• Title/Summary/Keyword: Cold heat source

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Winter Season Performance Characteristics of Raw Water-Source Heat Pump System with a Thermal Storage Tank (원수열원 히트펌프 축열시스템의 동절기 성능분석)

  • Cho, Yong;Lee, Dong Keun
    • 한국신재생에너지학회:학술대회논문집
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    • 2011.05a
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    • pp.202-202
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    • 2011
  • Performance of the raw water-source heat pump system with a thermal storage tank has been analyzed in winter season. The raw water is transferred through the multi-regional water supply system from Han river. Raw water is large temperature difference resource compared with groundwater. Although the raw water temperature drops to $0.6^{\circ}C$ due to the heavy snowfall and the severe cold in late January and early February, 2010, the system has been normally operated without any trouble this winter. The unit COP and system COP considered all pump power consumption were estimated based on the second-by-second data of the all sensors. The monthly averaged unit COP and system COP are 3.37 and 2.76 respectively with $1.4^{\circ}C$ of raw water in January, 3.55 and 2.89 with $1.6^{\circ}C$ raw water in February, 3.82 and 3.15 with $5.4^{\circ}C$ raw water in March. The performance of the system are increased with raw water temperature, and the COPs are higher than the water-to-air heat pump system using relatively high temperature raw water from Daecheong reservoir because the water-to-water system was operated on the full load condition and was stopped when the thermal storage tank was full of the high temperature water.

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Process Analysis and Simulation for System of Air Liquefaction Separation Using LNG Cold Energy (LNG 냉열을 이용한 공기액화분리시스템의 시뮬레이션 및 공정 해석)

  • HAN, DANBEE;BAEK, YOUNGSOON
    • Journal of Hydrogen and New Energy
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    • v.30 no.3
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    • pp.276-281
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    • 2019
  • The process of separating oxygen and nitrogen from the air is mainly performed by electric liquefaction, which consumes a lot of electricity, resulting in higher operating costs. On the other hand, when used for cold energy of LNG, electric power can be reduced compared to the electric Linde cycle. Currently, LNG cold energy is used in the cold refrigeration warehouse, separation of air-liquefaction, and LNG cold energy generation in Japan. In this study, the system using LNG cold energy and the Linde cycle process system were simulated by PRO/II simulators, respectively, to cool the elevated air temperature from the compressor to about $-183^{\circ}C$ in the air liquefaction separation process. The required amount of electricity was compared with the latent heat utilization fraction of LNG, the LNG supply pressure, and the LNG cold energy usage. At the air flow rate of $17,600m^3/h$, the power source unit of the Linde cycle system was $0.77kWh/m^3$, compared with $0.3kWh/m^3$.

HEATING PERFORMANCE OF AIR SOURCE HEAT PUMP WITH HEAT REGENERATIVE DEVICE USING FIBER BELT

  • Ryou, Y.S.;Chang, J.T.;Kim, Y.J.;Kang, G.C.;Yun, J.H.;Lee, K.J.
    • Proceedings of the Korean Society for Agricultural Machinery Conference
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    • 2000.11c
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    • pp.647-653
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    • 2000
  • In this research the heat regenerative technology was employed to eliminate frosting on evaporator coil and improve COP of the heat pump system. This heat regenerative device(HRD) has very simple structure consisting a geared motor and a porous fiber belt passing through alternatively between cold and warm air duct. The laboratory test showed that the heat pump system with HRD yielded an impressive COP higher than 3.5 at the outside air temperature of $-7^{circ}C$ in heating mode.

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The Influence of Groundwater Flow on the Performance of an Aquifer Thermal Energy Storage (ATES) System (지하수류가 대수층 열저장 시스템의 성능에 미치는 영향(3))

  • Hahn, Jeongsang;Lee, Juhyun;Kiem, Youngseek;Lee, Kwangjin;Hong, Kyungsik
    • Journal of Soil and Groundwater Environment
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    • v.22 no.4
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    • pp.9-26
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    • 2017
  • When a warm well located downgradient is captured by cold thermal plume originated from an upgradient cold well, the warm thermal plume is pushed further downgradient in the direction of groundwater flow. If groundwater flow direction is parallel to an aquifer thermal energy storage (ATES), the warm well can no longer be utilized as a heat source during the winter season because of the reduced heat capacity of the warm groundwater. It has been found that when the specific discharge is increased by $1{\times}10^{-7}m/s$ in this situation, the performance of ATES is decreased by approximately 2.9% in the warm thermal plume, and approximately 6.5% in the cold thermal plume. An increase of the specific discharge in a permeable hydrogeothermal system with a relatively large hydraulic gradient creates serious thermal interferences between warm and cold thermal plumes. Therefore, an area comprising a permeable aquifer system with large hydraulic gradient should not be used for ATES site. In case of ATES located perpendicular to groundwater flow, when the specific discharge is increased by $1{\times}10^{-7}m/s$ in the warm thermal plume, the performance of ATES is decreased by about 2.5%. This is 13.8% less reduced performance than the parallel case, indicating that an increase of groundwater flow tends to decrease the thermal interference between cold and warm wells. The system performance of ATES that is perpendicular to groundwater flow is much better than that of parallel ATES.

A Study on the Thermal and Flow Characteristics of Wind and Radiant Heat Shield for Offshore by using Mesh Screen (메쉬 스크린을 적용한 해양구조물용 방풍 및 복사열 차단막 열유동특성에 관한 연구)

  • Yi, Chung-Seob;Chin, Do-Hun
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.11 no.3
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    • pp.166-173
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    • 2012
  • This study is about comparison of thermal and flow characteristics on the wind & radiant heat shield with STS mesh type screen for offshore. Numerical analysis was conducted to find transmission coefficient in the mesh and then analyse the flow characteristics about wind & radiant heat shield. The experiment method of solar radiation has been used as thermal radiation source to get the performance of radiant heat shield measurement. The sensor radiation device has been used to measure the reduction of solar radiation with various size of cells and at a distance of 0.5m and 1m from the cold face of the wind & radiant heat shield.

A Fundamental Study on Sea Water Freezing Behavior in a Rectangular Vessel Cooled from Below (구형용기의 하부면 냉각에 의한 해수 동결거동의 기초적 연구)

  • 김명준;길병래;김명환
    • Journal of Advanced Marine Engineering and Technology
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    • v.21 no.5
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    • pp.564-570
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    • 1997
  • The most important factor for the desalination system is the fresh water production cost dependent upon the possible energy source which should be obtained easily and with low price. Recently in Korea the demand of LNG, as a cheap and clean energy which does not cause an environmental problem, has sharply been increased. In general, LNG is storaged in a tank as a liquid state below -162 'C. When it is serviced, however, the LNG absorbs energy from a heating source and transforms to the gaseous state with high pressure. During this process a huge amount of cold energy accumulated in LNG is wasted. This waste cold energy can be utilized for producing fresh water from sea water using a sea water freezing desalination system. In order to develop a sea water freezing desalination system and to establish its design technique, a qualitative and quantitative data regarding the freezing behavior of sea water is needed in advance. The goal of this study, therefore, are to reveal the freezing mechanism of sea water, to measure the freezing rate, and to investigate the freezing heat-transfer characteristics. The experimental results help to provide a general understanding of the sea water freezing behavior in a Rectangular vessel cooled from below.

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Flexible Thermoelectric Device Using Thick Films for Energy Harvesting from the Human Body

  • Cho, Han Ki;Kim, Da Hye;Sin, Hye Sun;Cho, Churl-Hee;Han, Seungwoo
    • Journal of the Korean Ceramic Society
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    • v.54 no.6
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    • pp.518-524
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    • 2017
  • A flexible thermoelectric device using body heat has drawn attention as a power source for wearable devices. In this study, thermoelectric thick films were fabricated by cold pressing method using p-type antimony telluride and n-type bismuth telluride powders in accordance with specific loads. Thermoelectric thick films were denser and improved the electrical and thermoelectric properties while increasing the load of the cold pressing. The thickness of the specimen can be controlled by the amount of material; specimens were approximately 700 um in thickness. Flexible thermoelectric devices were manufactured by using the thermoelectric thick films on PI (Polyimide) substrate. The process is cheap, efficient, easy and scalable. Evaluation of power generation performance and flexibility on the fabricated flexible thermoelectric device was carried out. The flexible thermoelectric device has great flexibility and good performance and can be applied to wearable electronics as a power source.

A Basic Study on the District Cooling System of LNG Cold Thermal Energy (LNG 냉열 에너지의 지역 냉방 시스템에 관한 기반 연구)

  • Kim Chung Kyun
    • Journal of the Korean Institute of Gas
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    • v.7 no.4 s.21
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    • pp.36-43
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    • 2003
  • This paper provides the possibility of the district cooling system by using a LNG cold thermal energy. A liquefied natural gas provides a plenty of cooling source energy during a gasification of a liquefied natural gas. In recent, an ice thermal storage system is used for cooling a building, and a deep water source cooling system has been introduced as a district cooling system in which is used to cool the office towers and other large buildings in old and new downtown. LNG cooling energy refers to the reuse of a large body of naturally cold fluids as a heat sink for process and comfort space cooling as an alternative of conventional, refrigerant based cooling systems. Coincident with significant clean energy and operating cost savings, LNG cold energy cooling system offers radical reductions in air-borne pollutants and the release of environmentally harmful refrigerants in comparison to the conventional air-conditioning system. This study provides useful information on the basic design concepts, environmental considerations and performance related to the application of LNG cold thermal energy.

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A Research of Definition and Treatment of Dizziness in the Books on Cold Damage (상한문헌에 나타난 현훈의 정의와 치료법에 대한 연구)

  • Kim, Sang-Un;Jung, Hyun-Jong
    • The Journal of the Society of Korean Medicine Diagnostics
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    • v.18 no.3
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    • pp.149-174
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    • 2014
  • Objectives to study definition and treatment of dizziness in the books of Cold damage which are classified as symptoms of all time. Methods 1. Quote provisions related to dizziness in "Sanghanlon(傷寒論)" 2. Among the books of Cold damage which are classified as symptoms, select 19 literatures on dizziness with table of contents and collect data and categorize in two perspectives on theories and disease pattern. 3. Compare and draw a chart all data collected in above methods. Results & Conclusions 1. In the books on Cold damage, dizziness is expressed in 2 ways such as head dizziness(頭眩) and fainting(鬱冒). fainting is much more several symptoms than head dizziness and it is the difference that it has mental confusion. 2. The cause of head dizziness after promoting sweating, vomiting and purgation is that source qi(元氣) of upper energizer(上焦) is deficiency, and cause of head dizziness before using method of treatment is wind(風), heat(熱), phlegm(痰), blood deficiency(血虛) and etc. 3. Main cause of fainting is that deficiency is getting severe so that cold invades, and symptoms are blood deficiency, after giving birth and excess pattern of fire and heat. 4. Remedies for head dizziness are using Yeonggyechulgam-tang(苓桂朮甘湯), jinmu-tang(眞武湯), sosiho-tang(小柴胡湯), sagunja-tang(四君子湯), samul-tang(四物湯) and etc. 5. Insamsambaek-tang (人蔘三白湯) and Sayeok-tang(四逆湯) are used for deficiency pattern of fainting, and Dojeok-san(導赤散), Daeseunggi-tang(大承氣湯), and Hwangryeonhaedok-tang(黃連解毒湯) are used for excess pattern(實證).

A Study on the Characteristics of Natural Convection in a Partially Opened Enclosure with a Heat Source (발열체와 부분 열림 수직벽을 갖는 사각 공간 내 자연대류 특성 해석)

  • Sim, Dong-Sik;Gang, Bo-Seon;Cha, Dong-Jin;Ju, Won-Jong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.12
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    • pp.1588-1595
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    • 2000
  • Natural convection heat transfer in an enclosure with an opening in the right veritcal wall and a heat source at the bottom surface is investigated using a holographic interferometric technique. The effects of the opening length, divider length attached to the top wall, and heater temperature on the temperature distribution are examined. The opening length as well as the divider length greatly affects the degree of inflow and outflow of air. In the case of small opening length, the opening doesnt affect much the upward warm air flow resulting in the symmetric temperature distribution .The upward flow in hindered by the divider resulting in the decrease of heat transfer from the heater region to the upper region. The longest divider shows the highest temperature in the lower region of enclosure. In the case of large opening length, the inward cold flow moves the upward flow to the left direction. Among the cases of different divider length, the case of H(sub)d=0.25H shows the highest temperature in the lower region of enclosure.