• Title/Summary/Keyword: Hybrid refrigeration system

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Study on the Energy Efficiency Improvement of Hybrid Dehumidification Air Conditioning System Compared with Refrigeration System (냉각식 시스템과 비교한 복합식 제습냉방시스템의 냉각 열량증가에 관한 실험적 연구)

  • Lee Su-Dong;Park Moon-Soo;Chung Jin-Eun;Choi Young-Seok
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.10
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    • pp.952-959
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    • 2004
  • The hybrid liquid desiccant air conditioning system has been in use for many years, primarily in industrial process applications requiring dehumidification and humidity control. In this study, the hybrid dehumidifier has been designed to study the dehumidification characteristic of the aqueous triethylene glycol (TEG) solution. The experimental results show energy efficient characteristics of hybrid liquid desiccant air conditioning system compared with the refrigeration system in terms of energy use, the difference of pressure loss between hybrid liquid desiccant air conditioning system and refrigeration system. Data obtained are useful for design guidance and performance analysis of the hybrid air conditioning system.

Cooling Performance of a Hybrid Refrigeration System for Telecommunication Equipment (통신기기 냉각용 하이브리드 냉방시스템의 성능특성)

  • Jeon, Jong-Ug;Kim, Yong-Chan;Choi, Jong-Min
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.489-494
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    • 2006
  • Electronic and telecommunication industries are constantly trying to develop compact components having high power density. Therefore, a proper heat dissipation method is very important to allow reliable operation of the telecommunication equipment. In this study, a hybrid refrigeration system for a telecommunication equipment room was designed to save energy consumption and improve reliability of the compressor In addition, the performance of the hybrid refrigeration system was measured with a variation of outdoor load. The designed hybrid refrigeration system for the telecommunication equipment shelter saved the energy approximately 50%e at the mode switch temperature of $8.3^{\circ}C$.

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Experimental study on cooling performance characteristics of hybrid refrigeration system in a heavy duty vehicle (상용차 하이브리드 냉방시스템 냉방 성능 특성 연구)

  • Lee, Ho-Seong;Jeon, Hanbyeol;Kim, Jung-Il;Lee, Moo-Yeon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.1
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    • pp.419-425
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    • 2019
  • The objective of this study was to investigate the cooling performance characteristics of a hybrid refrigeration system in a heavy duty vehicle. The tested hybrid refrigeration system had additionally an electric compressor besides the present mechanical compressor for selective use according to the operating conditions. The applied electric compressor was a scroll type and with 18.0 cc displacement. In order to analyze the performance characteristics of the hybrid refrigeration system with respect to the cooling capacity and Coefficient of Performance (COP), other components, including two different types of compressors, were installed and tested under various operating conditions such as compressor speed and air flow rate of the evaporator. When the electric compressor was operated at 4,500 rev/min, the cooling capacity was about 4.0kW and COP was 3.5. When the mechanical compressor was operated, whereas the cooling capacity was higher than the electric controlled compressor, COP was lower due to the larger displacement and higher power consumption. To analyze the hybrid system operating characteristics due to reasonable cooling capacity with electric compressor operation, the mechanical compressor and electric compressor were operated by turns every 10 minutes under certain system operating conditions. Because surge pressure occurred when both compressors were switched on, the operating strategy required some time to balance the system pressure.

Performance Characteristics of a Hybrid Air-Conditioner for Telecommunication Equipment Rooms (통신기지국용 하이브리드 냉방기의 성능특성 연구)

  • Kim, Yong-Chan;Choi, Jong-Min;Kang, Hoon;Yoon, Joon-Sang;Kim, Young-Bae;Choi, Kwang-Min;Lee, Ho-Seong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.11
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    • pp.874-880
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    • 2006
  • The power density and heat dissipation rate per unit area of the telecommunication equipment have been increased with the technology development in the footprint of telecommunication hardware. A proper heat dissipation method from the PCB module is very important to allow reliable operation of its electronic component. In this study, a hybrid air-conditioner for the telecommunication equipment room was designed to save energy and obtain system reliability. For high outdoor temperatures, the hybrid system operates in the vapor compression cycle, while, for low outdoor temperatures, the hybrid system works in the secondary fluid cooling cycle with no operation of the compressor. The performance of the hybrid air-conditioner was measured by varying outdoor and indoor temperatures. The hybrid air-conditioner yielded 50% energy saving compared with the conventional refrigeration system when the mode switch temperature was $8.3^{\circ}C$.

An Experimental Study on the Optimization of Performance Parameter for Membrane Based Dehumidification and Air Conditioning System (분리막 제습공조 시스템의 성능변수 최적화를 위한 실험적 연구)

  • Jang, Jeachul;Kang, Eun-Chul;Jeong, Siyoung;Park, Seong-Ryong
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.28 no.2
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    • pp.75-80
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    • 2016
  • There are three types of dehumidification systems : refrigeration dehumidification method, desiccant dehumidification method and hybrid dehumidification method. The first method involves removing moisture by condensation below the dew point, the second method involves absorption by a desiccant material and the last is an integration method. However, the refrigeration dehumidification system consumes too much power and controlling the humidity ratio is difficult. The desiccant dehumidification system uses less power but it has problems of environmental pollution. The hybrid dehumidification system has the disadvantage of a high initial cost. On the other hand, the energy consumption of the membrane based dehumidification system is lower than for the refrigeration dehumidification system. Also, it is an environmentally friendly technology. In this study, the performance parameters are evaluated for the dehumidification system using a hollow fiber membrane. Available area, duct side dry-bulb temperature, sweep gas flux (flow rate) and LMPD (Log Mean Pressure Difference) were used as the performance parameters.

A Study on Thermal Storage Performance and Characteristics of Daily Operation of a Hybrid Solar Air-Water Heater (복합형 태양열 가열기의 일일 운전 특성 및 축열 성능에 관한 연구)

  • Choi, Hwi-Ung;Rokhman, Fatkhur;Yoon, Jung-In;Son, Chang-Hyo;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.35 no.3
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    • pp.73-79
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    • 2015
  • In this study, a thermal storage performance and characteristics of daily operation were investigated when the air and the liquid were heated simultaneously by a hybrid solar air-water heater that can make hot water as well as heated air. The hybrid solar air-water heater is kind of a flat plate solar collector that can make hot water and heated air by installing air channel beneath absorber plate of traditional flat plate solar collector for hot water. As a result of daily operation, maximum water temperature reached in a thermal storage was shown $44^{\circ}C$ on 73kg/h of air mass flow rate and about $40^{\circ}C$ on 176kg/h of air mass flow rate. Thus, the necessity of heating water in thermal storage by operating only liquid side was confirmed when the temperature of liquid in thermal storage is lower than we need. In case of efficiency investigated on daily operation, the thermal efficiency of the liquid side was decreased with increment of the inlet liquid temperature and decrement of the solar radiation, but efficiency of the air side was increased with increment of inlet liquid temperature difference as the traditional solar air heater. Total thermal efficiency of the collector was shown from 65.85% to 78.23% and it was decreased with increment of the inlet liquid temperature and decrement of solar radiation same as the traditional system.

A Proposal of Hybrid Cooling System Coupled with Radiation Panel Cooling and Natural Ventilation (자연환기와 복사냉방을 병용한 하이브리드 시스템의 제안)

  • 송두삼
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.6
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    • pp.543-550
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    • 2003
  • In order to saving the energy for HVAC system of buildings, utilization of wind-induced cross ventilation is thought to be promising. However, utilization of natural ventilation alone is not sufficient for maintaining the human thermal-comfort such as in hot and humid regions. A hybrid air conditioning system with a controlled natural ventilation system, or combination of natural ventilation with mechanical air conditioning is thought to overcome the deficiency of wind-driven cross ventilation and to have significant effects on energy reduction. This paper describes a concept of hybrid system and propose a new type of hybrid system using radiational cooling with wind-induced cross ventilation. Moreover, a radiational cooling system is compared with an all-air cooling system. The characteristics of the indoor environment will be examined through CFD (Computational Fluid Dynamics) simulation, which is coupled with a radiation heat transfer simulation and with HVAC control in which the PMV value for the human model in the center of the room is controlled to attain the target value.

A Study on the Performance Evaluation of the Hybrid Ventilation System for Small Apartment Houses (소형 공동주택의 하이브리드 환기시스템 성능실험 연구)

  • Chun, Chu-Young;Kim, Gil-Tae;Lee, Jong-Sung;Kim, Sang-Hee
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.10
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    • pp.696-701
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    • 2008
  • From Feb. 2006, the ventilating systems with air exchange rate of over 0.7times/hour are installed at the apartment houses (over 100 units). Installation cost and maintenance cost are very important factors for ventilating system because consumers have to pay the expenses of that system. Especially small apartment needs more considerations because small apartment is comparatively the economically weak part. The purpose of this study is to the performance evaluation of the hybrid ventilation system for small apartment houses. Hybrid system 1 consists of natural ventilation system and duct type exhaust diffusers. Hybrid system 2 has natural ventilation system and toilet exhaust system with static pressure fan. Infiltration of test apartment houses with ventilation system is under 0.1 times/hour. Mean air age of hybrid system 1 is 1.52 hours and hybrid system 2 is 1.42 hours. Mean ventilation effectiveness of hybrid system 2(93%) is higher than that of hybrid system 1(81%).

Study on Non-uniform Thermal Comfort in Hybrid Air-Conditioning System with CFD Analysis (CFD 해석을 통한 하이브리드 공조시스템의 인체 온열감의 불균일성에 관한 연구)

  • Nam, Yu-Jin;Sung, Min-Ki;Song, Doo-Sam
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.3
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    • pp.216-222
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    • 2011
  • Recently, hybrid air-conditioning system has been proposed and applied to achieve building energy saving. One example is a system combining radiation panel with natural wind-induced cross-ventilation. However, few research works have been conducted on the non-uniformity of thermal comfort in such hybrid air-conditioning system. In this paper, both thermal environment and non-uniform thermal comfort of human thermal model under various air-conditioning system, including hybrid system, were evaluated in a typical office room using coupled simulation of computation fluid dynamics, radiation model and a human thermal model. The non-uniformity of thermal comfort was evaluated from the deviation of surface temperature of human thermal model. Flow fields and temperature distribution in each case were represented.

Performance Estimation of Hybrid Solar Air-Water Heater on Single Working of Heating Medium (복합형 태양열 가열기에서 열매체 단일운전에 따른 기기성능 평가)

  • Choi, Hwi-Ung;Yoon, Jung-In;Son, Chang-Hyo;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.34 no.6
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    • pp.49-56
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    • 2014
  • Research about hybrid solar air-water heater that can make heated air and hot water was conducted as a part of improving efficiency of solar thermal energy. At this experiment, ability of making heating air and hot water was investigated and compared with traditional solar air heater and flat plate solar collector for hot water when air or liquid was heated respectively. Comparing hybrid solar air-water heater that used in this experiment to other solar air heater studied already, it has a lower efficiency at same mass flow rate. Air channel structure, fin's shape and arrangement in the air channel result in these difference then the ability of air heating need to be improved with changing these thing. In case of making hot water, performance was shown as similar with traditional system although the air channels were established beneath absorbing plate. But the heat loss coefficient was shown higher value by installing of air channel. Also the performance of hot water making was shown lower value at same liquid mass flow rate with traditional flat plate solar collector for hot water. So the necessity of performance improvement at lower mass flow rate of each heating medium can be confirmed.