficiency were introduced. • We proved regenerated air cycle can make heating capacity in line with heating load. • We proved the regenerator does not always improve the air cycle efficiency.

[en] It is discussed about the importance of detecting SNM in anti-nuclear terrorism and SNM detection technology. (authors)

[en] The spent fuel pool cooling system in a nuclear power plant, which is comprised mainly by the cooling pumps and heat exchangers, ensures the safety of the spent fuel assemblies and the integrity of the fuel rods during the period of storage. With the development of the passive cooling technique, a spray cooling system for the spent fuels based on the gravity was designed to further enhance the safety of the spent fuel pool in case of accident conditions. This paper presents an experimental investigation of the validity of the spray-cooling system using two types of tight rod bundles, namely a 5 x 5 heated rod bundle and a 17 x 17 isothermal rod bundle. Results shows that the rod bundle heated with a lower power can be effectively cooled only by air without any spray water. With the increase of the heated power, the rod surface temperature increases gradually and the spray cooling has to be implemented to maintain the wall temperature at a certain level. The effect of flow rate on wall temperature was investigated. For the isothermal rod bundle, main interests were focused on the distribution of the spray water after it flowed along the rods.

[en] Using functional renormalization group method, we studied the phase diagram of the one-dimensional extended Hubbard model at different dopings. At half filling, variety of states strongly compete with each other. These states include spin-density wave, charge-density wave, s-wave and p -wave superconductivity, phase separation, and an exotic bond-order wave. By doping, system favours superconductivity more than density waves. At 1/8 doping, a new area of extended s-wave superconductivity emerges between charge density wave and bond-order wave regions. If the system is doped to 1/4-doping, a new area of p -wave superconductivity emerges between charge-density wave and spin-density wave regions. (paper)

[en] A series of Th and F co-doped superconductors Sm_1–xTh_xFeAsO_1–yF_y are synthesized and the variation of superconductivity with the doping level is investigated. At the fixed Th doping level x = 0.1, the superconducting transition temperature T_c increases monotonically with F content, and finally T_c reaches a maximum of about 55K around y = 0.1, and saturates for even more F content (y = 0.15). Similar to the SmFeAsO_1–yF_y system, the normal state thermopower increases monotonically with the doping level. However the decrease of T_c in the 'overdoped' regime is not observed and possible explanation is discussed

[en] Temperature dependence of the upper critical magnetic field (H_c2) near T_c of 20 K in a BaFe_1.9Ni_0.1As₂ single crystal is determined via magneto-resistance measurements, for the out-plane (Hperpendicularab) and in-plane (H || ab) directions in magnetic fields of up to 8 T. The upper critical fields at zero temperature estimated by the Werthamer-Helfand-Hohenberg (WHH) formula are μ₀H^||_c2(0) = 137 T and μ₀H^perpendicular_c2(0) = 51 T, both exceeding the weak-coupling Pauli paramagnetic limit (μ₀H_p = 1.84T_c). However, the WHH formula could overestimate the μ₀H^||_c2(0) value. The anisotropy of upper critical fields is around 3 in the temperature range close to T_c. The result is very similar to the Co-doped 122 superconductor BaFe_2–xCo_xAs₂, indicating that electron-doped 122 superconductors exhibit similar superconducting properties

[en] Highlights: • Experiment on pool boiling of a spent fuel bundle under dry-out condition. • Different exposed percentage of the bundle was considered. • Heat transfer coefficient of the bundle and two-phase flow pattern were studied. • Rod temperature won’t exceed 400 °C when the exposed percentage reached 45%. - Abstract: Under normal conditions, the decay heat of the spent fuel can be removed by the forced-circulation cooling system of the spent fuel pool. In the case of a system failure, the water level in the pool will be gradually decreased owing to an evaporation of the water, and the spent fuel bundles may be exposed to air, i.e., a dry out. Since the Fukushima accident, researchers have been paying significant attention to the safety of the spent fuel under such dry-out conditions. To study the boiling behaviour of the spent fuel bundle under a partial dry-out condition, an experimental investigation has been carried out. A newly constructed 9 × 9 heated tube bundle with the same geometry as the prototype spent fuel assembly in an AP1000 was used as the test section. Two-phase flow patterns were recorded. The heat transfer coefficient of the rods in different locations was obtained. A temperature fluctuation was observed at the beginning of the dry-out process mainly owing to the reduced heat transfer effectiveness of the steam. Although the maximum wall temperature (about 570 °C) exceeded the safety criterion when 50% of the tube bundle at the top end was exposed to air, the bundle maintained its integrity.

[en] Highlights: ► The salt and thermally modified clinoptilolite can effectively sorb NH₃-N and phosphates. ► The phosphorus and nitrogen removal was consistent with Langmuir isotherm model. ► The modified clinoptilolite possesses rapid adsorption and slow balance characteristics. ► The adsorption is more in line with the Elovich adsorption dynamics equation. ► The entropy effect plays the role of the main driving force in the adsorption. - Abstract: This paper presents the investigation of the ammonia-nitrogen and phosphates sorption from simulated reclaimed wastewater by modified clinoptilolite. The results showed that the modified clinoptilolite has a high sorption efficiency and removal performance. The ammonia-nitrogen and phosphates removal rate of the modified clinoptilolite reached to 98.46% and 99.80%, respectively. The surface of modified clinoptilolite became loose and some pores appeared, which enlarged the specific surface area; the contents of Na and Fe increased, and the contents of Ca and Mg decreased. The modified clinoptilolite possesses rapid sorption and slow balance characteristics and ammonia-nitrogen and phosphates sorption is more consistent with the Langmuir isotherm model. The adsorption kinetics of ammonia-nitrogen and phosphates follows the Elovich adsorption dynamics equation, which describes the sorption of ammonia-nitrogen and phosphates in aqueous solution as mainly a chemical sorption. Results from the thermodynamics experiment involving ammonia-nitrogen and phosphates sorption reveal that the process is a spontaneous and endothermic process, and is mainly driven by entropy effect.