scholarly journals Effects of Pulse Frequency on Performance of Electrochemical Cooling Water Treatment for Cooling Tower of Water-Cooled Chiller

2021 ◽  
Vol 19 ◽  
pp. 619-623
Author(s):  
Le Minh Nhut ◽  
◽  
Duong Huynh Minh Nhut ◽  
Keyword(s):  
Water Treatment ◽  
Current Density ◽  
Duty Cycle ◽  
Cooling Tower ◽  
Cooling Water ◽  
Operation Time ◽  
Pulse Frequency ◽  
Coefficient Of Performance ◽  
Total Hardness ◽  
Operational Parameters

Due to the rapid economic development in recent years, water-chiller is being used more and more in hotels, restaurants, resorts, and industrial zones in Vietnam. The cooling tower’s cooling water quality is an important factor in determining the effect on electrical consumption and the coefficient of performance of a water-cooled chiller. Therefore, it is necessary to maintain the quality of cooling water during the operation time of the water-cooled chiller. The aim of this work is to investigate the effects of the pulse frequency and operational parameters such as current density, pulse duty cycle, and energy consumption on the performance of removing hardness ion of electrochemical cooling water treatment for the cooling tower of the water-cooled chiller. The results show that the highest efficiency of the total hardness removal corresponding to a pulse frequency of 1 kHz, a pulse duty cycle of 0.7, and a current density of 80A/m2.

Experimental Research on Electroforming Nano-ZrO2 Reinforced Cu-Matrix Composite Aided by Pulse Power

2018 ◽  
Vol 764 ◽  
pp. 95-105
Author(s):  
Zhong Wen Sima ◽  
Zhi Yong Li ◽  
Hong Bin Cui ◽  
Hun Guo
Keyword(s):  
Surface Morphology ◽  
Matrix Composite ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Frequency ◽  
Cathodic Current Density ◽  
Ultrasonic Power ◽  
Cathodic Current ◽  
Maximum Content ◽  
Cycle Pulse

Prepared the nanoZrO2 reinforced Cu-matrix composite by pulse electroforming. The effects of the content of nanoZrO2 particle in the casting solution, average cathodic current density, duty cycle, pulse frequency and ultrasonic power on the content of nanoZrO2 in the electroforming Cu-matrix composite have been studied. The microhardness and surface morphology of Cu-ZrO2 composite were analyzed. The experimental results demonstrate that the maximum content of nanoZrO2 in the electroforming Cu-ZrO2 composite is 2.94%, microhardness is 492 HV, which is significantly improved compared with pulse pure copper’s 337 HV, when the content of nanoZrO2 is 40 g/L, average cathodic current density is 4A/dm2, duty cycle is 0.2 , pulse frequency is 1100 Hz and ultrasonic power is 20w .The surface of composite prepared by pulse electroforming is more smooth, organization is denser, grain is finer and agglomeration of nanoZrO2 particles is fewer compared with Direct-current electroforming nanoZrO2 reinforced Cu-ZrO2 composite.

Transient Modeling of a Lithium Bromide – Water Absorption Chiller

2013 ◽  
Vol 388 ◽  
pp. 83-90 ◽  
Author(s):  
Ang Li ◽  
Wai Soong Loh ◽  
Kim Choon Ng
Keyword(s):  
Water Absorption ◽  
Cooling Tower ◽  
Lithium Bromide ◽  
Cooling Water ◽  
Coefficient Of Performance ◽  
Absorption Chiller ◽  
Transient Model ◽  
Operation Conditions ◽  
Operation Process ◽  
Main Components

This article presents a thermodynamic framework for a lithium bromide – water absorption chiller, in which a transient model is developed to simulate the operation process. Local energy and mass balance within the main components like absorber, regenerator, condenser, evaporator and solution heat exchanger is respected to investigate the behavior of the chiller. Experimental correlations are used to predict heat transfer of the related working fluids. The cooling water is set to typical cooling tower conditions of tropical countries such as Singapore. The coefficient of performance (COP) is evaluated against a range of heat source temperatures from 75oC to 100oC. The results indicate the operation conditions of the chiller at its maximum COP is 95oC to 100oC.

Effects of Process Parameters on the Morphologies and Composition of Pulse Electrodeposition of Nickel-Rich Co-Ni Alloys

2012 ◽  
Vol 602-604 ◽  
pp. 565-569 ◽  
Author(s):  
Ming Ming Yu ◽  
Hong You Li ◽  
Yi Wang
Keyword(s):  
Current Density ◽  
Duty Cycle ◽  
Cobalt Content ◽  
Bath Temperature ◽  
Pulse Frequency ◽  
Pulse Electrodeposition ◽  
Average Current Density ◽  
High Microhardness ◽  
Average Current ◽  
Electrodeposition Of Nickel

Nickel-cobalt alloys have broad application prospect for their excellent properties (i.e. high microhardness, strength, abrasion, corrosion resistance and magnetic properties.etc). Nickel-rich Ni-Co coatings were produced on SUS304 substrates by pulse electrodeposition from sulfamate electrolytes with different average current density, pulse frequency, duty cycle and different bath temperature. It is clearly observed that the content of cobalt in the nickel-rich deposits gradually increases from 4.29 % to 25.47 % as the Co2+/Ni2+ concentration ratio increasing from 0.022 to 0.1(the current density applied was 2 A/dm2,bath temperature 25 °C). The Co content increases from 16.98 % to 25.47 % to 30.06 % when the duty cycle ranged from 20 % to 50 % to 60 %.The Co content seems to hardly change when pulse frequency changed from 500 Hz to 1000 Hz. The cobalt content decreases as the growth of the current density. The formation of good Ni-Co deposits with high cobalt content and smooth morphologies can be obtained by reducing current density, increasing bath temperature and pulse duty cycle.

A Study of the Microstructure and Properties of Electroformed Ni-P Model Insert

2007 ◽  
Vol 364-366 ◽  
pp. 232-236 ◽  
Author(s):  
Shih Tsung Ke ◽  
Jeou Long Lee ◽  
Yih Min Yeh ◽  
Shuo Jen Lee ◽  
Ming Der Ger
Keyword(s):  
Internal Stress ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Current ◽  
Pulse Frequency ◽  
Cathodic Current ◽  
Peak Current Density ◽  
Peak Current ◽  
Ultrafine Grained ◽  
Nanostructure Material

In this study, a Ni-P alloy electroforming nanostructure material with low surface roughness and low internal stress was developed by using a pulse current. Square-wave cathodic current modulation was employed to electrodeposit ultrafine-grained Ni-P films from an additivefree Sulfamate nickel bath. The effect of various factors, such as peak current density, duty cycle and pulse frequency on the roughness and internal stress were investigated. Pulse current significantly influences the microstructure of Ni-P alloys. The internal stress and roughness of Ni-P alloys increased as peak current density increased, but the internal stress of Ni-P alloys decreased as duty cycle decreased.

scholarly journals Treatment of oilfield produced water with electrocoagulation: improving the process performance by using pulse current

2016 ◽  
Vol 7 (3) ◽  
pp. 378-386 ◽  
Author(s):  
Tao Zheng
Keyword(s):  
Reaction Time ◽  
Current Density ◽  
Duty Cycle ◽  
Produced Water ◽  
Oxygen Demand ◽  
Current Method ◽  
Pulse Frequency ◽  
Economic Feasibility ◽  
Electrode Distance ◽  
Removal Efficiencies

The main aim of this study is to investigate the technical and economic feasibility of the pulse electrocoagulation (PE) process on the treatment of oilfield alkali/surfactant/polymer flooding produced water. By using an Fe electrode, the performance of the PE process was analyzed in terms of operating parameters such as pulse duty cycle, current density, pulse frequency, electrode distance, and reaction time with removal efficiencies, some of which are presented in figures and others are given in tables due to the numbers of parameters. Under the optimal conditions of a pulse duty cycle of 0.3, current density of 35 mA/cm2, pulse frequency of 3.0 kHz, electrode distance of 1.0 cm, and reaction time of 40 min, the removal efficiencies of chemical oxygen demand (COD), oils and greases, turbidity, total suspended solids, and polyacrylamide reach 98.3, 99.0, 98.8, 98.1 and 94.3%, respectively, with an energy consumption of 0.19 kWh/kg CODremoved and an electrode consumption of 3.1 kg Fe/kg CODremoved. The quality of the final effluent could satisfy the requirement of the national discharge standard. Compared with the traditional direct current method, the PE process could save 76% of the energy. Moreover, the treatment performance of PE is much better than traditional chemical coagulation treatment using polymeric ferric sulfate.

Experimental Investigation on the Effect of Fill Materials in Cooling Towers

2015 ◽  
Vol 766-767 ◽  
pp. 505-510 ◽  
Author(s):  
J. Jayaprabakar
Keyword(s):  
Corrosion Resistance ◽  
High Efficiency ◽  
Cooling Tower ◽  
Water System ◽  
Cooling Water ◽  
Cross Flow ◽  
Water Source ◽  
Coefficient Of Performance ◽  
Advanced Materials ◽  
Cooling Towers

The cooling water system is the industry’s primary way of conserving water. Modern water cooling towers were invented during the industrial age to dissipate heat when natural cooling water sources were available. The origin of cooling towers made the plant site selection independent of the availability of water source. The development of new, high efficiency film fills produced from light weights, flame retarded PVC reduces the size and weight of cross flow cooling towers. Today’s cooling tower combine the latest advanced materials to achieve the optimum balancing of High corrosion resistance, product durability and cost. Based on their specific functions, cooling tower components are designed using the materials with the best combination of corrosion resistance and physical properties. In this work, the coefficient of performance is determined by using Simpson’s rule and the performance of cooling tower at various L/G ratios is evaluated. The optimum approach of the tower is calculated.

scholarly journals Formulation of Coefficient of Performance Characteristics of Water-cooled Chillers and Evaluation of Composite COP for Combined Chillers

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1182
Author(s):  
Toru Yamamoto ◽  
Hirofumi Hayama ◽  
Takao Hayashi
Keyword(s):  
Water Temperature ◽  
Cooling Tower ◽  
Cooling Water ◽  
Weather Conditions ◽  
Coefficient Of Performance ◽  
Specific Enthalpy ◽  
Load Factor ◽  
Planning Stage ◽  
Cooling Water Temperature ◽  
Evaluation Time

The Coefficient of Performance of an ordinary water-cooled chiller is presented as a relationship with the chiller load factor and cooling water temperature. However, the cooling water temperature fluctuates according to the processed heat of the cooling tower originating in the cooling energy of the chiller and to the outside temperature and humidity. It is therefore difficult to obtain the cooling water temperature under the processed-heat and weather conditions at the time of evaluation. This, in turn, makes it difficult to determine the Coefficient of Performance of a water-cooled chiller at the evaluation time. In this research, we formulated the Coefficient of Performance of a water-cooled chiller as a relationship with the chiller load factor and specific enthalpy of outside air. Specifically, we used the Number of Transfer Units (NTU) model of a cooling tower to calculate the cooling water temperature corresponding to the cooling-tower load factor targeting a counterflow cooling tower for a range of values of outside-air specific enthalpy. This technique makes it possible to evaluate the Coefficient of Performance of a water-cooled chiller without determining the cooling water temperature. Furthermore, for the case of installing multiple units of chillers, it becomes possible to calculate the composite Coefficient of Performance of those chillers without having to determine the cooling water temperatures for the different operation load factors of those chillers. Moreover, since the composite Coefficient of Performance can be calculated by combining the different installation capacities of these chillers, the energy consumption of multiple chillers can be calculated at the basic planning stage.

scholarly journals Wear Behavior of Ni-TiO2 Nano-Composite Coating on AISI 1022 CS by Pulse Electrodeposition

2020 ◽  
Vol 23 (3) ◽  
pp. 177-181
Author(s):  
P. Natarajan ◽  
A. Jegan ◽  
M. Mohanraj
Keyword(s):  
Wear Rate ◽  
Surface Structure ◽  
Current Density ◽  
Duty Cycle ◽  
Pulse Frequency ◽  
Pulse Electrodeposition ◽  
Nano Particles ◽  
Experimental Result ◽  
Material Surface ◽  
Quadratic Term

The Ni-TiO2 nano-coatings were prepared on the AISI 1022 carbon steel (CS) surface using the pulse electrodeposition method. The surface structure of CS was considerably reformed owing to the titanium particles presence. The electroplating is widely used as a protection of the material surface to expand the life of vehicle components. The parameters of pulse frequency (PF - Hz), current density (CD - A/cm2) and duty cycle (DC - %) are combined into the RSM three factors and three level arrays to find the effect of the wear rate coating parameters. The Ni-TiO2 nano-particles deposited surface structure and wear of the surface were examined by field emission scanning electron microscopy (FESEM) and wear test was conducted by pin on disc wear tester. The experimental result revealed a lower specimen wear rate of the parameter is the frequency: 20 Hz, current density: 0.2 A/cm2 and duty cycle: 30 %. The ANOVA result revealed the pulse frequency and current density quadratic term are the most essential factor contributing 28.48, 29.95 % impact on wear resistance.

Influence of Process Parameters on Pulse Electroforming of Nickel-Rich Nickel-Cobalt Alloys from Sulfamate Electrolyte

2013 ◽  
Vol 641-642 ◽  
pp. 440-443 ◽  
Author(s):  
Hong You Li ◽  
Ming Ming Yu ◽  
Yi Wang ◽  
Mao Lin Shi
Keyword(s):  
Current Density ◽  
Duty Cycle ◽  
Bath Temperature ◽  
Pulse Frequency ◽  
Industrial Applications ◽  
Cobalt Alloys ◽  
Average Current Density ◽  
Influence Of Process Parameters ◽  
Nickel Cobalt ◽  
Wide Range

Nickel-cobalt alloys have a wide range of industrial applications because of high strength, good corrosion resistance, heat-conductive, etc. As an example, they are used in the electroforming of moulds for die-casting and plastics and in electrotyping. In this paper, experiments on pulse electroforming of nickel-rich nickel-cobalt alloys were studied on SUS304 substrates from sulfamate electrolyte with different average current density, pulse frequency, duty cycle and different bath temperature. It is clearly observed in the nickel-rich deposits that effect of cobalt content gradually increases as the Co2+/Ni2+ concentration ratio and duty cycle increasing; The Co content seems to hardly change when pulse frequency changed from 500 Hz to 1000 Hz; The Co content decreases as current density increasing. High Co content and smooth surface topography can be obtained by reducing current density, increasing bath temperature and pulse duty cycle.

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