• Title/Summary/Keyword: 가스인젝션

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Analytical Study on the Heating Performance Improvement of a CO2 Heat Pump Using Vapor Injection (가스인젝션을 적용한 이산화탄소 열펌프의 난방성능 향상에 관한 해석적 연구)

  • Jung, Jongho;Baek, Changhyun;Heo, Jaehyeok;Kim, Yongchan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.24 no.11
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    • pp.767-776
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    • 2012
  • In this study, a simulation model for a $CO_2$ heat pump using vapor injection was developed and validated. It was used to predict the improvement of the heating performance of the $CO_2$ heat pump at various operating conditions. The simulation results showed consistent results with the measured data. The heating performances of the vapor injection and non-injection heat pumps were compared by varying the outdoor temperature and compressor frequency. The heating capacity of the vapor injection heat pump was 40% higher than that of the non-injection heat pump at the outdoor temperature of $-8^{\circ}C$. The performance of the vapor injection heat pump was consistently higher than that of the non-injection heat pump even when the compressor frequency was reduced to 35 Hz at the outdoor temperature of $-3^{\circ}C$.

Experimental Study on the Heating Performance of a $CO_2$ Heat Pump with Gas Injeciton (가스인젝션을 적용한 이산화탄소 열펌프의 난방성능에 관한 실험적 연구)

  • Baek, Chang-Hyun;Lee, Eung-Chan;Kang, Hoon;Kim, Yong-Chan;Cho, Sung-Wook
    • Proceedings of the SAREK Conference
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    • pp.358-363
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    • 2007
  • In this study, experimental study on the heating performance of a $CO_2$ heat pump with gas injection was performed varying gas injection ratio and outdoor temperature to improve the heating performance of $CO_2$ heat pump. The twin rotary compressor having volume ratio of 0.7 was adopted in the $CO_2$ heat pump. From the test results, the heating capacity and COP were increased and the compressor discharge temperature was decreased with the increase of injection ratio. At the outdoor temperature of $-8^{\circ}C$, the heating capacity and COP with the injection were increased by 45% and 24%, respectively, compared with non-injection condition.

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The Cooling Performance Enhancement of a Variable Speed Heat Pump Using Gas Injection Technique (가스인젝션 기술을 적용한 공기열원 가변속 열펌프의 냉방성능 향상에 관한 연구)

  • Jeong, Min-Woo;Heo, Jae-Hhyeok;Jung, Hae-Won;Kim, Yong-Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.8
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    • pp.425-432
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    • 2009
  • In this study, the improvement of cooling capacity by applying gas injection technique in a two-stage heat pump using R410A was experimentally investigated. A twin rotary type compressor with gas injection was applied to the heat pump system. The optimum refrigerant charge for the injection and the non-injection cycles was selected to achieve the maximum COP at the cooling standard condition. The injection cycle showed less optimum refrigerant charge than that of the non-injection cycle. The cooling performances of the injection and the non-injection cycles were measured and compared by varying compressor frequency from 40 to 90 Hz. The cooling capacity of the gas injection cycle was 1.6% -11.3% higher than that of the non-injection cycle. The COP of the gas injection cycle was 13.7% to 28.9% higher than that of the non-injection cycle at the same cooling capacity. The heat pump system showed stable operation after 30% of the injection valve opening.

Effects of Vapor Injection on a Compressor in a Transcritical CO2 Cycle (초임계 CO2 사이클에서 가스 인젝션이 압축기 성능에 미치는 영향)

  • Kim, Woo-Young;Shim, Jae-Hwi;Lee, Yong-Ho;Kim, Hyun-Jin
    • The KSFM Journal of Fluid Machinery
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    • v.10 no.2
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    • pp.16-21
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    • 2007
  • Potential advantages of using vapor injection in a two stage rotary compressor for a $CO_2$ heat pump water heater system were addressed in this paper by numerical simulation. Vapor separated from a flash tank in the middle of the expansion process can be used for injection into the second stage suction plenum of the compressor to improve the system performance. Vapor injection increases the intermediate pressure between the two stages, thus increasing the first stage compressor work and reducing that of the second stage. As a whole, however, the compressor input power increases due to injected mass flow rate for the second stage. Computer simulation showed that increment of the cooling capacity by vapor injection exceeded that of the compressor work, thus improving the system performance. COP improvement by vapor injection was calculated to be about 5-14% for normal operating conditions. With vapor injection, a maximum COP was found when the displacement volume of the second stage becomes 90-95% of that of the first stage of the compressor.

Design of Gas-Injection Port of an Asymmetric Scroll Compressor for Heat Pump Systems (히트 펌프용 비대칭 스크롤 압축기의 가스 인젝션 포트 설계)

  • Kim, Yong-Hee;Kim, Hyun-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.6
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    • pp.300-306
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    • 2015
  • For an asymmetric scroll compressor for heat pump application, a numerical simulation was carried out to investigate the effects of injection port design on the compressor's performance under gas injection. To validate the simulation, the numerical results were compared with experimental results obtained from a scroll compressor with a base injection port design. There was good agreement between simulation and experimental results, with around a 1% difference in the injection mass flow rate when the injection pressure was below $12kgf/cm^2A$ for the heating mode. Various injection port angular positions were numerically tested to yield better injection performance. The largest improvement in heating capacity was obtained at angles of $240^{\circ}$ and $200^{\circ}$ inward from the scroll wrap end angle for low-temperature and standard heating conditions, respectively, while the maximum COP improvement was at $365^{\circ}$ and $280^{\circ}$, respectively. A considerable improvement in cooling capacity was also found at the injection port angle of $240^{\circ}$.

The Performance Improvement of a Gas Injection Heat Pump with a Flash Tank (기액분리기를 적용한 가스 인젝션 히트펌프의 성능 향상에 관한 실험적 연구)

  • Son, Kilsoo;Kim, Dongwoo;Choi, Sungkyung;Kim, Yongchan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.297-305
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    • 2017
  • Air-source heat pumps are widely used in residential heating systems. However, the decrease in the capacity of the heat pump is unavoidable when operating at very low and high ambient temperatures. The vapor injection technique is considered a promising technology to overcome this problem. Recent research on vapor injection cycles have mainly adopted a scroll compressor with an internal heat exchanger at severe operating conditions. This study measured the COP and EER of a gas injection heat pump using a flash tank with an inverter-driven rotary compressor at severe operating conditions. Compared to non-injection heat pumps, the heating capacity and COP of the gas injection heat pump improved up to 15% and 2.9%, respectively, at outdoor temperatures of $-10^{\circ}C$ to $7^{\circ}C$. The cooling capacity of the gas injection heat pump was 11% higher than the non-injection heat pump at an outdoor temperature of $35^{\circ}C$. At the same time, the EER of the gas injection heat pump was similar to that of the non-injection heat pump.

Performance Characteristics of a Vapor Injection Heat Pump System with Different Sub-cooler Capacity (과냉각 열교환기 용량 변화에 따른 인젝션 히트펌프의 성능 특성)

  • Choi, Jong Min;Park, Yong-Jung;Kang, Shin-Hyung
    • Journal of the Korean Society for Geothermal and Hydrothermal Energy
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    • v.10 no.3
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    • pp.17-23
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    • 2014
  • One major breakthrough in the field of heating, ventilation and air conditioning has been the development of heat pumps. Heat pump systems offer economic alternatives for recovering heat from different sources for use in various industrial, commercial and residential applications. In recent years, the heat pump has been tipped to have a very good potential for hot water production. This paper investigated the performance of a vapor injection heat pump with the variation of sub-cooler capacity at heating mode. The heating capacity of the vapor injection heat pump slightly increased with an increment of sub-cooler capacity, while COP didn't increase continuously. The 20% capacity of sub-cooler comparing with system capacity could be used as a standard to select sub-cooler capacity.

An Experimental Study on the Heating Performance Characteristics of a Vapor Injection Heat Pump for Electric Vehicles (가스 인젝션을 적용한 전기자동차용 히트펌프의 난방성능 특성에 대한 실험적 연구)

  • Kim, Dongwoo;Jung, Jongho;Kim, Yongchan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.7
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    • pp.308-314
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    • 2014
  • A heat pump has been considered as a thermal management unit for electric vehicles, including the heating and cooling of the cabin. However, the heat pump shows performance degradation at low outdoor temperatures or high compressor speeds. In this study, a R-134a heat pump for an electric vehicle was designed to improve system efficiency, by applying vapor injection with an internal heat exchanger. The heating performance characteristics of the vapor injection heat pump were analyzed at various compressor speeds and outdoor temperatures. The vapor injection heat pump showed 13.3% COP improvement over the non-injection heat pump, when the heating capacity was fixed at 5.2 kW. In addition, the heating capacity of the vapor injection system increased by 9.6%, as compared to the non-injection system.