Numerical investigation on uniformity of heat flux for semi-gray surfaces inside a solar cavity receiver

Tu, Ning; Wei, Jinjia; Fang, Jiabin

doi:10.1016/j.solener.2014.11.028

Cited by 37 publications

(13 citation statements)

References 26 publications

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“…Using ideal PDC, the LCR distribution on the cylindrical absorber surface shows a single peak variation characteristic that increases rapidly first and then decreases gradually, which has extremely nonuniformity, and high peak LCR is shown in Figure . The nonuniformity factor is 0.63, 0.58, and 0.55 respectively, and the peak LCR is 1140.00, 990.92, and 837.41, respectively, when the focal length f of ideal PDC is 6.00, 7.00, and 8.45 m. Because the peak LCR area of the absorber surface is easy to form high temperature hot spot, it will affect the safety and working lifetime of the absorber . So reducing the peak LCR is also important.…”

Section: Examples and Discussionmentioning

confidence: 99%

“…Because the PDC is a typical single point focusing imaging optical device, it usually forms an extremely nonuniform and high‐density solar radiation flux on the absorber surface inside the cavity receiver . This would not only reduce the work efficiency and reliability of the cavity receiver but more seriously will also form a high‐temperature hot spot or a larger temperature gradient on the absorber tube, which will lead to great thermal stress and thermal deformation, thus affecting the safety and service lifetime of the cavity receiver . Therefore, the nonuniform flux distribution will bring more severe challenges to the safe operation of solar dish concentrator/cavity receiver (SDCR) system.…”

Section: Introductionmentioning

confidence: 99%

“…To achieve better flux uniformity, the surface inside the cavity receiver needs to be divided into smaller region, and then, the absorptivity of each region is optimized. This method has been studied in the cavity receiver of solar tower power system by Tu et al and Wang et al In addition, designing a new type of cavity receiver is also an important way to improve its flux uniformity. Wang et al designed an innovative taper annulus structure for the SDCR system based on the optical principle analysis of the PDC .…”

Section: Introductionmentioning

confidence: 99%

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Mirror rearrangement optimization for uniform flux distribution on the cavity receiver of solar parabolic dish concentrator system

2018

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Summary The nonuniform and high‐gradient solar radiation flux on the absorber surface of solar dish concentrator/cavity receiver (SDCR) system will affect its operational reliability and service lifetime. Therefore, homogenization of the flux distribution is critical and important. In this paper, 2 mirror rearrangement strategies and its optimization method by combining a novel ray tracing method and the genetic algorithm are proposed to optimize the parabolic dish concentrator (PDC) so as to realize the uniform flux distribution on the absorber surface inside the cavity receiver of SDCR system. The mirror rearrangement strategy includes a mirror rotation strategy and mirror translation strategy, which rotate and translate (along the focal axis) each mirror unit of the PDC to achieve multipoint aiming, respectively. Firstly, a correlation model between the focus spot radius and mirror rearrangement parameters is derived as constraint model to optimize the PDC. Secondly, a novel method named motion accumulation ray‐tracing method is proposed to reduce the optical simulation time. The optical model by motion accumulation ray‐tracing method and optimization model of SDCR system are established in detailed, and then, an optimization program by combining a ray‐tracing code and genetic algorithm code in C++ is developed and verified. Finally, 3 typical cavity receivers, namely, cylindrical, conical, and spherical, are taken as examples to fully verify the effectiveness of these proposed methods. The results show that the optimized PDC by mirror rearrangement strategies can not only greatly improve the flux uniformity (ie, reduce the nonuniformity factor) and reduce the peak local concentration ratio of the absorber surface but also obtain excellent optical efficiency and direct useful energy ratio. A better optimization results when the PDC is optimized by mirror rotation strategy at aperture radius of 7.0 m, focal length of 6.00 m, and ring number of 6; the nonuniform factor of the cylindrical, conical, and spherical cavity receivers is greatly reduced from 0.63, 0.67, and 0.45 to 0.18, 0.17, and 0.26, respectively; the peak local concentration ratio is reduced from 1140.00, 1399.00, and 633.30 to 709.10, 794.00, and 505.90, respectively; and the optical efficiency of SDCR system is as high as 92.01%, 92.13%, and 92.71%, respectively. These results also show that the dish concentrator with same focal length can match different cavity receivers by mirror rearrangement and it can obtain excellent flux uniformity.

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Section: Examples and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Mirror rearrangement optimization for uniform flux distribution on the cavity receiver of solar parabolic dish concentrator system

2018

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“…The results obtained on the basis of tests carried out on the experimental prototype and CFD model proved to be very similar, the temperature differences between the measurements and CFD simulations was from 3.2 to 8.4%, which is an acceptable result. Solar cavity receiver used to transfer the energy absorbed from solar radiation to the working medium in solar tower system [5] was simulated using CFD method. Simulation results allowed to perform optimisation of surface heat flux distribution inside the receiver, especially its uniformity.…”

Section: Introductionmentioning

confidence: 99%

Research on high-temperature heat receiver in concentrated solar radiation system

et al. 2017

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Abstract. The article presents the results of experimental and computer simulations studies of the high temperature heat receiver working in the concentrated solar radiation system. In order to study the radiation absorption process and heat exchange, the two types of computer simulations were carried out. The first one was used to find the best location for absorber in the concentrating installation. Ray Tracing Monte Carlo (RTMC) method in Trace Pro software was used to perform the optical simulations. The results of these simulations were presented in the form of the solar radiation distribution map and chart. The data obtained in RTMC simulations were used as a second type boundary conditions for Computational Fluid Dynamics (CFD) simulations. These studies were used to optimize the internal geometry of the receiver and also to select the most effective flow parameters of the working medium. In order to validate the computer simulations, high temperature heat receiver was tested in experimental conditions. The article presents the results of experimental measurements in the form of temperature, radiation intensity and power graphs. The tests were performed for varied flow rate and receiver location. The experimental and computer simulation studies presented in this article allowed to optimize the configuration of concentrating and heat receiving system.

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“…The effects of different boundary conditions were revealed. Tu et al [21] proposed a modified combined method to simulate the thermal performance of a saturated water/steam solar cavity receiver. Capeillere et al [22] numerically studied the thermomechanical behavior of a plate solar receiver with asymmetric heating.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of the energy and exergy performance for a pressurized volumetric solar receiver

Zhu

Wang

et al. 2016

Applied Thermal Engineering

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h i g h l i g h t sPerformance of a pressurized volumetric solar receiver is experimentally discussed. Energy and exergy analysis is performed during a two-hour period in the morning. The efficiency of the solar receiver is maintained at around 60% under steady state. The highest exergy efficiency and energy efficiency is approximately 36% and 87%. a b s t r a c tThis article presents an experimental investigation of the heat transfer characteristics as well as energy and exergy performance for a pressurized volumetric solar receiver under variable mass flow rate conditions. During a two-hour period of continuous operation in the morning, the solar irradiance is relatively stable and maintained at approximately 600 W/m 2 , which is beneficial for analyzing the energy and exergy performance of the solar receiver. Experimental results show that the mass flow rate fluctuation has insignificant effect on the solar receiver outlet temperature, whereas the mass flow rate plays an important role in the solar receiver power, energy efficiency and exergy efficiency. The efficiency of the solar receiver is normally above 55% with the highest efficiency of 87%, and under steady state operating conditions the efficiency is maintained at approximately 60%. A very low value of the heat loss factor (0.014 kW/K) could be achieved during the current steady state operating conditions. The highest exergy efficiency is approximately 36%. In addition, as the temperature difference increases, the impact of the exergy factor increases. The highest exergy factor is 0.41 during the entire test.

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Numerical investigation on uniformity of heat flux for semi-gray surfaces inside a solar cavity receiver

Cited by 37 publications

References 26 publications

Mirror rearrangement optimization for uniform flux distribution on the cavity receiver of solar parabolic dish concentrator system

Mirror rearrangement optimization for uniform flux distribution on the cavity receiver of solar parabolic dish concentrator system

Research on high-temperature heat receiver in concentrated solar radiation system

Experimental study of the energy and exergy performance for a pressurized volumetric solar receiver

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