Kwangkook Jeong

Recovery of Water from Boiler Flue Gas

This project dealt with use of condensing heat exchangers to recover water vapor from flue gas at coal-fired power plants. Pilot-scale heat transfer tests were performed to determine the relationship between flue gas moisture concentration, heat exchanger design and operating conditions, and water vapor condensation rate. The tests also determined the extent to which the condensation processes for water and acid vapors in flue gas can be made to occur separately in different heat transfer sections. The results showed flue gas water vapor condensed in the low temperature region of the heat exchanger system, with water capture efficiencies depending strongly on flue gas moisture content, cooling water inlet temperature, heat exchanger design and flue gas and cooling water flow rates. Sulfuric acid vapor condensed in both the high temperature and low temperature regions of the heat transfer apparatus, while hydrochloric and nitric acid vapors condensed with the water vapor in the low temperature region. Measurements made of flue gas mercury concentrations upstream and downstream of the heat exchangers showed a significant reduction in flue gas mercury concentration within the heat exchangers. A theoretical heat and mass transfer model was developed for predicting rates of heat transfer and water vapor condensation and comparisons were made with pilot scale measurements. Analyses were also carried out to estimate how much flue gas moisture it would be practical to recover from boiler flue gas and the magnitude of the heat rate improvements which could be made by recovering sensible and latent heat from flue gas.

Synthesis and characterization of divalent metal complexes with bipyridylamide ligands

Abstract Reaction of N-(4-pyridyl)picolinamide (4-ppa), N-(4-pyridyl)nicotinamide (4-pna), N-(4-pyridyl)isonicotinamide (4-pina), and N-(2-pyridyl)isonicotinamide (2-pina) with divalent metal salts led to the formation of six new coordination complexes. The X-ray structure of [Zn(4-ppa)2Cl2] (1) shows a mononuclear structure with interesting intermolecular hydrogen bonding interactions. [Zn(4-pna)(OAc)2]n (2), Cu(4-pna)(OTf)2(DMF)2]n (3), {[Zn(4-pina)(DMF)4](OTf)2}n (4), {[Fe(4-pina)(DMF)4](OTf)2}n (5), and [Cu(2-pina)(OTf)2(DMF)2]n (6) are one-dimensional coordination polymers with conformational differences caused by the coordination donor disposition, which demonstrates the flexibility of the pyridylamide ligands in polymeric structures. Reflectance UV-visible spectra and thermal properties of the coordination polymers are also reported.

Integrated Computational and Experimental Framework on Advanced Flow Battery for Renewable Power Plant Applications

A study has been conducted to develop advanced vanadium redox flow battery (VRFB) for renewable energy storage applications using integrated computational and experimental framework. Analytical modeling has been performed to predict electrical outputs based on combined approach including fluid mechanics, electrochemistry, and electric circuit. A lab-scale experimental setup has been designed and built to validate the modeling results.The VRFB project has been collaborated between Arkansas State University Jonesboro and University of Arkansas Fayetteville to focus on pin pointing the transient characteristics of the vanadium redox flow battery in terms of chemical reaction, fluid flow, and electric circuit by obtaining exact solutions from the associated governing differential equations using a numerical approach. To obtain comparable experimental data, a test bed made of two half cells is constructed and joined together by a permeable membrane designed to facilitate ion transfer between two separate vanadium electrolytes, and then the system will be scaled up to multiple cell stacks.This research aims to better understand the transient characteristics of the VRFB in order to refine the system in hopes of improving efficiency. In turn alternative energy such as multi megawatt wind and solar farms should gain more support as the ability to store energy becomes more reliable and economically feasible. This paper will focus on the steps taken to validate the supporting mathematical models, and the preliminary results of the tests conducted using the VRFB test bed. Future work will be addressed to develop a pilot-scale VRFB with enhanced efficiency and temperature limits.Copyright

Conjugated Dynamic Modeling on Vanadium Redox Flow Battery With Non-Constant Variance for Renewable Power Plant Applications

A parametric modeling study has been carried out to investigate the effect of change in operating conditions on VRFB performance. The objective of this research is to develop a computer program to predict the dynamic behavior of single cell VRFB combining fluid mechanics, reaction kinetics, and electric circuit. This paper deals with the exact solutions obtained by solving the governing differential equations of VRFB by using Maple 2015. Calculations were made under electrolyte concentrations of 1M–3M of V2+, charging-discharging current of 1.85A–3.85A, and tank to cell ratio of 5:1 to 10:1. Results show that the discharging time increases from 2.2 hours to 6.7 hours when the value of electrolytes concentration of V2+ increases from 1M to 3M. However, the charging time decreases from 6.9 hours to 3.3 hours with the increment of applied current from 1.85A to 3.85A. Additionally, when the tank to cell ratio is increased from 5:1 to 10:1, the charging-discharging time increased from 4.5 hours to 8.2 hours. Ampere-hour capacity of the cell was found to increase when molar concentration of vanadium and, tank to cell ratio were increased.Copyright

Experimental Study on Test-Bed Vanadium Redox Flow Battery

An experimental study has been conducted to develop a test-bed for advanced vanadium redox flow battery (VRFB) for renewable energy applications. Lab scale experimental setup has been designed based on enhanced geometry of mechanical components and reduced power consumption in terms of fluid mechanics and thermodynamics. Two tests have been conducted with variations of flowrate, concentration of electrolytes and electrical input power. The VRFB project has been collaborated between Arkansas State University Jonesboro (ASUJ) and University of Arkansas Fayetteville (UAF) to integrate VRFB with micro-grid at UAF. To obtain comparable experimental data, a test bed made of two half cells was constructed and joined together by a permeable membrane designed to facilitate ion transfer between two separate vanadium electrolytes. This research aims to better understand and demonstrate the transient characteristics of VRFB in order to refine the system in hopes of improving efficiency. This paper will focus on the steps taken to experimentally validate preliminary performance of the VRFB test bed. An analytical model has been performed to validate design and test of VRFB. Future work will be addressed to develop a pilot-scale multiple cell stacks with enhanced efficiency and temperature limits.Copyright

Waste Heat Recovery and Saving Fresh Water Consumption in Power Plants

A section to delineate ‘waste heat recovery’ has been written to contribute for the ASME Power Plant Cooling Specification/Decision-making Guide to be published in 2013. This paper informs tentative contents for the section on how to beneficially apply waste heat and water recovery technology into power plants. This paper describes waste heat recovery in power plant, current/innovative technologies, specifications, case study, combined cycle, thermal benefits, effects on system efficiency, economic and exergetic benefits. It also outlines water recovery technologies, benefits in fresh water consumptions, reducing acids emission, additional cooling effects, economic analysis and critical considerations.© 2012 ASME