• 제목/요약/키워드: Variable speed refrigeration system

검색결과 55건 처리시간 0.025초

터보냉동기를 위한 실용적 모델링과 PI 제어기 설계 (Practical Modeling and PI Controller Design for Centrifugal Water Chillers)

  • 정석권;한성준;정영미
    • 설비공학논문집
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    • 제27권4호
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    • pp.187-194
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    • 2015
  • This paper describes the PI controller design based on a practical transfer function model for centrifugal water chillers. The rotational speed of a compressor and the opening angle of an electronic expansion valve were simultaneously regulated as manipulated variables to maintain temperature reference and to ensure high efficiency of the chiller. The COP according to the change in each variable was investigated by performing some static experiments, and it was reflected in the PI controller design to accomplish the high efficiency control. Especially, the practical transfer function model of the chiller was built based on the dynamic experimental data considering the strong inherent non-linearity and complexity of the chiller system. The validity of the designed PI controller was proven by some experimental results using the test facility and the results were also compared to the conventional evaporating pressure control results.

멀티형공조시스템의 효과적인 운전을 위한 시스템운전알고리즘 (A System Operating Algorithm for the Effective Operation of a Multi-type Air-conditioning System)

  • 한도영;박관준
    • 설비공학논문집
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    • 제18권7호
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    • pp.587-595
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    • 2006
  • A system operating algorithm was developed for the effective operation of a multi-type air-conditioning system. The system operating algorithm includes control algorithms for a safety mode, an initial operating mode, a stabilization mode, a fault diagnosis mode, an efficiency mode, and a tracking mode. Various tests were performed to show the effectiveness of these algorithms. Tests showed good results for the operation of a multi-type air-conditioning system. Therefore, these algorithms developed for this study may be used for the effective control of a multi-type air-conditioning system.

이산화탄소 열펌프 시스템의 퍼지 제어에 관한 연구 (Study on the Fuzzy Control of CO2 Heat Pump System)

  • 이재승;한융희;김민수
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 동계학술발표대회 논문집
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    • pp.513-518
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    • 2008
  • In the air-conditioning and refrigeration industry, the efforts to protect the environment have been made. One of them is to use carbon dioxide as an alternative refrigerant, however, several researches have shown that the transcritical heat pump system using $CO_2$ has relatively lower efficiency resulting in a degraded steady-state system performance. Capacity control with fuzzy controller was carried out for $CO_2$ heat pump system. Evaporator secondary fluid outlet temperature was suggested for the control variable of compressor speed modulation.

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회전수 상승폭 변화에 따른 인버터열펌프의 비정상 운전특성 (A study on the transient characteristics during speed up of inverter heat pump)

  • 황윤제;김호영
    • 설비공학논문집
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    • 제10권4호
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    • pp.495-507
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    • 1998
  • The transient characteristics of a 4.0㎾ inverter driven heat pump was investigated by theoretical and experimental studies. The heat pump used in this study consists of a high side scroll compressor and $\Phi$7 compact heat exchangers with two capillary tubes. A series of tests was peformed to examine the transient characteristics of heat pump in heating and cooling mode when the operating speed was varied from 30Hz to 102Hz. One of the major issues that has not been addressed so far is transient characteristics during speed modulation. A cycle simulation model has been developed to predict the cycle performance under frequency rise-up conditions, and the results of theoretical study were compared with the results of experimental study. The theoretical model was driven from mass conservation and energy conservation equations to predict the operation points of refrigerant cycle and the performances at various operating speeds. For transient conditions, the simulated results are in good agreement with the experimental results within 10%. The transient cycle migration of the liquid state refrigerant causes a significant dynamic change in system. Thus, the migration of refrigerant is the most important factor whenever An experimental analysis is performed or A simulation model is developed.

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내부열교환기 및 전자팽창장치를 적용한 가변속 이산화탄소 사이클의 냉방성능에 관한 실험적 연구 (Experimental Study on the Cooling Performance of a Variable Speed $CO_2$ Cycle with Internal Heat Exchanger and Electronic Expansion Valve)

  • 조홍현;류창기;김용찬
    • 설비공학논문집
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    • 제17권3호
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    • pp.209-215
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    • 2005
  • Since a transcritical $CO_2$ cycle shows lower performance than conventional air conditioners in the cooling mode operation, it is required to enhance the performance of the $CO_2$ cycle by applying advanced technologies and optimizing components. In this study, the cooling performance of a $CO_2$ system measured by varying refrigerant charge amount, compressor frequency, EEV opening and length of internal heat exchanger. As a result, the cooling COP of the basic system without internal heat exchanger was 2.1. The cooling performance of the modified cycle applying internal heat exchanger improved by $4-9\%$ over the basic cycle.

설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰 (Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016)

  • 이대영;김사량;김현정;김동선;박준석;임병찬
    • 설비공학논문집
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    • 제29권6호
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

R22/R142b 혼합냉매를 사용한 열펌프의 성능 (Experimental Study on the Performance of Heat Pump Using Refrigerant Mixture R22/R142b)

  • 김민수;장세동;노승탁
    • 설비공학논문집
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    • 제4권1호
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    • pp.33-47
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    • 1992
  • Experimental investigation on the performance of a heat pump system using refrigerant mixtures is done. The condenser and the evaporator are double pipe heat exchangers of counter flow type and the compressor is driven by a variable speed motor. The refrigerant mixture used in the experiment is R22/R142b. Experiments are performed by changing the compressor speed, composition on ratio of mixture, and the average temperatures of condenser and evaporator. The compressor work, heating capacity and the coefficient of performance are calculated. Results show that the heating capacity can be changed by varying the mass flow rate of refrigerant mixtures to meet the heating load. It is shown that the capacity control by changing the composition ratio is more effective than by changing the compressor speed. Under the condition where the external conditions are fixed and the heating loads are equal, the coefficient of performance has its maximum value near 50 : 50 mass fraction of the refrigerant mixture in this study.

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멀티형 열펌프의 유량분배 및 용량조절 특성 (Performance of the Flow Distribution and Capacity Modulation of a Multi-Heat Pump System)

  • 최종민;김용찬;하진호
    • 설비공학논문집
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    • 제13권5호
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    • pp.313-320
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    • 2001
  • In the present study, various experiments were performed to investigate capacity modulation and refrigerant flow distribution of a multi-heat pump using a variable speed compressor and electronic expansion valves(EEVs) in the cooling mode. Based on the experimental results, it was possible to understand the interrelation of dual indoor units which provides some difficulties in capacity control of each indoor unit. The characteristics of capacity modulation of two indoor units were measured by controlling two EEVs with a cooling load of each indoor unit.

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동시냉난방 열펌프 시스템의 운전모드별 성능특성에 관한 실험적 연구 (Experimental Study on the Performance Characteristics of a Simultaneous Heating and Cooling Heat Pump System at Each Operating Mode)

  • 강훈;이선일;주영주;정현준;김용찬;최종민
    • 설비공학논문집
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    • 제19권10호
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    • pp.679-686
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    • 2007
  • The cooling load in winter season is significant in many commercial buildings and hotels because of the usage of office equipments and the high efficiency of wall insulation. The development of a multi-heat pump that can cover heating and cooling simultaneously for each indoor unit is required. In this study, a 4-room simultaneous heating and cooling heat pump system was designed and its performance was measured at each operating mode. The system used R-410A and adopted variable speed compressor. The problems on the designed system were analyzed and defined. In addition, the solutions of the problems were suggested to improve system efficiency and to obtain the stable operation.

온도, 습도, 기류를 이용한 하절기 VRF 시스템의 쾌적 제어 알고리즘 개발 (Development of Comfort Control Logic for VRF System in Summer Season by using 3 Environment Factors(Temperature, Humidity and Air flow))

  • 김종민;최재붕;이상원;조두호;이필호;김영진
    • 설비공학논문집
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    • 제23권9호
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    • pp.610-619
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    • 2011
  • This paper investigates the simplified comfort index and control logic for VRF (Variable Refrigerant Flow) system by using 3 environmental factors such as temperature, humidity and air flow. Indoor test under thermal load was conducted to explore relationship of each environment factors that is related to simplified comfort index. Simplified comfort function that has 3 environmental variables was proposed based on survey results. Each factor is measured and comfort preference was surveyed by more than 30 subjects in the indoor comfort test. Moreover, control logic for VRF system was developed and then simulated by using thermal load calculation method and verified with test. The proposed comfort function was in good agreement with survey results, and also verification test trend of comfort change and maintenance are quite similar with survey. Furthermore, through the additional test data analysis some differences of comfort according to position of people staying in the test room were additionally investigated by air flow. People being under an exit of air in the indoor air-conditioner feel more comfortable condition and speed of response to comfort change is relatively fast.