• Journal of Institute of Control, Robotics and Systems
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• v.1 no.2
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• pp.119-126
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• 1995

The purpose of this study is to develop the technique of energy recovery and energy saving by using the optimization of heat exchanger network synthesis. This article proposes a new method of determining the optimal target of a heat exchanger network synthesis problem of which data feature multiple pinch points. The system separation method we suggest here is to subdivide the original system into independent subsystems with one pinch point. The optimal cost target was evaluated and the original pinch rules at each subsystem were employed. The software developed in this study was applied to the Alko prosess, which is an alcohol production process, for the synthesis of heat exchanger network. It was possible to save about 15% of the total annual cost.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.376-379
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• 1996

Synthesis for qualitative analysis in connection with quantitative analysis from the pinch design method, EVOP and Operations Research is proposed for the optimal synthesis of heat exchanger networks, that is through of the transportation model of the linear programming for synthesizing chemical processing systems, to determine the location of pinch points, the stream matches and the corresponding heat flowrate exchanged at each match. In the second place, according to the optimization, the optimal design of heat transfer enhancement is carried on a fixed optimum heat exchanger network structure, in which this design determines optimal operational parameters and the chosen type of heat exchangers as well. Finally, the method of this paper is applied to the study of the optimal synthetic design of heat exchanger network of constant-decompress distillation plants.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.819-824
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• 1989

This paper proposes a new method for the discovery and design of an optimal heat exchanger network. The method is based upon the concept of pinch, a problem reduction technique and the heuristics developed in this work. It generates subproblems in a logical way and solves the subproblems by the heuristics to synthesize an optimal network structure. It is thought that the heuristics can preserve the minimum utility consumption, the minimum number of heat exchanger units, and the minimum number of stream splittings needed for a given problem. The minimum heat exchanger area for the optimal network can then be obtained by adjusting the temperatures associate with the heat exchanger in the optimal network structure. The method is applied to the problems appeared in the literatures. The results show the reductions in the number of heat exchanger units for some problems.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.1259-1264
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• 1990

During the past two decades, a lot of researches have been done on the synthesis of grassroot heat exchanger networks(HEN). However, few have been dedicated to retrofit of existing heat exchanger networks, which usually use more amount of utilities (i.e. steam and/or cooling water) than the minimum requirements. This excess gives motivation of trades-off between energy saving and rearranging investment. In this paper, an algorithmic-evolutionary synthesis procedure for retrofitting heat exchanger networks is proposed. It consists of two stages. First, after the amount of maximum energy recovery(MER) is computed, a grass-root network featuring minimum number of units(MNU) is synthesized. In this stage, a systematic procedure of synthesizing MNU networks is presented. It is based upon the concept of pinch, from which networks are synthesized in a logical way by the heuristics verified by the pinch technology. In the second stage, since an initial feasible network is synthesized based on the pre-analysis result of MER and must-matches, an assignment problem between new and existing units is solved to minimize total required additional areas. After the existing units are assigned, the network can be improved by switching some units. For this purpose, an improvement problem is formulated and solved to utilize the areas of existing units as much as possible. An example is used to demonstrate the effectiveness of the proposed method.

• 제어로봇시스템학회:학술대회논문집
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• 1986.10a
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• pp.613-618
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• 1986

In this study a s/w system(HENSPIN) for the automatic synthesis of HEN(heat exchanger network) was developed based on Pinch Design Method. The synthesized HEN by HENSPIN are satisfying performance targets such as minimum utility usage with as few as possible capital items. The invented network is near optimal in capital and operating cost. It will be used as initial structure for evolution to the structure which has optimal operability.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.256-263
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• 1998

Among process synthesis problems, the heat exchanger network (HEN) has been subjected to the most concentrated effort because this kind of problems was well defined for solving it and 20-30% energy savings could be realized in the present chemical processes. In this paper, we use an evolutionary approach for HEN synthesis because this approach can overcome the local optimum and combine some heuristic rules. The basic evolutionary approach is composed of three parts, that is, initialization step, growth step and mutation step, as in the simulated annealing and genetic algorithm. This algorithm uses the ecological rule that a better cell will live and worse cell should decompose after repeated generations. With this basic concept, a new procedure is developed and a more efficient method is proposed to generate initial solutions. Its effectiveness is shown using test examples.

• Journal of Energy Engineering
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• v.2 no.2
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• pp.215-224
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• 1993

Heat exchanger network synthesis is very useful to aspects of energy recovery and saving. In order to obtain the optimal network structure for minimum utility cost, multiple utilities were used. In this study, the practical matches of process streams were not considered, but only evaluation of targets was demonstrated. The program developed in this work was applied to the alcohol production process and it was possible to find the optimal cost targets.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.515-524
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• 2022

In this study, the on-site hydrogen production process for refueling stations that were not energy-optimized was improved through exergy analysis and heat exchange network synthesis. Furthermore, the process was scaled up from 30 Nm3/h to 150 Nm3/h to improve hydrogen production capacity. Exergy analysis results show that exergy destruction in the SMR reactor and the heat exchanger accounts for 58.1 and 19.8%, respectively. Thus, the process is improved by modifying the heat exchange network to reduce the exergy loss in these units. As a result of the process simulation analysis, thermal and exergy efficiency is improved from 75.7 to 78.6% and 68.1 to 70.4%, respectively. In conclusion, it is expected to improve the process efficiency when installing on-site hydrogen refueling stations.

• Journal of Energy Engineering
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• v.1 no.1
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• pp.87-96
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• 1992

Two major difficulties with finding an optimal solution to the heat exchanger network synthesis problems are the large solutionspace and the uncertainty in the formulation of the annual cost function. In this work, to overcome the first difficulty a problem reduction technique was developed. The second difficulty was also removed by dividing the annual cost function into four cost items. The optimal network structure for minimum equipment cost is then obtained by repeatedly applying the problem reduction technique and the heuristics in turn. The efficiency and the superiority of the method is demonstrated by examining two selected example problems.

• Plant Journal
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• v.12 no.2
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• pp.24-30
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• 2016

The membrane separation processes have received attention due to advantages such as compactness, modularity, ease of installation, flexibility of operation, lower capital cost and lower energy consumption. In this study, we evaluated accuracy of cross-flow, co-current and counter-current models. With the most accurate model, we identified the operating conditions of the two-stage membrane separation and examined the effects of permeance and selectivity of the membrane by simulation. Futhermore, power requirements and operating cost savings due to the introduction of the heat exchanger were investigated by applying heat exchanger network synthesis technique in the two-stage membrane separation using vapor sweep.