• Title/Summary/Keyword: Ammonia-water Rankine cycle

Search Result 17, Processing Time 0.034 seconds

Thermodynamic Performance Analysis of Ammonia-Water Rankine Cycle and Organic Rankine Cycle Using Cold Energy of LNG (LNG 냉열을 이용하는 암모니아-물 랭킨 사이클과 유기 랭킨 사이클의 열역학적 성능 특성 해석)

  • KIM, KYOUNG HOON
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.31 no.4
    • /
    • pp.363-371
    • /
    • 2020
  • Recently, the technologies to utilize the cold energy of liquefied natural gas (LNG) have attracted significant attention. In this paper, thermodynamic performance analysis of combined cycles consisting of ammonia Rankine cycle (AWR) and organic Rankine cycle (ORC) with LNG Rankine cycle to recover low-grade heat source and the cold energy of LNG. The mathematical models are developed and the effects of the important system parameters such as turbine inlet pressure, ammonia mass fraction, working fluid on the system performance are systematically investigated. The results show that the thermal efficiency of AWR-LNG cycle is higher but the total power production of ORC-LNG cycle is higher.

Comparative Thermodynamic Analysis of Organic Rankine Cycle and Ammonia-Water Rankine Cycle (유기랭킨사이클과 암모니아-물 랭킨사이클의 열역학적 성능의 비교 해석)

  • KIM, KYOUNG HOON;KIM, MAN-HOE
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.27 no.5
    • /
    • pp.597-603
    • /
    • 2016
  • In this paper a comparative thermodynamics analysis is carried out for organic Rankine cycle (ORC) and ammonia-water Rankine cycle (AWRC) utilizing low-grade heat sources. Effects of the working fluid, ammonia concentration, and turbine inlet pressure are systematically investigated on the system performance such as mass flow rate, pressure ratio, turbine-exit volume flow, and net power production as well as the thermal efficiency. Results show that ORC with a proper working fluid shows higher thermal efficiency than AWRC, however, AWRC shows lower mass flow rate of working fluid and lower pressure ratio of expander than ORC.

A Study of Ocean Thermal Energy Conversion Systems Using Kalina cycle and Regenerative Rankine cycle (Kalina 사이클과 재생 Rankine 사이클을 이용한 해양 온도차 발진 시스템)

  • Shin, S.H.;Jung, D.S.;Kim, C.B.;Seo, T.B.
    • Solar Energy
    • /
    • v.19 no.3
    • /
    • pp.101-113
    • /
    • 1999
  • Thermodynamic performance of a simple Rankine cycle, regenerative Rankine cycle, and Kalina cycle for Ocean thermal Energy Conversion(OTEC) is evaluated under the same condition with various working fluids. The evaporator and condenser are modeled by a UA and LMTD method while the turbine and pump are modeled by considering isentropic efficiencies. As for the working fluids, R22, R134a, R32, propylene, ammonia are used for the Rankine cycles while ammonia/water and R32/R134a mixtures are used for Kalina cycle. Calculated results show that newly developed fluids such non-ozone depleting refrigerants as R134a and R32 perform as well as R22 and ammonia. The regenerative Rankine cycle showed a 1.2 to 2.8% increase in energy efficiency as compared to the simple Rankine cycle while the Kalina cycle with ammonia/water mixture showed a 1.8% increase in energy efficiency. The efficiency of the Kalina cycle with R32/R134a mixtures is the same as that of a simple Rankine cycle using R22. Therefore, the regenerative Rankine cycle turns out to be best choice for OTEC applications.

  • PDF

Comparative Performance Analysis of Ammonia-Water Rankine Cycle and Kalina Cycle for Recovery of Low-Temperature Heat Source (저온 열원 발전을 위한 암모니아-물 랭킨 사이클과 칼리나 사이클의 성능특성의 비교 해석)

  • KIM, KYOUNGHOON;BAE, YOOGEUN;JUNG, YOUNGGUAN;KIM, SEWOONG
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.29 no.2
    • /
    • pp.148-154
    • /
    • 2018
  • This paper presents a comparative analysis of thermodynamic performance of ammonia-water Rankine cycles with and without regeneration and Kalina cycle for recovery of low-temperature heat source. Special attention is paid to the effect of system parameters such as ammonia mass fraction and turbine inlet pressure on the characteristics of the system. Results show that maximum net power can be obtained in the regenerative Rankine cycle for high turbine inlet pressures. However, Kalina cycle shows better net power and thermal efficiency for low turbine inlet pressures, and the optimum ammonia mass fractions of Kalina cycle are lower than Rankine cycles.

Exergy Analysis of Regenerative Ammonia-Water Rankine Cycle for Use of Low-Temperature Heat Source (저온열원 활용을 위한 암모니아-물 재생 랭킨사이클의 엑서지 해석)

  • Kim, Kyoung-Hoon;Ko, Hyung-Jong;Kim, Se-Woong
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.23 no.1
    • /
    • pp.65-72
    • /
    • 2012
  • Rankine cycle using ammonia-water mixture as a working fluid has attracted much attention, since it may be a very useful device to extract power from low-temperature heat source. In this work, the thermodynamic performance of regenerative ammonia-water Rankine cycle is thoroughly investigated based on the second law of thermodynamics and exergy analysis, when the energy source is low-temperature heat source in the form of sensible energy. In analyzing the power cycle, several key system parameters such as ammonia mass concentration in the mixture and turbine inlet pressure are studied to examine their effects on the system performance including exergy destructions or anergies of system components, efficiencies based on the first and second laws of thermodynamics. The results show that as the ammonia concentration increases, exergy exhaust increases but exergy destruction at the heat exchanger increases. The second-law efficiency has an optimum value with respect to the ammonia concentration.

Study on Regenerative Rankine Cycle with Partial-Boiling Flow Using Ammonia-Water Mixture as Working Fluid (암모니아-물 작동유체의 부분증발유동을 적용한 재생 랭킨사이클에 관한 연구)

  • Kim, Kyoung-Hoon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.23 no.3
    • /
    • pp.223-230
    • /
    • 2011
  • The power cycle using ammonia-water mixture as a working fluid is a possible way to improve efficiency of the system of low-temperature source. In this work thermodynamic performance of the ammonia-water regenerative Rankine cycle with partial-boiling flow is analyzed for purpose of extracting maximum power from the source. Effects of the system parameters such as mass fraction of ammonia, turbine inlet pressure or ratio of partial-boiling flow on the system are parametrically investigated. Results show that the power output increases with the mass fraction of ammonia but has a maximum value with respect to the turbine inlet pressure, and is able to reach 22 kW per unit mass flow rate of source air at $180^{\circ}C$.

Study on the Rankine Cycle using Ammonia-Water Mixture as Working Fluid for Use of Low-Temperature Waste Heat (저온폐열 활용을 위한 암모니아-물 혼합물을 작업유체로 하는 랭킨사이클에 관한 연구)

  • Kim, Kyoung-Hoon;Kim, Se-Woong;Ko, Hyung-Jong
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.21 no.6
    • /
    • pp.570-579
    • /
    • 2010
  • Since the temperature of waste heat source is relatively low, it is difficult to maintain high level of efficiency in power generation when the waste heat recovery is employed in the system. In an effort to improve the thermal efficiency and power output, use of ammonia-water mixture as a working fluid in the power cycle becomes a viable option. In this work, the performance of ammonia-water mixture based Rankine cycle is thoroughly investigated in order to maximize the power generation from the low temperature waste heat. In analyzing the power cycle, several key system parameters such as mass fraction of ammonia in the mixture and turbine inlet pressure are studied to examine their effects on the system performance. The results of the cycle analysis find a substantial increase both in power output and thermal efficiency if the fraction of ammonia increases in the working fluid.

A Study on the Thermodynamic Cycle of OTEC system (해양 온도차발전 시스템의 열역학 사이클에 대한 연구)

  • Kim, Nam-Jin;Shin, Sang-Ho;Chun, Won-Gee
    • Journal of the Korean Solar Energy Society
    • /
    • v.26 no.2
    • /
    • pp.9-18
    • /
    • 2006
  • In this paper, the thermodynamic performance of OTEC cycle was examined. Computer simulation programs were developed for simple Rankine cycle, regenerative Rankine cycle, Kalina cycle, open cycle and hybrid cycle. For the simple Rankine cycle, the results show that newly developed fluids such as R410A and R32 that do not cause stratospheric ozone layer depletion perform as well as R22 and ammonia. Also, simple Rankine cycle OTEC power plant can practically generate electricity when the difference in warm and cold sea water inlet temperatures are greater than $14^{\circ}C$. The regenerative Rankine cycle showed a 1.5 to 2% increase in energy efficiency compared to the simple Rankine cycle while the Kalina cycle employing ammonia/water mixture showed a 2-to-3% increase in energy efficiency, and the overall cycle efficiencies of hybrid cycle and open cycle were 3.35% and 4.86%, respectively.

Performance Characteristics of a Combined Regenerative Ammonia-Water Based Power Generation Cycle Using LNG Cold Energy (LNG 냉열을 이용하는 암모니아-물 복합 재생 동력 사이클의 성능 특성)

  • Kim, Kyounghoon;Oh, Jaehyeong;Jeong, Youngguan
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.24 no.6
    • /
    • pp.510-517
    • /
    • 2013
  • The ammonia-water based power generation cycle utilizing liquefied natural gas (LNG) as its heat sink has attracted much attention, since the ammonia-water cycle has many thermodynamic advantages in conversion of low-grade heat source in the form of sensible energy and LNG has a great cold energy. In this paper, we carry out thermodynamic performance analysis of a combined power generation cycle which is consisted of an ammonia-water regenerative Rankine cycle and LNG power generation cycle. LNG is able to condense the ammonia-water mixture at a very low condensing temperature in a heat exchanger, which leads to an increased power output. Based on the thermodynamic models, the effects of the key parameters such as source temperature, ammonia concentration and turbine inlet pressure on the characteristics of system are throughly investigated. The results show that the thermodynamic performance of the ammonia-water power generation cycle can be improved by the LNG cold energy and there exist an optimum ammonia concentration to reach the maximum system net work production.

Performance Analysis of Ammonia-Water Regenerative Rankine Cycles for Use of Low-Temperature Energy Source (저온 열원 활용을 위한 암모니아-물 재생 랭킨 사이클의 성능 해석)

  • Kim, Kyoung-Hoon;Han, Chul-Ho
    • Journal of the Korean Solar Energy Society
    • /
    • v.31 no.1
    • /
    • pp.15-22
    • /
    • 2011
  • It is a great interest to convert more energy in the heat source into the power and to improve the efficiency of power generating processes. Since the efficiency of power generating processes becomes poorer as the temperature of the source decreases, to use an ammonia-water mixture instead of water as working fluid is a possible way to improve the efficiency of the system. In this work performance of ammonia-water regenerative Rankine cycle is investigated for the purpose of extracting maximum power from low-temperature waste heat in the form of sensible energy. Special attention is paid to the effect of system parameters such as mass fraction of ammonia and turbine inlet pressure on the characteristics of system. Results show that the power output increases with the mass fraction of ammonia in the mixture, however workable range of the mass fraction becomes narrower as turbine inlet pressure increases and is able to reach 16.5kW per unit mass flow rate of source air at $180^{\circ}C$.