A novel solar polygeneration system for heat, power and fresh water production with absorption heat pump(AHP) and humidification-dehumidification(HDH) desalination system was proposed for high-efficiency utilization o...A novel solar polygeneration system for heat, power and fresh water production with absorption heat pump(AHP) and humidification-dehumidification(HDH) desalination system was proposed for high-efficiency utilization of solar energy. A case study of the proposed system was investigated based on 1 MW solar thermal power(STP) tower plant located in Beijing. Depending on mathematical modeling of the proposed system, corresponding modules were developed in TRNSYS. Meanwhile, control and operation strategies were fully studied with principal of solar energy cascade utilization. The thermodynamic performance of the proposed system was dynamically simulated at one minute intervals in a typical day. It was found that solar energy utilization level was improved with the help of solar thermal storage system and continuous heating in different operation modes met well with flexible heating loads from 93.76 kW to 169.49 kW. During AHP operation period, its Coefficient of Performance(COP) varied from 1.39 to 1.73 due to recoverable condensate heat restricted by heating demand. Meanwhile, fresh water production of HDH increased from 352.05 kg/h to 416.62 kg/h with Gained Output Ratio(GOR) increase from 2.48 to 2.67. Compared with original STP tower plant, maximum power generation efficiency was increased from 18.66% to 19.22% with power from 1169.69 kW to 1204.44 kW.展开更多
The volumetric receiver has received wide attention due to its high thermal efficiency. This paper studied a new type of a solid-liquid composite volumetric receiver. The heat transfer in a solid-liquid composite volu...The volumetric receiver has received wide attention due to its high thermal efficiency. This paper studied a new type of a solid-liquid composite volumetric receiver. The heat transfer in a solid-liquid composite volumetric solar receiver was analyzed using a one-dimensional unsteady simulation model of the solid-liquid receiver. The model included absorption of the incident solar radiation by the glass window, the silicon carbide porous ceramic heat absorber panel and the water. The results were verified against experimental data for a volumetric receiver and the error did not exceed 10%. It can be used to predict the heat transfer in solid-liquid composite volumetric receivers.展开更多
To better understand the characteristics of a large-scaled parabolic trough solar field(PTSF)under cloud passages,a novel method which combines a closed-loop thermal hydraulic model(CLTHM)and cloud vector(CV)is develo...To better understand the characteristics of a large-scaled parabolic trough solar field(PTSF)under cloud passages,a novel method which combines a closed-loop thermal hydraulic model(CLTHM)and cloud vector(CV)is developed.Besides,the CLTHM is established and validated based on a pilot plant.Moreover,some key parameters which are used to characterize a typical PTSF and CV are presented for further simulation.Furthermore,two sets of results simulated by the CLTHM are compared and discussed.One set deals with cloud passages by the CV,while the other by the traditionally distributed weather stations(DWSs).Because of considering the solar irradiance distribution in a more detailed and realistically way,compared with the distributed weather station(DWS)simulation,all essential parameters,such as the total flowrate,flow distribution,outlet temperature,thermal and exergetic efficiency,and exergetic destruction tend to be more precise and smoother in the CV simulation.For example,for the runner outlet temperature,which is the most crucial parameter for a running PTSF,the maximum relative error reaches−15%in the comparison.In addition,the mechanism of thermal and hydraulic unbalance caused by cloud passages are explained based on the simulation.展开更多
The parabolic trough solar concentrating system has been well developed and widely used in commercial solar thermal power plants. However, the conventional system has its drawbacks when connecting receiver tube parts ...The parabolic trough solar concentrating system has been well developed and widely used in commercial solar thermal power plants. However, the conventional system has its drawbacks when connecting receiver tube parts and enhancing the concentration ratio. To overcome those inherent disadvantages, in this paper, an innovative concept of linear focus secondary trough concentrating system was proposed, which consists of a fixed parabolic trough concentrator, one or more heliostats, and a fixed tube receiver. The proposed system not only avoids the end loss and connection problem on the receiver during the tracking process but also opens up the possibility to increase the concentration ratio by enlarging aperture. The design scheme of the proposed system was elaborated in detail in this paper.Besides, the optical performance of the semi and the whole secondary solar trough concentrator was evaluated by using the ray tracing method. This innovative solar concentrating system shows a high application value as a solar energy experimental device.展开更多
It is difficult to accurately measure the temperature of the falling particle receiver since thermocouples may directly be exposed to the solar flux.This study analyzes the thermal performance of a packed bed receiver...It is difficult to accurately measure the temperature of the falling particle receiver since thermocouples may directly be exposed to the solar flux.This study analyzes the thermal performance of a packed bed receiver using large metal spheres to minimize the measurement error of particle temperature with the sphere temperature reaching more than 700°C in experiments in a solar furnace and a solar simulator.The numerical models of a single sphere and multiple spheres are verified by the experiments.The multiple spheres model includes calculations of the external incidence,view factors,and heat transfer.The effects of parameters on the temperature variations of the spheres,the transient thermal efficiency,and the temperature uniformity are investigated,such as the ambient temperature,particle thermal conductivity,energy flux,sphere diameter,and sphere emissivity.When the convection is not considered,the results show that the sphere emissivity has a significant influence on the transient thermal efficiency and that the temperature uniformity is strongly affected by the energy flux,sphere diameter,and sphere emissivity.As the emissivity increases from 0.5 to 0.9,the transient thermal efficiency and the average temperature variance increase from 53.5%to 75.7%and from 14.3%to 27.1%at 3.9 min,respectively.The average temperature variance decreases from 29.7%to 9.3%at 2.2 min with the sphere diameter increasing from 28.57 mm to 50 mm.As the dimensionless energy flux increases from 0.8 to 1.2,the average temperature variance increases from 13.4%to 26.6%at 3.4 min.展开更多
This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radi...This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radiation was absorbed and converted into thermal energy by the solid particles flowed inside the quartz tube. Several experiments were conducted to test the dynamic thermal performance of the receiver on solar furnace system. During the experiments, the maximum particle temperature rise is 212~C, with an efficiency of 61.2%, which shows a good thermal performance with a falling distance of 0.2 m in a small scale particle receiver. The average outlet particle temperature is affected by direct normal irradiance （DNI） and other factors such as wind speed. The solid particles obtain a larger viscosity with a higher temperature while smaller solid particles are easier to get stuck in the helix quartz tube. The heat capacity of the silicon carbide gets larger with the rise of particle temperature, because as the temperature of solid particles increases, the temperature rise of the silicon carbide decreases.展开更多
Parabolic trough receiver is a key component to convert solar energy into thermal energy in the parabolic trough solar system.The heat loss of the receiver has an important influence on the thermal efficiency and the ...Parabolic trough receiver is a key component to convert solar energy into thermal energy in the parabolic trough solar system.The heat loss of the receiver has an important influence on the thermal efficiency and the operating cost of the power station.In this paper,conduction and radiation heat losses are analyzed respectively to identify the heat loss mechanism of the receiver.A 2-D heat transfer model is established by using the direct simulation Monte Carlo method for rarefied gas flow and heat transfer within the annulus of the receiver to predict the conduction heat loss caused by residual gases.The numerical results conform to the experimental results,and show the temperature of the glass envelope and heat loss for various conditions in detail.The effects of annulus pressure,gas species,temperature of heat transfer fluid,and annulus size on the conduction and radiation heat losses are systematically analyzed.Besides,the main factors that cause heat loss are analyzed,providing a theoretical basis for guiding the improvement of receiver,as well as the operation and maintenance strategy to reduce heat loss.展开更多
Thermal energy storage(TES) is an important part of concentrating solar power(CSP) plants. The primary advantage of TES in CSP plants is the ability to dispatch electrical output to match peak demand periods and reduc...Thermal energy storage(TES) is an important part of concentrating solar power(CSP) plants. The primary advantage of TES in CSP plants is the ability to dispatch electrical output to match peak demand periods and reduce the levelized cost of electricity. The major challenge of the molten salt is its high freezing point, leading to additional complicating freeze protection. This paper presents the experimental results of melting process of a mixed nitrate salt with a melting temperature of 115℃ in a 20 m^3 industrial level tank. Twenty electrical heaters inside the tank are used to heat the salt with a total maximum input power of 240 kW. In order to ensure a safe and fast melting process, the whole process adopted an operating strategy of combining automatic control with manual control. The whole melting process lasted for 314 hours. The salt temperature showed the greatest increase in the first 38 hours. Finally, an economic operation mode of molten salt heat storage tank was obtained.展开更多
基金This study was supported by the International Partnership Program of Chinese Academy of Sciences(CAS,Grant No.182111KYSB20160005)the National Nature Science Foundation of China(Grant No.51476164).
文摘A novel solar polygeneration system for heat, power and fresh water production with absorption heat pump(AHP) and humidification-dehumidification(HDH) desalination system was proposed for high-efficiency utilization of solar energy. A case study of the proposed system was investigated based on 1 MW solar thermal power(STP) tower plant located in Beijing. Depending on mathematical modeling of the proposed system, corresponding modules were developed in TRNSYS. Meanwhile, control and operation strategies were fully studied with principal of solar energy cascade utilization. The thermodynamic performance of the proposed system was dynamically simulated at one minute intervals in a typical day. It was found that solar energy utilization level was improved with the help of solar thermal storage system and continuous heating in different operation modes met well with flexible heating loads from 93.76 kW to 169.49 kW. During AHP operation period, its Coefficient of Performance(COP) varied from 1.39 to 1.73 due to recoverable condensate heat restricted by heating demand. Meanwhile, fresh water production of HDH increased from 352.05 kg/h to 416.62 kg/h with Gained Output Ratio(GOR) increase from 2.48 to 2.67. Compared with original STP tower plant, maximum power generation efficiency was increased from 18.66% to 19.22% with power from 1169.69 kW to 1204.44 kW.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (No. XDA21050200)the National Natural Science Foundation of China Project (No. 61671429)supported by the Guangdong Innovative and Entrepreneurial Research Team Program (No. 2013N070)
文摘The volumetric receiver has received wide attention due to its high thermal efficiency. This paper studied a new type of a solid-liquid composite volumetric receiver. The heat transfer in a solid-liquid composite volumetric solar receiver was analyzed using a one-dimensional unsteady simulation model of the solid-liquid receiver. The model included absorption of the incident solar radiation by the glass window, the silicon carbide porous ceramic heat absorber panel and the water. The results were verified against experimental data for a volumetric receiver and the error did not exceed 10%. It can be used to predict the heat transfer in solid-liquid composite volumetric receivers.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB-0905102).
文摘To better understand the characteristics of a large-scaled parabolic trough solar field(PTSF)under cloud passages,a novel method which combines a closed-loop thermal hydraulic model(CLTHM)and cloud vector(CV)is developed.Besides,the CLTHM is established and validated based on a pilot plant.Moreover,some key parameters which are used to characterize a typical PTSF and CV are presented for further simulation.Furthermore,two sets of results simulated by the CLTHM are compared and discussed.One set deals with cloud passages by the CV,while the other by the traditionally distributed weather stations(DWSs).Because of considering the solar irradiance distribution in a more detailed and realistically way,compared with the distributed weather station(DWS)simulation,all essential parameters,such as the total flowrate,flow distribution,outlet temperature,thermal and exergetic efficiency,and exergetic destruction tend to be more precise and smoother in the CV simulation.For example,for the runner outlet temperature,which is the most crucial parameter for a running PTSF,the maximum relative error reaches−15%in the comparison.In addition,the mechanism of thermal and hydraulic unbalance caused by cloud passages are explained based on the simulation.
文摘The parabolic trough solar concentrating system has been well developed and widely used in commercial solar thermal power plants. However, the conventional system has its drawbacks when connecting receiver tube parts and enhancing the concentration ratio. To overcome those inherent disadvantages, in this paper, an innovative concept of linear focus secondary trough concentrating system was proposed, which consists of a fixed parabolic trough concentrator, one or more heliostats, and a fixed tube receiver. The proposed system not only avoids the end loss and connection problem on the receiver during the tracking process but also opens up the possibility to increase the concentration ratio by enlarging aperture. The design scheme of the proposed system was elaborated in detail in this paper.Besides, the optical performance of the semi and the whole secondary solar trough concentrator was evaluated by using the ray tracing method. This innovative solar concentrating system shows a high application value as a solar energy experimental device.
基金This work was financially supported by Beijing Municipal Science and Technology Commission(No.Z181100004718002).
文摘It is difficult to accurately measure the temperature of the falling particle receiver since thermocouples may directly be exposed to the solar flux.This study analyzes the thermal performance of a packed bed receiver using large metal spheres to minimize the measurement error of particle temperature with the sphere temperature reaching more than 700°C in experiments in a solar furnace and a solar simulator.The numerical models of a single sphere and multiple spheres are verified by the experiments.The multiple spheres model includes calculations of the external incidence,view factors,and heat transfer.The effects of parameters on the temperature variations of the spheres,the transient thermal efficiency,and the temperature uniformity are investigated,such as the ambient temperature,particle thermal conductivity,energy flux,sphere diameter,and sphere emissivity.When the convection is not considered,the results show that the sphere emissivity has a significant influence on the transient thermal efficiency and that the temperature uniformity is strongly affected by the energy flux,sphere diameter,and sphere emissivity.As the emissivity increases from 0.5 to 0.9,the transient thermal efficiency and the average temperature variance increase from 53.5%to 75.7%and from 14.3%to 27.1%at 3.9 min,respectively.The average temperature variance decreases from 29.7%to 9.3%at 2.2 min with the sphere diameter increasing from 28.57 mm to 50 mm.As the dimensionless energy flux increases from 0.8 to 1.2,the average temperature variance increases from 13.4%to 26.6%at 3.4 min.
文摘This paper presents an experimental evaluation of a specially designed falling particle receiver. A quartz tube was used in the design, with which the particles would not be blown away by wind. Concentrated solar radiation was absorbed and converted into thermal energy by the solid particles flowed inside the quartz tube. Several experiments were conducted to test the dynamic thermal performance of the receiver on solar furnace system. During the experiments, the maximum particle temperature rise is 212~C, with an efficiency of 61.2%, which shows a good thermal performance with a falling distance of 0.2 m in a small scale particle receiver. The average outlet particle temperature is affected by direct normal irradiance （DNI） and other factors such as wind speed. The solid particles obtain a larger viscosity with a higher temperature while smaller solid particles are easier to get stuck in the helix quartz tube. The heat capacity of the silicon carbide gets larger with the rise of particle temperature, because as the temperature of solid particles increases, the temperature rise of the silicon carbide decreases.
基金funded by the National Key R&D Program of China(No.2019YFE0102000)the National Natural Science Foundation of China(Grant No.51476165).
文摘Parabolic trough receiver is a key component to convert solar energy into thermal energy in the parabolic trough solar system.The heat loss of the receiver has an important influence on the thermal efficiency and the operating cost of the power station.In this paper,conduction and radiation heat losses are analyzed respectively to identify the heat loss mechanism of the receiver.A 2-D heat transfer model is established by using the direct simulation Monte Carlo method for rarefied gas flow and heat transfer within the annulus of the receiver to predict the conduction heat loss caused by residual gases.The numerical results conform to the experimental results,and show the temperature of the glass envelope and heat loss for various conditions in detail.The effects of annulus pressure,gas species,temperature of heat transfer fluid,and annulus size on the conduction and radiation heat losses are systematically analyzed.Besides,the main factors that cause heat loss are analyzed,providing a theoretical basis for guiding the improvement of receiver,as well as the operation and maintenance strategy to reduce heat loss.
基金This work was supported by the National Natural Science Foundation of China(No.51606184)the Beijing Natural Science Foundation(No.3164052).
文摘Thermal energy storage(TES) is an important part of concentrating solar power(CSP) plants. The primary advantage of TES in CSP plants is the ability to dispatch electrical output to match peak demand periods and reduce the levelized cost of electricity. The major challenge of the molten salt is its high freezing point, leading to additional complicating freeze protection. This paper presents the experimental results of melting process of a mixed nitrate salt with a melting temperature of 115℃ in a 20 m^3 industrial level tank. Twenty electrical heaters inside the tank are used to heat the salt with a total maximum input power of 240 kW. In order to ensure a safe and fast melting process, the whole process adopted an operating strategy of combining automatic control with manual control. The whole melting process lasted for 314 hours. The salt temperature showed the greatest increase in the first 38 hours. Finally, an economic operation mode of molten salt heat storage tank was obtained.
