• Title/Summary/Keyword: Cooling cycle

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Performance Analysis for CO2 System with Sub-cooling loop (과냉 회로를 갖는 이산화탄소 냉동시스템에 대한 성능 해석)

  • Kim, Jin-Man;Ko, Sung-Gyu;Kim, Moo-Geun
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.6
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    • pp.723-728
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    • 2007
  • In order to evaluate the performance of carbon dioxide cycle with a sub-cooling loop. a simulation system was developed to predict the steady state of $CO_2$ trans-critical cycle. Mathematical models are derived to describe the relationships between the system's coefficient of performance and other operating parameters The mathematical models are based entirely on the basic mass and energy conservation law and thermodynamic and transport properties of carbon dioxide A parametric study has been conducted in order to investigate the effect of sub-cooling loop and various operating conditions on the cycle performance. An optimal mass fraction of a refrigerant flowing through sub-cooling cycle existed for the given evaporating temperature, high pressure and air inlet temperature through gas cooler.

Effects of regenerator and cooler on the cooling performance of a vuilleumier cycle heat pump (재생기 및 냉각기가 VM열펌프의 냉방성능에 미치는 영향)

  • Lee, G.T.;Kang, B.H.;Yoo, H.;Lee, J.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.9 no.3
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    • pp.333-342
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    • 1997
  • An experimental study has been carried out to investigate the effects of the combination of the different wire mesh number in a regenerator and the tube number in a cooler on the cooling performance of a Vuilleumier cycle heat pump. Effects of operating conditions, such as charging pressure, operating speed, and heat input, on the cooling performance are also studied. The experimental results obtained indicate that the cooling performance could be improved with the proper combination of different wire meshes in a regenerator. More tubes in a cooler are desirable for better cooling performance. It is also found that the cooling capacity is enhanced, whereas COP is reduced with an increase in the heater tube temperature and the revolution speed. Both the cooling capacity and COP are incereased with a higher charging pressure.

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A Thermodynamic Study on Suction Cooling-Steam Injected Gas Turbine Cycle (吸氣冷却-蒸氣噴射 가스터빈 사이클에 관한 열역학적 연구)

  • 박종구;양옥룡
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.1
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    • pp.77-86
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    • 1992
  • This paper discusses the thermodynamic study on the suction cooling-steam injected gas turbine cycle. The aim of this study is to improve the thermal efficiency and the specific output by steam injection produced by the waste heat from the waste heat recovery boiler and by cooling compressor inlet air by an ammonia absorption-type suction cooling system. The operating region of this newly devised cycle depends upon the pinch point limit and the outlet temperature of refrigerator. The higher steam injection ratio and the lower the evaporating temperature of refrigerant allow the higher thermal efficiency and the specific output. The optimum pressure ratios and the steam injection ratios for the maximum thermal efficiency and the specific output can be found. It is evident that this cycle considered as one of the most effective methods which can obtain the higher thermal efficiency and the specific output comparing with the conventional simple cycle and steam injected gas turbine cycle.

Analysis of Performance Enhancement of a Combined Cycle Power Plant by the Change of Design Parameters of Gas Turbine Using Coolant Pre-cooling (냉각공기 예냉각을 통한 가스터빈 설계변수 변화에 의한 복합발전시스템 성능향상 분석)

  • Kwon, Hyun Min;Kim, Tong Seop;Kang, Do Won;Sohn, Jeong Lak
    • The KSFM Journal of Fluid Machinery
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    • v.19 no.5
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    • pp.61-67
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    • 2016
  • Turbine blade cooling is one of the major technologies to enhance the performance of gas turbine and combined cycle power plants. In this study, two cases of coolant pre-cooling schemes were applied in combined cycle power plant: decrease of coolant mass flow needed to cool turbine blade and increase of turbine inlet temperature (TIT). Both schemes are benefited by the decrease of coolant temperature through coolant pre-cooling. Under the same degree of pre-cooling, increasing TIT exhibits larger plant power boost and higher plant efficiency than reducing coolant flow. As a result, the former produces the same gas turbine power with a much smaller degree of pre-cooling than the latter. Another advantage of increasing TIT is a higher plant efficiency. Even with an assumption of partial achievement of the theoretically predicted TIT, the method of increasing TIT can provide considerably larger power output.

Simulation of the Characteristics of High-Performance Absorption Cycles (고성능 흡수냉동 사이클의 특성 시뮬레이션)

  • 윤정인;오후규;이용화
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.1
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    • pp.231-239
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    • 1995
  • This paper describes a computer simulation of the triple effect, water-lithium bromide absorption cooling cycles. The performance of the absorption systems is investigated through cycle simulation to obtain the system characteristics with the cooling water inlet temperature, the working solution concentrations, the ratio of the amount of the weak solution to the high, middle and low temperature generators, and the temperature difference of each solution heat exchanger. The efficiency of different cycles has been studied and the simulation results show that higher coefficient of performance could be obtained for the parallel cycle of constant solution distribution rate. As a result of this analysis, the optimum designs and operating conditions were determined based on the operating conditions and coefficient of performance.

Effects of Individual Components on the System Performance in a Desiccant Cooling System (제습냉방시스템에서 요소성능이 시스템성능에 미치는 영향)

  • Chang, Young-Soo;Lee, Dae-Young
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.19 no.10
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    • pp.687-694
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    • 2007
  • Cycle simulation is peformed for two types of the desiccant cooling system incorporating a regenerative evaporative cooler. The cooling capacity and COP are evaluated at various effectiveness values of the regenerative evaporative cooler, the desiccant rotor and the sensible heat exchanger. As either of the effectiveness of the regenerative evaporative cooler or the humidity effectiveness of the desiccant rotor increases, both the cooling capacity and COP increase, but the enthalpy leak ratio gives the opposite effect on the system performance. It is found that COP of cycle A mainly depends on the humidity effectiveness of the desiccant rotor, while for cycle B enthalpy leak ratio of desiccant rotor has the major impact on COP. The effect of the sensible heat exchanger on the cooling capacity is small about 1/10 compared with those of other components.

Development of Specific Impulse Analysis Program for a Gas Generator Cycle Rocket Engine (가스발생기 사이클 로켓엔진의 비추력 해석 프로그램 개발)

  • Cho, Won-Kook;Park, Soon-Young;Seol, Woo-Seok
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.3518-3523
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    • 2007
  • An analysis program of specific impulse has been developed for a gas generator cycle rocket engine. The program has been verified by comparing the published performance data of the same cycle engine with RP-1 as fuel. A model for pressure drop of regenerative cooling and film cooling mass flow rate has been suggested to satisfy the necessary cooling condition with Jet-A1 as fuel. The engine mixture ratio is defined by the film cooling mass flow rate and the core mixture ratio. The optimal condition of the combustor pressure and engine mixture ratio has been found for maximum specific impulse.

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Cycle Simulation of an Adsorption Chiller Using Silica Gel-water (실리카겔-물계 흡착식 냉동기 사이클 시뮬레이션)

  • Kwon, Oh-Kyung;Yun, Jae-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.2 s.257
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    • pp.116-124
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    • 2007
  • An adsorption chiller is expected to have high energy-efficiency in utilizing the waste heat exhausted from a process. The objective of this paper is to investigate the performance of silica gel-water adsorption chiller from the cycle simulation and to provide a guideline for design of the adsorption chiller. The effect of cycle time, inlet temperature and water flow rate on the cooling capacity and COP is quantified during the cycle operation. It is found that the performance of adsorption chiller is more sensitive to the change of inlet water temperature rather than the water flow rate. It is concluded that the COP is 0.57 in the standard conditions(hot water $80^{\circ}C$, cooling water $30^{\circ}C$, chilled water inlet temperatures $14^{\circ}C$ and cycle time 420sec).

Life Cycle Cost Analysis of Primary Cooling System by Systematic Support Cost (각종지원금제도에 의한 냉열원시스템의 라이프 사이클 코스트 분석)

  • Kim, C.M.;Jung, S.S.;Choi, C.H.
    • Journal of the Korean Solar Energy Society
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    • v.22 no.4
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    • pp.97-106
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    • 2002
  • The purpose of this study is to analyze the life cycle cost of primary cooling system by systematic support cost. Life Cycle Cost(LCC) is the process of making an economic assessment of an item, area, system, or facility by considering all significant costs of ownership over an economic life, expressed in terms of equivalent costs. The essence of life cycle costing is the analysis of equivalent costs of various alternative proposals. In order to select economical primary cooling system in early heat source plan stages, the research investigates cost items and cost characteristics during project process phases such as planning/design, construction, maintenance /management, and demolition/sell phases. The study also analyze the life cycle cost by capacity leading to suggest the most economical primary cooling system by systematic support cost.

Comparison Between Two Solar Absorption Cooling System Using Single Effect and Single Effect/Double Lift Cycle (일중효용 사이클과 일중효용/2단승온 사이클을 이용한 태양열 흡수식 냉방시스템의 비교)

  • 정시영;이상수;조광운;백남춘
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.3
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    • pp.267-276
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    • 2000
  • A numerical study has been carried out to find out the optimal design condition of a solar absorption cooling system. The system was composed of solar collectors and an absorption chiller with LiBr/water The System performance with commercial single effect(SE) cycle and a new single effect/double lift(SE/DL) cycle utilizing low temperature hot water was calculated and compared. It was found that the required solar collector area grew exponentially as the overall heat loss coefficient of solar collectors increased. For instance, the required area for cooling capacity of 1 USRT was $17m^2$ if heat loss coefficient was 4 W/$m^2\;cdot\;K$. If heat loss coefficient was doubled($8\;W/m^2\;cdot\;$K), the required collector area was increased by 6 times($100m^2$) .It was also found that the SE-cycle as the heat loss coefficient of solar collectors increased. Generally, a SE/DL-cycle seems to be more advantageous than a SE-cycle if loss coefficient of solar collector is greater than 4 W/$m^2\;cdot\;K$.

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