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Li Hua,윤정인(J. I. Yoon),정석권(S. K. Jeong) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-
This paper presents a numerical study on dynamic characteristics of evaporator to control evaporator superheat and compressor capacity with optimum. A general concern among engineer is system optimization in order to reduce energy consumption and to keep room temperature within a very restricted range with minimum oscillation in some special applications. Heat exchange is mainly happened in the evaporator. So, making mathematical model and analyzing evaporator characteristics are necessary in order to control the superheat and the capacity. A mathematical model describing the transient phenomena of two-phase flow heat exchanges is based on the one-dimensional partial-differential equations representing mass and energy conservation and a tube-wall energy. Ordinary-differential equation is formulated by integrating separately over the two region(two-phase and vapor) generally present in a heat exchange.
Li Hua,이동우(D. W. Lee),정석권(S. K. Jeong) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
This paper describes PI controller design to control the variable speed refrigeration system effectively. The conventional control schemes of the system are mainly focused on representative two control methods, superheat control and capacity control. In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. The capacity and superheat can not be controlled independently because of interfering loop when the compressor speed and opening angle electronic expansion valve is varied. Therefore, we suggest decoupling model to eliminate the interfering loop at first. Next, we designed PI controller and investigated the control performance through some numerical simulations.
Li Hua,이동우(D. W. Lee),정석권(S. K. Jeong) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
To obtain high efficiency, high intelligence, and energy saving for refrigeration system, the optimum control of the refrigeration system is inevitable. The conventional control schemes are mainly based on representative two control methods. One is capacity control for room temperature control and energy saving by compressor speed variation. The other is superheat control for enhancing coefficient of performance of the refrigeration system by varying opening angle of an electronic expansion valve. They have been controlled not be coupled but be separated. However, the refrigeration system's elements are deeply connected with the pipe each other, so optimum control is not easy. This paper presents an experimental study for heat dynamic characteristics analysis of the refrigeration system to control evaporator superheat and compressor capacity with optimum.
Li Hua,윤정인(J. I. Yoon),정석권(S. K. Jeong) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In this paper, we described the dynamic characteristics of refrigeration system to control evaporator superheat and compressor capacity. Mathematical model is necessary in order to control the superheat and the capacity. Therefore, we obtained the models from the equation of mass, energy, and momentum balances. Finally, numerical simulations were performed to prove the validity of the proposed control model.
PI 제어에 의한 가변속 냉동시스템의 과열도 및 용량제어
Li Hua,이동우(D. W. Lee),정석권(S. K. Jeong) 대한설비공학회 2006 대한설비공학회 학술발표대회논문집 Vol.2006 No.11
In this paper, we suggest the high efficient control method based on general PI control law to control the variable speed refrigeration system effectively. In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. Thus, we propose decoupling model to eliminate the interfering at first. Next, we design PI controller to control capacity and superheat independently. Finally the control performance was investigated through some experiments. The experiments results show that the PI control design can obtain good control performance deal with the varied control reference and thermal load.
이화(Li Hua),이동우(D. W. Lee),정석권(S. K. Jeong) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
This paper deals with an empirical model for decoupling control to control the refrigeration system effectively. The conventional control schemes of the system are mainly focused on representative two control methods, superheat control and capacity control. The capacity control is basically conducted to respond partial loading conditions on the purpose of energy saving. The superheat control is mainly carried out to maintain maximum coefficient of performance (COP). In the variable speed refrigeration system, the capacity and the superheat are controlled by inverters and electronic expansion valves respectively for saving energy and improving cost performance. The capacity and superheat can not be controlled independently because of interfering loop when the compressor speed and opening angle electronic expansion valve is varied. Therefore, we suggest decoupling model to eliminate the interfering loop at first. Next, each transfer function in decoupling control model is obtained from number of experiments.
과열도와 용량제어를 위한 가변속 냉동시스템의 퍼지제어기 설계
이동우(D. W. Lee),Li Hua,정석권(S. K. Jeong),양주호(J. H. Yang) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
In this paper, we suggest fuzzy control to progress both energy saving and coefficient of performance(COP) in a refrigeration system. The capacity and superheat are controlled simultaneously and independently by inverters and electronic expansion valves respectively for saving energy and improving COP in the variable speed refrigeration system. By adopting the fuzzy control theory, the controller design for the capacity and superheat is possible without depending on dynamic model of the system. Some control experiments are conducted to design fuzzy controller by trial and errors manner. The experimental results show that the proposed fuzzy controller can establish good control performance for the complicated refrigeration system with inherent strong non-linearity.