Ching-Song Jwo

Effects of nanolubricant on performance of hydrocarbon refrigerant system

This work discusses the replacement of the R-134a refrigerant and polyester lubricant with a hydrocarbon refrigerant and mineral lubricant. The mineral lubricant included added Al2O3 nanoparticles (0.05, 0.1, and 0.2wt% ) to improve the lubrication and heat-transfer performance. Experimental results indicated that the 60% R-134a and 0.1wt% Al2O3 nanoparticles were optimal. Under these conditions, the power consumption was reduced by about 2.4%, and the coefficient of performance was increased by 4.4%. These results show that replacing R-134a refrigerant with hydrocarbon refrigerant and adding Al2O3 nanoparticles to the lubricant effectively reduced power consumption.

Research and development of measurement device for thermal conductivity of nanofluids

This research aims to develop a device for measuring thermal conductivity of nanofluid using transient hot-wire methodology. The proposed measurement system comprises of sensing wires coupled with an electrical measurement unit kept in a constant-temperature environment. The wires are made of nickel-chromium alloy a coating with Teflon for insulation. Enhanced ratio of thermal conductivity in a nanofluid is calculated from the difference in electrical parameters with and without CuO nanoparticles added. The results show that thermal conductivities are enhanced by 5.8% and 9.6% when CuO nanoparticles of 1.1%wt and 2.2%wt are added, respectively. Resultant data was then compared with that obtained by two other measurement devices. The difference in measurements was within 5%. This proves that the system developed in this study can perform effective measurement of thermal conductivity of nanofluids.

Simulation Of Refrigerants Flowing Through Adiabatic Capillary Tubes

This paper presents a model for the flow of refrigerants through adiabatic capillary tubes. The flow of refrigerant is characterized by a subcooled liquid region, a metastable liquid region, a metastable two-phase region, and an equilibrium two-phase region. The mass and momentum conservation equations for each of these four regions are converted into finite difference forms and solved using a 4th order Runge-Kutta method. The calculated results compare well with experimental data on R-22. The predictions from the model are employed to develop correlations for the design of refrigerant 134a through adiabatic capillary tubes with the tube exit in the choked flow condition.

The study of hydrophilic characteristics of ethylene glycol

This paper describes the way to measure Ethylene Glycol resistance (Ω). The Electronic Sensing of Hydrophilic Characteristics was design to measure Ethylene Glycol moisture contain in real-time. Many liquids contain the Glycol such as brake fluid, antifreeze and cosmetic. The percent of water contain may affect those liquids functions. It will measure the Ethylene Glycol resistance (Ω) and could be converted into voltage for the use of moisture meter. The relation between Ethylene Glycol with moisture contain and its resistance (Ω) is closed to linear. The hydrophilic characteristics is the molecular model of OH structure which has a Hydrogen atom (H) bonded to the Oxygen atom (O) ; it will absorb the electron cloud at the outer layer of Hydrogen atom; so the electrons within O-H bond have a higher probability of appearance around the Oxygen atom. The O-H bond is similar to a chemical bond which can absorb the water molecules.

Solar energy and clean energy: Trends and developments 2014

Solar energy and other clean energy are emerging and growing rapidly in the globe nowadays. Solar energy with less carbon emission is renewable and clean energy for our living environment. Solar energy can be converted to electricity in photovoltaic (PV) devices, solar cells, or solar thermal/electric power plants. It is a current trend that solar energy becomes the important renewable energy. This special issue addresses the role of the development of solar energy. The themes include dyesensitized solar cells (DSSCs), organic solar cells (OSCs), copper indium gallium diselenide (CIGS), zinc, crystalline silicon solar cells, light-emitting diode (LED), semiconductor sensors, photovoltaic generation system (PVGS), solar cell applications, solar cell, and LED development trend. From 60 submissions, 33 papers are published in this special issue. Each paperwas reviewed by at least two reviewers and revised according to review comments.

Process development and photocatalytic property of nanofluid prepared by combined ASNSS

Abstract This study proposes a new method: the combined arc-submerged nanoparticle synthesis system (ASNSS) for preparing TiO2 nanofluid. In addition to the influence of the various process variables such as breakdown voltage, peak current and dielectric liquid temperature on nanoparticles, this study will also discuss the photocatalytic activity of the prepared TiO2 nanoparticle suspension. To examine the photocatalytic activity of the TiO2, the photodecomposition of salicylic acid was carried out. Experimental results show that the proposed method can successfully prepare anatase TiO2 and this nanofluid can be stabilised for longer than six months. The rate constant of photocatalytic reaction of TiO2 nanoparticles for salicylic acid is 0·0035. Experimental results indicate that the TiO2 nanoparticle fluid possesses excellent photocatalytic activity in photodegradation of salicylic acid.

The electrochemical properties of SiC nanoparticle suspension

This study places SiC nanoparticles into deionized water and uses NaOH and H2SO4 to produce alkaline and acid nanofluids, respectively. A Cu electrode was then inserted into the SiC nanofluid with different voltages activated to observe particle absorption at the electrode and to investigate the electrochemical properties of SiC nanofluid under the influence of voltage, as well as the aggregation and precipitation of particles. In addition, the three-polar method is used to produce anodic polarization curves of the acid and alkaline solutions with the SiC particles to determine the electric potentials of oxidation reduction of the acid and alkaline nanofluids, respectively. The overall purpose of this research was to investigate the electrical properties of SiC nanoparticles in SiC nanofluids of varying pH values.

Experimental Investigation on an Absorption Refrigerator Driven by Solar Cells

This experiment is to study an absorption refrigerator driven by solar cells. Hand-held or carried in vehicle can be powered by solar energy in places without power. In the evenings or rainy days, it is powered by storage battery, and it can be directly powered by alternating current (AC) power supply if available, and the storage battery can be charged full as a backup supply. The proposed system was tested by the alternation of solar irradiance 550 to 700 W/m2 as solar energy and 500ml ambient temperature water as cooling load. After 160 minutes, the proposal refrigerator can maintain the temperature at 5–8°C, and the coefficient of performance (COP) of NH3-H2O absorption refrigeration system is about 0.25. Therefore, this system can be expected to be used in remote areas for refrigeration of food and beverages in outdoor activities in remote and desert areas or long-distance road transportation of food or low temperature refrigeration of vaccine to avoid the deterioration of the food or the vaccines.

Performance Assessment of an R-134A Domestic Dehumidifier Retrofitted with a Hydrocarbon Mixture

This study evaluates the feasibility and coefficient of performance of a domestic dehumidifier when its refrigerant is changed from R-134a to R-600a/R-290 mixed refrigerant (50:50 by mass). Without changing any dehumidifier components, experimental results demonstrate that superior performance characteristics can be achieved with 67.5 g of HC refrigerant, which is only 50% of the original mass of the R-134a refrigerant. Generally, the refrigerant in domestic dehumidifiers can be changed from R-134a to a R-600a/R-290 refrigerant mixture, and the ozone depletion potential and global warming potential are negligible when compared with those of the R-134a refrigerant.

Photodecomposition of gaseous toluene using TiO2 prepared by SANSS

This study examined the photodecomposition of volatile organic compounds (VOCs) using TiO2 catalyst fabricated by the Submerged Arc Nanoparticle Synthesis System (SANSS). The TiO2 catalyst was employed to decompose gaseous toluene and compared with Degussa- P25 TiO2 in terms of decomposition efficiency. It was found that gaseous toluene exposed to UV irradiation produced intermediates that were even harder to decompose. After 60-min of photocomposition, Degussa-P25 TiO2 reduced the concentration of gaseous toluene to 8.18% while the concentration after decomposition by SANSS TiO2 catalyst dropped to 0.35%. The results show that TiO2 prepared by SANSS has great efficiency in decomposing both gaseous toluene and its intermediates.