Combined Cooling, Heating, and Power Systems

Modeling, Optimization, and Operation

Yang Shi, Mingxi Liu, Fang Fang

• Publisher: Wiley-ASME Press Series
• Year: 2017
• Print ISBN: 9781119283355
• eBook ISBN: 9781119283423
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Quality Control in Engineering
• Index: Technology & Engineering

A comprehensive review of state-of-the-art CCHP modeling, optimization, and operation theory and practice

This book was written by an international author team at the forefront of combined cooling, heating, and power (CCHP) systems R&D. It offers systematic coverage of state-of-the-art mathematical modeling, structure optimization, and CCHP system operation, supplemented with numerous illustrative case studies and examples.

CCHP systems are an exciting emerging energy technology offering significant economic and environmental benefits. Combined Cooling, Heating, and Power Systems: Modelling, Optimization, and Operation is a timely response to ongoing efforts to maximize the efficiency of that technology. It begins with a survey of CCHP systems from the technological and societal perspectives, offering readers a broad and stimulating overview of the field. It then digs down into topics crucial for optimal CCHP operation. Discussions of each topic are carefully structured, walking readers from introduction and background to technical details.A set of new methodologies for the modeling, optimization and control of CCHP systems are presented within a unified framework. And the authors demonstrate innovative solutions to a variety of CCHP systems problems using new approaches to optimal power flow, load forecasting, and system operation design.

• Provides a comprehensive review of state-of-the-art of CCHP system development
• Presents new methodologies for mathematical modeling, optimization, and advanced control
• Combines theoretical rigor with real-world application perspectives
• Features numerous examples demonstrating an array of new design strategies
• Reflects the combined experience of veteran researchers in the field whose contributions are well recognized within the energy community
• Offers excellent background reading for students currently enrolled in the growing number of courses on energy systems at universities worldwide

Timely, authoritative, and offering a balanced presentation of theory and practice, Combined Cooling, Heating, and Power Systems: Modelling, Optimization, and Operation is a valuable resource forresearchers, design practitioners, and graduate students in the areas of control theory, energy management, and energy systems design.

Chapter 1
State-of-the-Art of Combined Cooling, Heating, and Power (CCHP) Systems

1.1 Introduction

With the rapid development of distributed energy supply systems [1–4], combined heating and power (CHP) systems and combined cooling, heating, and power (CCHP) systems have become the core solutions to improve the energy efficiency and to reduce greenhouse gas (GHG) emissions [5–9]. The CCHP system is an extended concept of the CHP system, which has been widely utilized in large-scale centralized power plants and industrial applications [10]. CHP systems are developed to conquer the problem of low energy efficiency of conventional separation production (SP) systems. In SP systems, electric demands, which include daily electricity usage and electric chiller usage, and heating demands are provided by the purchased electricity and fuel, respectively. Since no self-generation exists in SP systems, they are proved to be of low efficiency; however, in CHP systems, most of the electric and heating demands are provided simultaneously by a prime mover together with a heat recovery system, a heat storage system, and so on. Energy demands beyond the system capacity can be supplied by the local grid and an auxiliary boiler. If some thermally activated technologies are introduced, for example, absorption and adsorption chillers, into the CHP to provide the cooling energy, the original CHP system evolves to a CCHP system [11], which can also be referred to as a trigeneration system and building cooling heating and power (BCHP) system. Since there is no cooling need in winter, the CHP system can be regarded as a special case of the CCHP system. A CCHP system can achieve up to 50% greater system efficiency than a CHP plant of the same size [12].

A typical CCHP system is shown in Figure 1.1. The power generation unit (PGU) provides electricity for the user. Heat, produced as a by-product, is collected to meet cooling and heating demands via the absorption chiller and heating unit. If the PGU cannot provide enough electricity or by-product heat, additional electricity and fuel need to be purchased to compensate for the electric gap and feed the auxiliary boiler, respectively. In this way, three types of energy, that is, cooling, heating, and electricity, can be supplied simultaneously.

Figure 1.1 A typical CCHP system

Compared with conventional generating plants, the advantages of a CCHP system are three-fold: high efficiency, low GHG emissions, and high reliability.

First, the high overall efficiency of a CCHP system implies that less primary fuel is consumed in this system to obtain the same amount of electric and thermal energy. In [10], the authors give an example to show that, compared with the traditional energy supply mode, the CCHP system can improve the overall efficiency from 59% to 88%. This improvement owes to the cascade utilization of different energy carriers and the adoption of the thermally activated technologies. As the main electricity source, the PGU has an electric efficiency as low as 30%. By implementing the heat recovery system, the CCHP system can collect the by-product heat to feed the absorption/adsorption chiller and heating unit to provide cooling and heating energy, respectively. By adopting the absorption chiller, no additional electricity needs to be purchased from the local grid to drive the electric chiller in summer, but only the recovered heat is used. In winter, a CCHP system degenerates to be a CHP system. The high efficiency of the CHP system is investigated in [13–20]. In a nutshell, a CCHP system can dramatically reduce the primary consumption and improve the energy efficiency.

The second advantage involved in the CCHP system is the low GHG emissions. On the one hand, the trigeneration structure of the CCHP system contributes to this reduction. Compared with SP systems, if within the capacity limitation of the prime mover, no additional electricity needs to be purchased from the local grid, which is supplied by fossil-fired power plants. It is well known that, even though the penetration of some types of renewable energy, for example, the wind, tide and solar energy, increase significantly [21–23], because of their intermittency, the main electricity producer is still the fossil-fired power plant. By reducing the consumption of electricity from the local grid, GHG emissions from fossil-fired power plants can be decreased. Moreover, adopting the thermally activated technologies can also reduce the electricity consumption by the electric chiller, which will result in less consumption of fossil fuel in the grid power plant. On the other hand, new technologies in the prime mover also contribute to the GHG emissions reduction. Incorporating fuel cells, which are one of the hottest topics in recent years, in the CCHP system can increase the system efficiency up to 85–90% [24]. Compared with some conventional prime movers, such as the internal combustion (IC) engine and combustion turbine, the new-tech prime movers can provide the same amount of electricity with less fuel supply and less GHG emissions. In recent years, aiming to reduce GHG emissions, an increasing number of countries have begun to run the carbon tax act [25–29]. As a result of these acts, reducing GHG emissions can not only reduce the contaminant of the air, but also can improve the system's economic efficiency.

The other benefit brought by the CCHP system is reliability, which can be regarded as the ability to guarantee the energy supply at a reasonable price [30]. Recent cases have demonstrated that centralized power plants are vulnerable to natural disasters and unexpected phenomena [31]. Changes in climate, terrorism, customer needs, and the electricity market are all fatal threats to the centralized power plants [10]. The CCHP system, which adopts the distributed energy technologies, can be resistant to external risks and has no electricity blackouts, for it is independent of electricity distribution. A comparison of the reliability between the distributed and centralized energy systems in Finland and Sweden can be found in [30].

A typical CCHP system consists of a PGU, a heat recovery system, thermally activated chillers, and a heating unit. Normally, the PGU is a combination of a prime mover and an electricity generator. The rotary motion generated by the prime mover can be used to drive the electricity generator. There are various options for the prime mover, for example, steam turbines, stirling engines, reciprocating IC engines, combustion turbines, micro-turbines, and fuel cells. The selection of the prime mover depends on current local resources, system size, budget limitation and GHG emissions policy. The heat recovery system plays a role in collecting the by-product heat from the prime mover. The most frequently used thermally activated technology in the CHP/CCHP system is the absorption chiller. Some novel solutions, such as the adsorption chiller, and the hybrid chiller, are also adopted in CCHP systems [32–36]. The selection of the heating unit depends on the design of the heating, ventilation and air conditioning (HVAC) components.

With the benefits of high system and economic efficiency, and less GHG emissions, CCHP systems have been widely installed in hospitals, universities, office buildings, hotels, parks, supermarkets, and so on [37–41]. For example, in China, the CCHP project at Shanghai Pudong International Airport generates combined cooling, heating, and electricity for the airport's terminals at peak demand times. It is fuelled by natural gas from offshore in the East China Sea [42]. This system is equipped with one 4 MW natural gas turbine, one 11 t/h waste heat boiler, cooling units of four YORK OM 14 067 kW, two YORK 4220 kW, four 5275 kW steam LiBr/water chillers, three 30 t/h gas boilers and one 20 t/h as standby for heat supply [43]. In the last decade, the installation of CCHP systems has plateaued. Especially, the development is much slower in developing countries than that in developed countries due ...

Table of contents

• Cover
• Title Page
• Copyright
• Dedication
• Table of Contents
• List of Figures
• List of Tables
• Series Preface
• Preface
• Acknowledgment
• Acronyms
• Symbols
• Introduction
• Chapter 1: State-of-the-Art of Combined Cooling, Heating, and Power (CCHP) Systems
• Chapter 2: An Optimal Switching Strategy for Operating CCHP Systems
• Chapter 3: A Balance-Space-Based Operation Strategy for CCHP Systems
• Chapter 4: Energy Hub Modeling and Optimization-Based Operation Strategy for CCHP Systems
• Chapter 5: Short-Term Load Forecasting and Post-Strategy Design for CCHP Systems
• Chapter 6: Complementary Configuration and Operation of a CCHP-ORC System
• Index
• End User License Agreement