Effect of Cavitation Flow on Energy Conversion Characteristics of Nuclear Main Pump

In order to study the relationship between the cavitation flow and energy conversion, based on the continuity equation, Renault N-S equation and RNG k-ε turbulence model, the whole flow field cavitation numerical simulation on unclear main pump model under design condition is carried out. Through the variation of pressure and velocity on the streamlines, combined with the basic equation of the pump, the dynamic and hydrostatic head of the nuclear main pump under different cavitation conditions are studied. The results show that the energy of fluid of nuclear main pump is provided by posterior segment of impeller, and the energy of the fluid decreases gradually from the shroud to the hub. Cavitation interferes with the flow of liquid in the impeller, which leads to the relative velocity increases and the pressure decreases in cavitation region, and the work capacity of blades is almost zero in bubble areas. At the same time, in non-cavitation region along with streamlines the dynamic head increases and the hydrostatic head decreases with the development of cavitation, and the decrease of the hydrostatic head is greater than the increase of the dynamic head, which results in the decrease of pump head and efficiency. In addition, in the cavitation region, with the development of cavitation, the sudden change of the dynamic and hydrostatic head increases, which increase the flow loss in the impeller and results in the decrease of pump head and efficiency moreover.

Falling film evaporators in beet and cane sugar industry

The falling film evaporator has been widely used in the beet sugar industry for more than 30 years. This technology has been adapted and optimized for cane sugar factories addressing the increased risks of incrustation of the juice distribution system and heating surface due to an increased scaling propensity of cane juice. The developments carried out by Fives on falling film evaporator permitted the elimination of these problems. The absence of a hydrostatic head means that for the same thermal power, lower Ts are possible, especially for intermediate and last effects of the evaporator station. Thus, reconfigurations of the bleedings may be possible, achieving lower steam consumptions than can be obtained with other evaporator technologies.

IMPACT OF SMALL HYDROPOWER PLANTS ON PHYSICOCHEMICAL AND BIOTIC ENVIRONMENTS IN FLATLAND RIVERBEDS OF LITHUANIA

The impact of a small hydropower plant (SHP) on river water quality and macroinvertebrates has been investigated in 5 Lithuanian rivers and involved 17 dams of which ten are in a sequence in the same river system. The hydrostatic head of SHP dams ranged from 2.75 to 14.50 m and the capacities of their reservoirs varied from 40×103 to 15,500×103 m3. Physicochemical characteristics, as well as macroinvertebrate communities, were evaluated in sites above and below the SHP dams comparing them with reference sites. It was established that construction of SHP dams (H15 m) in Lithuania substantially changed regimes of suspended solids, fine particles and nutrients only locally regardless of hydrostatic head of the dam. Compared to reference sites, SHP reservoirs and sites below SHP dams had relatively more Chironomidae larvae and Oligochaeta, and less Coleoptera larvae as well as the relative abundance of pollution-sensitive Ephemeroptera and EPT. Water quality according to biotic indexes (DSFI and HBI) in the sites influenced by SHP dams was recognised to be moderate or poor, but impact was only local. This suggests that increment of catchment’s area and intensive land use for agriculture within the river basin plays more important role than SHP dams

Small Hydro Plant Using Archimedes Screw: Modeling and Analysis

In this paper we introduce a small hydro plant that uses Archimedes screws. This is an alternate solution to small-scale hydropower as it exploits unused resources such as small rivers or streams. Based on hydrological study, we developped a theoretical static model to estimate the annual energy production depending on flow rate, hydrostatic head and Archimedes screw efficiency variations. Then, we studied the flood and low-water periods in order to exclude harmful climatic events of the annual energy production estimation, used for the Archimedes screw design.

Investigates of Fabric Coating Approaches: Parameters for Fabric Performance

This study examined the effect of the coating speed, coating solution, cure temperature, knife gap and fabric matrixes on surface properties, water vapor permeability and hydrostatic head test. The optimum conditions for surface high water vapour permeability that enables the user to “dial in” the right balance of properties based on the findings of the experimental. This sample showed high excellent resistance to +7m in hydrostatic head tests for a single-layer coated fabric and. Surface morphology showed that the coating was continuous without cracks or pin holes and appeared to be well adhered to the substrate even after a harsh wash.

Study on Relationship between the Groove Structure and Efficiency of Electromagnetic Pump Used in Aluminum Alloy Casting

The relationship between the groove structure of the direct current plane electromagnetic pump and efficiency has been investigated in this paper. Methods By using mercury as working medium, experiments have been conducted through simulation of direct current plane electromagnetic pump. The comparision of efficiencies is obtained by measuring the values of hydrostatic head of various groove structures under the fixed working parameters are measured. The groove structure of the electromagnetic pump has a great influence on its hydrostatic head and its relative efficiency. Several important ways can be used to improve the efficiency of the electromagnetic pump including restraining the overflow of working current, optimizing the direction of the electrolines, reducing the inner surface area of the groove and increasing the entrance force.