• Title/Summary/Keyword: Series-flow type

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The Influences of the Refrigerant Adulteration by an Absorbent on the Cooling Capacity and COP of the Absorption Chiller (흡수식 냉동기에서 흡수액이 증발기로 혼입시 냉각용량과 성능계수에 미치는 영향)

  • Park, Chan-Woo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.9
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    • pp.753-760
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    • 2006
  • The purpose of the present work is to investigate the influence of the refrigerant adulteration by LiBr solution on the cooling capacity and COP for three different types of abso게tion chillers: a single-effect type, a series-flow double-effect type and a parallel-flow with double-effect type. A simulation program has been prepared for the cyclic analysis of absorption chillers. With some assumptions, the calculations have been performed by solving the mass balance equation, energy balance equation and the state equation simultaneously. The range of the LiBr concentration of refrigerant was 0% to 20% in the present study. For the single-effect absorption chiller, the maximum decrease in the cooling capacity was 10% at the 20% of LiBr concentration. For the double-effect chiller, the capacity was decreased by 11.1% for the parallel-flow type and the series-flow type. Also, the COP was reduced by 3.0% in single-effect, 2.8% in series-flow type (SR=0.4) and 2.3% in parallel-flow type.

Effects of Operation Conditions on the Performance of Type II LiBr-H2O Absorption Heat Pump (제 2종 LiBr-H2O 흡수식 히트펌프의 운전 변수에 따른 성능 특성 수치 해석)

  • Yoon, Jun Seong;Kwon, Oh Kyung;Cha, Dong An;Bae, Kyung Jin;Kim, In Gwan;Kim, Min Soo;Park, Chan Woo
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.1
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    • pp.7-14
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    • 2017
  • This study carried out a numerical analysis of the effects of hot waste water supply on the performance of a Type II absorption heat pump. There are two types of hot waste water supply, regular series flow and reverse series flow. Also it investigated the interaction between each type of flow and heat exchange solutions. As the effectiveness of heat exchange solutions increase, the steam generation and (COP) increase as well. If the effectiveness of a heat exchange solution is lower than 0.566, the steam generation rate of the reverse flow is lower than that of the regular series flow. A high effectiveness of heat exchange solution is therefore required to make a larger amount of steam in reverse series flow than with ordinary series flow. The COP difference between the two types of flow decreases with the increasing effectiveness of the heat exchange solution. Thus, a reverse flow type absorption heat pump can match the high steam generation rate and COP of the ordinary flow type when a highly effective heat exchange solution is applied.

A Method of Evaluating Profitability and Risk of Multiple Investments Applying Internal Rate of Return

  • Mizumachi, Tadahiro
    • Industrial Engineering and Management Systems
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    • v.9 no.2
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    • pp.121-130
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    • 2010
  • In today's uncertain economic environment, economic risk is inherent in making large investments on manufacturing facilities. It is, therefore, practically meaningful to divide investment over multiple periods, reducing the risk of investment. Then, the cash-flow over the entire planning horizon would comprise positive inflow and negative outflow. In this case, in general, evaluation by internal rate of return (IRR) is not feasible, because multiple IRRs are involved. This paper deals with a problem of evaluating profitability, as well as risk, of investment alternatives made in multiple times of investment over the entire horizon. Typically, an additional investment is required after the initial one, for expanding manufacturing capacity or other reasons. The paper pays attention to a unit cash-flow over two periods, decomposing the total cash-flow into a series of unit cash-flow patterns. It is easy to evaluate profitability of a unit cash-flow by using IRR. The total cash-flow can be decomposed into the series of two types of unit cash-flows: an investment type one (negative-positive) and the borrowing type one (positive-negative). This paper, therefore, proposes a method in which only the borrowing type unit cash-flow is eliminated in the series by converting total cash-flow using capital interest rate. Then, a unique IRR can be obtained and the profitability is evaluated. Thus, the paper extends the method of IRR so that it may help decision making in complicated cash-flow pattern observed in practice.

Interfacial Boundary Estimation in Stratified Flow of Two Immiscible Liquids Using Hybrid-type Fourier Series

  • Kim, Bong Seok;Choi, Bong-Yeol;Kim, Kyung Youn
    • Journal of IKEEE
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    • v.18 no.4
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    • pp.463-470
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    • 2014
  • In stratified flows of two immiscible liquids, due to the vibration in a pipe, the shape of the interface is not always periodic and it causes the different end points of the interfacial boundary. In this case the performance is not good. To solve this, in this paper, the hybrid-type Fourier series is proposed, which consists of both the polynomial and the trigonometric terms. Under the stationary interfacial boundary during acquiring a full set of voltage data, the performance of the proposed method is evaluated through the numerical experiments. The results show that the proposed method performs better than the conventional Fourier series in estimating the interfacial boundary.

Analysis of Absorption Refrigeration Cycles to Utilize Treated Sewage (하수처리수이용 흡수식냉동사이클의 해석)

  • Lee, Y.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.8 no.2
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    • pp.288-298
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    • 1996
  • The gas-fired absorption refrigeration system to utilize treated sewage is available for environmental protection and energy conservation. Simulation analysis on the double-effect absorption refrigeration cycles with parallel or series flow type has been performed. The working fluid is Lithium Bromide and water solution. The main purpose of this study is evaluating the possibilities of effective utilization of treated sewage as a cooling water for the absorber and condenser. The efficiency of a couple of cycles has been studied and simulation results show that higher coefficient of performance could be obtained for parallel flow type. The other purpose of the present study is to determine the optimum designs and operating conditions based on the operating constraints and the coefficent of performance in the paralledl flow type.

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Study on the flood frequency analysis for the annual exceedance series -Centering along the Geum River basin- (연초과치 계열의 홍수빈도 분석에 관한 연구 -금강유역을 중심으로-)

  • 박영근;이순혁
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.24 no.1
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    • pp.53-62
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    • 1982
  • This study was attempted to find best fitted distribution and the equations for probable maximum flow with the evaluation of parameters by the method of moment for the rat- ional design of hydraulic structures in the annual exceedance series. Six subwatersheds were selected as studying basins along Geum River basin. The results obtained through this study were analyzed and summarized as follows. 1. Fitted probability distribution was showed in the order of Three Parameter Lognorm al, Type 1 Extremal, Exponential, Pearson Type III, and Log Pearson Type I distribu- tion as the results of x$^2$ goodness of fit test. 2. Kolmogorov-Smirnov test showed in the order of Three Parameter Lognormal, Exp- onential' Pearson Type III, Log Pearson Type III and Type 1 Extremal distribution for the fitted probability distribution. 3. It can be concluded that Three parameter Lognormal distribution is a best fitted one among some other distributions out of respect for each both tests. An Exponential distribution was proposed as a suitable one by Chow, V.T. showeci lower fittness than that of Three Parameter Lognormal in Geum River basin. 5. Probable flood flow equations followins the return periods for each station were obt- ained by Three Parameter Lognormal distribution. 6. It is urgently essential that best fitted probability distribution should be established for the annual exceedance series in the main river systems of Korea.

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A Study of Elapsed Time Change on Concrete for Top-Down Method (역타공법 적용을 위한 콘크리트 경시변화 특성 연구)

  • 정근호;이종균;박선길;이영도;정상진
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.487-492
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    • 1999
  • The purpose of this study to find the mixture of concrete for Top-Down method. Throughout test of elapsed time change and L-type flow, it was proposed basic performance and level of top-down method concrete. When change as to elapsed time is considered, so series of F10 added 10% S.P satisfied slump and demanded flow (60$\pm$5cm), and L-type slump, L-type flow satisfied liquidity, it can be considered basic mixture of designed actual frame later.

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Evaluation of Goundwater Flow Pattern at the Site of Crystalline Rock using Time Series and Factor Analyses (시계열분석과 요인분석에 의한 결정질 암반의 지하수 유동 평가)

  • Lee, Jeong-Hwan;Jung, Haeryong;Yun, Si-Tae;Kim, Jee-Yeon;Cho, Sung-Il
    • Journal of Soil and Groundwater Environment
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    • v.19 no.4
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    • pp.12-22
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    • 2014
  • This study evaluated the pattern of groundwater fluctuation in cyrstalline rock using time series and factor analyses. From the results, groundwater level for the 18 wells was classified into 4 types reflecting the hydrogeological properties and rainfall event. Type 1 (DB1-5, DB1-6, DB2-2, KB-10, KB-13) was significantly influenced by groundwater flow through water-conducting features, whereas type 2 (DB1-3, DB1-7, KB-1~KB-3, KB-7, KB-11, KB-14, KB-15) was affected by minor fracture network as well as rainfall event. Type 3 (DB1-1, DB1-2) was mainly influenced by surface infiltration of rainfall event. Type 4 (DB1-8, KB-9) was reflected by the irregular variation of groundwater level caused by anisotropy and heterogeneity of crystalline rock.

A Probabilistic Determination of the Active Storage Capacity of A Reservoir Using the Monthly Streamflows Generated by Stochastic Models (월유하량(月流下量)의 추계학적(推計學的) 모의발생자료(模擬發生資料)를 사용(使用)한 저수지(貯水池) 활용(活用) 저수용량(貯水容量)의 확률론적(確率論的) 결정(決定))

  • Yoon, Yong Nam;Yoon, Kang Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.6 no.3
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    • pp.63-74
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    • 1986
  • A methodology for the probabilistic determination of active storage capacity of an impounding reservoir is proposed with due considerations to the durations and return periods of the low flow series at the reservoir site. For more reliable probabilistic analysis the best-fit stochastic generation model of Monte Carlo type was first selected for the generation of monthly flow series, the models tested being the Month Carlo Model based on the month-by-month flow series (Monte Carlo-A Type), Monte Carlo Model based on the standardized sequential monthly flow series (Monte Carlo-B Type), and the Thomas-Fiering Model. Monte Carlo-B Model was final1y selected and synthetic monthly flows of 200 years at Hong Cheon dam site were generated. With so generated 200 years' monthly flows partial duration series of low flows were developed for various durations. Each low flow series was further processed by a nonsequential mass analysis for specified draft rates. This mass analysis furnished the storage-draft-recurrence interval relationship which gives the reservoir storage requirement for a specified water demand from the reservoir during a drought of given return period. Illustrations are given on the application of these results in analyzing the water supply capacity of a particlar reservoir, existing or proposed.

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Coolant Flow Characteristics and Cooling Effects in the Cylinder Head with Coolant Flow System and Local Water Passage (냉각수 공급방식 및 국부적인 물통로의 형상 변화에 따른 냉각수 유동특성 및 연소실 벽면의 냉각효과)

  • 위신환;민영대;이종태
    • Transactions of the Korean Society of Automotive Engineers
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    • v.11 no.1
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    • pp.32-41
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    • 2003
  • For the countermeasure of expected higher thermal load in miller cycle engine, coolant flows in the cylinder head of base engine with several coolant flow methods and drilled hole passages were measured by using PIV technique. And the cooling effect was evaluated by measurements of wall temperatures according to each coolant flow method. It was found that the series flow system was most suitable among the discussed 3 types of coolant flow methods since it had the best cooling effect in cylinder head by the fastest coolant flow velocity It was also found that for drilled water passage to decrease the large thermal load in exhaust valve bridge, nozzle type is more effective compared with round type of water passage, and its size has to be determined according to the coolant flow pattern and velocity in each cylinder.