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Author: Song Chun Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
A dynamic model of a radiant floor heating (RFH) system which predicts the dynamic response of RFH system has been developed. The overall model consists of a boiler, an embedded tube floor slab and building enclosure. The overall model was described by nonlinear differential equations, which were programmed and solved using in MATLAB. The RFH system model has been applied to both a single zone and a multi-zone RFH system. The predicted dynamic responses of the model under several operating conditions were studied. Also, a zonal model of RFH system was developed to study the air temperature distribution in the zone. Three different control strategies for improving the performance of RFH systems were explored. These are: (i) a conventional PI control, (ii) a predictive control and (iii) an optimal control. The simulation results show that PI control strategy is an efficient control strategy for RFH system from the point of view of temperature regulation. The simulation results also show that the predictive PI control maintains zone air temperature close to the set-point better than the conventional PI control. Besides, the predictive PI control strategy saves 10∼15% energy, compared to the conventional PI control strategy. In addition, the simulation results also show that the optimal PI control strategy could slightly improve both the zone air temperature regulation and energy efficiency, compared to the predictive PI control. Since the predictive control strategy is simple and easy to implement, it is considered as a good candidate strategy for RFH systems.
Author: Song Chun Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
A dynamic model of a radiant floor heating (RFH) system which predicts the dynamic response of RFH system has been developed. The overall model consists of a boiler, an embedded tube floor slab and building enclosure. The overall model was described by nonlinear differential equations, which were programmed and solved using in MATLAB. The RFH system model has been applied to both a single zone and a multi-zone RFH system. The predicted dynamic responses of the model under several operating conditions were studied. Also, a zonal model of RFH system was developed to study the air temperature distribution in the zone. Three different control strategies for improving the performance of RFH systems were explored. These are: (i) a conventional PI control, (ii) a predictive control and (iii) an optimal control. The simulation results show that PI control strategy is an efficient control strategy for RFH system from the point of view of temperature regulation. The simulation results also show that the predictive PI control maintains zone air temperature close to the set-point better than the conventional PI control. Besides, the predictive PI control strategy saves 10∼15% energy, compared to the conventional PI control strategy. In addition, the simulation results also show that the optimal PI control strategy could slightly improve both the zone air temperature regulation and energy efficiency, compared to the predictive PI control. Since the predictive control strategy is simple and easy to implement, it is considered as a good candidate strategy for RFH systems.
Author: Zhi Long Zhang
Publisher:
ISBN:
Category : Heating
Languages : en
Pages : 0
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Book Description
A dynamic model of a radiant floor heating (RFH) system useful for control analysis is developed. The overall model consists of a boiler, an embedded tube floor slab and building enclosure. The overall model was described by nonlinear differential equations, which were solved using finite numerical methods. The predicted responses from the model were compared with published experimental data. The comparisons were made covering a wide range of weather and operating conditions under several different control strategies. The model predictions compare well with the experimental data. The effective thermal capacity of the floor slab was found being an important parameter in calibrating the model results with the experimental data. Three different control strategies for improving the temperature regulation in RFH systems are proposed. These are: a multistage on-off control, an augmented constant gain control (ACGC) and a variable gain control (VGC). Simulation results show that the multistage control maintains zone air temperature close to the setpoint better than the existing on-off control scheme does. Likewise, ACGC gives good zone temperature control compared to the classical proportional control. A model based approach for updating the controller gains of the VGC is proposed. Both ACGC and VGC are shown to be robust to changes in weather conditions and internal heat gains. The advantage of the control strategies proposed in this thesis is that they eliminate the use of outdoor temperature sensor required in some existing control schemes. Being simple and robust, the multistage control scheme with two stages and the ACGC are good candidate controls for RFH systems.
Author: Ali Saberi Derakhtenjani
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Radiant slab heating systems are receiving considerable attention due to the multiple advantages they offer such as improved thermal comfort in buildings and suitability for other related applications in cold climates, particularly snow melting and de-icing of pavements and infrastructure. Hydronic radiant heating can utilize low temperature renewable energy heat sources. The operation of these systems can be optimized by applying predictive control and further the energy costs can be reduced by optimizing their interaction with smart grids by utilizing the flexibility in their demand profiles. However, compared to conventional air heating systems, radiant systems have several added complexities such as the slow transient heat conduction within the slab. Efficient design and operation of radiant slabs require several critical decisions on design and control variables to maintain comfortable thermal conditions in the space and achieve slab surface temperatures within the recommended range depending on the application. This thesis presents a methodology for modelling of hydronic radiant slab heating systems with significant thermal mass (a concrete layer with embedded tubes) for predictive control to utilize the energy flexibility of the building and/or infrastructure in interaction with smart grids and dynamic pricing of electricity. The modelling approaches include low-order grey box models as well as frequency domain techniques. Each approach has its own specific advantages and unique information can be obtained from each one that complement each other when optimizing system operation and designing the control strategies. Using the developed frequency domain model of the zone, key transfer functions are calculated for a case study. By means of transfer functions, the effect of different levels of thermal mass on the zone thermal response and quantification of the energy flexibility in response to grid signals is studied. The model is used to evaluate different design and operation options on a relative basis. It is shown how transfer function analysis provides insight into the building thermal dynamics without the need for simulations. A new transfer function that relates the radiant floor heat source at the bottom of the slab to the zone air temperature is introduced and its derivation is demonstrated. By means of the transfer function, the delay between the heat input of the radiant slab and zone air temperature is determined. Experiments with a full scale test room in an environmental chamber are used to validate the key design parameters obtained from the frequency domain transfer function regarding the operational strategies for energy flexibility of the thermal zone. Frequency domain techniques may also be utilized to establish the appropriate order for low-order RC models for different applications. A low-order thermal network RC model for a case study, validated with experimental measurements, is utilized to study several predictive control strategies in response to changes in the grid price signal, including short term, more reactive changes of the order of 10-15 minutes notice. An index is utilized to quantify the energy flexibility with the focus on the peak demand reduction for specific periods of time when the electricity prices are higher than usual. It is shown that the developed predictive control strategies can aid greatly in minimizing the electricity cost of the building and up to 100% reduction in peak power demand and energy consumption is achieved during the high price periods. Low-order thermal models are also utilized to study radiant slab heating systems of infrastructure that have much higher thermal mass than the radiant slabs in buildings due to structural reasons. Hydronic heating of roads and pavements surfaces to avoid ice formation has several advantages compared to traditional surface salting and other anti-skid methods which have a lot of limitations. However, the traditional method of designing such systems does not consider the thermal mass of the system and its potential for predictive control, energy flexibility and optimized performance. Finally, predictive control strategies are presented and studied to take advantage of the hydronic slab thermal mass and minimize the energy consumption and peak power demand and are validated in a full scale experiment in an environmental chamber.
Author: SEUNG-BOK LEIGH
Publisher:
ISBN:
Category :
Languages : en
Pages : 514
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Book Description
to the space. In contrast, MacCluer (1989) proposed the new concept of proportional flux-modulation: control of heat flow rate, not temperature.
Author: Richard D. Watson
Publisher: McGraw-Hill Professional Publishing
ISBN: 9780070684997
Category : Heat
Languages : en
Pages : 0
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Book Description
Packed with tools to make the work of HVAC systems designers; engineers; and technicians go smoothly; this text will help you select; design; size; and position popular and efficient systems for industrial; commercial; and residential applications. --
Author: YiTeng MA
Publisher:
ISBN:
Category :
Languages : en
Pages : 115
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Book Description
A dynamic model of a hybrid hydronic heating system has been developed. Simulations of the control strategies and the model-based energy analysis for the overall system have been presented in this thesis. The hybrid hydronic system is composed of a conventional natural gas fired boiler hot water heating and a ground source heat pump system. The overall system consists of several components such as a boiler, a heat exchanger, a ground loop heat pump, a ground loop heat exchanger, baseboard heaters, and radiant floor hydraulic piping systems. The system model was described by nonlinear differential equations, which were programmed and solved using MATLAB. Two control strategies for improving the overall system performance were explored: (i) a conventional PI control, and (ii) an adaptive gain control. The simulation results subject to set-point changes showed that the performance of the adaptive controller is better than the fixed gain PI controller in disturbance rejection and stability. Energy simulations under three different operating strategies were conducted: (i) a conventional fixed set-point PI control, (ii) an outdoor air temperature reset control, and (iii) an optimal set-point PI control. It was shown that the outdoor temperature reset strategy can save 4.5% and 19.9% energy under cold day and mild day conditions compared to the conventional fixed set-point PI control strategy. In addition, the iv implementation of the optimal PI control strategy result in higher energy savings 6.6% and 22% as compared to the base case under cold and mild day conditions, respectively.
Author: Xiangyu Cai
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
A dynamic model of a solar-assisted hydronic space heating system for a multi-function building has been developed. The system performance under different control strategies and the model-based energy simulations studies have been conducted. The system consists of several components including a boiler, heat exchangers, flat-plate solar collectors, a water storage tank, baseboard heaters and a radiant floor heating system. The model consists of nonlinear differential equations which were programmed and solved using the MATLAB software. Two control strategies have been explored to compare the system performance: (i) a conventional PI control and (ii) a gain-scheduling adaptive (GSA) PI control. The simulation results indicate that the system performance under GSA PI control is better than the conventional PI control with respect to disturbance rejection and stability. An optimization problem was formulated and solved to study the energy performance of the system. Preliminary simulation results with assumed outdoor temperature profiles showed that the optimized set-point operating strategy contributes 7% and 14.87% to boiler energy saving in mild and warm day conditions compared with constant set-point strategy. One week energy simulations under actual weather conditions based on typical meteorological year (TMY) data have been conducted to investigate the percent contribution of solar energy to space heating. The simulation results show that the solar system contributes less energy during cold winter conditions such as in the month of December. However, it can reduce 16.94% of boiler energy supplied to the radiant floor heating system in the month of March. Besides, the implementation of the optimal GSA PI control strategy can result in higher solar fractions of 5.71% and 30.36% as compared to the base case PI control under cold (December) and mild (March) weather conditions, respectively.
Author: Juan M. Morales
Publisher: Springer Science & Business Media
ISBN: 1461494117
Category : Business & Economics
Languages : en
Pages : 434
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Book Description
This addition to the ISOR series addresses the analytics of the operations of electric energy systems with increasing penetration of stochastic renewable production facilities, such as wind- and solar-based generation units. As stochastic renewable production units become ubiquitous throughout electric energy systems, an increasing level of flexible backup provided by non-stochastic units and other system agents is needed if supply security and quality are to be maintained. Within the context above, this book provides up-to-date analytical tools to address challenging operational problems such as: • The modeling and forecasting of stochastic renewable power production. • The characterization of the impact of renewable production on market outcomes. • The clearing of electricity markets with high penetration of stochastic renewable units. • The development of mechanisms to counteract the variability and unpredictability of stochastic renewable units so that supply security is not at risk. • The trading of the electric energy produced by stochastic renewable producers. • The association of a number of electricity production facilities, stochastic and others, to increase their competitive edge in the electricity market. • The development of procedures to enable demand response and to facilitate the integration of stochastic renewable units. This book is written in a modular and tutorial manner and includes many illustrative examples to facilitate its comprehension. It is intended for advanced undergraduate and graduate students in the fields of electric energy systems, applied mathematics and economics. Practitioners in the electric energy sector will benefit as well from the concepts and techniques explained in this book.
Author: J. M. Schultz
Publisher:
ISBN:
Category :
Languages : en
Pages : 27
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Book Description
Author: Richard Watson
Publisher: McGraw Hill Professional
ISBN: 0071500227
Category : Technology & Engineering
Languages : en
Pages : 769
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Book Description
Design radiant heating and cooling systems with help from top experts The first and only professional guide of its kind, Radiant Heating and Cooling Handbook is packed with tools that make the work of HVAC systems designers, engineers, and technicians go more smoothly and easily. Relating heating and cooling theory to the principles of thermal comfort, this expert handbook by pros Richard Watson and Kirby Chapman provides all the help you need to select, design, size, and position the most popular and efficient systems for industrial, commercial, and residential applications. You get: *Case studies that clarify application and installation of every system type *Models for coupling radiant and forced air heating and cooling for the ultimate in comfortable, energy-saving interiors *Examples and sample calculations to solve real-world radiant heating and cooling problems in building, contracting, and engineering *Equations, strategies, and analyses to help you set parameters from sizing and cost to human comfortability
