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[en] Highlights: • Field test was conducted on high-level cooling tower under crosswind conditions. • Inflow air uniformity coefficient decreases with the rising of crosswind velocity. • The uniformity coefficient decreases to 0.61 and 0.49 under θ1 = 5° and θ2 = 35°. • In 3.74 m/s, the ventilation rate reduces by 30.13% under 5° condition. • The ventilation performance is better under 5° condition. - Abstract: Field test was performed on the high level water collecting wet cooling towers (HWCTs) of a 1000 MW unit to investigate ventilation performance under crosswind conditions, the circumferential inflow air distribution rules and ventilation rate were analyzed in this paper. The test results manifest that crosswind destroys the uniformity of circumferential inflow air, increases the wind velocity in the windward side, and reduces wind velocity in the lateral and leeward side. Moreover, the uniformity coefficient of circumferential inflow air and ventilation rate continuously decrease with the increasing of crosswind velocity. In this study, θ represents the angle between cross walls and crosswind direction. When crosswind velocity reaches to 3.74 m/s, the uniformity coefficient decreases to 0.61 and 0.49 under θ1 = 5° and θ2 = 35°. Compared with 0.28 m/s condition, the ventilation rate reduces by 30.13% under θ1 = 5° and 34.36% under θ2 = 35°. Additionally, at the same crosswind velocity, the smaller the θ is, the better the ventilation performance becomes. Compared with θ2 = 35°, the uniformity of circumferential inlet air is better and the ventilation rate is larger than that under θ1 = 5° condition.
[en] This paper presents the measurement and analysis results for the performance of HGCHP system using a cooling tower as a supplemental heat rejector. In order to demonstrate the performance of the hybrid approach, we installed the monitoring equipments including sensors for measuring temperature and power consumption, and measured operation parameters from February 1, 2014 to February 28, 2015. Leaving load temperatures to building showed an average value of 11.7℃ for cooling and 39.5℃ for heating, respectively. From the analysis, the daily PF of hybrid GCHP system varied from 2.6 to 6.6 over the measurement period.
[en] Highlights: • A half-cylindrical NDDCT CFD model is built and validated by a hot state test rig. • FLF is derived and verified to quantitatively describe flow characteristics effect. • Rear side flow separation area and main stream vortices are critical to ventilation. • The contributions of each flow field region on ventilation degradation is exhibited. • Flow convergence are transformed to be vortices barrier under high crosswind. - Abstract: The natural draft dry cooling tower (NDDCT) is a critical facility for an indirect dry cooling power plant in arid area for its merit of excellent water-saving. While crosswind degrades the performance of a NDDCT by changing the flow field inside and outside. In order to quantitatively study the influence of different flow characteristics on the performance of a NDDCT, hence to grasp the affecting mechanism of crosswind, a half-cylindrical computational fluid dynamics (CFD) model of a Heller type 660 MW NDDCT is developed and validated by a hot state modelling test rig. A flow loss factor (FLF) is derived and verified to linearly describe the effect of local flow field changing on the overall performance of a NDDCT. Based on the conjoint studies of the local FLF variation trends and the changing processes of correspondent flow characteristics in each specific flow segments, the critical factors influencing the performance of a NDDCT are identified under different crosswind conditions.
[en] An outcome of the Joint Review Panel that evaluated the proposal by Ontario Power Generation (OPG) for the Darlington New Nuclear Project was that OPG must undertake a formal quantitative cost-benefit analysis for cooling tower versus once-through condenser cooling water systems. While OPG's analysis concluded the preference for the once-through condenser approach, the possibility for using cooling towers remains. This paper presents an analysis of the different cooling tower designs that could be used for a potential CANDU new build at the Darlington Site. The work was completed in partial fulfilment of the requirements of a capstone design project by a group of nuclear engineering students. The project considered the various cooling tower designs used in similar applications for both nuclear and thermal power plants, and identified the preferred option based on criteria such as: energy penalty, cost, thermal/aquatic effects, social acceptance and land use. (author)
[en] The paper considers the operating effect of the evaporative cooling towers of the Belarusian NPP on the formation of the local microclimate. The formation mechanisms and conditions for the occurrence of such natural phenomena of fogging and icing are analyzed. Mathematical modeling of the dynamics of moisture-containing emissions from the cooling tower was carried out taking into account the moisture content of the environment and the processes of icing. In order to determine and predict ice loads on power lines, an example of modeling the icing process is given: the deposition of liquid droplets on the surface of the wire, the calculation of the thickness and shape of the layer of ice formed. (authors)
[en] Highlights: • A mass transfer coefficient correlation is developed for ceramic foam packing. • The correlation is evaluated by experimental data. • The effects of pressure and inlet conditions on heat and mass transfer are analyzed. - Abstract: The cooling tower model is simple but has necessary precision for the packing design and outlet conditions forecast of the humidifier, especially under the pressure and temperature level of micro humid air turbine. This research focuses on developing a mass transfer correlation of the novel ceramic foam packing, which has the potential to be used in humidification. The heat and mass transfer properties of the packing are investigated with the mass transfer coefficients calculated from 105 groups of experimental data, and the effects of pressure, water/air mass flow ratio, inlet water temperature and inlet air enthalpy are analyzed. It is shown that the mass transfer coefficient increases with the increase of water/air mass flow ratio, but decreases with the increase of inlet water temperature and inlet air enthalpy. The effect of pressure on heat and mass transfer is related with air mass flow. A dimensionless group correlation of mass transfer coefficient is developed and evaluated. It is shown that the deviations between the predicted and experimental values are estimated within ±12% for 75% experimental conditions. The developed correlation can be used to predict the packing height and the water/air outlet conditions of the ceramic foam packing humidifier.
[en] The response of the San Pietro monumental bell-tower located in Perugia, Italy, to the 2016 Central Italy seismic sequence is investigated, taking advantage of the availability of field data recorded by a vibration-based SHM system installed in December 2014 to detect earthquake-induced damages. The tower is located about 85 km in the NW direction from the epicenter of the first major shock of the sequence, the Accumoli Mw6.0 earthquake of August 24th, resulting in a small local PGA of about 30 cm/s2, whereby near-field PGA was measured as 915.97 cm/s2 (E–W component) and 445.59 cm/s2 (N–S component). Similar PGA values also characterized the two other major shocks of the sequence (Ussita Mw5.9 and Norcia Mw6.5 earthquakes of October 26th and 30th, respectively). Despite the relatively low intensity of such earthquakes in Perugia, the analysis of long-term monitoring data clearly highlights that small permanent changes in the structural behavior of the bell-tower have occurred after the earthquakes, with decreases in all identified natural frequencies. Such natural frequency decays are fully consistent with what predicted by non-linear finite element simulations and, in particular, with the development of microcracks at the base of the columns of the belfry. Microcracks in these regions, and in the rest of tower, are however hardly distinguishable from pre-existing ones and from the physiological cracking of a masonry structure, what validates the effectiveness of the SHM system in detecting earthquake-induced damage at a stage where this is not yet detectable by visual inspections.
[en] Preliminary design of offshore wind turbines requires high precision simplified methods for the analysis of the system fundamental frequency. Based on the Rayleigh method and Lagrange’s Equation, this study establishes a simple formula for the analysis of system fundamental frequency in the preliminary design of an offshore wind turbine with a monopile foundation. This method takes into consideration the variation of cross-section geometry of the wind turbine tower along its length, with the inertia moment and distributed mass both changing with diameter. Also the rotational flexibility of the monopile foundation is mainly considered. The rigid pile and elastic middle long pile are calculated separately. The method is validated against both FEM analysis cases and field measurements, showing good agreement. The method is then used in a parametric study, showing that the tower length Lt, tower base diameter d0, tower wall thickness δt, pile diameter db and pile length Lb are the major factors influencing the fundamental frequency of the offshore wind turbine system. In the design of offshore wind turbine systems, these five parameters should be adjusted comprehensively. The seabed soil condition also needs to be carefully considered for soft clay and loose sand.
[en] Mechanical filters are very important to ensure smooth operation of the secondary cooling system. The present condition of the mechanical filter treatment duration of PA-02 BT001 is increasing compared to other mechanical filters (PA-01 BT001 and PA-03 BT001). Seeing these conditions, it is very important to conduct an evaluation / study to find the cause and resolution through operating data starting in 2010 - 2017, collection of maintenance data starting from 2010 - 2017. After evaluation and review it can be concluded that the mechanical filter causes (PA-02 BT001) maintenance is most often compared to other mechanical filters, this is due to the location of the mechanical filter (PA-02 BT001) located on the side of the pipe straight at the far end so that dirt and lichen will be carried to the section. Besides this, PA-02 BT001 also serves cooling towers on the outside so that the growth of moss is more than the others. Based on these results, it is very important to review the mechanical filter operating schedule, maintenance scheme and the use of anti-moss in secondary cooling system water. (author)