• Title, Summary, Keyword: temperature control

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Actual Energy Consumption Analysis of Temperature Control Strategies for Secondary Side Hot Water District Heating System with an Inverter (인버터시스템 적용 지역난방 시스템의 2차측 공급수 온도 제어방안에 따른 에너지사용량 실증 비교)

  • Cho, Sung-Hwan;Hong, Seong-Ki
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.4
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    • pp.179-186
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    • 2015
  • In this study, the actual energy consumption of the secondary side District Heating System (DHS) with different hot water supply temperature control methods is compared. The two methods are Outdoor Temperature Reset Control and Outdoor Temperature Predictive Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side system, the results show that the Outdoor Temperature Predictive Control method saves more energy. In general, the Outdoor Temperature Predictive Control method lowers the supply temperature of hot water, and it reduces standby losses and increases the overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, the Outdoor Temperature predictive Control method saves about 6.6% of energy when compared to the Outdoor Temperature Reset Control method. Also, it is found that at partial load condition, such as during daytime, the fluctuation of hot water supply temperature with Outdoor Temperature Reset Control is more severe than that with Outdoor Temperature Predictive Control. Thus, it proves that Outdoor Temperature Predictive Control is more stable even at partial load conditions.

Actual Energy Consumption Analysis on Temperature Control Strategies (Set-point Control, Outdoor Temperature Reset Control and Outdoor Temperature Predictive Control) of Secondary Side Hot Water of District Heating System (지역난방 2차측 공급수 온도 제어방안(설정온도 제어, 외기온 보상제어, 외기온 예측제어)에 따른 에너지사용량 실증 비교)

  • Cho, Sung-Hwan;Hong, Seong-Ki;Lee, Sang-Jun
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.3
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    • pp.137-145
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    • 2015
  • In this study, the actual energy consumption of the secondary side of District Heating System (DHS) with different hot water supply temperature control methods are compared. Three methods are Set-point Control, Outdoor Temperature Reset Control and Outdoor Temperature Prediction Control. While Outdoor Temperature Reset Control has been widely used for energy savings of the secondary side of the system, the results show that Outdoor Temperature Prediction Control method saves more energy. In general, Outdoor Temperature Prediction Control method lowers the supply temperature of hot water, and it reduces standby losses and increases overall heat transfer value of heated spaces due to more flow into the space. During actual energy consumption monitoring, Outdoor Temperature Prediction Control method saves about 7.1% in comparison to Outdoor Temperature Reset Control method and about 15.7% in comparison to Set-point Control method. Also, it is found that at when partial load condition, such as daytime, the fluctuation of hot water supply temperature with Set-point Control is more severe than Outdoor Temperature Prediction Control. Therefore, it proves that Outdoor Temperature Prediction Control is more stable even at the partial load conditions.

Power Line Communication-based Heated Glass Temperature Control System (전력선통신을 이용한 선박 및 건축용 발열유리 온도제어 시스템)

  • Lee, Su-Hyeong;Kim, In-Dong
    • The Transactions of the Korean Institute of Power Electronics
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    • v.20 no.2
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    • pp.105-114
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    • 2015
  • Heated glasses are widely used to prevent surface condensation and freezing in ship and building windows. This study proposes a heated glass temperature control system composed of power and control circuits to control the temperature of heated glasses. The proposed temperature control system adopts a digital controller instead of a conventional analog controller. Thus, the proposed system has better characteristics, such as precise setup and control of glass temperature, setup and control of output power, and control mode change between ON/OFF and phase controls. The system can also implement multi-functional control algorithms. The control characteristics are not dependent upon external disturbances, such as ambient temperature and electrical noises. Furthermore, the proposed temperature control system utilizes the power line communication (PLC) method to control the number of heated glasses without any extra communication lines. The system proposes a new communication protocol with strong immunity to electrical switching noises. A new sensorless algorithm is used to detect the temperature of the heated glass. This study presents the design guidelines in detail and its effectiveness are confirmed by implementing a 4-kw prototype temperature control system.

Temperature Control Technology for Once Through Boiler (500MW급 초임계압 관류형 보일러 온도제어에 대한 기술)

  • Lee, Kwang-Hoon;Lee, Joo-Hyun
    • Proceedings of the KIEE Conference
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    • pp.719-721
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    • 1998
  • In this paper, we reviewed the steam temperature control in an once through boiler. The steam temperature control is very difficult. Generally, steam temperature of an once through boiler is not only controlled by boiler spray water flow, but also influenced by feed water flow and fuel flow. An advanced control strategy has been developed by experienced engineer. Specifically, We reviewed temperature control strategy for Taian power plant in this paper. This control strategy is represented by state control observer. This state control observer algorithm for temperature control has been used since the late 1980's. This paper describes control strategy employed and observed benefits from advanced steam temperature control.

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A study on a precision temperature control unit using thermoelectirc module (열전소자를 이용한 정밀 항온 유지 장치에 관한 실험 및 시뮬레이션 연구)

  • Park, Kyung-Seo;Song, Young-Joog;Im, Hong-Jae;Jang, Si-Yeol;Lee, Kee-Sung;Jeong, Jay;Shin, Dong-Hoon
    • Proceedings of the KSME Conference
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    • pp.1937-1941
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    • 2007
  • During a process of a nanoimprint for manufacturing LCD, a small temperature variation on the LCD glass can cause thermal stress and generate unexpected displacement. To avoid this trouble, a precision temperature control unit using thermoelectric modules is appropriate for nanoimprint processes. The unit consists of an air control system, a cooling water control system, and a power control system. The air control system includes a thermoelectric module, thermocouples measuring temperatures of air and a duct-stale fin, and two air fans. The heat generated by the thermoelectric module is absorbed by the cooling water control system. The power control system catches the temperature of the thermoelectric module, and a PID controller with SCR controls the input power of the thermoelectric module. Temperature control performance is evaluated by experiment and simulation. The temperature control unit is able to control the exit temperature about ${\pm}2^{\circ}C$ from the incoming fluid temperature, and the error range is ${\pm}0.1^{\circ}C$. However, the control time is approximately 30minute, which needs further study of active control

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A PID Control of Supply Duct Outlet Air Temperature in Personal Environment Module

  • Park, Young-Chil
    • International Journal of Air-Conditioning and Refrigeration
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    • v.11 no.2
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    • pp.82-90
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    • 2003
  • The work presented here is a design and an implementation of PID control system to regulate a supply duct outlet air temperature in PEM (Personal Environment Module). In PEM, the air is heated to the required temperature while it flows through the supply duct without any mixing chamber. This makes the control of air temperature in PEM difficult. A simulation is done first to understand the relationship between a temperature distribution in working area, flow rate and the outlet air temperature of PEM. Then a linear dynamic model of heating process in PEM is derived. P, PD and PID type control systems, to provide the rapid response without overshoot and saturation in heater command voltage, are designed using a linear model obtained. Experimentally obtained data shows that the control system satisfies the design criteria and works properly in controlling the supply duct outlet air temperature.

Immune Based 2-DOF PID Controller Design for Complex Process Control

  • Kim, Dong-Hwa
    • 제어로봇시스템학회:학술대회논문집
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    • pp.70.2-70
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    • 2002
  • In the thermal power plant, it is difficult to maintain strict control of the steam temperature in order to avoid thermal stress, because of variation of the heating value according to the fuel source, the time delay of changes in main steam temperature versus changes in fuel flow rate, difficulty of control on the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, fluctuation of inner fluid water and steam flow rates widely during load-following operation. Up to the present time, the PID controller has been used to operate this system...

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가변 풍량 유닛에 의한 실내 공간의 온도제어를 위한 공간의 분할 모델과 상태궤환 제어기의 개발에 관한 연구

  • 박세화;신승철
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.10
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    • pp.947-959
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    • 2001
  • We propose a control scheme to control the indoor zone temperature via variable air volume (VAV) unit. To control the room temperature, state space model of the conditioned zone which is partitioned into nine artificial sectional regions is derived. The nonlinearity of the damper motion and actuator are considered for the practical use in the state space system description. The temperature control of the room temperature is performed by manipulating the degree of openness of the damper in relation to the local room temperature and the supplied air flow rate. In general, since a local temperature in the conditioned zone is measured, it is required to estimate the temperature values in each regions for the precise temperature control. We thus design a state observer to estimate the regional temperature, and use these values in the controller. The overall control system consists of the state observer based state feedback with the integral control. We compared the control results of the proposed scheme with those of cascade proportional and integral (PI) control, and showed that the scheme achieved precise control of the conditioned system.

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A Study on the Control of Water Flow and Water Temperature in the Radiant Cooling System through Simulations (시뮬레이션을 통한 바닥복사냉방 시스템의 공급유량 및 냉수온도 제어에 관한 연구)

  • 김용이;윤혜림;여명석
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.13 no.6
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    • pp.532-540
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    • 2001
  • The objectives of this study are to analyze the control variables according to condensation occurrence, to find the range in floor surface temperature and frequency of condensation, and to evaluate the control methods through simulations when the radiant heating system is used for cooling. Through the simulation analysis the control methods such as on/off control, variable flow control and outdoor reset with indoor temperature feedback control are evaluated and compared. The results show that the lowest floor surface temperature is around $23^{\circ}C$, the surface condensation can be prevented by controlling indoor humidity within 20g/kg(DA0, and that outdoor reset with indoor temperature feedback control is more appropriate than on/off control and variable flow control with regard to prevention of the condensation and thermal comfort.

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Temperature and Property Control of High Strength Steel in Hot Strip Mills (열간압연 고강도강의 온도 및 재질제어)

  • Park, Cheol-Jae
    • Journal of The Korean Society of Manufacturing Technology Engineers
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    • v.20 no.6
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    • pp.817-823
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    • 2011
  • This paper proposes a cooling stop temperature control(CST) and a phase transformation control(PTR) which aim at obtaining the uniform temperature and quality along the longitudinal direction of the high strength steel on the run-out table(ROT) process. The problems of the temperature control are analyzed for the conventional steel and the new control concepts are derived from a time-temperature transformation(TTT) diagram. The proposed control technologies are verified from the simulation results under the temperature prediction model by the heat transfer governing equation, and the temperature estimation simulator. It is shown through the field test of the hot strip mills that the phase transformation ratio of the high strength steel is considerably improved by the proposed temperature controls.