• Title/Summary/Keyword: Higher Heating Value

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Calculation of Outdoor Air Fraction through Economizer Control Types during Intermediate Season

  • Hong, Goopyo;Hong, Jun;Kim, Byungseon Sean
    • KIEAE Journal
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    • v.16 no.6
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    • pp.13-19
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    • 2016
  • Purpose: In this study, we examined outdoor air fraction using historical data of actual Air Handling Unit (AHU) in the existing building during intermediate season and analyzed optimal outdoor air fraction by control types for economizer. Method: Control types for economizer which was used in analysis are No Economizer(NE), Differential Dry-bulb Temperature(DT), Diffrential Enthalpy(DE), Differential Dry-bulb Temperature+Differential Enthalpy(DTDE), and Differential Enthalpy+Differential Dry-bulb Temperature (DEDT). In addition, the system heating and cooling load were analyzed by calculating the outdoor air fraction through existing AHU operating method and control types for economizer. Result: Optimized outdoor air fraction through control types was the lowest in March and distribution over 50% was shown in May. In case of DE control type, outdoor air fraction was the highest of other control types and the value was average 63% in May. System heating load was shown the lowest value in NE, however, system cooling load was shown 1.7 times higher than DT control type and 5 times higher than DE control type. For system heating load, DT and DTDE is similar during intermediate season. However, system cooling load was shown 3 times higher than DE and DEDT. Accordingly, it was found as the method to save cooling energy most efficiently with DE control considering enthalpy of outdoor air and return air in intermediate season.

Chemical Compositions and Thermal Characteristics of Rice Husk and Rice Husk Ash in Korea (왕겨 및 왕겨재의 화학적 조성 성분과 열적 특성)

  • Park S. J.;Kim M. H.;Shin H. M.
    • Journal of Biosystems Engineering
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    • v.30 no.4 s.111
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    • pp.235-241
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    • 2005
  • For better and large utilization of rice husk, the production and consumption status, differences in chemical composition and heating value due to region and variety, and thermogravimetric characteristic of rice husk were studied. In addition, the differences in chemical composition due to region and variety and the crystallization characteristic of rice husk ash were also studied. Approximately 800,000 M/T of rice husk was produced per year in Korea, which is about $18\%$ of the paddy production by weight. Noticeable varietal and regional difference pattern in chemical composition was not found among the domestic rice husk samples. Their average ash content and higher heating value were $16.4\%$ and 16,660 kJ/kg by dry basis, respectively. A relation seemed to exist between the carbon content and higher heating value. Noticeable difference pattern in chemical composition was not found among the domestic rice husk ash samples. The $SiO_2$ contents were a little low, the maximum being $92.9\%,$ and the contents of major components such as CaO, MgO, and $K_2O$ were also lower compared with foreign rice husk ash due to the deficiency of compost matters in domestic soils. Thermogravimetry study showed the thermal decomposition of rice husk started at about $250^{\circ}C,$ followed by relatively fast combustion of combustible gas until the temperature rose to $350^{\circ}C.$ After $350^{\circ}C,$ combustion of the carbon component proceeded relatively slowly as the temperature increased. Therefore, the ignition temperature of the rice husk could be estimated around $300^{\circ}C$. Crystallization of $SiO_2$ in the rice husk ash was found from the combustion temperature of $750^{\circ}C$ and became distinctly when the combustion temperature exceeded $900^{\circ}C$. The ash became darker with $SiO_2$ crystallization.

Comparison of Thermal Stability of Alkali Refined and Esterified Rice Bran Oils (알칼리 정제(精製)와 에스테르화에 의한 미강유의 열안정성(熱安定性)의 비교(比較))

  • Kim, Hyun-Ku;Shin, Dong-Hwa;Shin, Hyo-Sun
    • Korean Journal of Food Science and Technology
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    • v.17 no.3
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    • pp.180-185
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    • 1985
  • The alkali refined rice bran oil (ARBO) and the esterified rice bran oil (ERBO) with glycerol were compared for their thermal stabilities at $150^{\circ}C$ and $180^{\circ}C$, respectively. The acid value gradually increased in ARBO during heating period but increased slowly in ERBO-2 and declined gradually in ERBO-1. The peroxide value was somewhat fluctuated during heating period, and the maximum peroxide value in all samples was 13.3 meq/kg. TBA value was sharply increased for the first 10 hr. heating and slowed down thereafter for all samples but ERBO were intensely colored after the heat treatment. The TG ratio of the oils after 90 hr. heating was not different at $150^{\circ}C$ but ERBO was 2-7% higher ratio of TG than ARBO at $180^{\circ}C$. The oxidative stability of ARBO was twice higher than ERBO according to the result of active oxygen test.

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A Direct Calculation of Higher Heating Values of Ultrasonic Reformed Diesel Fuels by Using Their Viscosity and Surface Tension Measurements (초음파 개질 경유의 점도 및 표면장력 측정을 이용한 발열량 직접 계산)

  • Lee, B.O.;Ryu, J.I.
    • Journal of ILASS-Korea
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    • v.6 no.4
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    • pp.22-30
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    • 2001
  • The objective of this study is to develop the new equations for the calculation of higher heating values(HHVs) of reformed diesel fuels by ultrasonic treatment. Therefore, higher heating values of reformed diesel fuels by ultrasonic treatment are determined experimentally and calculated from their viscosity and surface tension measurements. The HHVs of the fuels are supposed to be a function of viscosity(Pa s) and surface tension(N/cm). The equations developed for the samples represent the correlation obtained by means of regression analysis. The HHVs calculated by developing new equations using viscosities showes the differences from the measured values ranging from -0.66 to 1.19 % and the correlation coefficient was -0.9411. The HHVs calculated by developing new equations using surface tensions showed the differences from the measured values ranging from -0.70 to 1.51 % and the correlation coefficient was 0.9999. The viscosity and the surface tension are characteristic properties of ultrasonic reformed diesel fuels for developing new formulae.

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Estimating the Higher Heating Value of Eco-fuel mixed Biomass with Municipal Organic Wastes from Ultimate Analysis Data (원소분석을 통한 바이오매스에 도시형 유기성 폐기물을 혼합한 신연료의 고위발열량 예측)

  • Oh, Song-Yul;Kim, Lae-Hyun;Han, Hee-Joon;Moon, Jang-Soo;Kim, Hee-Joon
    • Journal of Energy Engineering
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    • v.16 no.4
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    • pp.194-201
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    • 2007
  • HHV (Higher Heating Value) of biomass fuel is calculated by using ultimate analysis data and has been proposed by using correlation equation, and compared with the experiment the adequacy about each correlation equation with measured HHV and examined. Samples used for experiment are prepared by mixing biomass (i.e. rice husk and sawdust) with organic waste (i.e. polystyrene polypropylene and waste paper) of 10, 30, 50 wt% of composition. Ultimate analysis and measurement of HHV are respectively measured by using KS standard method. The average error value of estimated HHV results is about 880 kJ/kg(about 3.8% of measured HHV). The corresponding correlation coefficients ($R^2$) of experimental result and estimated HHV result are $0.957{\sim}0.996$.

The Effect of Soil Warming on the Greenhouse Heating Load (지중가온이 온실의 난방부하에 미치는 영향)

  • Nam, Sang-Woon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.48 no.5
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    • pp.51-60
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    • 2006
  • In order to examine the heat transfer characteristic of a soil warming system and effects of soil warming on the greenhouse heating load, control experiments were performed in two greenhouses covered with double polyethylene film. One treated the soil warming with an electric heat wire and the other treated a control. Inside and outside air temperature, soil temperature and heat flux, and heating energy consumption were measured under the set point of heating temperature of $5,\;10,\;15,\;and\;20^{\circ}C$, respectively. Soil temperatures in a soil warming treatment were observed $4.1\;to\;4.9^{\circ}C$ higher than a control. Heating energy consumptions decreased by 14.6 to 30.8% in a soil warming treatment. As the set point of heating temperature became lower, the rate of decrease in the heating energy consumptions increased. The percentage of soil heat flux in total heating load was -49.4 to 24.4% and as the set point of heating temperature became higher, the percentage increased. When the set point of heating temperature was low in a soil warming treatment, the soil heat flux load was minus value and it had an effect on reducing the heating load. Soil heat flux loads showed in proportion to the air temperature difference between the inside and outside of greenhouse but they showed big difference according to the soil warming treatment. So new model for estimation of the soil heat flux load should be introduced. Convective heat transfer coefficients were in proportion to the 1/3 power of temperature difference between the soil surface and the inside air. They were $3.41\;to\;12.42\;W/m^{2}^{\circ}C$ in their temperature difference of $0\;to\;10^{\circ}C$. Radiative heat loss from soil surface in greenhouse was about 66 to 130% of total heating load. To cut the radiation loss by the use of thermal curtains must be able to contribute for the energy saving in greenhouse.

The Mixing Effect of Methanol and Ethanol in Lard and Soybean Oil Based Biodiesel Production (돈지와 대두유를 이용한 바이오디젤 제조에서 메탄올과 에탄올의 혼합효과)

  • Lee, Seung Bum;Kim, Hyungjin
    • Applied Chemistry for Engineering
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    • v.25 no.5
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    • pp.515-519
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    • 2014
  • The fuel properties of biodiesel produced by changing the mixing ratio of methanol and ethanol in trans-esterification of soybean oil and lard were evaluated in this paper. The solubility of oil and fat in ethanol was higher than that in methanol. Also the more homogeneous biodiesel was produced as increasing the mole ratio of ethanol. The conversion characteristics of lard was the best at the mixing mole ratio of methanol and ethanol was 6 : 6 at the reaction temperature of $60^{\circ}C$. On the other hands, the best biodiesel conversion characteristics for soybean oil was obtained at the mixing mole ratio of 3 : 3. The kinematic viscosities of soybean oil and lard based biodiesel were 4.17~4.35 cSt and 4.69~4.93 cSt, respectively. The oxidation stability and higher heating value increased with increasing the mole ratio of ethanol. The oxidation stability satisfied the criteria of biodiesel quality of 6 hours. And finally, the higher heating value was approximately 40 MJ/kg.

A study on the anti-freezing of light weight electric traction system testing road (경량전철 시스템 선로 결빙방지에 관한 연구)

  • Woo, Jae-Ho;Han, Kyu-Il;Kim, Jong-Soo
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.2256-2261
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    • 2008
  • The electric snow melting and deicing system by electric heating cable which is adopted in this study is a part of road facilities to keep surface temperature of the road higher than freezing point of water for melting the snow or ice accumulated on it. The electric heating cables are buried under paved road at a certain depth and a certain pitch and operated automatically and manually. Design theory, amount of heating, and installation standard vary according to economic situation, weather condition, and installation place. A main purpose of this study is figuring out the appropriate range of required heat capacity and installation depth and pitches for solving snowdrifts and freezing problems with minimum electric power consumption. This study was performed under the ambient air temperature($-2^{\circ}C$, $-5^{\circ}C$), the pitches of the electric heating cables (200 mm, 300 mm), heating value ($250\;W/m^2$, $300\;W/m^2$, $350\;W/m^2$).

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A study on welding structure and thermal behavior in friction welding of austenitic stainless steel (오스테나이트계 스테인레스강의 마찰압접시 압접조직과 열적거동에 관한 연구)

  • 강춘식;정태용
    • Journal of Welding and Joining
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    • v.8 no.1
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    • pp.43-53
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    • 1990
  • The transient temperature distribution in the continuous friction welding 304 stainless steel bars is investigated by experimental and analytical methods. It is calculated by F.D.M. (finite difference method). The heating pressure, the rotational speed and friction coefficient obtained from experiment are used to determine the heat input at the contacting surface. Thermal properties of the workpiece are the function of temperature. The calculated temperature is well coincided with the measured value. The grain size at weld interface is extremely small due to the severe plastic deformation at high temperature, and result of this refined zone reveals higher hardness value. Because the HAZ is very narror about 2-3 mm, welding defects do not occure.

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A Study on the Maintenance Cost Estimation Model of the Apartment Housing (공동주택의 관리비 추정모델 연구)

  • Lee, Kang-Hee;Yang, Jae-Hyuk;Chae, Chang-U
    • Journal of the Korean housing association
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    • v.21 no.2
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    • pp.59-67
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    • 2010
  • The maintenance cost plays a important role to plan the scale of the apartment housing such as a number of household, building area and building type. Therefore, it is required to forecast the cost considering various maintenance characteristics. The maintenance characteristics are floor area, number of household, heating type, site area and etc.. In addition, the maintenance cost are classified into 5 area. These are a personal expense, facility maintenance cost, energy and water cost, insurance and sanitary cost. These five cost area are related with various characteristics and brought up the estimation model using the stepwise multiple regression analysis. The energy and heating cost share over the 50% in the total cost and the personal expense cost shares about 40%. The personal expense cost per area is 5,272 won/$m^2{\cdot}yr$ irregardless of heating type and the district heating type is a higher cost than other type. In facility maintenance cost, the central heating type is 2,015 won/$m^2{\cdot}yr$ and higher than other type. The estimation models have good statistics in each model. Most of the model have a determination coefficient over 0.7 and Durbin Watson value between 1.5 and 2.5.