Numerical Investigation of Performance Improvement and Erosion Characteristics of Vortex Pump Using Particle Model

Vortex pump has characteristics of low efficiency and serious surface erosion of blade, which seriously affects service life. Therefore, it is particularly important to improve the efficiency of vortex pump and reduce erosion of blade surface. In this investigation, the design of experiment was used to determine the test plan and the number of samples tested. The relationship between geometric factors of vortex pump and efficiency and erosion rate of blade was established using the kriging approximation model. The genetic algorithm solved the multiobjective optimization and obtained the Pareto front solution using NSGA-II. The results showed that the width of nonblade cavity of the vortex pump is reduced by 18.93%, the number of blades of the impeller is increased by one, and the outlet width of the blade is increased by 19.81%. The performance after optimization is significantly improved compared with the original prototype. At design flow rate, the efficiency of the vortex pump increases by 3.24%, while the efficiency increases by 2.59% and 6.24% at 0.8Qd and 1.2Qd, respectively. The maximum erosion rate of blade surface 8.52 × 10−4 kg/(m2·s) is reduced to 7.18 × 10−4 kg/(m2·s) at 1.0Qd by optimization, which is reduced by 15.73%. The blade erosion after optimization is significantly controlled, and the angle of particle hitting blade surface is reduced.

Combined economic-emission load dispatch solution using firefly algorithm and fuzzy approach

This paper proposes Firefly Algorithm (FA) with fuzzy approach for solving combined economic-emission load dispatch (CEELD) problem in power generation. The main objective of the CEELD problem is to determine the optimal cost and emission level of power generation and fulfill the load demand and operational constraints. The CEELD problem used weighted sum method to combine two objective functions (cost and emission) into single objective. Then, the Fuzzy-based mechanism approach is integrated in FA to find the best compromise solution for both conflicting cost and emission level. The FA has been tested on IEEE 118-bus 14-unit test system for minimization both cost of power generation and emission level. The performance of FA for solving CEELD problem has been investigated in terms of optimal solution, convergence characteristics and Pareto front solution. From the comparison of the CEELD solutions, it found that FA can provide significant cost and emission reduction compared to other methods. Thus, it can be used as alternative approach for solving any optimization problems.

Multi-Objective Optimisation of the Energy Performance of Lightweight Constructions Combining Evolutionary Algorithms and Life Cycle Cost

This paper discusses the thermal and energy performance of a detached lightweight building. The building was monitored with hygrothermal sensors to collect data for building energy model calibration. The calibration was performed using a dynamic simulation through EnergyPlus® (EP) (Version 8.5, United States Department of Energy (DOE), Washington, DC, USA) with a hybrid evolutionary algorithm to minimise the root mean square error of the differences between the predicted and real recorded data. The results attained reveal a good agreement between predicted and real data with a goodness of fit below the limits imposed by the guidelines. Then, the evolutionary algorithm was used to meet the compliance criteria defined by the Passive House standard for different regions in Portugal’s mainland using different approaches in the overheating evaluation. The multi-objective optimisation was developed to study the interaction between annual heating demand and overheating rate objectives to assess their trade-offs, tracing the Pareto front solution for different climate regions throughout the whole of Portugal. However, the overheating issue is present, and numerous best solutions from multi-objective optimisation were determined, hindering the selection of a single best option. Hence, the life cycle cost of the Pareto solutions was determined, using the life cycle cost as the final criterion to single out the optimal solution or a combination of parameters.

Drift perturbation’s influence on traveling wave speed in KPP-Fisher system

This paper dressed the drift perturbation effects on the traveling wave speed in a reaction-diffusion system. We prove the existence of a traveling front solution of a KPP-Fisher equation and we show an asymptotic expansion of her speed. Finally, we discuss according all parameters of our system regions of the plane in which the traveling wave speed increases or decreases as a function of a small parameter ε.