• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.108-114
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• 2018

In this study, the thermal and rheological characteristics of a 10 wt.% addition of aluminum particles and the effect of the particle size were investigated to qualitatively analyze the paraffin fuel entrainment regression rate. The results revealed that the addition of aluminum particles and their relative particle size affected the rheological characteristics, rather than the thermal characteristics. Moreover, it was found that the variation of thermal properties had a minor effect on the entrainment regression rate, in comparison to the variation in rheological properties.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.1 no.1
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• pp.29-37
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• 1995

The purpose of this study was to development the waxed rice straw pulp tray(WRSPT) which had low water sensitivity. The quality changes of mushrooms(Agaricus bisporus) packaged respectively in the WRSPT, non-treated rice straw pulp tray(NRSPT) and expanded polystyrene tray(EPST) were observed during storage. The weight losses of mushrooms in the WRSPTs were less than in the NRSPTs by maintaining below 3% at $0^{\circ}C$ and the applications of WRSPTs were more effective at $20^{\circ}C$. The weight increases of WRSPTs were more lowered than those of NRSPTs by marking below 15% during storage at $0^{\circ}C$. There were no significant differences in the Hunter L values and hardness values of mushrooms in the three types of trays at $0^{\circ}C$. The cap openings of mushrooms were more proceeded in NRSPTs than in WRSPTs and EPSTs at $20^{\circ}C$. As a result, it may be favorable to control excessive moisture absorption of the NRSPT mainly composed of cellulose pulp by introducing such chemical treatments as wax treatment.

• Polymer(Korea)
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• v.37 no.1
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• pp.15-21
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• 2013

Encapsulation of a paraffin wax core as a phase change material with polystyrene shell and the its thermal characteristics caused by the encapsulation were studied. For the nanoencapsulation, the miniemulsion polymerization method was selected. The factors affecting the thermal properties of prepared nanocapsule particles of phase change material were analysed in aspect of the structure of crosslinking agents, amounts of surfactant, ratio of paraffin wax to monomer, and hydrophilicity of initiators. It was assumed that Oswald ripening plays the most important role in the changes of particle size, particle morphology, and thermal capacity of nanocapsule core. It was elucidated that the thermal capacity was also dependent on the hydrophilicity and crosslinking density of polystyrene shell components.

• Solar Energy
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• v.11 no.1
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• pp.69-77
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• 1991

A two-phase closed thermosyphon with circular fins was used as the heat transfer device for storing the thermal energy in paraffin wax. Experiments were carried out for 4, 6 and 8 fins and for various initial temperatures of the wax and power inputs. Heat transfer characteristics along the heat flow path were investigated as well as the overall performance of the system. Some of the important results are as follows:(1) The thermosyphon heat transfer coefficient and the overall heat transfer coefficient increased with the number of fins, whereas the heat transfer coefficient between the fin and the wax decreased; (2) Facilitation of heat transfer by the fins seemed to alleviate the dry-out phenomenon that had been reported to occur in case of bare thermosyphon; and (3) The horizontal fins had adverse effect of subduing a full scale convection in the wax, and the increase of the number of fins delayed the onset of local convection between the fins.

• Polymer(Korea)
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• v.39 no.1
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• pp.23-32
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• 2015

Phase change materials based on ultra high molecular weight of polyethylene (UHMWPE) blended with paraffin wax (mp $65^{\circ}C$) were studied in this paper. In addition, this paper reviews recent studies on the preparation of shape stabilized phase change materials (SSPCM), such as SSPCM from UHMWPE and paraffin wax (mp $65^{\circ}C$), their basic properties and possible applications to latent heat storage. The preparation method was an absorption method. Also, SSPCM composites were prepared by using a hot press at $200^{\circ}C$ for 10 min. The analysis for the shape ability of SSPCM to improve heat efficiency was measured by FTIR, SEM, DSC, XRD, and ARES. UHMWPE composites with 30 wt% paraffin wax (mp $65^{\circ}C$) demonstrated less deterioration of physical property and effective thermal property compared with other conditions. As a result, these SSPCMs could be used for the heat storage and release materials for various products.

• Korean journal of applied entomology
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• v.54 no.4
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• pp.369-374
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• 2015

Grapholita molesta (GM) has been considered as a major problem to apple and peach orchards. Mating disrupters have been applied to control the pest over the world as an Integrated Pest Management [IPM] tool. Various types of dispensers releasing mating disrupters have been developed with different formulation of wax, polyethylene tube and aerosol. In this study, the dispensers that were composed of ester waxes and polypropylene (PP) film were used as dispenser materials to analyze release pattern of GM pheromone compared with paraffin wax and polyethylene (PE) film. The release pattern in PP film group was consistent with time while PE film group irregular. Based on these results, Japan wax_PP film dispenser (Japan_PP) was manufactured and showed the mating disruption effect of 98% during 5months in peach orchard.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.11-19
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• 2018

Viscosity measurements were conducted to investigate the rheological characteristics of aluminized paraffin wax fuel. To identify the effect of size and contents of the aluminum particles on the variation of viscosity, samples of nano- and micro- sized aluminum particles with an average particle size of 100 nm and $8{\mu}m$ were prepared and measured using a rheometer. The observed viscosity increment patterns of the nano- and micro-sized particles were vey different, and particularly above 10 wt%, where a relatively low overall regression rate is expected for nano- content fuel. It is possible that this phenomenon could cause the reduced entrainment regression rate.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.9 no.3
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• pp.161-169
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• 1980

In order to enhance the thermal energy storage capacity of cement mortar and to improve the effective thermal conductivity of paraffin waxes, cement- sand- paraffin wax mixture was investigated. By means of finite difference method, the transient temperature distribution in a hollow cylinder with phase change using average composite properties was obtained, and compared with experimental results. It was shown that the heat absorbed by mixture with $25\%$ paraffin fraction was as much as $50\%$ more than either a concrete mortar or pure paraffin wax in the case of ${\Delta}T=\;18.25^{\circ}C$.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.474-482
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• 2016

A Kelvin foam plate - widely used in the energy and transport industries as a lightweight structural material - was examined to estimate its Young's modulus using ultrasound. An isotropic tetrakaidecahedron foam structure was designed in SolidWorks and printed using 3D printer with an ABS plastic material. The 3D printed foam structure was used to build a foam plate with a 14 mm thickness ($50mm{\times}100mm$ in size) for the ultrasonic test. The Kelvin foam plate, a significantly porous medium, was completely filled with paraffin wax to enable the ultrasound to penetrate through the porous medium. The acoustic wave velocity of the wax-filled Kelvin foam was measured using the time of flight (TOF) method. Furthermore, the elastic modulus of the Kelvin foam was estimated based on an elastic structural model developed in this study. The Young's modulus of the produced Kelvin foam was observed to be approximately 3.4% of the bulk value of the constituent material (ABS plastic). This finding is consistent with experimental and theoretical results reported by previous studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.7
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• pp.573-580
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• 2021

Paraffin wax is attracting many attentions for promising solid fuel of hybrid rocket because of its higher regression than other fuels. However, even with paraffin fuel combustion, unsteady low-frequency oscillation of combustion pressure is still observed. And, this is related to the formation of liquid layer and the entrainment of fuel droplets entering the axial combustion gas flow. This study investigates the effect of additional combustion of fuel droplets on the occurrence of low-frequency combustion instability. On the other hand, the formation of fuel droplets depends on Weber Number (the ratio of the inertial force to the surface tension of the liquid) and Reynolds Number of the oxidizer flow. Therefore, a laboratory-scale hybrid rocket was used to monitor the occurrence of combustion instability while changing We number. A series of combustion tests were conducted to control We number by changing the oxidizer flow rate or adding LDPE (low density polyethylene) to base fuel. In the results, it was confirmed that there is a critical We number above which the low-frequency combustion instability occurs.