• Journal of Navigation and Port Research
• /
• v.47 no.2
• /
• pp.106-119
• /
• 2023

Due to global decarbonization movement and tightening of maritime emissions restrictions, the shipping industry is going to switch to alternative fuels. Among candidates of alternative fuel, methanol is promising for decreasing SOx and CO2 emissions, resulting in minimum climate change and meeting the goal of green shipping. In this study, a novel combined system of direct methanol solid oxide fuel cells (SOFC), proton exchange membrane fuel cells (PEMFC), gas turbine (GT), and organic Rankine cycle (ORC) targeted for marine vessels was proposed. The SOFC is the main power generator of the system, whereas the GT and PEMFC could recover waste heat from the SOFC to generate useful power and increase waste heat utilizing efficiency of the system. Thermodynamics model of the combined system and each component were established and analyzed. Energy and exergy efficiencies of subsystems and the entire system were estimated with participation of the first and second laws of thermodynamics. The energy and exergy efficiencies of the overall multigeneration system were estimated to be 76.2% and 30.3%, respectively. The combination of GT and PEMFC increased the energy efficiency by 18.91% compared to the SOFC stand-alone system. By changing the methanol distribution ratio from 0.05 to 0.4, energy and exergy efficiencies decreased by 15.49% and 5.41%, respectively. During the starting up and maneuvering period of vessels, a quick response from the power supply system and propulsion plant is necessary. Utilization of PEMFC coupled with SOFC has remarkable meaning and benefits.

• Macromolecular Research
• /
• v.12 no.4
• /
• pp.413-421
• /
• 2004

Sulfonated poly(phthalazinone ether sulfone ketone) (SPPESK) membranes and sol-gel derived SPPESK/silica hybrid membranes have been investigated as potential polymer electrolyte membranes for direct methanol fuel cell (DMFC) applications. In comparison with the SPPESK membrane, the SPPESK/silica membranes exhibited higher water content, improved proton conductivity, and lower methanol permeability. Notably, the silica embedded in the membrane acted as a material for reducing the fraction of free water and as a barrier for methanol transport through the membrane. From the results of proton conductivity and methanol permeability studies, we suggest that the fractions of bound and free water should be optimized to obtain desirable proton conductivities and methanol permeabilities. The highly sulfonated PPESK hybrid membrane (HSP-Si) displayed higher proton conductivity (3.42 ${\times}$ 10$^2$ S/cm) and lower methanol permeability (4.15 ${\times}$ 10$\^$7/ $\textrm{cm}^2$/s) than those of Nafion 117 (2.54 ${\times}$ 10$^2$ S/cm; 2.36 ${\times}$ 10$\^$6/ $\textrm{cm}^2$/s, respectively) at 30$^{\circ}C$. This characteristic of the SPPESK/silica membranes is desirable for future applications related to DMFCs.

• Carbon letters
• /
• v.14 no.2
• /
• pp.117-120
• /
• 2013

In this study, an electro-catalyst of Pt nanoparticles supported by polypyrrole-functionalized graphene (Pt/PPy-reduced graphene oxide [RGO]) is reported. The Pt nanoparticles are deposited on the PPy-RGO composite by chemical reduction of H2PtCl6 using NaBH4. The presence of graphene (RGO) caused higher activity. This might have been due to increased electro-chemically accessible surface areas, increased electronic conductivity, and easier charge-transfer at polymer-electrolyte interfaces, allowing higher dispersion and utilization of the deposited Pt nano-particles. Microstructure, morphology and crystallinity of the synthesized materials were investigated using X-ray diffraction and transmission electron microscopy. The results showed successful deposition of Pt nano-particles, with crystallite size of about 2.7 nm, on the PPy-RGO support film. Catalytic activity for methanol electro-oxidation in fuel cells was investigated using cyclic voltammetry. The fundamental electrochemical test results indicated that the electro-catalytic activity, for methanol oxidation, of the Pt/PPy-RGO combination was much better than for commercial catalyst.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.20 no.7
• /
• pp.2421-2429
• /
• 1996

The objective of this research is to apply effect of the pre-mixed combustion quantity and smoke emission in diesel engine. According as air fuel ratio is increased, emission of smoke concentration is linearly reduced. As Injection timing is advanced, smoke concentration is remarkably reduced. It is considered to be the primary cause of the increase in the premixed combustible mixture during long ignition delay period with advancing injection timing. Smoke is increased with increasing engine speed, so it is considered to be the primary cause of the increase of the mass of fuel injected. Smoke is decreased according to the increase of methanol volume ratio. It is considered that the primary cause of the increase in the quantity of pre-mixed combustion.

• Journal of the Korean Applied Science and Technology
• /
• v.19 no.4
• /
• pp.327-334
• /
• 2002

Transesterfication of vegetable oils and methanol with alkaline catalyst was carried out to produce biodiesel fuel by continuous process. The process consists of two static mixers, one tubular reactor and two coolers and gave $96{\sim}99$% of methyl ester yield from soybean oil and rapeseed oil. Experimental variables were the molar ratios of methanol to vegetable oil, alkaline catalyst contents, flow rates, mixer element number. The optimum ranges of operating variables were as follows; reaction temperature of $70^{\circ}C$, l:6 of molar ratio of methanol to oil, O.4%(w/w) sodium hydroxide based on oil, static mixer elements number of 24 and 4 min. residence time.

• Journal of the korean Society of Automotive Engineers
• /
• v.10 no.4
• /
• pp.75-84
• /
• 1988

The performance and emission for the 4-cylinder 4-cycle gasoline engine fueled with methanol is predicted in this paper. The model for all the processes is illustrated. It computes the gas pressure, gas temperature and the rate of formation of nitric oxide and carbon monoxide at each crank angle using basic energy equation and reaction kinetic mechanism. The results are obtained at different operating conditions encompassing changes in fuel-air equivalence ratio, engine speed, spark timing and compression ratio. The special characteristics of methanol such as high power output and nitric oxide emissions have been truthfully predicted by the model.

• Carbon letters
• /
• v.1 no.1
• /
• pp.27-30
• /
• 2000

Performance of direct methanol fuel cell using high porous active carbon as an uncatalysed diffusion layer in anode (composite electrode) has been evaluated. Effects of porous active carbon in anode were investigated by galvanostatic method and Fourier Transform Infrared spectroscopy. The single cell was operated with 2.5 M methanol at temperature of $80-120^{\circ}C$ and showed performance of $210-510\;mA/cm^2$ at 0.4V. By replacing conventional electrode with composite electrode, the increment of $290\;mA/cm^2$ in current density was obtained at $90^{\circ}C$and 0.4V. The potential decay of the single cell was about 14.5% for 20 days operation.

• Clean Technology
• /
• v.10 no.2
• /
• pp.53-59
• /
• 2004

Direct methanol fuel cells (DMFC) are presently paid attention due to their higher energy density and portability. In order to slove problems such as high anodic overpotential and methanol crossover in DMFC, an analytical analysis for electrochemical model using Tafel equation and limiting current density was performed. Change of operational parameters such as temperature, transfer coefficients and membrane thickness results in helpful informations on voltage-current curves.

• Journal of Hydrogen and New Energy
• /
• v.12 no.4
• /
• pp.257-265
• /
• 2001

Placing a hydrogen conducting, methanol impermeable metallic barrier like palladium (Pd) is a well-known method for preventing methanol crossover through solid polymer electrolyte for direct methanol fuel cells (DMFC). Applying a bias potential between the anode and the barrier can further develop this concept so that the hydrogen transfer rate is enhanced. Since hydrogen diffuses in Pd as atomic form while it moves through nafion electrolyte as ion, it has to be reduced or oxidized whenever it passes the interface formed by Pd and the electrolyte. We performed experiments to measure the hydrogen transport through the Pd membrane placed in Nafion electrolyte of hydrogen/oxygen fuel cell (PEMFC). Applying a bias potential between the hydrogen electrode of the cell and the Pd membrane facilitated the hydrogen passage through the Pd membrane. The results show that the cell current measured with the Pd membrane placed reached almost 40 % the value measured with the cell without Pd membrane. It was found that the current flown through the bias path is only a few percent of the cell current.

• 한국가스학회:학술대회논문집
• /
• 2005.10a
• /
• pp.141-145
• /
• 2005

DME (Di-Methyl Ether) is a new clean fuel and an environmental-friendly energy resource, also is recently increasing with an alternative interest because of the industrial use. DME has been shown to have excellent properties as a diesel fuel giving emission level better than ULEV standard. So it has been attracting considerable as an alternative diesel fuel. In this study, we carried out simulation of separation and purification process of demo plant for 101on per day DME production, which cause the effect that is important in productivity, from operation results of pilot plant for 50kg per day DME production. The liquefied stream, which was separated by gas-liquid separator after DME reactor, includes $CO_2$, DME, Methanol and $H_2O$. We established three distillation columns for separation and purification of the stream. $CO_2$ was extracted from the stream by first distillation column, DME was extracted by second column and Methanol was extracted by third column. We investigated and analyzed the effect which the actual operation variables cause in efficiency of process and optimized process, finally we got the DME of purity $100\%$.