Investigation on Multi-Objective Optimal Design of a Two Pass Condenser

2013 ◽  
Author(s):  
Lei Chen ◽  
Chang-qi Yan ◽  
Jian-jun Wang
Keyword(s):  
Flow Rate ◽  
Optimization Design ◽  
Optimization Techniques ◽  
Coolant Flow ◽  
Geometric Constraints ◽  
Coolant Flow Rate ◽  
Coolant Temperature ◽  
Outer Diameter ◽  
Pressurized Water ◽  
Multi Objective

Condenser is one of the key components in nuclear power plant with pressurized water reactor. It is important to control the dimension and weight in the design of condenser through optimization techniques. In this paper, a mathematic model of a two pass condenser is set up for Qinshan I condenser. Some modifications are made based on the original multi-objective algorithm, and the comparison between modified algorithm and the original one is conducted. Furthermore, the multi-objective optimization design of the condenser, taking minimization of the coolant flow-rate and net weight as objectives, is carried out considering thermohydraulic and geometric constraints through hybrid Pareto-sorting multi-objective genetic algorithm (HPSMOGA). The sensitivities of some parameters, which may influence the coolant flow-rate and the net weight of condenser, are also analyzed. The results show that the mathematical model is agreeable for the condenser. it is also shown that the proposed multi-objective optimal method is more effective in searching non-dominated solutions. the sensitivity analysis show that the tube outer diameter, tube pitch, coolant velocity and coolant temperature rising influence the coolant flow-rate and net weight of the condenser more than other variables. The corresponding results would provide guidance in the engineering design of this type of condenser.

Analysis of the Particulate Debris Bed Quenching During Top and Bottom Flood

2014 ◽  
Author(s):  
Tao Huang ◽  
Wenxi Tian ◽  
Yapei Zhang ◽  
Suizheng Qiu ◽  
Guanghui Su
Keyword(s):  
Flow Rate ◽  
Single Phase ◽  
Phase Region ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Coolant Temperature ◽  
Two Phase ◽  
Flood Model ◽  
Quenching Process ◽  
Particulate Debris

The quenching characteristics of particulate debris bed during bottom and top flood is analyzed in this paper. The top flood model is formulated by dividing the quenching process into downward frontal period and upward frontal period, which are controlled by the counter-current flow limitation (CCFL) condition and effects of the incoming coolant subcooling and steam cooling in dry channels during quenching process. The bottom flood model is based on porous media theory under the assumption that the height of the two phase region is negligible and the particulate debris bed is divided into single phase liquid and single phase vapor region. The results calculated by these models were compared with the experimental data. The influences of porosity, initial debris temperature and other parameters on both the top and bottom quenching process were studied in this paper. During the top flood, the quenching velocity increased with the increase of the porosity and the decrease of the initial debris temperature. The porosity and initial debris temperature had a larger influence on quenching velocity compared with other parameters, such as initial coolant temperature and coolant flow rate. During the bottom flood, the quenching velocity also increased with the increase of the porosity and the decrease of the initial debris temperature. However, the coolant flow rate had a large influence on the quenching velocity unlike that during the top flood. Quenching from bottom may be superior to the quenching from top. The results can be expected to be useful to evaluate the quenching process of the particulate debris bed.

scholarly journals Safety Analysis of Small Modular Natural Circulation Lead-Cooled Fast Reactor SNCLFR-100 Under Unprotected Transient

2021 ◽  
Vol 9 ◽  
Author(s):  
Chao Guo ◽  
Pengcheng Zhao ◽  
Jian Deng ◽  
Hongxing Yu
Keyword(s):  
Fuel Assembly ◽  
Flow Rate ◽  
Fast Reactor ◽  
Optimization Design ◽  
Natural Circulation ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Design Stage ◽  
Large Power ◽  
The Core

SNCLFR-100 is a small modular natural circulation lead-cooled fast reactor, developed by University of Science and Technology of China, aiming at taking full advantage of the good economics and inherent safety of lead-cooled fast reactors to develop miniaturized, lightweight and multi-purpose special nuclear reactor technology. SNCLFR-100 is still in the conceptual design stage, in order to fully evaluate the safety features of the reactor and provide reference for the optimization design of the next stage, three typical transients are selected based on the analysis of the SNCLFR-100 initiating events by using the code Analysis of Thermal-hydraulics of Leaks and Transients (ATHLET), which are unprotected transient overpower (UTOP), unprotected loss of heat sink (ULOHS) and unprotected partial blockage in the hottest fuel assembly. For UTOP, the unexpected positive reactivity insertion of 0.7$ in 15s led to two large power peaks in the core quickly, and then the core power began to decrease and gradually stabilized under the action of various of negative feedbacks of the reactor, the peak temperatures of fuel and cladding rose rapidly with the increase of core power and eventually stabilized at a higher temperature. For ULOHS, as the reactor were driven by natural circulation, the coolant mass flow rate continued to decline after the transient, both core and cladding temperatures rose quickly and the temperature rise were smaller than that of UTOP transient, the reactor shutdown by itself and the peak temperatures of fuel and cladding were smaller than the safety limit. For unprotected partial blockage in the hottest fuel assembly, with the increase of the blockage rate of the hottest fuel assembly inlet, the coolant flow rate, the peak temperatures of coolant, fuel and cladding increased significantly, when the blockage rate increased to 0.9, the coolant flow rate of the hottest fuel assembly dropped to about 12.6% of the normal value, and the cladding peak temperature would exceed the cladding melting point, measures should be taken to avoid the happening of severe accident.

Multi-objective optimization of squirrel cage fan for range hood based on Kriging model

2021 ◽  
pp. 095440622199586
Author(s):  
Qianhao Xiao ◽  
Jun Wang ◽  
Boyan Jiang ◽  
Weigang Yang ◽  
Xiaopei Yang
Keyword(s):  
Flow Rate ◽  
Optimization Design ◽  
Volume Flow Rate ◽  
Kriging Model ◽  
Volume Flow ◽  
Design Parameters ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Multi Objective ◽  
Squirrel Cage

In view of the multi-objective optimization design of the squirrel cage fan for the range hood, a blade parameterization method based on the quadratic non-uniform B-spline (NUBS) determined by four control points was proposed to control the outlet angle, chord length and maximum camber of the blade. Morris-Mitchell criteria were used to obtain the optimal Latin hypercube sample based on the evolutionary operation, and different subsets of sample numbers were created to study the influence of sample numbers on the multi-objective optimization results. The Kriging model, which can accurately reflect the response relationship between design variables and optimization objectives, was established. The second-generation Non-dominated Sorting Genetic algorithm (NSGA-II) was used to optimize the volume flow rate at the best efficiency point (BEP) and the maximum volume flow rate point (MVP). The results show that the design parameters corresponding to the optimization results under different sample numbers are not the same, and the fluctuation range of the optimal design parameters is related to the influence of the design parameters on the optimization objectives. Compared with the prototype, the optimized impeller increases the radial velocity of the impeller outlet, reduces the flow loss in the volute, and increases the diffusion capacity, which improves the volume flow rate, and efficiency of the range hood system under multiple working conditions.

Effect of Outer Fin Axial Gap on the Sealing Effectiveness and Fluid Dynamics of Radial Rim Seal

2017 ◽  
Author(s):  
Zhigang Li ◽  
Jun Li ◽  
Liming Song ◽  
Qing Gao ◽  
Xin Yan ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Flow Rate ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Navier Stokes ◽  
Hot Gas

The modern gas turbine is widely applied in the aviation propulsion and power generation. The rim seal is usually designed at the periphery of the wheel-space and prevented the hot gas ingestion in modern gas turbines. The high sealing effectiveness of rim seal can improve the aerodynamic performance of gas turbines and avoid of the disc overheating. Effect of outer fin axial gap of radial rim seal on the sealing effectiveness and fluid dynamics was numerically investigated in this work. The sealing effectiveness and fluid dynamics of radial rim seal with three different outer fin axial gaps was conducted at different coolant flow rates using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and SST turbulent model solutions. The accuracy of the presented numerical approach for the prediction of the sealing performance of the turbine rim seal was demonstrated. The obtained results show that the sealing effectiveness of radial rim seal increases with increase of coolant flow rate at the fixed axial outer fin gap. The sealing effectiveness increases with decrease of the axial outer fin gap at the fixed coolant flow rate. Furthermore, at the fixed coolant flow rate, the hot gas ingestion increases with the increase of the axial outer fin gap. This flow behavior intensifies the interaction between the hot gas and coolant flow at the clearance of radial rim seal. The preswirl coefficient in the wheel-space cavity is also illustrated to analyze the flow dynamics of radial rim seal at different axial outer fin gaps.

Simulation on the Temperature Field of Milling Roller Using Fluent Software

2015 ◽  
Vol 1095 ◽  
pp. 846-850
Author(s):  
Min Wang ◽  
Ke Ping Zhang ◽  
Feng Wei Zhang
Keyword(s):  
Temperature Field ◽  
Flow Rate ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Roller Surface ◽  
Fluent Software ◽  
The Law

In order to study the law between the internal coolant flow rate and the temperature of milling roller, the temperature field of water-cooled roller was simulated with Fluent software. The results showed that with the increase of the coolant flow rate, the temperature on roller surface decreased, but after the flow rate of coolant increased to 3.5 kg/s, the temperature of roller maintained invariant almost, so 3.5 kg/s was the best flow rate.

Numerical Studies on the Effect of Tip Clearance and Tip Cooling Flow on Endwall Losses of an Unshrouded Axial Turbine Rotor

2013 ◽  
Author(s):  
K. Asgar Ali ◽  
Quamber H. Nagpurwala ◽  
Abdul Nassar ◽  
S. V. Ramanamurthy
Keyword(s):  
Flow Rate ◽  
Layer Growth ◽  
Coolant Flow ◽  
Tip Clearance ◽  
Coolant Flow Rate ◽  
Total Efficiency ◽  
Turbine Stage ◽  
Suction Surface ◽  
Axial Turbine ◽  
Ejection Rate

This paper deals with the numerical investigations on a low pressure axial turbine stage to assess the effect of variation in rotor tip clearance and tip coolant ejection rate on the end wall losses. The rotor, along with the NGV, was modeled to represent the entire turbine stage. The CFX TASCflow software was used to perform steady state analysis for different rotor tip clearances and different tip coolant ejection rates. The locations of the cooling slots were identified on the blade tip and the coolant ejection rate was specified at these areas. The simulations were carried out with tip clearances of 0%, 1% and 2% of blade height and ejection flow rates of 0.5%, 0.75% and 1% of main turbine flow rate. It is shown that the size and strength of the leakage vortex is directly related to the tip clearance. The reduction in efficiency is not in linearity with the tip clearance owing to the effect of boundary layer growth on the end walls. Introduction of the tip coolant flow shows increased total–total efficiency compared to that of the uncooled tip. This is attributed to a reduction in the strength of the leakage vortex due to reduced cross-flow over the tip clearance from pressure surface to suction surface. At a coolant flow rate of 0.75% of the main flow rate, there is significant increase in efficiency of about 0.5%. Optimum tip clearance and coolant flow rate are obtained based on the results of the present analysis.

Effects of Endwall Film Coolant Flow Rate on Secondary Flows and Coolant Mixing in a First Stage Nozzle Guide Vane

2021 ◽  
Author(s):  
Mahmood Alqefl ◽  
Kedar Nawathe ◽  
Pingting Chen ◽  
Rui Zhu ◽  
Yong Kim ◽  
...  
Keyword(s):  
Flow Rate ◽  
Guide Vane ◽  
Secondary Flows ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Nozzle Guide Vane ◽  
Nozzle Guide

Analytical Model Quantifying the Net Coolant Flow Rate to a Microstructured Copper Surface validated with Two-Phase PIV Measurements

2021 ◽  
Author(s):  
Matt Harrison ◽  
Joshua Gess
Keyword(s):  
Heat Transfer ◽  
Analytical Model ◽  
Flow Rate ◽  
Circular Disk ◽  
Nucleate Boiling ◽  
High Heat ◽  
Heat Fluxes ◽  
Coolant Flow ◽  
Coolant Flow Rate ◽  
Two Phase

Abstract Using Particle Image Velocimetry (PIV), the amount of fluid required to sustain nucleate boiling was quantified to a microstructured copper circular disk. Having prepared the disk with preferential nucleation sites, an analytical model of the net coolant flow rate requirements to a single site has been produced and validated against experimental data. The model assumes that there are three primary phenomena contributing to the coolant flow rate requirements at the boiling surface; radial growth of vapor throughout incipience to departure, bubble rise, and natural convection around the periphery. The total mass flowrate is the sum of these contributing portions. The model accurately predicts the quenching fluid flow rate at low and high heat fluxes with 4% and 30% error of the measured value respectively. For the microstructured surface examined in this study, coolant flow rate requirements ranged from 0.1 to 0.16 kg/sec for a range of heat fluxes from 5.5 to 11.0 W/cm2. Under subcooled conditions, the coolant flow rate requirements plummeted to a nearly negligible value due to domination of transient conduction as the primary heat transfer mechanism at the liquid/vapor/surface interface. PIV and the validated analytical model could be used as a test standard where the amount of coolant the surface needs in relation to its heat transfer coefficient or thermal resistance is a benchmark for the efficacy of a standard surface or boiling enhancement coating/surface structure.

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