• 한국지열·수열에너지학회논문집
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• 제9권4호
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• pp.1-7
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• 2013

This study is to compare energy consumption of air-source, ground-source and dual-source heat pump systems during intermediate season using dynamic simulation. Ground-source heat pump has higher COP than that of air-source but requires additional power consumption of auxiliary equipment such as circulation pump. During intermediate season when the outdoor air temperature is favorable, total COP of air-source heat pump may be greater than that of ground-source when circulation pump power consumption is included. Dual-source heat pump which selects the more favorable heat source is compared with air-source only and ground-source only heat pumps for total power consumption. Results show that power consumption of dual-source heat pump is lower than that of ground-source only by 0.73%.

• 한국지열·수열에너지학회논문집
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• 제19권4호
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• pp.8-17
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• 2023

The air temperature is gradually increasing owing to global warming, especially in summer, therefore, the performance of an air source heat pump (ASHP) is expected to be decreased. Accordingly, the performance gap between the ASHP and ground source heat pump (GSHP) should be increased, however, the quantitative comparison has not been yet investigated. In this study, impact of global warming on the performance of the ASHP and GSHP is investigated based on the climate data for 1930, 1980, and 2030. The coefficient of performance (COP) as well as annual power consumption of the ASHP and GSHP are compared and analyzed. In the case of COP, the COP of GSHP hardly changes over the years owing to the constant ground temperature, while that of ASHP decreases by 3.7% for cooling and increases by 0.71% for heating. In the case of annual power consumption, the cooling and heating power consumption of GSHP increases by 12.69% and decreases by 15.58%, respectively, over the year owing to the changes in heating and cooling loads. As for the ASHP, the cooling and heating power consumption increases by 16.64% and decreases by 17.8%, respectively. For a more accurate comparison, power consumption ratio is introduced and shows that total annual power consumption of the GSHP to ASHP decreased from 68% in 1930 to 65% in 2030. Therefore, as global warming accelerates, the effect of reducing power consumption by using GSHP compared to ASHP is expected to be increasing.

• 산업경영시스템학회지
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• 제38권1호
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• pp.143-151
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• 2015

In this paper, we investigate how the power consumption of a heat pump dryer depends on various factors in the drying process by analyzing variables that affect the power consumption. Since there are in general many variables that affect the power consumption, for a feasible analysis, we utilize the principal component analysis to reduce the number of variables (or dimensionality) to two or three. We find that the first component is correlated positively to the entrance temperature of various devices such as compressor, expander, evaporator, and the second, negatively to condenser. We then model the power consumption as a multiple regression with two and/or three transformed variables of the selected principal components. We find that fitted value from the multiple regression explains 80~90% of the observed value of the power consumption. This results can be applied to a more elaborate control of the power consumption in the heat pump dryer.

• 드라이브 ㆍ 컨트롤
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• 제11권4호
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• pp.53-60
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• 2014

This paper proposes a control scheme to reduce the power consumption of a variable displacement swash-plate type piston pump supplying oil to a valve-controlled hydraulic cylinder at constant pressure. Whenever flow rate demand was absent, the swash plate angle and the pump speed were changed to the minimum values required to compensate for the internal leakage flow. In response to command signals, the pump speed was changed in proportion to the absolute mean value of the speed component for position commands. At the same time, a pressure regulator was activated to maintain constant system pressure by precisely adjusting the pump speed with the swash plate angle fixed at the maximum. The conventional system consisting of a pressure-compensated variable displacement type pump is driven at a constant speed of 1,800rpm. By comparison, computer simulation and experimental results showed that idling power at stand-by status could be reduced by up to 70% by reducing the pump speed from 1,800rpm to 300rpm and the swash plate angle to the minimum.

• 한국지열·수열에너지학회논문집
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• 제13권4호
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• pp.8-13
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• 2017

The effects of operational conditions of cooling water system on energy consumption for central cooling system are researched by using TRNSYS program. Cooling tower water pump flow rate, cooling tower fan flow rate, and condenser water temperature with various dry-bulb and wet-bulb temperatures are varied and their effects on total and component power consumption are studied. If the fan maximum flow rates of cooling tower is decreased, cooling tower fan and total power consumptions are increased. If the cooling tower water pump maximum flow rates is decreased, chiller and total power consumptions are increased. If condenser water set-point temperature is increased, chiller power consumption is increased and cooling tower fan power consumption is decreased, respectively.

• 한국진공학회지
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• 제17권4호
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• pp.278-291
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• 2008

반도체 소자 제조 공정을 진행하기 위해서는 수많은 진공 시스템이 사용되어야 하고 이로 인하여 많은 소비전력을 필요로 한다. 소비전력 문제는 환경 문제와도 연관되기 때문에 반도체 소자 제조업체들 입장에서는 깊은 관심을 가지고 해결해야 할 사항으로 여러 가지 방안들이 제안되고 있다. 진공 펌프 제조업체들 입장에서는 진공 펌프의 설계/제작에 있어 소비 전력절감을 감안하게 되지만, 반도체 팹(fab)내부에서 소비 전력을 줄이기 위해서는 진공 펌프를 사용하는 사용자의 사용 방법 및 환경도 매우 중요하다. 본 연구에서는 반도체 소자 제조 공정에 사용되는 진공 펌프의 소비 전력을 줄이는 여러 가지 방법들에 대해 간략하게 설명하고 반도체 산업의 기술 발전 방향이 진공 펌프 소비 전력에 미치는 영향을 살펴보고자 한다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권5호
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• pp.563-569
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• 2015

For some low-frequency applications such as power-related circuits, NEM relays have been known to show better performance than MOSFETs. For example, in a step-down charge pump circuit, the NEM relays showed much smaller layout area and better energy efficiency than MOSFETs. However, severe process variations of NEM relays hinder them from being widely used in various low-frequency applications. To mitigate the process-variation problems of NEM relays, in this paper, a new NEM-relay charge pump circuit with the self-adjustment is proposed. By self-adjusting a pulse amplitude voltage according to process variations, the power consumption can be saved by 4.6%, compared to the conventional scheme without the self-adjustment. This power saving can also be helpful in improving the power efficiency of the proposed scheme. From the circuit simulation of NEM-relay charge pump circuit, the efficiency of the proposed scheme is improved better by 4.1% than the conventional.

• 한국진공학회지
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• 제12권2호
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• pp.93-104
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• 2003

저진공펌프의 내구성평가와 관련하여 펌프의 성능이나 상태의 저하에 관한 기술적 근거를 확보함으로써 펌프의 운전상태를 진단할 수 있는 기초기술을 확보할 수 있으며, 이는 진공펌프의 기계적 결함 및 성능평가 장치의 동적 응답과 신뢰도 구축에 중점을 두고 신호 분석을 통하여 실험적으로 기계적인 동적 특성을 확인하는 과정을 통하여 수행할 수 있다. 저진공펌프의 압축일에 소요되는 전력을 이론적으로 규명하고 펌프의 압축일을 계산하였으며, 소비전력에 대한 진공펌프의 에너지 효율을 예측하여 펌프 노화에 따르는 소비전력의 증가 원인을 규명하는 자료로 활용할 수 있다. 또한 저진공펌프의 가동 중에 측정한 진동, 압력신호, 배기속도 및 소비전력을 측정하고 분석하여 펌프 운전상태를 감시하는데 매우 유용한 인자가 무엇인지 확인하였으며 추후 연구의 방향과 내구성평가의 기초기술을 확보하였다.

• 동력기계공학회지
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• 제18권2호
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• pp.25-30
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• 2014

In this paper, the heat transfer coefficient and pump consumption power of indirect refrigeration system using $CO_2$ as a secondary refrigerant were investigated experimentally. First, from the comparison of pump consumption powers of existing brines(EG, PG, EA etc.) and $CO_2$ as secondary refrigerants at the same experimental conditions, PG and $CO_2$ show the highest and lowest power, respectively. Second, the heat transfer coefficient of $CaCl_2$ is the highest, but PG is the lowest among other secondary refrigerants. From the above results, it is confirmed that $CO_2$ as the secondary refrigerant has excellent characteristics when comparing to existing brines. Thus, it is concluded that $CO_2$ is applicable as the secondary refrigerant of indirect refrigeration system.

• 한국자기학회지
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• 제20권6호
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• pp.234-238
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• 2010

캠샤프트의 구동력을 활용한 기계식 연료펌프 시스템을 대체할 솔레노이드 격막 연료펌프는 최근 각광받고 있는 고효율 그린카 부품 중 하나이다. 하지만 솔레노이드 격막 연료펌프의 경우 왕복운동에 필요한 자속을 오직 솔레노이드에 의존하므로 전력소비가 비교적 큰 단점이 있다. 따라서 본 연구에서는 전력소모를 최소화 하기 위하여 영구자석형 VCA 연료펌프 시스템을 제안한다. 또한 상용전자기해석소프트웨어인 MAXWELL을 활용하여 유한요소 해석을 통해 기존의 솔레노이드 격막 펌프와의 전력소모 및 동적 성능을 비교 분석한다.