• Title/Summary/Keyword: Variable speed refrigeration system

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Operating Number Control of Compressors Based on Cooperative Logic for a High Efficiency Centrifugal Water Chiller (터보냉동기의 고효율 운전을 위한 협조 방식 기반의 압축기 대수제어)

  • Jeong, Seok-Kwon;Lim, Seung-Kwan;Ryu, Keon-Su
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.5
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    • pp.233-240
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    • 2015
  • This paper discusses compressors operating number control strategy using cooperative logic to cope with variable partial load for high efficiency of a centrifugal water chiller. The cooperative logic is composed of a speed-up and speed-down controller, enabling smooth operation of compressors and equivalent distribution of thermal load in each compressor. This centrifugal water chiller design can be operated with high efficiency without incurring excessive energy waste and large transient phenomena at partial load states. Simulations in MATLAB and experiments in a real chiller system were conducted and verified the high efficiency control of a centrifugal water chiller achieved by the suggested strategy.

Capacity Modulation of a Multi-Type Heat Pump System using PID Control with Fuzzy Logic (퍼지 로직 적용 PID 제어를 이용한 멀티형 열펌프의 용량조절)

  • 김세영;김민수
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.9
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    • pp.810-817
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    • 2001
  • Performance of a water-to-water multi-type heat pump system using R22 which has tow indoor units has been investigated experimentally. The refrigerant flow rate of each indoor unit was regulated by an electronic expansion valve and the total refrigerant flow rate of the system was controlled by a variable speed compressor. In the system, evaporator outlet pressure of refrigerant and outlet temperatures of secondary fluid from indoor units were selected as control variables. Experiments were executed for both cooling and heating modes using PID control method with fuzzy logic, and results of the test are compared with a classical PID method. In the case of PID control with fuzzy logic, the fuzzy control rules corrects PID parameters each time. Results show that PID control with fuzzy logic has the merits of quick response and reduced overshoot.

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Heating Performance Characteristics of a Heat Pump with a Variable Speed Injection Scroll Compressor (인젝션형 가변속 스크롤 압축기를 적용한 히트펌프의 난방성능 특성에 관한 연구)

  • Ko, Suk-Bin;Heo, Jae-Hyeok;Cho, Il-Yong;Kim, Yong-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.5
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    • pp.377-384
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    • 2012
  • Vapor injection technique has been applied to prevent performance degrdation of a heat pump at low ambient temperatures. In this study, the heating performance of a heat pump with a variable speed injection scroll compressor using R-410A was investigated by applying sub-cooler vapor injection(SCVI) and flash tank vapor injection(FTVI). The heating performance of the heat pump was measured by varying compressor frequency and outdoor temperature. The heating capacity of the FTVI system was 8~10% higher than that of the SCVI system at all operating conditions. On the other hand, the heating performance improvement with the increase in the compressor frequency was more prominent in the SCVI system than in the FTVI system.

Capacity Modulation of a Multi-Type Heat Pump System Using PID Control (PID 제어를 이용한 멀티형 열펌프의 용량조절)

  • 정대성;김민성;김민수;이원용
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.5
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    • pp.446-475
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    • 2000
  • Performance of a water-to-water multi-type heat pump system using R22 has been experimentally investigated. Total refrigerant flow rate was adjusted with a variable speed compressor and the refrigerant flow rate for two indoor units were controlled by electronic expansion valves. Evaporator outlet pressure of refrigerant and indoor unit outlet temperatures of secondary fluid were selected as controlled variables. Experiments were carried out for both cooling and heating modes using PID control method. Results show that the multi-type heat pump system can be adequately controlled by keeping control gains at certain levels for various operating conditions.

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Characteristics of Capacity Control of Variable Speed Water Cooler with the Electronic Expansion Valve Open/Close Degree (전자팽창밸브 개도에 따른 가변속 수냉각기의 용량제어 특성)

  • Beak, Seung-Moon;Moon, Choon-Geun;Kim, Hyun-Woo;Jeong, Seok-Kwon;Yoon, Jung-In
    • Journal of Advanced Marine Engineering and Technology
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    • v.34 no.2
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    • pp.282-288
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    • 2010
  • The paper presents the characteristics of capacity control of variable speed water cooler with the electronic expansion valve open/close degree. It is a preliminary study on the optimum control of the water cooler system using a variable speed compressor controlled by inverter. The electronic expansion valve controlled by the variation of compressor speed maintains the constant degree of superheat at the evaporator outlet, which aims to find the degree of superheat obtaining the optimum refrigeration effect. The investigation indicates that there is a point achieving the maximum cooling capacity by the variation of the electronic expansion valve open/close degree with constant compressor speed.

Study on the Performance of a Variable Speed Cascade Heat Pump under Various Operating Conditions (운전조건에 따른 가변속 캐스케이드 열펌프의 성능 특성 연구)

  • Jeong, Kwangmoo;Choi, Jong Min
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.9 no.2
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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.

Compressor Control of a Multi-type AIr Conditioning System (멀티형 냉방시스템의 압축기 제어)

  • 한도영;권형진
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.8
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    • pp.780-786
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    • 2001
  • For the compressor speed control of a multi-type air conditioning system, a fuzzy control algorithm was developed. The sum of zone temperature errors and its derivative were used as input variables, and the compressor speed was selected as the output variable. To test the effectiveness of the control algorithm, one outdoor environmental chamber and four indoor environmental chambers were used. In the chambers the zone temperature step change test and the indoor unit change over test were performed. Test results showed that, for the control of compressor speed, the fuzzy control algorithm was more effective than the conventional proportional control algorithm for the energy conservation.

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An Analysis of the Water Supply System with Pressurizing Tank (가압탱크를 이용한 급수시스템의 해석 및 최적화 연구)

  • Lee, T.W.;Kim, T.H.;Choi, D.H.;Kim, S.D.;Kim, J.P.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.6 no.2
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    • pp.93-102
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    • 1994
  • It is the goal of this study to provide the essential data for design and operation of optimum water supply system. Experimental and theoretical analyses have been conducted for various parameters, for example, volume and air percent of pressurizing tank, pump speed and pressure range inside tank, etc. Pressure inside tank with time, flow rate, energy consumption rate and pump operation time have been obtained for design and operating parameters to optimize the components and to establish the operating method of system, and therefore to contribute to the development of technology from a point of view of the improvement of quality, the enhancement of system efficiency and the reduction of construction cost.

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Experimental and Theoretical Studies on the Dynamic Characteristics During Speed Down of Inverter Heat Pump

  • Hwang, Yoon-Jei;Kim, Ho-Young
    • International Journal of Air-Conditioning and Refrigeration
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    • v.8 no.1
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    • pp.29-39
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    • 2000
  • A series of tests were performed to verify the transient characteristics of heat pump in heating and cooling mode when operating speed was varied over the 30 to 102Hz. One of the major issues that has not been addressed so far is transient characteristics during speed modulation. The model for cycle simulation has been developed to predict the cycle performance under conditions of decreasing drive frequency and the results of the theoretical study were compared with the results of the experimental study. The simulated results were in good agreement with the experimental result within 10%. The transient cycle migration of the liquid state refrigerant causes significant dynamic change in system. Thus, the migration of refrigerant was the most important factor whenever do experimental results analysis or develop simulation model.

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Performance Characteristics of a Drop-in System for a Mobile Air Conditioner Using Refrigerant R1234yf (냉매 R1234yf 적용 자동차용 에어컨 Drop-in 성능 특성)

  • Cho, Honghyun;Lee, Hoseong;Park, Chasik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.12
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    • pp.823-829
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    • 2012
  • In this study, the performance of mobile air conditioner(MAC) systems to which the refrigerants R134a and R1234yf were used was evaluated to compare the characteristic of automotive refrigeration cycles with refrigerant. The experimental setup of a MAC consists of an belt driven compressor, a condenser, an evaporator and a block type thermal expansion valve. The drop-in test on MAC were carried out under variable compressor speed from 800 to 2500 rpm. Performance test by using R1234yf and R134a in the same system revealed low the charge amount and mass flow rates for using R1234yf, that is, up to 10% and 17%, respectively. The compressor discharge temperature of R1234yf is $8^{\circ}C$ lower than that of R134a. The cooling capacity with R1234yf system decreased by 4~7% compared with R134a system. In addition, The COP of R1234yf system is lower 3~4% than that of R134a system.