• Title/Summary/Keyword: Heat accumulation

Search Result 228, Processing Time 0.022 seconds

A study of Heat Analysis on Track Rubber Parts (궤도고무부품의 열해석에 관한 연구)

  • Kim, Young-Soo
    • Journal of the Korean Society for Precision Engineering
    • /
    • v.16 no.9
    • /
    • pp.117-122
    • /
    • 1999
  • Track rubber parts has heat built-up as long as dynamic loading is applied from running tracked vehicles. Durability is required for rubber part to sustain the heat accumulation and heat exchange between rubber-metal assembly and environmental air and ground. For this research, the track assembly was divided into four parts i.e., bottom track shoe, upper track pad, pin busing and metal structure. Three rubber parts and metal structure were modelled and analyzed with MARC package program to obtain time-temperature data which was induced form mechanical work of tracked vehicles. heat accumulation data was obtained from special experiments under the room temperature of 25$^{\circ}C\;and\;35^{\circ}C$ to simulate the actual environmental conditions. From this research, it is cleared that the environmental temperature does not affect to the heat accumulation speed in rubber parts. Also, the heat built-up mechanism was clarified from the thermo-mechanical work based on numerical analysis and experiments.

  • PDF

Study on the Correlation between Thermal Characteristics and Heat Accumulation in the Coal Pile (석탄의 열적 특성과 석탄 내부의 승온 특성과의 상관관계 연구)

  • Lee, Hyun-Dong;Kim, Jae-Kwan
    • Journal of the Korean Society of Combustion
    • /
    • v.15 no.4
    • /
    • pp.58-64
    • /
    • 2010
  • Spontaneous ignition tests of five different coals with non-iso-thermal and iso-thermal test method based on the standard test procedure of NF T20-036 were carried. These five coals included the 2 low rank coals and 3 bituminous coals. Test results showed that the ignition temperatures of all coals at the iso-thermal conditions were higher than that of non-isothermal condition, and those of low rank SM and BR coal in both nonisothermal and isothermal conditions were lower than bituminous AN and CN coals. The chemical species of coals such as oxygen and hematite also plays an important role in enhancing the ignition rate that the ignition temperature of SM coal was lowered. The heat accumulation tendency of five coals inside outdoor stack pile was monitored with emphasis on the change in the temperature of the coal depth in stack pile. In case of low rank BR coal, its temperature inside coal stack pile due to the rate of high heat accumulation and oxidation was $59^{\circ}C$ compared to $51^{\circ}C$ for other SW bituminous coal. And the heat accumulation rate inside coal stack piles was increased with increased the Cp value which it was defined as the specific heat of coal at constant pressure, whereas other factors such as thermal diffusivity and conductivity of coal relatively had less effect on heat accumulation.

Dust accumulation effect on solar thermal energy systems performance

  • Alsaad, Mohammad A.
    • Advances in Energy Research
    • /
    • v.3 no.3
    • /
    • pp.157-165
    • /
    • 2015
  • This research investigates the effect of natural dust accumulation on the glass cover of solar thermal energy conversion systems. Four similar, locally manufactured, flat plate solar collectors are used. All collectors are South oriented with tilt angle of $40^{\circ}$. The glass cover of one collector is kept clean of dust during the experimental period while the second collector is cleaned at the beginning of each month. The third collector is cleaned every two months while the fourth collector is kept un-cleaned throughout the experimental period of four months. The calculated parameters are the solar heat gain rates and the corresponding values of the thermal efficiency. The result of the present work indicates that the percentage of fractional reduction of the useful heat gain rate due to dust accumulation during a period of one and two months is 11.4% and 17.0%, respectively. The percentage decrease of thermal efficiency during the same duration periods is 4.0% and 6.1%, respectively. The percentage of fractional reduction of the useful heat gain rate due to dust accumulation during a period of three and four months is 27.8% and 31.9%, respectively. The percentage decrease of monthly thermal efficiency during the same duration period is 10.2% and 11.3%, respectively.

Effect of Trehalose Accumulation on the Intrinsic and Acquired Thermotolerance in a Natural Isolate, Saccharomyces cerevisiae KNU5377

  • PAIK, SANG-KYOO;HAE-SUN YUN;HO-YONG SOHN;INGNYOL JIN
    • Journal of Microbiology and Biotechnology
    • /
    • v.13 no.1
    • /
    • pp.85-89
    • /
    • 2003
  • The difference in the thermotolerance between Saccharomyces cerevisiae KNU5377 and ATCC24858 was compared by assaying the amounts of trehalose accumulated under growth and heat shock conditions. Both strains exhibited similar trehalose accumulation during the growth period, but an intrinsic thermotolerance was much higher in KNU5377 than in the control strain. This result implied that some strain-specific characteristics of KNU5377, other than trehalose accumulation, primarily were responsible fur its higher intrinsic thermotolerance. Heat shock at $43^{\circ}C$ for 90 min to the exponentially growing cells resulted in the maximum level of trehalose In both strains. Trehalose accumulated at least twice more in KNU5377 by the heat shock than in the control, due to the maintenance of its neutral trehalase activity even after the heat shock. Consequently, the Increase of acquired thermotolerance in both strains correlated with an increase in the trehalose content in each strain. In conclusion, KNU5377 exhibited a well-modulated trehalose-related mechanism to accumulate more trehalose by means of maintaining neutral trehalase activity after heat shock than the control strain, thereby contributing to its acquired thermotolerance.

Relationship Between Heat Unit Requirement and Growth and Yield of Mulberry, Morns indica L.

  • Sarkar A.;Rekha M.;Keshavacharyulu K.
    • International Journal of Industrial Entomology and Biomaterials
    • /
    • v.10 no.1
    • /
    • pp.65-68
    • /
    • 2005
  • Growth and development of a plant over a growing season is closely related to the daily accumulation of heat. Heat unit measured by accumulated growing degree days (GDD) is becoming increasingly popular to estimate the growth of a plant or even in insect. GDD or heat accumulation per day is measured by calculating average daily temperature and then subtracting the base temperature below which growth does not occur. Heat accumulation per day is added for the desired period and accumulated GDD is determined. The present study was conducted in five seasons in an established garden with K-2, S-36 and V-1 mulberry varieties belonging to Morus indica L. grown under completely irrigated condition at the farm of CSRTI, Mysore during 2001 - 2002. Plants were pruned in each season and the growth of the plant measured by total shoot length and fresh leaf yield was recorded at an interval of 5 days starting from 30 days of pruning (DAP) to 70 days when all the plants were pruned. The accumulated GDD for the corresponding days were recorded and used for analysis. Accumulated growing degree days (GDD) have been found to be perfectly correlated with both growth and yield in all the seasons in all the varieties studied. The high $R^2$ values indicated a strong relationship between the accumulated GDD and, growth and yield of mulberry.

A Study on the Mechanical Behavior of Welded Parts in Thick Plate during Post Welding Heat Treatment (厚板熔接部의 應力除去 熱處理時의 力學的 擧動에 關한 硏究)

  • 방한서
    • Journal of Welding and Joining
    • /
    • v.11 no.4
    • /
    • pp.103-111
    • /
    • 1993
  • Recently, several high-tensile steels(e.g. 80kg and above, $2^{1/4}Cr$-1Mo)having good quality to high temperature and pressure-resistance are widely used to construct petroleum-plant and pressure vessel of heat or nuclear-power plant. However, in the steels, reheating crack at grain boundaries of the heat affected zone(HAZ) occures during post welding heat treatment(PWHT)to remove welding residual stress. In order to study theoretically the characteristics of reheating crack created by PWHT, the computer program of three-dimensional thermal-elasto-plasto-creep analysis based on finite element method are developed, and then the mechanical behavior(history of creep strain accumulation and stress relaxation, etc)of welded join in thick plate during PWTH is clarified by the numerical results.

  • PDF

Heat Transfer Characteristics of the Asphalt pavement by Solar Energy accumulation (열에너지 누적에 따른 아스팔트 포장의 열전달 특성 변화)

  • Lee, Kwan-Ho;Kim, Seong-Kyum;Oh, Seung-Sig
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.21 no.6
    • /
    • pp.490-497
    • /
    • 2020
  • Asphalt pavement accounts for more than 90% of the total pavement in Korea. Pavement is most widely constructed among construction structures. The heat transfer characteristics (Thermophysical Properties) of the asphalt pavement cause the heat island effect in downtown areas. An increasing asphalt surface temperature is one of the major causes of damage to asphalt pavement. This study examined the heat transfer characteristic factors according to solar energy accumulation in an asphalt mixture. The specimens (WC-2 & PA-13, Recycled aggregate used WC-2) used in the experiment were compacted with a Gyratory Compactor. The thermo-physical properties (thermal conductivity, specific heat capacity, thermal diffusivity, and thermal emissivity) and solar energy accumulation were evaluated. The thermal accumulation and HFM tests revealed a 1.2- to 2.0-fold difference. This indicates that the thermal conductivity of the asphalt mixture pavement changes with the accumulation of solar energy. An analysis of the correlation of thermal conductivity according to the surface temperature of the asphalt mixture showed that WC-2 was logarithmic, and PA-13 was linear. Experiments on the heat transfer characteristics of asphalt pavement that can be used for thermal failure modeling of asphalt were conducted.

A Research on the Epidermic disease of Yang etc. in SangHanMyungRiSokLon (상한명리속론(傷寒明理續論).양독(陽毒)외 14증(證)에 대한 연구(硏究))

  • Lee, Dong-Su;Sheen, Yeong-Il
    • Journal of Korean Medical classics
    • /
    • v.19 no.2 s.33
    • /
    • pp.266-293
    • /
    • 2006
  • Accumulation of pathogens in chest refers to a syndrome of fullness, stuffiness and pain in the chest, diaphragm, epigastrium and abdomen, which is ascribable to accumulation of pathogenic heat with stagnancy of fluid or phlegm in the chest. Retching refers to vomiting with sound but without any vomitus. It is usually ascribable to adverse flow of ki due to deficiency of stomach, or by pathogenic heat or cold, and failure in descending of the stomach-ki. It may also be found in Soyang disease. Bloody purulent stool refers to passing stool with blood and pus. It is formed mainly due to invasion of the stomach and the intestines by epidemic pathogenic summer-heat, steaming of stagnateed damp-heat fighting against ki and blood, or improper diet, obstruction of bu-ki stagnation of blood and ki.

  • PDF

Expression and Accumulation of LMW HSPs under Various Heat Shock Conditions (다양한 열처리 조건에서 LMW HSPs의 발현 및 축적량 조사)

  • Kim, Ki-Yong;Jang, Yo-Soon;Lee, Byung-Hyun;Jo, Jinki
    • Journal of The Korean Society of Grassland and Forage Science
    • /
    • v.18 no.4
    • /
    • pp.303-310
    • /
    • 1998
  • We studied expression patterns of thermotolerance gene (BcHSP17.6) in cabbages which was isolated from Chinese cabbage and we will attempt transformation of forage crops with the gene in order to increase thermotolerance of forage crops. Antiserum against a BcHSP17.6 protein was reacted with its antigen. With this antiserum, the accumulation of the 15- to 18-kD LMW HSPs under various heat shock (HS) conditions was quantified. The LMW HSPs began to be detectable at $35^{\circ}C$, and after 4 hours at $40^{\circ}C$ they were accumulated to a maximum level of 1.56 micrograms per 100 micrograms of total proteins in cabbage leaves and remained almost unchanged up to 24 hours after HS. Accumulation of the HSPs was reduced at temperatures higher than $40^{\circ}C$. We conclude that accumulation of these LMW HSPs are necessary for Chinese cabbages to survive at an otherwise lethal temperature.

  • PDF

A Study on the Determination of Grain Size of Heat-treated Stainless Steel Using Digital Ultrasonic Signal Processing Techniques. (디지털 초음파 신호처리 기법을 이용한 열처리된 스테인레스 스틸의 그레인 크기 결정에 관한 연구)

  • 임내묵;이영석;김성환
    • The Journal of the Acoustical Society of Korea
    • /
    • v.18 no.8
    • /
    • pp.84-93
    • /
    • 1999
  • Determination of grain size of heat-treated stainless steel based fm digital ultrasonic signal processing technique is presented. This techniques consist in evidence accumulation with multiple feature parameters, difference absolute mean value(DAMV), variance(VAR), mean frequency (MEANF), auto regressive model coefficient(ARC) and linear cepstrum coefficient(LCC). Feature parameters were extracted from ultrasonic echo signal of heat-treated metals. It was found that a few parameters might not be sufficient to exactly evaluate the grain size of heat-treated metals. The determination of grain size of heat-treated metals was carried out through the evidence accumulation procedure using the distances measured with reference parameters. A fuzzy mapping function is designed to transform the distances for the application of the evidence accumulation method. In the work presented, heat-treated stainless steel samples with various grain sizes are examined. The processed experimental results supports the feasibility of the grain size determination technique presented.

  • PDF