• Title/Summary/Keyword: R-717

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Toward residential building energy conservation through the Trombe wall and ammonia ground source heat pump retrofit options, applying eQuest model

  • Ataei, Abtin;Dehghani, Mohammad Javad
    • Advances in Energy Research
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    • v.4 no.2
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    • pp.107-120
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    • 2016
  • The aim of this research is to apply the eQuest model to investigate the energy conservation in a multifamily building located in Dayton, Ohio by using a Trombe wall and an ammonia ground source heat pump (R-717 GSHP). Integration of the Trombe wall into the building is the first retrofitting measure in this study. Trombe wall as a passive solar system, has a simple structure which may reduce the heating demand of buildings significantly. Utilization of ground source heat pump is an effective approach where conventional air source heat pump doesn't have an efficient performance, especially in cold climates. Furthermore, the type of refrigerant in the heat pumps has a substantial effect on energy efficiency. Natural refrigerant, ammonia (R-717), which has a high performance and no negative impacts on the environment, could be the best choice for using in heat pumps. After implementing the eQUEST model in the said multifamily building, the total annual energy consumption with a conventional R-717 air-source-heat-pump (ASHP) system was estimated as the baseline model. The baseline model results were compared to those of the following scenarios: using R-717 GSHP, R410a GSHP and integration of the Trombe wall into the building. The Results specified that, compared to the baseline model, applying the R-717 GSHP and Trombe wall, led to 20% and 9% of energy conservation in the building, respectively. In addition, it was noticed that by using R-410a instead of R-717 in the GSHP, the energy demand increased by 14%.

Exergy analysis of R717 high-efficiency OTEC power cycle for the efficiency and pressure drop in main components

  • Yoon, Jung-In;Son, Chang-Hyo;Yang, Dong-Il;Kim, Hyeon-Uk;Kim, Hyeon-Ju;Lee, Ho-Saeng
    • Journal of Power System Engineering
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    • v.17 no.5
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    • pp.52-57
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    • 2013
  • In this paper, an analysis on exergy efficiency of high-efficiency R717 OTEC power system for the efficiency and pressure drop in main components were investigated theoretically in order to optimize the design for the operating parameters of this system. The operating parameters considered in this study include turbine and pump efficiency, and pressure drop in a condenser and evaporator, respectively. As the turbine efficiency of R717 OTEC power system increases, the exergy efficiency of this system increases. But pressure drop in the evaporator of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, in case of exergy efficiency of this OTEC system, the turbine efficiency and pressure drop in a condenser on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

Exergy analysis of R717 high-efficiency OTEC cycle (R717용 고효율 해양온도차 발전 사이클의 엑서지 분석)

  • Yoon, Jung-In;Son, Chang-Hyo;Yang, Dong-Il;Kim, Hyeon-Uk;Kim, Hyeon-Ju;Lee, Ho-Saeng
    • Journal of Advanced Marine Engineering and Technology
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    • v.37 no.8
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    • pp.829-835
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    • 2013
  • This paper describes an analysis on exergy efficiency of proposed high-efficiency R717 OTEC power system to optimize the design for the operating parameters of this system. The operating parameters considered in this study include outlet pressure in an evaporator and high turbine, inlet pressure condenser and vapor quality at cooler outlet, respectively. The main results are summarized as follows : As the outlet pressure in an evaporator and vapor quality at cooler outlet of R717 OTEC power system increases, the exergy efficiency of this system increases, respectively. But outlet pressure in the high turbine, inlet pressure in the condenser of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, incase of exergy efficiency of this OTEC system, the effect of inlet pressure in an evaporator and outlet pressure in the high turbine on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

Performance Analysis of an Ammonia(R717) and Carbon Dioxide(R744) Two-Stage Cascade Refrigeration System ($NH_3-CO_2$를 사용하는 이원 냉동 시스템의 성능 분석)

  • Son, Chang-Hyo
    • Journal of the Korean Institute of Gas
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    • v.14 no.1
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    • pp.1-7
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    • 2010
  • In this paper, cycle performance analysis of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The main results were summarized as follows : The COP of two-stage cascade refrigeration system increases with the increasing subcooling degree, but decreases with the increasing superheating degree. The COP of two-stage cascade refrigeration system decreases with the increasing condensing temperature, but increases with the increasing evaporating temperature. And the COP of two-stage cascade refrigeration system increases with increasing the compressor efficiency. Therefore, superheating and subcoolng degree, compressor efficiency, and evaporating and condensing temperature of $NH_3-CO_2$(R717-R744) two-stage cascade refrigeration system have an effect on the COP of this system.

Prediction on Maximum Performance of Cascade Refrigeration System Using R717 and R744 (R718-R744용 캐스케이드 냉동시스템의 최대 성능 예측)

  • Roh, Geun-Sang;Son, Chang-Hyo
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.10 no.10
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    • pp.2565-2571
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    • 2009
  • In this paper, cycle performance analysis of cascade refrigeration system using $NH_3-CO_2$(R717-R744) is presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree and condensing and evaporating temperature in the ammonia(R717) high temperature cycle and the carbon dioxide low temperature cycle. The COP of cascade refrigeration system increases with the increasing superheating degree, but decreases with the increasing subcooling degree. The COP of cascade refrigeration system increases with the increasing condensing temperature, but decreases with the increasing evaporating temperature. Therefore, superheating and subcoolng degree, evaporating and condensing temperature of cascade refrigeration system using $NH_3-CO_2$ have an effect on the COP of this system. A multilinear regression analysis was employed in terms of subcooling, superheating, evaporating, condensing, and cascade heat exchanger temperature difference in order to develop mathematical expressions for maximum COP and an optimum evaporating temperature.

FINITELY GENERATED gr-MULTIPLICATION MODULES

  • Park, Seungkook
    • Journal of the Chungcheong Mathematical Society
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    • v.25 no.4
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    • pp.717-723
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    • 2012
  • In this paper, we investigate when gr-multiplication modules are finitely generated and show that if M is a finitely generated gr-multiplication R-module then there is a lattice isomorphism between the lattice of all graded ideals I of R containing ann(M) and the lattice of all graded submodules of M.

Performance Simulation of a R744-R717 Cascade Refrigeration System According to Operating Conditions (R744-R717 캐스케이드 냉동시스템에서 운전조건 변화에 따른 성능 해석)

  • Ryu, Jiho;Cho, Honghyun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.10
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    • pp.497-505
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    • 2015
  • The evaporating temperature range required for the low temperature freezing system is from $-50^{\circ}C$ to $-30^{\circ}C$. Since it is difficult to keep the required capacity in a cabinet, it is advantageous to design the system using a cascade refrigeration system. Use of carbon dioxide and ammonia would be advantageous since ammonia is an environment-friendly working fluid and has a high capacity for performance improvement. To investigate the performance characteristics of the R744-R717 cascade refrigeration system, a theoretical model was developed and performance was analyzed according to cascade heat exchanger operating temperature. The optimal cascade R744 condensing temperature was $-5^{\circ}C$, and maximum COP was 1.13 when the temperature difference of the cascade heat exchanger was $5^{\circ}C$. In addition, the total system COP increased by 1.17 when the cascade temperature gap was $3^{\circ}C$ at the middle temperature of $-7.5^{\circ}C$.

Reaction Characteristics and Kinetics of Ni-bsed Oxygen Carrier for Chemical Looping Combustion (매체순환연소를 위한 Ni계열 산소전달입자의 반응 특성 및 반응 모델)

  • PARK, JI HYE;HWANG, RA HYUN;BAEK, JEOM-IN;RYU, HO-JUNG;YI, KWANG BOK
    • Journal of Hydrogen and New Energy
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    • v.29 no.1
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    • pp.90-96
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    • 2018
  • Reaction characteristics and kinetics of a oxygen carrier (OCN717-R1SU) for chemical looping combustion (CLC) have been investigated using TGA by changing gas concentration (10-30 vol.% $CH_4$) and reaction temperature ($825-900^{\circ}C$). Reaction rate of OCN717-R1SU increased as temperature increased and it was found that reaction is delayed at the initial reaction regime. Johnson-Mehl-Avrami (JMA) model was adopted to explain the reaction phenomenon. The activation energy (E) determined by JMA model in reduction reaction of OCN717-R1SU is $151.7{\pm}2.03kJ/mol$ and pre-exponential factor and JMA exponent were also obtained. The parameters calculated in this study will be applied in design of the reactor and operation conditions for CLC process.