• 한국농공학회논문집
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• 제53권2호
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• pp.61-65
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• 2011

Biomass is considered to be a major potential fuel and renewable resource for the future. In fact, there is high potential to produce the large amount of energy from biomass around the world. In this study, to obtain basic data for practical application of agricultural and forest by-products as fuel of heating system in agriculture, agricultural and forest biomass resources were surveyed, the pelletizer with capacity of $50\;kg{\cdot}h^{-1}$ was designed and manufactured and pellets were made by the pelletizer. High heating value, ash content, etc. of pellets made of agricultural and forest by-products were estimated. Straw of rice was the largest agricultural biomass in 2009 and the total amount of rice straw converted into energy of $299{\times}10^3$ TOE. And in 2009, amount of forest by-product converted into energy of $9,579{\times}10^3$ TOE. High heating values of pellets made of stem and seed of rape, stem of oat, rice straw and rice husk were 16,034, 16,026, 16,089, 15,650, $15,044\;kJ{\cdot}kg^{-1}$ respectively. High heating values of pellets made of agricultural by-products were average 83.6% compared to that of wood pellet. Average bulk density of pellets made of stem and seed of rape, stem of oat, rice straw and rice husk was $1,400\;kg{\cdot}m^{-3}$ ($1.4\;g{\cdot}cm^{-3}$). Ash contents of the pellets were 6.6, 7, 6.2, 5.5, 33% respectively. Rice husk pellet produced the largest ash content compared to other kinds of pellets.

• 한국태양에너지학회 논문집
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• 제32권5호
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• pp.25-30
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• 2012

Ground source heat pumps(GSHPs) are among the most efficient and comfortable heating and cooling technologies currently available, because they use the earth's natural heat to provide heating, cooling, and often, water heating. And Building Integrated Geothermal System(BIGS) is one of GSHPs which install ground heat exchanger(GHE) in energy pile without borehole to save the investment cost. Therefore, the experiment is to evaluate the heating performance of BIGS in Korea. The experimental results indicate that the average heat pump COP and overall system's COP values are approximately 4.4 and 3.0 in one week. This study shows that the BIGS could be used for heating in Korea.

• 설비공학논문집
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• 제16권12호
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• pp.1204-1211
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• 2004

It is difficult to apply a conventional selection guide for diffusers when the diffuser is installed in a perimeter zone, because the air diffusion performance index (ADPI) vs. throw/length (T/L) ratio curve listed in conventional guide does not consider the perimetric heating load through the walls. The objective of this study is to evaluate the effect of the perimetric heating load on the ADPI and propose a selection guide for a proper line diffuser when perimetric heating load exists. The velocity and temperature distributions and the ADPI values are obtained numerically with various heat load ratios and air flow rates. The velocity and temperature distributions and the ADPI values are analyzed by CFD in case of various heat load ratios and air flow rates. Also, ADPI was calculated by those results. The ADPI values by numerical results are compared with an existing experimental data to verify the method for the evaluation of ADPI proposed in a present study. In case of a line diffuser installed at the high side wall, the ADPI decreases according to the increases of the flow rate on every heat load ratio of the present study except 0.75. The ADPI vs. T/L ratio curves have been proposed for the heat load ratios of 0.25, 0.5, 0.75 to guarantee the comport thermal environment when diffusers are installed in perimeter zone.

• 유기물자원화
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• 제17권1호
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• pp.27-38
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• 2009

본 연구는 유기성폐기물인 음식물폐기물과 하수슬러지를 가연성폐기물을 혼재하여 연료로 사용하기 위해서 제조과정과 연소공정에서 발생되는 특성을 분석하였다. 연료화 재질의 특성은 연도분석기를 이용하여 배연가스 성분을 조사하였고, 발열량은 봄베식 열량계를 이용하여 분석하였다. 연료화 재료의 특성연구를 위하여 기초조사 수분함량(%), 가연성 폐기물 비율, 회분량, 중금속, 각 성분 원소분석, 발열량, 중량 혼재비율에 따라서 분석하였다. $RDF_{k-1}$의 연료는 건조하수슬러지, 음식물폐기물 및 가연성폐기물 혼재비율에 따라 제조하였고, $RDF_{k-2}$는 피트모스, 타르 및 하수슬러지 혼합비율에 의해서 제조하였다. 연소실험은 공기비 2와 연소온도 $850^{\circ}C$의 최적조건 상태에서 실험을 실행하였다. 연소실험장치에서 연소시간 5, 10, 15분의 간격으로 실험하였다. 연소장치로의 주입 연료량은 50g을 주입하여 실행하였다. $RDF_{k-1}$의 연료는 혼재비율에 따라서 발열량 실험결과 6,900에서 8,120 kcal/kg까지 분석되었고, $RDF_{k-2}$는 4,014에서 8,050 kcal/kg까지 나타났다. 연도실험에서 연소의 효율은 RDF의 발열량, 수분, 원소구성성분과 재질의 다양한 혼재비율에 큰 영향을 미치는 것으로 나타났다. 제조된 연료의 $RDF_{k-1}$ 연소실험에서 가연성 성분의 혼재비율이 높은 경우 발열량과 $C_xH_y$ 농도 및 회분량이 증가하였다. $RDF_{k-2}$ 경우는 tar의 혼재비율의 증가함에 따라 발열량은 증가하나 회분량, CO와 $C_xH_y$의 농도발생이 증가하는 것으로 나타났다.

• Journal of Biosystems Engineering
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• 제37권1호
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• pp.19-27
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• 2012

Purpose: Utilizing air thermal energy during over-heated time in the greenhouse is a necessary component to save greenhouse heating costs for nighttime. However, there is no practical way to implement the related principles. Methods: In this study, a heating and cooling system which utilizes the surplus air thermal energy in a greenhouse was developed. Available air thermal energy and heating load for this experimental glasshouse were estimated based on temperature conditions of the plant growth and weather data. Results: Estimated values were 400 MJ/day for maximum surplus air thermal energy and 340 MJ/day for maximum heating energy which were target values of the design as well. The system consists of a heat pump, fan-coil units and heat storage tanks which are divided into low and high temperature tanks. Moreover, a new control logic was developed for surplus air thermal energy utilization. Conclusions: This paper explains the details of conceptual design process of the system. Results of test operations showed that the developed system performed the recovery and supply of the thermal energy according to design purposes.

• 동아시아식생활학회지
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• 제24권1호
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• pp.80-91
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• 2014

The aim of this study was to establish the superiority of ohmic heating over conventional heating for the sterilization of mulberry juice. Heat treatment of fresh juice significantly reduced the concentration of soluble solids, lowered the pH, and lowered the reducing sugar content (p<0.01). Color measurements showed decreases in the L and a values and increases in the b, H and C values after heat treatment, although the total color differences were smaller after ohmic heating than after conventional heating of fresh juice. The antioxidant capacities, such as reducing power, FRAP, and DPPH, decreased in the order of fresh juice, ohmically heated juice and conventionally heated juice. Furthermore, the anthocyanin, flovonoid, and total antioxidant capacities of the juices significantly decreased in the same order. Sensory evaluations showed no difference between fresh and ohmically heated mulberry fruit juice excluding off-flavor, whereas conventionally heated juice received significantly lower evaluations. The microbial counts were zero in the juice after either heat treatment. Thus, ohmic heat treatment can be effectively used to sterilize fresh mulberry juice to obtain good shelf life with minimal physicochemical, color, antioxidant and sensory deterioration.

• 한국염색가공학회지
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• 제30권3호
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• pp.216-226
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• 2018

The combination dyeing have been attempted to get the various color. The objective of this research was to study the color developing effects on cotton fabrics dyed with persimmon, catechu and combination of the both by heat treatment process. These dye were applied on bleached cotton fabrics for the dyeing before post mordanting with aluminium potassium sulfate, copper sulfate, and iron sulfate. The various color changes on cotton fabric were measured by color spectrophotometer. The heat treatment of temperature around $150^{\circ}C$ for an hour can reach the highest color developing. The dyed fabrics with mordanting were heated for specific time period, which was compared without the mordanting. The post mordanted fabrics showed that more various colors can be obtained using combination dyeing. K/S values of dyed fabrics with Al, Fe, and Cu mordants were higher than the cases without mordants. The Cu mordanted fabric showed very effective color developing by the heating process. The fabrics dyed with catechu lowered L* value with little changes in a* and b* values, while the a* and b* values became higher with heat treatment. The fabrics dyed with persimmon has the lowest L* value and more changes in a*, b* value with heating process. Therefore, K/S values can be increased effectively by the combination dyeing of persimmon and catechu. Colorfastness to washing in color change was grade 2-3 in non-mordanted fabric, and grade 3 in mordanted fabric. Lightfastness of the dyed fabrics was above grade 4.

• 한국식품영양과학회지
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• 제25권6호
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• pp.951-957
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• 1996

당근, 쪽파, 시금치와 같은 채소류에 대한 데치기 실험에서 데치기 시간은 전자레인지 CCT가 빨랐으며, 색도 및 절단강도 변화에서는 데치기 처리로 명암도, 적녹도, 황청도, 절단 강도가 대조구에 비하여 감소하였으며 그 감소 폭은 전자레인지 CCT의 경우가 적었다. 미세구조 관찰에서는 전자레인지 CCT가 NCCT보다 조직 구조가 덜 파괴하는 것으로 나타났으며, vitamin C 함량에서도 전자레인지 CCT가 손실이 적었다.

• Journal of Mechanical Science and Technology
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• 제18권2호
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• pp.294-301
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• 2004

The natural convective heat transfer in a rectangular enclosure with a heating source has been studied by experiment and numerical analysis. The governing equations were solved by a finite volume method, a SIMPLE algorithm was adopted to solve a pressure term. The parameters for the numerical study are positions and surface temperatures of a heating source i.e., Y /H =0.25, 0.5, 0.75 and 11$^{\circ}C$ $\leq$ΔT$\leq$59$^{\circ}C$. The results of isotherms and velocity vectors have been represented, and the numerical results showed a good agreement with experimental values. Based on the numerical results, the mean Nusselt number of the rectangular enclosure wall could be expressed as a function of Grashof number.

• 한국지열·수열에너지학회논문집
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• 제9권2호
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• pp.1-7
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• 2013

Most researches done on heat pumps have been on heat pumps for refrigeration, cooling and heating. There is therefore the need for more research on hot water heat pumps, especially for high temperature. Even though the cascade heat pump cycle has a great potential more efficient hot water generation even at low evaporating temperatures, it has been researched least for this purpose. In this study, the heating performance of a variable speed cascade heat pump was investigated by varying operating conditions. For the same heating capacity values, it was found that increasing the low stage compressor speed was more suitable for enhancing the performance of the system to get a higher temperature.