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About this book

This book, based on the research experience and outcomes of a group of international contributors, addresses a range of advanced energy efficiency technologies and their applications in solar heating, cooling and power generation, while also providing solutions for tackling recurring low efficiency problems in today’s systems. It highlights the latest technologies and methods, which can significantly improve the performance of solar systems, enabling readers to design, construct and apply high-performance solar systems in or for their own projects.

The contributors provide a systematic introduction to state-of-the-art energy efficiency technologies that demonstrates how to implement innovative solar systems. These technologies include:

• heat pipes and loop heat pipes;

• phase change materials (PCMs) and PCM slurries;

• micro-channel panels;

• desiccant/adsorption cycling;

• ejector cooling and heat pumps; and

• solar concentration and thermoelectric units.

The book shows how innovative solar systems applicable to rural and urban buildings can be analysed and demonstrates the successful implementation of these advanced technologies. It delivers the design principles and associated energy performance assessment methods for a range of selected solar heating, cooling and power generation projects.

This book offers a valuable source of information for final-year undergraduate students, as well as graduate students and academic lecturers, as it promotes the widespread deployment of advanced solar heating, cooling and power generation technologies applicable for buildings across the globe. The book is also a good point of reference for design engineers and energy consultants who wish to extend their knowledge of advanced technologies used to achieve energy efficiency.

Table of Contents


Solar Energy Resource and Its Global Distribution

The sun is an extremely powerful energy resource, and the solar energy is an important renewable energy. Solar energy can be used for producing heat and generating electricity. The amount of solar energy incident on earth is enormous, and it is larger than current and predicted energy requirements in the future. In this chapter, the basic concepts and parametrical performance of the sun and its radiation across the space and earth surface including solar irradiance on earth(i.e., diffuse irradiance and direct normal irradiance, the solar constant, extraterrestrial solar spectrum, extraterrestrial solar irradiance, and extraterrestrial solar radiation on a surface), ground-level solar radiation characteristics(atmosphere effects and solar spectrum), solar angles(i.e., the earth–sun angles, hour angle, declination angle, latitude angle, solar altitude, zenith, and azimuth angles), are described. Solar energy global distribution by belt and nation at variable geometrical regions on the globe is also presented.
Zhongzhu Qiu, Peng Li

Solar Heating, Cooling and Power Generation—Current Profiles and Future Potentials

Due to the large amount of consumption of the fossil fuels, the ecological environment has suffered serious pollution and damage. Solar power technologies provide the best solution to the current energy and environment issues. In past decades, global solar thermal capacity increased rapidly, and now it has been used worldwide to provide heating, cooling and power generation. However, after years of development, solar energy utilization technology still faces problems such as low efficiency, high cost, difficulty in energy storage and unstable energy supply, which have been seriously restricting its applications. This chapter briefly summarizes the concept and classification of solar heating, cooling and power generation. Furthermore, some technology development and potential applications relating to solar heating, cooling and power generation are discussed.
Wei He, Xinghui Zhang, Xingxing Zhang

Heat Pipe and Loop Heat Pipe Technologies and Their Applications in Solar Systems

Solar energy is considered as the renewable and carbon-neutral energy source of enough scale to replace fossil fuels. The direct utilisation of solar energy can be categorised into two types, i.e. photovoltaic (PV) and solar thermal. However, some disadvantages, e.g. high thermal losses, low conversion rate, still limit the widespread of the solar systems. The solar systems using the heat pipe (HP) and loop heat pipe (LHP) technologies have been developed to tackle the existing problems of the solar system. In this chapter, the working principle and classification of HPs and LHPs for use in the solar system would be comprehensively introduced. The mathematical methods related to the heat transfers limits (i.e. capillary limit, entrainment limit, viscous limit, boiling limit, sonic limit and filled liquid mass limit) and thermal balance (i.e. heat input into the evaporator, heat transportation from the evaporator to the condenser via evaporation and condensation of the heat transfer fluid in the heat pipes, and heat output from the condenser) will be presented. The research works relating the solar systems using heat pipes and loop heat pipes will also be reviewed and analysed from the aspects of characteristic performance, on-site testing, and economic and social assessment. This chapter potentially revealed the further development of HP and/or LHP for use in the solar system.
Zhangyuan Wang, Haopeng Zhang, Fucheng Chen, Siming Zheng, Zicong Huang, Xudong Zhao

PCM and PCM Slurries and Their Application in Solar Systems

PCM/MPCM and their slurries, acting as thermal storage, heat transfer enhancement, and temperature constancy medium, have drawn extensive concerns. Their basic concepts, classification, physical and chemical properties, MPCM fabrications, and applications in solar systems were presented in this chapter. PCMs can be divided into solid–solid, solid–liquid, solid–gas and liquid–gas types. MPCM is composed of PCM as core and a polymer or inorganic material as shell to maintain the shape and prevent PCM from leakage during the phase change process. There are several processes that can be applied to produce microcapsules. Depending on the nature of the processes, they are classified into physical, physical–chemical, and chemical processes. Commercially available PCM and MPCM properties are also dedicatedly described in this chapter. Afterward, compilation of PCM emulsion and MPCM slurries was provided in terms of their main characteristics. Thereafter, a portfolio of suppressing the instability of MPCM slurries, a near-zero density difference, combining the appropriate setup of the other parameters involving surfactant type, its concentration, pH value, was proposed based on a series of experimental works. Finally, some applications of PCMs and its slurries in solar systems, acting as a thermal storage, heat transfer enhancement or temperature constancy medium, were presented in this chapter.
Zhongzhu Qiu, Peng Li, Zhangyuan Wang, Han Zhao, Xudong Zhao

Modular Solar System for Building Integration

Building integrated solar systems, which means components of solar thermal collectors and/or solar photovoltaics (PV) are completely integrated with building envelopes, can potentially provide additional functions of on-site hot water and electric generation over the building envelopes’ basic functions, i.e. weatherproof and thermal insulation. This is different from the conventional approach of applying solar systems into buildings. Traditionally, end-users purchase and install solar thermal collectors and/or PV panels on a building’s roof or façade according to their own requirements after the completion of building construction. Potential risks of the conventional approach, such as that the appearance and internal structure of the building envelope can be damaged, seriously restrict the development and implementation of solar technologies’ building application. Building integrated solar systems can eliminate these risks by taking the advantage of using areas of building envelopes (i.e. walls, roofs and windows) for immediate solar energy capture and conservation. In so doing, it can effectively reduce the construction time and cost, and enhance building envelopes’ security. In addition, some latest building integrated solar systems will also improve the thermal performance of building envelope and thus reduce building heating and cooling demands. This chapter mainly introduces how to integrate solar systems into building envelopes, and thus provides a reference for achieving effective and efficient utilization of solar energy in buildings and improving the prediction and optimization of building energy demands.
Gang Ren, Zishang Zhu, Yanyi Sun, Xudong Zhao

Micro (Mini)-Channels and Their Applications in Solar Systems

This chapter presented micro (mini)-channels and their applications in solar systems. Two types of channels, micro (mini)-tubes and micro (mini)-heat pipes, have been presented, and the performance of their use in solar systems has been illustrated by studies in the literature. For solar thermal systems, the integration of micro (mini)-channels can increase significantly the thermal performance that achieves an increase of 28% compared to conventional channels. For PVT systems, the use of micro (mini)-channels enhances also the electrical output by decreasing the temperature of PV panels. Consequently, the use of these channels increases the overall efficiency of PVT systems that can achieve the overall efficiency of around 70%. Furthermore, in this paper, the use of micro-channel has been illustrated by the investigation of a novel solar PVT loop heat pipe employing a micro-channel heat pipe evaporator and a PCM triple heat exchanger. This illustration showed environmental parameters (i.e. solar radiation, air temperature, wind velocity), structural parameters (i.e. glazing covers, number of the absorbing heat pipes, PC cell packing factor) and the variable inputs (i.e. water inlet temperature, mass flow rate) that can influence the overall efficiency of the novel PVT system. This chapter showed that application of micro (mini)-channels in solar systems is promising, and their integration in solar technologies can enhance significantly their performance and their market share.
Thierno Diallo, Min Yu, Jinzhi Zhou, Yi Fan, Xudong Zhao

Solar Desiccant (Absorption/Adsorption) Cooling/Dehumidification Technologies

Air dehumidification in humid climates can improve the people’s living environment to promote the life quality and improve working environment significantly to increase production rate and product quality. Desiccants are key materials used in the dehumidification technologies. In this chapter, the conventional solid desiccant materials and different types of desiccant systems are introduced. Furthermore, the performance of solid dehumidification materials is emphatically analysed. In addition, desiccant regeneration methods are summarized, and two examples of their applications are presented in the last part of the chapter, namely the novel solar solid. dehumidification/regeneration bed and solar-powered dehumidification window. This chapter would be helpful for researchers and engineers in this area to exploit the potential applications of solar desiccant technologies in building sector.
Wansheng Yang, Shuli Liu, Xiaoqiang Zhai, Yin Bi, Zhangyuan Wang, Xudong Zhao

Solar Ejector Cooling Technologies

Using low-grade thermal energy instead of electricity to operate a refrigeration system can have important environmental benefits, especially when it is powered by a renewable energy source. Ejector refrigeration is one of the most promising technologies because of its relative simplicity and low capital cost when compared to an absorption refrigerator. An ejector heat pump is a heat-operated cycle capable of utilizing solar energy, waste energy, natural gas or hybrid sources (e.g. solar/gas). An ejector system basically consists of a generator, evaporator, condenser, ejector, expansion valve, and a pump. The ejector system has very few moving parts and so is simple in design. In addition, it has the potential of long life and, unlike vapour-compression systems, produces no noise or vibration. The system could be manufactured at relatively low cost, since inexpensive construction materials may be used. Although they have a relatively low coefficient of performance compared to air-conditioning systems using mechanical compressors, the ejector cooling technologies have attracted extensive attentions with ever-increasing awareness and pressures for protecting the environment and have achieved significant improvement in coefficient of performance as compared to other systems. The continuous developments in solar collector technology open the way to the effective utilization of solar energy to power the ejector systems and utilization of environmental friendly refrigerants is also the major concern. This chapter introduces the principle of the ejector, basic ejector cycle, solar-driven ejector system and its operating. The refrigerants, solar collectors, and PCM heat storage for solar ejector system applications are also introduced. A complete solar ejector air-conditioning system used in a building is presented in this chapter.
Xiaoli Ma, Wei Zhang, Fenglei Li, S. B. Riffat

Heat Pump Technologies and Their Applications in Solar Systems

As the well known that global energy demand is on a trend of continuous growth, reducing energy demand and making good use of renewable energy are thought to be the major routes toward low carbon and sustainable future, in particular for the building sector. Compared to traditional gas-fired heating systems, heat pumps have been proved to be an energy-efficient heating technology which can save fossil fuel energy and consequently reduce CO2 emission. However, the most outstanding challenges for the application of heat pumps lie in their high demand for electrical power, and the insufficient heat transfer between the heat source and the refrigerant. To overcome these difficulties, a solar-assisted heat pump has been proposed to tackle these challenges. A solar-assisted heat pump combines a heat pump with a solar collector, enabling the use of solar energy to provide space heating and hot water for buildings. This chapter introduces heat pump technologies and their applications in solar systems. Two types of solar-assisted heat pump, direct and indirect expansion, are illustrated in details. This work has provided the fundamental research and experience for developing a solar heat pump system and contributing to a significant fossil fuel saving and carbon reduction in the global extent.
Xingxing Zhang, Manxuan Xiao, Wei He, Zhongzhu Qiu, Xudong Zhao

Solar Thermoelectric Technologies for Power Generation

Thermoelectric power generation (TEG) is the most effective process that can create electrical current from a thermal gradient directly, based on the Seebeck effect. Solar energy as renewable energy can provide the thermal energy to produce the temperature difference between the hot and cold sides of the thermoelectric device. This chapter introduces various solar thermoelectric technologies including micro-channel heat pipe evacuated tube solar collector incorporated thermoelectric power generation system, solar concentrating thermoelectric generator using the micro-channel heat pipe array, and novel photovoltaic–thermoelectric power generation system. The details of these systems are illustrated, and their performance is analyzed. This chapter would provide a valuable reference for the study and applications of the solar thermoelectric power generation technologies.
Guiqiang Li, Xiaoli Ma, Samson Shittu, Xudong Zhao

Solar Systems for Urban Building Applications—Heating, Cooling, Hot Water, and Power Supply

With the rapid development of urbanization, the energy consumption problem has attracted more and more attention. Solar energy, a kind of inexhaustible renewable energy, has played an important role in the energy sector. Solar energy can be used through the solar thermal transformation process and solar photovoltaic process. Then, the heat and electricity gained by those two processes can be used for many urban building applications, such as heating, cooling, hot water, and power supply. In this chapter, a detailed introduction on solar heating and cooling and domestic hot water applications for urban buildings is presented, which includes the integration of solar collectors with buildings, solar domestic hot water, space heating, and cooling applications for buildings and building-integrated photovoltaics.
Bin Li, Xuemei Chen, Xiwen Cheng, Xiaoqiang Zhai, Xudong Zhao

Solar System Design and Energy Performance Assessment Approaches

Recently, solar system has gained a rapid development in many countries because it is clean and sustainable. Many solar systems including the solar photovoltaic/loop-heat-pipe (PV/LHP), solar loop-heat-pipe (LHP), solar photovoltaic/micro-channel heat pipe (PV/MCHP) system, and solar thermal facade system (STF) have been designed for energy saving. To assess these systems’ performance, there are many approaches such as energy and exergy assessment which is used in this chapter to analyze their performance. Besides the system design, the authors set up dedicated experimental models in combination with computer models to test the systems’ performance. Furthermore, some systems are compared with the conventional system, and the performance of these solar systems is better than the conventional system. In addition, these solar systems are applied in many real buildings and their performance is examined, the results show that the solar systems have more potential to boost the building energy efficiency and create the possibility of solar development in buildings.
Xingxing Zhang, Xinru Wang, Xudong Zhao

Solar Systems’ Economic and Environmental Performance Assessment

The economic and environmental performance assessment of the solar system plays a critical role in building design, operation and retrofit. A dedicated economic model is necessary to assess the investment feasibility on a new technology, which allows investors to decide on a profitable investment, compare investment projects and know about the benefits of the best investment. An environmental model is adopted to predict carbon emission reduction in the solar system relative to the traditional heating and electronic systems. This chapter introduced three up-to-date solar system models and corresponding assessments related to their applications, including solar photovoltaic/loop heat pipe (PV/LHP) heat pump water heating system, loop heat pipe-based solar thermal facade (LHP-STF), heat pump water heating system as well as solar thermal facade (STF). The research results will be able to assist in decision-making in implementation of the proposed PV/T technology and analyses of the associated economic and environmental benefits, thus contributing to realization of regional and global targets on fossil fuel energy saving and environmental sustainability.
Xingxing Zhang, Yixuan Wei, Wei He, Zhongzhu Qiu, Xudong Zhao

Solar Heating, Cooling, and Power Generation Projects—Case Studies

Building energy use currently accounts for over 40% of total primary energy consumption in the USA (Cao et al. in Energy Build 128:198–213, 2016 [1]) and EU and accounts for over 33% of total energy consumption in China. When it comes to the energy consumption of the thermal process in building, i.e., space heating, hot-water supply, and cooling, these three kinds of energy consumption account for 34, 24, and 2%, respectively, in residential buildings and account for 33, 12, and 7%, respectively, in commercial buildings (Ürge-Vorsatz et al. in Renew Sustain Energy Rev 41:85–98, 2015 [2]). Large energy consumptions like these can consume vast amounts of fossil fuels and release large masses of carbon emissions and pollution into the environment. As a kind of sustainable and clean energy, solar energy can act as an alternative in the building thermal process, thus reducing fossil fuel consumption globally. In this chapter, five sets of solar systems including space heating, hot-water generation and cooling have been presented as case studies. Among them, four sets of solar thermal space heating systems have been established and equipped with novel PV/T mini-channel solar thermal panels. By applying different auxiliary heating devices, different systems have been designed and connected with different pipelines. The solar-absorption cooling system was designed and installed in Shanghai Jiao Tong University. The system used an absorption chiller with the rated cooling capacity of 8 kW, and a 3 m3 heat storage water storage tank. The chilled water can be delivered either into fan coils or into radiant cooling panels which were installed to satisfy the indoor thermal environment of the test room. All the systems have presented a practical application of solar energy and have provided some cutting-edge design ideas about solar heating and cooling systems, which can lead the design by related practitioners in order to further improve the solar system. The aim of all the solar energy applied systems presented is to contribute toward significant fossil fuel saving and carbon reduction on a global extent.
Yi Fan, Jinzhi Zhou, Xiaoqiang Zhai, Han Zhao, Xudong Zhao
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