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Pressure drop is one of the most important parameter to evaluate the performance of venturi scrubber. A prototype self-priming venturi scrubber having throat length of 0.11m and diameter 0.034m is used. The throat gas varies from 30 to 220 m/s and liquid flow rate from 0.2 to 1.7 l/m3. Yung's model for pressure drop is modified to predict pressure drop in self-priming venturi scrubber. The experimental results show good agreement with the proposed model.

This article focuses on the development of an improved particle swarm optimization algorithm and its application in the optimal design of the nuclear power system, whose goal is to find a combination of system parameter values that minimize the weight of the system given the power capacity requirement and safety criteria. An improved particle swarm optimization (IPSO) algorithm was developed using the feasibility rule constraints handling method, crossover and mutation operator. Using the improved compound shape algorithm to do the local search after the particle swarm reaches a satisfactory point. The algorithm gave satisfactory optimization results from both search efficiency and accuracy perspectives. This IPSO successfully solved the design optimization problem of nuclear power system. It is an advanced and efficient methodology that can be applied to the similar optimization problems in other areas.

Conceptual design of advanced passive residual heat removal system in which density lock is applied is proposed, moreover theoretical analysis and experimental study on its feasibility is carried out. According to the design, atmospheric-pressure experimental loop is built so that researches on working performance of density lock in the system are done at steady-state operation and pump trip conditions. The results show that at steady-state operation conditions, density lock can keep close in a long run, which will separate passive residual heat removal system from primary circuit system. As a result, passive residual heat removal system is in the non-operating conditions, which do not influence normal operation of reactors. At the pump trip conditions, density lock can be automatically opened quickly, which will make primary and passive heat removal system communicated. The natural circulation is well established in the two systems, and is enough to ensure removal of residual heat. In addition, experimental study on operating reliability of density lock is made on the condition of small flow surge. The result show that the flow surge do not lead to the failure of the function of density lock, but bring about a little position change of temperature interface in the density lock, moreover, a new balance steady state will arrive very soon.

A lot of the lubricating-oil cooler with mixing integral pin-fin bundles were studied experimentally. The one shell-pass and two shell-pass cooling experiments have been done with the same flow area of the shell. The characteristics of heat transfer and flow resistance were analyzed. Compared a one shell-pass with Double shell-pass arrangement, heat transfer capacity unit volume is 1.5 times ; heat transfer coefficient is 1.3 times; shell side pressure drop less than a third. Experimental results for process selection and arrangement of tube reference. At last heat transfer equation from experimental was suggested for engineering application in the paper.

Reactor coolant pump is a key equipment in nuclear power plants, which has direct impact on the overall weight and the arrangement of nuclear power plants. The optimization design of the weight of the reactor coolant pump is carried out based on colony complex algorithm. Gradient crossover genetic algorithm is also used to optimize the weight of the pump's inner motor for attaining the optimization result of the pump. Both the algorithms are developed ourselves. The results show that the optimized weight is 12.482% less than the prototype's, the optimization effect is obvious. The start-up transient and flow coast down transient of the optimized pump are analyzed. The results indicate that the optimized results are feasible. The effects of the operating parameters of primary loop and rotating speed of pump on the weight of reactor coolant pump, and the effects of relevant parameters on the weight of motor is also analyzed in this paper. The corresponding results can provide a reference for engineering design.

Lots of experimental researches have been done to a plain tubes segmental baffles lubricating-oil cooler and integral pin-fin tube cooler and the new lubricating-oil cooler made from integral pin-fin tubes and plain tubes mixing in bundles and with double-flow. It is introduced that oil mass flow rate has great influence on coolers performance. Heat transfer coefficient, pressure drop, the heat of unit volume and integrated performance k/ΔP changing with oil mass flow rate are analyzed, on which the choose of lubricating-oil cooler can be based.

A lot of experimental research has been done to two kinds of new oil coolers using the pin-fin tube as the heat transfer elements, of which one form is longitudinal flow and the other one is crosswise flow . It was found that the heat transfer coefficient of the former one is 2.2 times as big as that of the latter one when the flow rate is (0.5kg/s) and the number of tubes is the same. The results showed that the longitudinal flow cooler with integral pin-fin tubes owns high heat transfer capacity but low pressure drop in the shell side. Especially in low flow rate the integrated performance is superior. For the integral pin-fin lubricating-oil cooler, it is suggested the flow direction should be longitudinal, which means the flow direction is parallel to the heat transfer tubes.

The integral pin-fin tube is a new type of non-continuous finned tubes, increasing the effective heat transfer area, while its non-continuous fin structure can strongly stimulate the fluid boundary layer separation, to achieve enhanced heat transfer effect. Using fluent software three-dimensional numerical simulation on integral pin-fin tube is got. The results is accord to the actual situation, verifies the fluent software on integral pin-fin tube complex numerical simulation method is feasible, wile for the pin-fin tube heat exchanger simulation study provides some reference. In the energy conversion system of the nuclear power plants, the oil cooler is a large heat exchanger, as the development of heat transfer enhancement technology in recent years (1); oil cooler miniaturization technology is further researched. Integral pin-fin tube as a new type of non-continuous finned tubes, increasing the effective heat transfer area of the fin can also damage the fluid formed in the wall boundary layer, and make the near wall fluid and the fluid outside the mainstream effectively and strongly mixed, forming secondary flow and increasing the heat transfer effect greatly. As the pin-fin tube is complex, previous studies are mostly experimental research, in recent years with large-scale heat transfer equipment and high-parameter; numerical simulation of heat exchanger has been great developed (2-3). In this paper, the integral pin-fin tube heat exchanger components used as the oil cooler, with different flow rates, the integral pin-fin tube side of the velocity field, temperature field and pressure field have been numerically simulated by Fluent on three-dimensional condition, and pin-fin structure effect on flow and heat exchange is also studied microcosmically. The simulation results agree with the actual situation, and the feasibility of numerical simulation method is verified. II. SIMULATION MODEL A. Geometric model

The design A lot of comparison experimental researches have been done to the lubricating-oil cooler with mixing integral pin-fin tubes and plain tubes double-flowing from an plain tubes lubricating-oil cooler. It is discovered that when oil volume flowing rate is same, exchanged heat per volume by the former is higher, and the pressure is lower, and the ability to transferred heat is better. What's more, integrated performance is excellent, which makes lubricating-oil cooler miniaturize in the same heat changing condition.

In view of the character that wetness measurement for steam is difficult and inaccurate, a novel sensor of wetness measurement for flowing wet steam is developed by making use of capacitance method based on the fact that the water and steam have great different permittivities. The sensor can be installed in the steam pipe directly, so the steam will flow through it with full flow rate. Therefore the error due to drawing steam sample inaccurately is eliminated. By means of this sensor, on‐line measurement of the wetness of wet steam can be realized. Based on the fact that air and steam have almost same permittivities, the flowing wet steam is simulated by spraying water into air flow in the experiment. Experiment with the novel sensor of wetness measurement in water/air flows shows that the frequency output decreases as the absolute humidity of flowing wet air increases. The relationship between the absolute humidity of air and the relative frequency deviation are obtained from the experimental data and this result accords with the theoretic conclusion. The sensor can endure high temperature and high pressure and has preferable precision, so it can be used to measure not only the wetness of flowing wet steam in nuclear power plants but also the water content of solid materials on‐line after precise calibration.

A series of experimental studies of frictional pressure drop for single phase and two-phase bubble flow in smooth rolling tubes were carried out. The tube inside diameters were 15 mm, 25 mm and 34.5 mm respectively, the rolling angles of tubes could be set as 10 deg. and 20 deg., and the rolling periods could be set as 5 s, 10 s and 15 s. Combining with the analysis of single-phase water motion, it was found that the traditional correlations for calculating single-phase frictional coefficient were not suitable for the rolling condition. Based on the experimental data, a new correlation for calculating single-phase frictional coefficient under rolling condition was presented, and the calculations not only agreed well with the experimental data, but also could display the periodically dynamic characteristics of frictional coefficients. Applying the new correlation to homogeneous flow model, two-phase frictional pressure drop of bubble flow in rolling tubes could be calculated, the results showed that the relative error between calculation and experimental data was less than {+-} 25%. (authors)

The Passive Residual Heat Removal System (PRHRS) is very important for the safety of the heating reactor after shutdown. PRHRS is a natural circulation system driven by density difference, therefore, the heat transfer performance of the Passive Residual Heat Removal Heat Exchanger (PRHR HX) has a great impact to the heat transfer efficiency of PRHRS. However, the most research object of PRHR HX is the C-shape heat exchanger at present, which located in In-containment Refueling Water Storage Tank (IRWST). This heat exchanger is mainly used for the PRHRS of nuclear power plants. In the swimming pool-type low-temperature heating reactor (SPLTHR), the PRHR HX is placed in the reactor pool, which the pressure and temperature of the reactor pool are relatively low, and the outside heat transfer mode of tube bundle is mainly natural convection heat transfer. In this study, a miniaturized single-phase pool water cooling system was built to investigate the natural convective heat transfer coefficient of the heat exchanger under the large space and low temperature conditions. The experimental data had been compared with several correlations. The results show that the predicted value of Yang correlation is the closest to the experimental data, which the maximum deviation is about 11%.