Research prospects
Tingzhen Ming1,2, Wei Liu2, Tingrui Gong2, Wei Yang2, Dong Chen2 and Zhengtong Li2, 1School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, P.R. China, 2School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan, P.R. China
Abstract
Close attention has been paid to the research on solar chimney power plants in the past few decades. However, quite a few topics have not been discussed yet. In this chapter, a brief introduction on the future research points of the SCPPS has been presented from the basic theories to the commercial applications.
Keywords
Solar chimney power plant system; future research
Obviously, existing research on the technical aspects of the solar chimney power plant (SCPP) is quite numerous. However, there are still many issues that have not been entirely addressed. Key scientific issues associated with the system are shown in Fig. 9.1. The author of this book contributes only a small part to the whole work in this field research. Just for the purposes of analyzing the heat and mass transfer processes in the solar chimney power generation system, the author believes that at least the following points need to be investigated in further research.
9.1 Thermodynamic Theory for the Large-Scale SCPP
Compared with the conventional thermodynamic cycle system, there is a large-scale interface between the SCPP system and the environment. Transient atmospheric and terrestrial environment will have significant influence on the thermodynamic cycle processes. Heated air and the system energy conversion medium have complex flow characteristics, which will have significant effect on the efficiency of solar chimney system. There is no decisive breakthrough in the existing thermodynamic research; thus the system efficiency is low, the relative humidity of the working fluid will further deteriorate the overall efficiency. As a result, the chimney should be built up to 1–3 km which is a big challenge for architecture and civil engineering. In order to improve the energy conversion and utilization efficiency, thermodynamic theory and energy conversation mechanisms in large-scale SCPPS should be carefully studied. In addition, innovative design on the SCPP will also be helpful to increase the system output. Decreasing the heat losses in the processes, researching the interactions between the atmospheric environment and the system based on the thermodynamic processes in different solar chimney systems, and exploring the calculation methods for thermodynamic cycles also need to be investigated.
9.2 External Fluid Flow and Heat Transfer in Large-Scale channels
A remarkable feature of the large-scale solar chimney plant is the large-scale dimension, so the internal and external flow characteristics are significantly different from conventional sized channels. The existing theoretical models, technical data, and calculation methods for the large-scale may not be able to be adapted or may be even completely invalid. To this end, we have to conduct an in-depth study on the mechanism of energy conversion of the large-scale SCPPSs, based on relative theories on fluid flow and heat and mass transfer mechanics.
Meanwhile, we should explore the energy conversion process, analyze the coupling relationships between the various physical fields, and explore the turbulent models in complex flow channels. Further study should be carried out to research energy storage, release, and distribution in the energy storage layer. We should design energy storage systems and find power generation peak regulation solutions for different seasonal conditions. Finally, more work should be done to reveal the relationship between the structural parameters and the solar system—thermal energy—mechanical energy conversion efficiency.
9.3 Turbine Running Theory for the Large-Scale SCPPS
The coupling mechanism of fluid and solid regions, airfoil type of the turbine blades, and flow channel design theory are challenging issues in SCPPS. The fundamental theory of unsteady flow, related research including dynamic balance in the large-scale thermal airflow turbine machine, unsteady flow mechanism inside the thermal airflow turbine, and unsteady trail interference between turbine blades need further research. Besides, more research should be conducted to explore damping methods for the blade torsional vibration and to study the blades abrasion mechanism caused by the wind and sand within the turbine. What’s more, further research should be conducted to analyze the coupled heat transfer and flow characteristics in the storage layer, collector, turbine, and chimney, the four essential parts of the solar chimney system. Also, more attention should be drawn on the impacts of the circadian, the weather, and the changes in solar radiation on the coupling heat transfer and flowed characteristics within the entire system.
9.4 The Impacts of Environmental Factors on of Large-Scale SCPPS
Various natural environmental factors such as wind, storms, dust storms, earthquakes, and other work environment factors will exert a crucial influence on the reliability and life-cycle of facilities and equipment in large-scale solar chimney power system. Considering the chimney and collector’s scale (the chimney height of MW-scale solar thermal airflow power plants is in hundred meters, collector diameter is in kilometers) and harsh environmental conditions in West China, comprehensive study should be conducted to analyze the physical basis, mechanical properties, and structural stability of the ultra-high solar chimney from many aspects, including the structure design, simulation, and virtual design, etc. We must study in-depth the excitation effect and coupled physical response of the external environment, research the structural shape characteristics and mechanical properties of ultra-high solar chimneys and large solar greenhouses, explore the interaction between environmental factors and system responses and anti-interference mechanism of system, provide a theoretical basis for the system to protect against ecological disaster, and improve system reliability.
9.5 New-Type Large-Scale SCPPS
Though many researchers have proposed a variety of ecotype solar chimney power generation systems, the reports conducting an in-depth study of these new systems are rare. Most of these works only proposed a feasible plan. However, there has been no comprehensive study covering all aspects of the system including theory, technology, economy, and feasibility. More research should be conducted to explore the use of the solar chimney plant to form a new “Energy—Environment—Ecology” coordinated development model, and to establish the comprehensive benefits evaluation system. Utilizing the greenhouse of SCPPS to conduct fundamental research in agricultural facilities, we may grow vegetables, plants or agricultural crops in Western China. To achieve these, many problems should be addressed, such as developing agricultural facilities suitable for the local environment, getting investment, and achieving benefits. All the issues above are worthy of further attention.
If the energy problem is not solved, it will constrain China’s economic development. In addition, it is an urgent task for researchers to find more fossil alternative energies to alleviate the severe ecological and environmental situation in China. Further attempts should be made to achieve environmental improvement and ecological reconstruction in China and worldwide.