• Title/Summary/Keyword: temperature and diameter effect

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Heating Efficiency of the Underground Heat Exchanger by Different Pipe Materials (지열교환기의 배관자재에 따른 난방효율 분석)

  • 오인환;이준학;정우철
    • Journal of Animal Environmental Science
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    • v.4 no.2
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    • pp.127-136
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    • 1998
  • To use the earth heat for the livestock housing, an underground heat exchanger is developed and pipes are layed in the depth of 2.5m under the ground. The pipes have two different kinds of diameter (200mm, 100mm) and materials (PE, PVC). The results of heating effect in winter and spring are following. The temperature in different soil depth varies from 5$^{\circ}C$ by 1.5m depth, to 9$^{\circ}C$ by 3.5m. So it should be better to have the depth greater than 2.5m. The difference of air temperature between the inside and outside pipe was 9.9 Kelvin(K) with 200mm diameter and 13.4K with the 100mm diameter with the same material in winter. By the lower outside temperature from -7.2$^{\circ}C$, it could keep the air temperature above 6$^{\circ}C$ through the 100mm diameter pipe. The heating performance was 593 W with 200mm diameter, 118W with 100mm diameter (PE), and 115W with 100m diameter (PVC), respectively. As the outside temperature varies from -1.5$^{\circ}C$ to 18.6$^{\circ}C$ in early spring, the air temperature through the pipes show 4∼8$^{\circ}C$. While the difference between maximum and minimum outside temperature is 14K, the one through the pipes could be reduced by 2K. Pipes with small diameter can more reduce the difference than the pipe with larger diameter.

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A Study for Energy Separation of Vortex Tube using Air Supply System (I) - the effect of diameter of cold end orifice - (공기공급 시스템에 적용되는 Vortex Tube의 에너지 분리특성에 관한 연구(I) -저온출구 orifice의 직경변화에 의한 영향-)

  • 이병화;추홍록;상희선
    • Journal of the Korean Society of Safety
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    • v.13 no.4
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    • pp.9-18
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    • 1998
  • The vortex tube is a simple device for separating a compressed gaseous fluid stream into two flows of high and low temperature without any chemical reactions. Recently, vortex tube is widely used to local cooler of industrial equipments and air supply system. The phenomena of energy separation through the vortex tube was investigated experimentally. This study is focused on the effect of the diameter of cold end orifice diameter on the energy separation. The experiment was carried out with various cold end orifice diameter ratio from 0.22 to 0.78 for different input pressure and cold air flow ratio. The experimental results were indicated that there are an optimum diameter of cold end orifice for the best cooling performance. The maximum cold air temperature difference was appeared when the diameter ratio of the cold end orifice was 0.5. The maximum cooling capacity was obtained when the diameter ratio of the cold end orifice was 0.6 and cold air flow ratio was 0.7.

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Temperature and diameter effect on hydrodynamic characteristic of surfactant drag-reducing flows

  • Indartono Y.S.;Usui H.;Suzuki H.;Komoda Y.
    • Korea-Australia Rheology Journal
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    • v.17 no.4
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    • pp.157-164
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    • 2005
  • Hydrodynamic characteristic of surfactant drag-reducing flows is still not fully understood. This work investigated the temperature and diameter effect on hydrodynamic characteristic of cationic surfactant drag reducing flows in pipes. Solution of oleyl bishydroxyethyl methyl ammonium chloride (Ethoquad O/12), 900 ppm, as a cationic surfactant and sodium salicylate (NaSal), 540 ppm, as a counter-ion was tested at 12, 25, 40, and $50^{\circ}C$ in pipes with diameter of 13, 25, and 40 mm. Drag reduction effectiveness of this surfactant solution was evaluated in 25 mm pipe from 6 to $75^{\circ}C$. Rheological characteristic of this solution was measured by stress control type rheometer with cone-and-plate geometry. Scale-up laws proposed by previous investigators were used to evaluate the flow characteristic of the solution. It was found that this surfactant solution has clear DR capability until $70^{\circ}C$. Result of this work suggested that temperature has a significant influence in changing the hydrodynamic entrance length of surfactant drag reducing flows. From rheological measurement, it was found that the solution exhibits Shear Induced Structure at all temperatures with different degree of peak viscosity and critical shear rate.

Size-of-source Effect and Self-radiation Effect of an Infrared Radiation Thermometer (적외선 복사온도계의 복사원 크기효과 및 자기복사효과)

  • Yoo, Yong-Shim;Kim, Bong-Hwak;Park, Chul-Woung;Park, Seung-Nam
    • Korean Journal of Optics and Photonics
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    • v.21 no.4
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    • pp.133-138
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    • 2010
  • All radiation thermometers have a size-of-source effect (SSE) and a self-radiation effect (SRE). The SSE,defined as dependence of the detector signal of a radiation thermometer on the diameter of a source, is critically dependent on the wavelength since diffraction is the main cause. In this paper, we have measured the SSE and the SRE of TRT2 (Transfer Radiation Thermometer 2, HEITRONICS) widely used as a transfer standard in low and middle temperature range. At $300^{\circ}C$, The radiation temperature difference between the 60 mm diameter blackbody and 10 mm diameter blackbody due to the SSE was estimated to be $3.5^{\circ}C$ in low temperature mode ($8-14\;{\mu}m$) and $0.5^{\circ}C$ in middle temperature mode ($3.9\;{\mu}m$). In addition, the measured radiation temperature difference of the blackbody due to the SRE was found to be 110 mK when the body temperature change of TRT2 was set at $2.6^{\circ}C$.

The Effect of a Vortex Chamber Diameter Ratio on Energy Separation (보텍스 생성실 지름비가 에너지 분리에 미치는 영향)

  • 유갑종;이병화;최인수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.8
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    • pp.667-673
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    • 2001
  • As an alternative cooling method to reduce environmental hazard, vortex tubes have been studied for energy separation into cold and hot streams. Hence, the experiments were carried out systematically to find the best ratio of vortex chamber diameter to tube diameter. Also, the work was don to investigate how inlet pressure and geometric ratios of vortex tube affected temperature differences at tow needs as ell as cooling capacity and cooling efficiency. The result showed that the maximum temperature differences at the both ends and the maximum cooling efficiency were obtained when the ratio of vortex chamber diameter was about 1.45, while the inlet pressure ws not higher than 0.7 MPa.

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Pump and Temperature Effects on Drag Reducing Additives in Turbulent Pipe Flows (난류 관유동에서 마찰저항감소 첨가제에 대한 펌프와 온도의 영향)

  • Park, S.R.;Suh, H.S.;Yoon, H.K.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.8 no.3
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    • pp.330-337
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    • 1996
  • The effects of pump and temperature on drag reducing characteristics were investigated with a polymer(PAAM : Polyacrylamide) and three kinds of surfactants(CTAC, STAC, Habon-G) in fully developed turbulent pipe flows with various experimental parameters such as additive concentration(30~500ppm), pipe diameter(4.65mm, 10.85mm), Reynolds number($4{\times}10^4{\sim}10^5$) and working fluid temperature($20{\sim}80^{\circ}C$). The pump effect on PAAM was severe such that the drag reduction rates obtained with pump were decreased upto 30% as compared with those obtained with compressed air in 4.65mm test section. The temperature effect on PAAM was noticeably considerable, that is, the higher temperaute, the less drag reduction rate. On the other hand, no significant pump effect on the surfactants was observed. The drag reducing effectiveness of CTAC was totally lost in the temperature ragne of 60 to $80^{\circ}C$, whereas STAC and Habon-G kept their distinct drag reducing capability at a temperature of $80^{\circ}C$. This study clearly elucidated that for DHC application of drag reducing additives, the pump and temperature effects as well as additive concentration and pipe diameter should be carefully taken into consideration.

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Temperature History of Inner-form and Re-bars in Aluminum Concrete form During a Cold Weather Condition (한중 환경에서 알루미늄 폼 내부 철근의 직경변화에 따른 온도 특성)

  • Jung, Sang-Woon;Kim, Kyoung-Hoon;Heo, Young-Sun;Han, Min-Cheol;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2013.05a
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    • pp.113-114
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    • 2013
  • This study is to investigate the effect of the diameter of reinforcement bars located in an aluminum-form on the temperature histories of the re-bars before placing concrete during a cold weather condition. The diameters of reinforcement bars with 13 mm, 19 mm, 25 mm and 32 mm were prepared for the experimental tests. Results showed that the larger the size of the diameter of the bars, the higher were the temperature drop. However, this study found that its effect on the temperature drop of the bars was insignificant.

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Effect of Storage Temperature on the Dispersion Stability of O/W Nano-emulsions (O/W 나노에멀젼 분산안정성에 미치는 보관온도의 영향)

  • Lee, Ye-Eun;Yoo, In-Sang
    • KSBB Journal
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    • v.29 no.5
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    • pp.385-391
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    • 2014
  • In this study, the emulsion dispersion stability of optimizing storage temperature was investigated. The system was based on oil/water (O/W) emulsions. In order to evaluate the stability, mean diameter of droplet was measured as a function of temperature with various mixed hydrophilic lipophilic balance (HLB). In addition, the correlations between phase inversion temperature (PIT) and the optimum storage temperature were probed. In this system, majority of the smallest droplet was shown at temperature of $20^{\circ}C$ below PIT. Whether the temperature was increased or decreased from the optimum, size of the droplet increased. According to the mixed HLB, the particle size and optimum storage temperature were also affected. As the concentrations of surfactant were increased, the size of particle decreased with lower optimum temperature for storage. If the surfactant (4 wt%) were mixed with HLB, the optimum storage temperature was $21^{\circ}C$ for maintaining the size of smallest droplet at 108.3 nm in diameter. At above optimum condition, increased size of particle was observed approximately 4 % increases from 108.2 nm to 112.3 nm after 600 hours. The size of particle in emulsion was maintained stably without any considerable effect of Ostwald ripening phenomena at the optimum storage temperature with low polydispersity index.

The Effect of Nozzle Diameter on Heat Transfer to a Fully Developed Round Impinging Jet (완전 발달된 원형 충돌제트의 노즐 직경이 열전달에 미치는 영향)

  • Lee, Dae-Hee;Won, Se-Youl;Lee, Young-Min;Cho, Heon-No
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.4
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    • pp.519-525
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    • 2000
  • The effect of nozzle diameter on the local Nusselt number distributions has been investigated for an axisymmetric turbulent jet impinging on the flat plate surface. The flow at the nozzle exit has a fully developed velocity profile. A uniform heat flux boundary condition at the plate surface was created using gold film Intrex. Liquid Crystal was used to measure the plate surface temperature. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle to surface distance (L/d) from 2 to 14, and the nozzle diameter (d) from 1.36 to 3.40 cm. The results show that the Nusselt number at and near the stagnation point increase with an increasing value of the nozzle diameter.

Growth of SiC Nanorod Using Tetramethylsilane (테트라메틸사일렌을 이용한 탄화규소 나노로드의 성장)

  • Rho, Dae-Ho;Kim, Jae-Soo;Byun, Dong-Jin;Yang, Jae-Woong;Kim, Na-Ri
    • Korean Journal of Materials Research
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    • v.13 no.6
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    • pp.404-408
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    • 2003
  • SiC nanorods have been grown on Si (100) substrate directly. Tetramethylsilane and Ni were used for SiC nanorod growth. After 3minute, SiC nanorod had grown by CVD. Growth regions ware divided by two regions with diameter. The First region consisted of thin SiC nanorods having below 10 nm diameter, but second region's diameter was 10∼50 nm. This appearance shows by reduction of growth rate. The effect of temperature and growth time was investigated by scanning electron microscopy. Growth temperature and time affected nanorod's diameter and morphology. With increasing growth time, nanorod's diameter increased because of the deactivation effect. But growth temperatures affected little. By TEM characterization, grown SiC nanorods consisted of the polycrystalline grain.