The Experts below are selected from a list of 81 Experts worldwide ranked by ideXlab platform
John E Seem - One of the best experts on this subject based on the ideXlab platform.
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Experimental Study on Extremum Seeking Control for Efficient Operation of Air-side Economizer
2014Co-Authors: John E SeemAbstract:The Air-side economizers have been developed as a major class of energy-saving equipment to enhance the energy efficiency of central Air-conditioning systems by taking advantage of Outdoor Air during cool or cold weather. In current practice, the Outdoor Air Damper is controlled to maintain either the maximum or minimum opening by comparing the Outdoor Air temperature/enthalpy with the setpoint temperature/enthalpy or return-Air temperature/enthalpy. However, in practice many economizers do not behave as expected or even waste more energy due to the erroneous Damper actions because of the inaccurate or failed temperature and/or relative humidity (RH) sensors. Recently, a self-optimizing controller based on extremum seeking control (ESC) has been proposed in an earlier study by Li et al. (2010) for efficient operation of an Air-side economizer. This paper presents two experimental studies of the ESC Air-side economizer control: one is a laboratory setup with a direct-expansion Air conditioning unit, and the other is a chilled-water based Air handling unit (AHU) facility at Iowa Energy Center. Experimental results from both studies validate the effectiveness of the ESC scheme as a model free optimal control strategy for Air-side economizer operation.
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efficient operation of Air side economizer using extremum seeking control
Journal of Dynamic Systems Measurement and Control-transactions of The Asme, 2010Co-Authors: Pengfei Li, Yaoyu Li, John E SeemAbstract:As the heating, ventilating, and Air conditioning (HVAC) systems accounts for a major sector of energy consumption for commercial buildings, there has been a greater demand for improving the efficiency of such systems. The Air-side economizers have been developed as a class of energy-saving HVAC devices that may increase the energy efficiency by taking advantage of Outdoor Air during cool or cold weather. However, many economizers do not operate in the expected manner and waste even more energy than before installation, mostly due to the unreliable sensors and actuators in practice. Better control strategy is needed for optimal and robust operation. In this paper, an extremum-seeking control (ESC) based self-optimizing strategy is proposed to minimize the energy consumption, with the feedback of chilled water supply command rather than the temperature and humidity measurements. The mechanical cooling load is minimized by seeking the optimal Outdoor Air Damper opening in real time. Such scheme does not need temperature and humidity sensors, and depends much less on the knowledge of the economizer model. Simulation was performed on a MODELICA based transient model of a single-duct Air-handling unit developed with DYMOLA and AirCONDITIONING LIBRARY . The simulation results demonstrated the potential of using ESC to achieve the minimal mechanical cooling load in a self-optimizing manner. In addition, an antiwindup ESC scheme is proposed to handle the ESC windup issue due to actuator (Damper) saturation. The simulation results validated the effectiveness of the proposed antiwindup ESC.
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ACC - Extremum seeking control for efficient and reliable operation of Air-side economizers
2009 American Control Conference, 2009Co-Authors: John E SeemAbstract:Economizers have been recognized as a class of energy-saving devices for heating, ventilating and Air conditioning (HVAC) systems that may increase the energy efficiency by taking advantage of Outdoor Air during cool or cold weather. There has been a tremendous demand for reducing energy consumption of HVAC systems in commercial buildings. However, many economizers do not operate in the expected manner and waste even more energy than before installation, mostly traceable to the unreliable sensors and actuators in practice. In this paper, an extremum seeking control (ESC) based self-optimizing strategy is proposed to minimize the energy consumption. Rather than depending on the unreliable temperature and humidity measurements, the proposed strategy is based on the feedback of chilled-water supply command. The mechanical cooling load is minimized by seeking the optimal Outdoor-Air Damper opening in real time. Such scheme does not need temperature and humidity sensors and depends much less on the knowledge of the economizer model. Simulation was performed on a Modelica based transient model of a single-duct Air-handling unit (AHU) developed with Dymola and the AirConditioning Library. The simulation results demonstrated the potential of using ESC to achieve minimal mechanical cooling load in a self-optimizing manner. In addition, an anti-windup ESC scheme is proposed to overcome the ESC windup issue due to actuator (Damper) saturation. The simulation results validated the effectiveness of the proposed anti-windup ESC.
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Efficient and reliable operation of Air-side economizers using extremum seeking control
ASME 2008 Dynamic Systems and Control Conference Parts A and B, 2008Co-Authors: John E SeemAbstract:For the heating, ventilating, and Air conditioning (HVAC) systems for commercial buildings, there has been a greater demand for reducing energy consumption. The economizers have been developed as a class of energy-saving HVAC devices that may increase the energy efficiency by taking advantage of Outdoor Air during cool or cold weather. However, many economizers do not operate in the expected manner and waste even more energy than before installation, mostly due to the unreliable sensors and actuators in practice. Better control strategy is needed for optimal and robust operation. In this paper, an extremum seeking control (ESC) based self-optimizing strategy is proposed to minimize the energy consumption, with the feedback of chilled water supply command rather than the temperature and humidity measurements. The mechanical cooling load is minimized by seeking the optimal Outdoor-Air Damper opening in real time. Such scheme does not need temperature and humidity sensors and depends much less on the knowledge of economizer model. Simulation was performed on a Modelica based transient model of a single-duct Air-handling unit (AHU) developed with Dymola and AirConditioning Library. The simulation results demonstrated the potential of using ESC to achieve the minimal mechanical cooling load in a self-optimizing manner. In addition, an anti-windup ESC scheme is proposed to handle the ESC windup due to actuator (Damper) saturation. The simulation results validated the effectiveness of the proposed anti-windup ESC.Copyright © 2008 by ASME
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Dynamic Modeling and Self-Optimizing Control of Air-Side Economizers
2008Co-Authors: John E SeemAbstract:For the heating, ventilating, and Air conditioning (HVAC) systems for commercial buildings, there has been a greater demand for reducing energy consumption. The economizers have been developed as a class of energy saving devices that may increase the energy efficiency by taking advantage of Outdoor Air during cool or cold weather. However, in practice, many economizers do not operate in the expected manner and waste even more energy than before installation. Better control strategy is needed for optimal and robust operation. This paper presents two related aspects of research on dynamic modeling and control for economizers. First, a Modelica based dynamic model is developed for a single-duct Air-side economizer. The model development was based on Dymola and AirConditioning Library with some revision on water medium and heat exchanger modeling. Such transient model will lay a more quality foundation for control design. Second, for a threestate operation for Air-side economizers, a selfoptimizing control strategy is developed based on the extremum seeking control (ESC). The mechanical cooling can be minimized by optimizing the Outdoor Air Damper opening via extremum seeking. Such has much less dependency on the knowledge of economizer model, and thus has more promise for practical operation. In addition, an anti-windup ESC scheme is proposed as an enhancement for the existing ESC techniques. The simulation results validated the effectiveness of the dynamic model of the economizer, demonstrated the potential of using ESC to achieve the minimal mechanical cooling load in a selfoptimizing manner, and illustrated the possibility of ESC malfunctioning under actuator (Damper) saturation and the capability of anti-windup ESC in preventing such undesirable behavior.
Curtis J. Klaassen - One of the best experts on this subject based on the ideXlab platform.
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A Damper Control System for Preventing Reverse Airflow Through the Exhaust Air Damper of Variable-Air-Volume Air-Handling Units
Hvac&r Research, 2000Co-Authors: John E Seem, John M. House, George E. Kelly, Curtis J. KlaassenAbstract:Traditional Air-handling unit (AHU) control systems link the position of the exhaust, recirculation, and Outdoor Air Dampers. Laboratory tests of a variable-Air-volume AHU using the traditional Damper control approach revealed that Outdoor Air could enter the AHU through the exhaust Air Damper. This can negatively impact indoor Air quality. This paper examines the conditions that lead to this phenomenon and presents a new control system that can help alleviate the problem. The new control system links only the position of the exhaust and recirculation Air Dampers. During occupied times, the Outdoor Air Damper is fully open. Simulation results are presented that demonstrate that the new Damper control system prevents Air from entering the AHU through the exhaust Air outlet for all but extreme conditions that are described in the paper. Laboratory and field test results are presented that demonstrate that the new control system prevents Air from entering the AHU through the exhaust Air outlet for the same c...
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Leave the Outdoor Air Damper Wide Open
Ashrae Journal, 1998Co-Authors: John E Seem, John M. House, Curtis J. KlaassenAbstract:This article describes a new control system for variable-Air-volume AHUs that uses volume matching to control the return fan. The purpose of the new control system is to prevent Outdoor Air from entering an AHU through the exhaust Air outlet
James E. Braun - One of the best experts on this subject based on the ideXlab platform.
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Development of an Energy Impact Model for RTU Economizer Faults
2014Co-Authors: Andrew L Hjortland, James E. BraunAbstract:Stuck Outdoor-Air Dampers can lead to significant energy waste when undetected for extended periods of time. This is especially true for rooftop Air-conditioners (RTUs) where preventative maintenance may not be frequent or is only reserved for emergencies. Automated fault detection and diagnosis (AFDD) tools for Outdoor-Air Dampers and economizers have been proposed to reduce the effort and cost of maintenance and are even required by some new building standards California Energy Commission (2012). While qualitatively, the effects of stuck Outdoor-Air Damper faults are understood, less has been written about impacts these faults have on cooling cycle performance and actual energy usage over time. An investigation of the effects of improper Outdoor-Air fraction caused by a stuck Outdoor-Air Damper with respect to cooling capacity, cycle efficiency, equipment run-time, and energy usage is presented. Fault impact ratios for equipment performance are derived and demonstrated with laboratory data. In addition, a methodology for fault impact evaluation is presented and example results are shown for several Outdoor-Air Damper positions and ambient conditions. The resulting fault impact ratios and evaluation method could be embedded into an existing AFDD tool in order to aid in optimal maintenance scheduling.
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Development of Economic Impact Models for RTU Economizer Faults
2014Co-Authors: Andrew L Hjortland, James E. BraunAbstract:Stuck Outdoor-Air Dampers can lead to significant energy waste when undetected for extended periods of time. This is especially true for rooftop Air-conditioners (RTUs) where preventative maintenance may not be frequent or is only reserved for emergencies. Automated fault detection and diagnosis (AFDD) tools for Outdoor-Air Dampers and economizers have been proposed to reduce the effort and cost of maintenance and are even required by some new building standards California Energy Commission (2012). While qualitatively, the effects of stuck Outdoor-Air Damper faults are understood, less has been written about impacts these faults have on cooling cycle performance and actual energy usage over time. An investigation of the effects of improper Outdoor-Air fraction caused by a stuck Outdoor-Air Damper with respect to cooling capacity, cycle efficiency, equipment run-time, and energy usage is presented. Fault impact ratios for equipment performance are derived and demonstrated with laboratory data. In addition, a methodology for fault impact evaluation is presented and example results are shown for several Outdoor-Air Damper positions and ambient conditions. The resulting fault impact ratios and evaluation method could be embedded into an existing AFDD tool in order to aid in optimal maintenance scheduling.
John M. House - One of the best experts on this subject based on the ideXlab platform.
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Experimental evaluation of anti-windup extremum seeking control for Airside economizers
Control Engineering Practice, 2016Co-Authors: John M. House, Timothy I. SalsburyAbstract:Abstract The performance of anti-windup extremum seeking control (ESC) as a model free online optimization strategy is evaluated by experimental studies for energy efficient operation of both chilled-water and direct-expansion Airside economizers. For the chilled-water based system, the ESC takes the chilled-water valve control signal as the feedback, and controls the Outdoor Air Damper (OAD) position to minimize the cooling coil load. For the direct-expansion system, the ESC takes the total electricity power consumption as the feedback, and controls the OAD position to minimize the power consumption. Experimental results verify the effectiveness of the ESC scheme for model-free operation without temperature and humidity measurements.
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A Damper Control System for Preventing Reverse Airflow Through the Exhaust Air Damper of Variable-Air-Volume Air-Handling Units
Hvac&r Research, 2000Co-Authors: John E Seem, John M. House, George E. Kelly, Curtis J. KlaassenAbstract:Traditional Air-handling unit (AHU) control systems link the position of the exhaust, recirculation, and Outdoor Air Dampers. Laboratory tests of a variable-Air-volume AHU using the traditional Damper control approach revealed that Outdoor Air could enter the AHU through the exhaust Air Damper. This can negatively impact indoor Air quality. This paper examines the conditions that lead to this phenomenon and presents a new control system that can help alleviate the problem. The new control system links only the position of the exhaust and recirculation Air Dampers. During occupied times, the Outdoor Air Damper is fully open. Simulation results are presented that demonstrate that the new Damper control system prevents Air from entering the AHU through the exhaust Air outlet for all but extreme conditions that are described in the paper. Laboratory and field test results are presented that demonstrate that the new control system prevents Air from entering the AHU through the exhaust Air outlet for the same c...
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Leave the Outdoor Air Damper Wide Open
Ashrae Journal, 1998Co-Authors: John E Seem, John M. House, Curtis J. KlaassenAbstract:This article describes a new control system for variable-Air-volume AHUs that uses volume matching to control the return fan. The purpose of the new control system is to prevent Outdoor Air from entering an AHU through the exhaust Air outlet
Andrew L Hjortland - One of the best experts on this subject based on the ideXlab platform.
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Development of an Energy Impact Model for RTU Economizer Faults
2014Co-Authors: Andrew L Hjortland, James E. BraunAbstract:Stuck Outdoor-Air Dampers can lead to significant energy waste when undetected for extended periods of time. This is especially true for rooftop Air-conditioners (RTUs) where preventative maintenance may not be frequent or is only reserved for emergencies. Automated fault detection and diagnosis (AFDD) tools for Outdoor-Air Dampers and economizers have been proposed to reduce the effort and cost of maintenance and are even required by some new building standards California Energy Commission (2012). While qualitatively, the effects of stuck Outdoor-Air Damper faults are understood, less has been written about impacts these faults have on cooling cycle performance and actual energy usage over time. An investigation of the effects of improper Outdoor-Air fraction caused by a stuck Outdoor-Air Damper with respect to cooling capacity, cycle efficiency, equipment run-time, and energy usage is presented. Fault impact ratios for equipment performance are derived and demonstrated with laboratory data. In addition, a methodology for fault impact evaluation is presented and example results are shown for several Outdoor-Air Damper positions and ambient conditions. The resulting fault impact ratios and evaluation method could be embedded into an existing AFDD tool in order to aid in optimal maintenance scheduling.
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Development of Economic Impact Models for RTU Economizer Faults
2014Co-Authors: Andrew L Hjortland, James E. BraunAbstract:Stuck Outdoor-Air Dampers can lead to significant energy waste when undetected for extended periods of time. This is especially true for rooftop Air-conditioners (RTUs) where preventative maintenance may not be frequent or is only reserved for emergencies. Automated fault detection and diagnosis (AFDD) tools for Outdoor-Air Dampers and economizers have been proposed to reduce the effort and cost of maintenance and are even required by some new building standards California Energy Commission (2012). While qualitatively, the effects of stuck Outdoor-Air Damper faults are understood, less has been written about impacts these faults have on cooling cycle performance and actual energy usage over time. An investigation of the effects of improper Outdoor-Air fraction caused by a stuck Outdoor-Air Damper with respect to cooling capacity, cycle efficiency, equipment run-time, and energy usage is presented. Fault impact ratios for equipment performance are derived and demonstrated with laboratory data. In addition, a methodology for fault impact evaluation is presented and example results are shown for several Outdoor-Air Damper positions and ambient conditions. The resulting fault impact ratios and evaluation method could be embedded into an existing AFDD tool in order to aid in optimal maintenance scheduling.
