• Title/Summary/Keyword: Vapor injection

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Performance of the Geothermal Heat Pump using Vapor Injection for Hot Water (증기분사를 적용한 고온수용 지열 히트펌프의 성능특성)

  • Park, Yong-Jung;Park, Byung-Duck
    • Transactions of the Korean hydrogen and new energy society
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    • v.25 no.3
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    • pp.297-304
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    • 2014
  • The purpose of this study is to evaluate the experimental performance characteristics of a water-to-water geothermal heat pump featuring a vapor refrigerant injection for the production of hot water. The performance of geothermal heat pump with a vapor injection was evaluated by comparing with that of a conventional geothermal heat pump without a vapor injection. For heating operation, the geothermal heat pump with a vapor injection is superior in COP and heating capacity. The vapor injection was more effective for supplying hot water while overloading. The vapor injection was effective for the improvement of the cooling capacity. However, the vapor injection was not effective for the increasing of COP according to the increased input of a compressor. The advantage of vapor injection in water-to-water geothermal heat pump become disappeared while cooling operation with lower part loading.

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.

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 $-3^{\circ}C$.

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.

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.

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.

Analysis of n-Hexanal in Headspace Vapor over Cooked Brown Rice by Direct Vapor Injection Gas Chromatography (현미취반시 생성되는 n-hexanal의 가스크로마토그래피에 의한 분리및 정량)

  • Shin, Myung-Gon;Rhee, Joon-Shick;Kwon, Tai-Wan
    • Korean Journal of Food Science and Technology
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    • v.17 no.5
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    • pp.406-408
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    • 1985
  • n-Hexanal in headspace over the cooked brown rice stored at $5^{\circ}C$ and $35^{\circ}C$ for 0. 4, 8 and 12 months was determined by a modified direct vapor injection gas chromatographic method. The retention time of n-hexanal was 3.5 min and n-hexanal could be rapidly separated from other compounds at the operational conditions of gas chromatography. n-Hexanal contents of cooked brown rice also showed a standard deviation of less than 10% of the average.

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Operating characteristics of 3RT heat pumps

  • Moon, Chang-Uk;Choi, Kwang-Hwan;Yoon, Jung-In;Jeon, Min-Ju;Heo, Seong-Kwan;Sung, Yo-Han;Park, Sung-Hyeon;Lee, Jin-Kook;Son, Chang-Hyo
    • Journal of Advanced Marine Engineering and Technology
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    • v.41 no.2
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    • pp.140-145
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    • 2017
  • Newly designed vapor-injection heat pumps have been proposed and analyzed in the present study. An economizer-type vapor-injection (V-I) system has been employed as the standard system because of its reliability and simple control method. The V-I system has a re-cooler and re-heater for cooling and heating, respectively. Solar panels have been installed in the V-I heat pump as well as in the re-heater in order to enhance heating capacity and performance. R410A has been employed as a working fluid and performance analysis has been conducted under various conditions. Results are summarized as follows: (1) The V-I system with the re-cooler yielded a marginally higher coefficient of performance (COP) than the conventional V-I refrigeration system. (2) By increasing the re-cooler cooling capacity, enhanced system performance as compared to the conventional V-I system was observed. (3) The re-heater negatively affected the system performance; hence, the V-I heat pump with the re-heater yielded a lower COP than that of the conventional V-I heat pump used for heating. (4) Although the solar panels increased the system performance, this increase could not offset performance degradation by the re-heater.

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.

Heating Performance Characteristics of Heat Pump with VI cycle using Re-Heater and Solar-Assisted (태양열과 재열기를 사용한 VI heat pump의 성능 특성에 관한 연구)

  • Lee, Jin-Kook;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
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    • v.35 no.6
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    • pp.25-33
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    • 2015
  • In this study, heating performance of the air-cooled heat pump with vapor-injection (VI) cycles, re-heater and solar heat storage tank was investigated experimentally. Devices used in the experiment were comprised of a VI compressor, re-heater, economizer, variable evaporator, flat-plate solar collector for hot water, thermal storage tank, etc. As working fluid, refrigerant R410A for heat pump and propylene glycol (PG) for solar collector were used. In this experiment, heating performance was compared by three cycles, A, B and C. In case of Cycle B, heat exchange was conducted between VI suction refrigerant and inlet refrigerant of condenser by re-heater (Re-heater in Fig. 3, No. 3) (Cycle B), and Cycle A was not use re-heater on the same operating conditions. In case of Cycle C, outlet refrigerant from evaporator go to thermal storage tank for getting a thermal energy from solar thermal storage tank while re-heater also used. As a result, Cycle C reached the target temperature of water in a shorter time than Cycle B and Cycle A. In addition, it was founded that, as for the coefficient of heating performance($COP_h$), the performance in Cycle C was improved by 13.6% higher than the performance of Cycle B shown the average $COP_h$ of 3.0 and by 18.9% higher than the performance of Cycle A shown the average $COP_h$ of 2.86. From this results, It was confirmed that the performance of heat pump system with refrigerant re-heater and VI cycle can be improved by applying solar thermal energy as an auxiliary heat source.