Conical Cavity Receiver Research Articles

Performance studies on solar parabolic dish collector using conical cavity receiver for community heating applications

Abstract The Solar Parabolic Dish Collector (SPDC) is considered as a significance part in solar thermal energy conversion process in high temperature applications. This prime work focuses on the enhancement of performance characteristics of solar dish collector, coupled with conical cavity receiver. The design of SPDC utilizes segments of mirror finished stainless steel leaflets. The higher thermal efficiency is accomplished by employing the conical receiver design. It is demonstrated that the average collector efficiency of solar dish collector is in the range of 45% to 62%, for the various design and operating conditions. The heat transfer characteristics and thermal performance of the parabolic dish collector were studied. The outcomes of these experimentation are to be exploited for the appropriate assessments of the SPDC on a regular basis.

Investigation of steam generation performance on conical cavity receiver by different geometric concentration ratios for fresnel lens solar concentrator

The paper discusses the comparison of the performance of steam generators in large and small receivers, using a Fresnel lens concentrator. The goal is to get the best value from the efficiency of a steam generator between large and small receivers, with the following task details: a) design a conical cavity receiver that has the most efficient geometric concentration ratio; b) compare the thermal efficiency of conical cavity receivers that have different geometric concentration ratios; c) analyze the potential of the steam energy from the conical cavity receiver produced by the PMMA Fresnel lens concentrator based on the amount of average radiation directly at the study site. The study uses an experimental field research method, which is conducted outdoors. This research was conducted in the energy conversion laboratory, Universitas Brawijaya (Latitude: 7.9553° S and Longitude: 112.6145° W), in September 2019. The PMMA Fresnel lens is used for the solar thermal concentrators. The two receivers with a conical cavity that were compared were made of copper with a volume of 2 litres and 0.25 litres, respectively. They are coated with a glass wool insulator with a thickness of 10 mm. Direct Normal Irradiance (I b ) is measured by a solar power meter. The cup anemometer is used to measure wind speed (v w ) around the receiver. Digi-Sense 12 Channel Scanning Benchtop Thermometer connected to the laptop is used to measure temperature. The positions of the four K-type thermocouples are as follows: 1) ambient temperature (T a ); 2) focal point temperature (T f ); 3) receiver wall temperature (T r ); 4) steam/water temperature (T w ). A pressure gauge to measure the pressure of the steam that goes to the measuring cup was used. After saturation pressure (P sat ) has been reached, it will be known from the condensation process through the copper coil, which functions as a condenser. From the results of the study, the large receivers have specifications CR g =8 and a volume of 2 litres of water. Whereas, the small receiver is CR g =30 and 0.25 L. The large receivers can produce steam latent heat energy Q s =1.37 MJ per cycle with useful efficiency (utilization efficiency) η Th =31.81 %. Whereas the small receiver can produce steam energy, Q s =579.17 kJ per cycle with useful efficiency, η Th =33.31 %. Hence, from the two types of conical cavity receivers, small receivers have that higher effectiveness than large ones can be recommended

Combined optics and heat transfer numerical model of a solar conical receiver with built-in helical pipe

The performance of a solar conical receiver greatly influences the concentrated solar power (CSP) system. It is worthy to devote efforts on performance optimization for a solar conical receiver with a built-in helical pipe. A comprehensive investigation on the whole solar-heat conversion process is significant. Using a combined optics and heat transfer model, this study simulated the influence of the conical angle, loop number, and insulation thickness on cavity receiver performances. The combination consists of two parts: an optical simulation using the optics software TracePro 7.3.4 and a heat-transfer simulation using the CFD software ANSYS 17.0. Model validation is performed by comparing the simulation results to the published experiment data. Good agreement is achieved. The results indicate that the optimal value of conical angle is 5°, the overall efficiency in this case is 63.6%. From 4 to 15, both thermal efficiency and overall efficiency increase as the loop number increases; however, optical efficiency shows a different trend. The optimal value of insulation thickness ranging from 25 mm to 200 mm is 175 mm, achieving 70.4% overall efficiency. This study provides an effective method of performance optimization for a conical cavity receiver.

Effects of critical geometric parameters on the optical performance of a conical cavity receiver

The optical performance of a receiver has a great influence on the efficiency and stability of a solar thermal power system. Most of the literature focuses on the optical performance of receivers with different geometric shapes, but less research is conducted on the effects of critical geometric parameters. In this paper, the commercial software TracePro was used to investigate the effects of some factors on a conical cavity receiver, such as the conical angle, the number of loops of the helical tube, and the distance between the focal point of the collector and the aperture. These factors affect the optical efficiency, the maximum heat flux density, and the light distribution in the conical cavity. The optical performance of the conical receiver was studied and analyzed using the Monte Carlo ray tracing method. To make a reliable simulation, the helical tube was attached to the inner wall of the cavity in the proposed model. The results showed that the amount of light rays reaching the helical tube increases with the increasing of the conical angle, while the optical efficiency decreases and the maximum heat flux density increases. The increase in the number of loops contributed to an increase in the optical efficiency and a uniform light distribution. The conical cavity receiver had an optimal optical performance when the focal point of the collector was near the aperture.

Effect of aspect ratio on thermal performance of cavity receiver for solar parabolic dish concentrator: An experimental study

Proper design of the receiver is vital to maximize the performance of solar parabolic dish concentrator. In this paper, an experimental study on the thermal performance of the conical cavity receiver with different aspect ratios for solar parabolic dish concentrator is presented. The receivers of aspect ratio 0.8, 1.0 and 1.2 are constructed for a given cone angle and tested in bright sunny days with average beam radiation above 600 W/m2. The energy efficiency, exergy efficiency and overall heat loss factor of the receivers were evaluated and compared. As expected, the receiver surface temperature got reduced with increase in aspect ratio. However the thermal performance is observed to decrease. The receiver with aspect ratio of 0.8 shown highest performance among all the receivers tested. It is revealed that reduction in receiver surface temperature alone is not adequate to improve the thermal performance, the surface area is also an influencing factor. Hence the aspect ratio of the receiver has a significant impact on the thermal performance and should be carefully chosen while designing the receiver. The results presented in this work are useful for further optimization of the receiver design.

Effects of receiver parameters on the optical performance of a fixed-focus Fresnel lens solar concentrator/cavity receiver system in solar cooker

To facilitate building integration with solar cooker for household, a solar cooker based on a fixed-focus Fresnel lens solar concentrator/cavity receiver system was proposed. To increase the system optical efficiency, the cavity receiver with bottom reflective cone was used as a fixed receiver. Expecting to optimize the system and receiver of better optical performance, the effects of receiver parameters on it were studied. To evaluate the effects, a significance test of key factors was conducted. Comparative analysis of fixed-focus food cooking system was undertaken. The analysis shows that average optical efficiencies using cavity receiver with bottom reflective cone of spherical, cylindrical, conical are 72.23%, 68.37% and 76.40%, respectively, while that of their corresponding conventional cavity receivers are 68.49%, 31.91% and 74.61%. The former significantly increased 3.74%, 36.46% and 1.79%, respectively. Moreover, cavity receiver with bottom reflective cone angle 90° is able to hold a higher amount of incoming energy from concentrator, compared to other three angles. Increasing the bottom reflective cone reflectivity and cavity receiver surface absorptivity can improve optical efficiency. In addition, the cavity receiver surface absorptivity and concentrated sunlight incidence angle have the most significant influence on the optical efficiency and flux uniformity, respectively. The conical cavity receiver with bottom reflective cone is the most suitable one for system. This work is expected to be useful for further optimization of solar concentrator/cavity receiver system.

An experimental study on energy and exergy performance of a cavity receiver for solar parabolic dish concentrator

In this paper, an experimental study is carried out to investigate the thermal performance of a conical frustum cavity receiver for a 16 m2 Scheffler concentrator, using energy and exergy analyses. The experiment is conducted with heat transfer fluid having a flow rate of 2.5 litres per minute (LPM) under an average beam radiation of 608.17 W/m2. The average thermal energy efficiency of the receiver is found to be 57.39% with a peak value of 66.75%. The receiver could attain a very low overall heat loss factor of about 0.027 kW/K. The overall system efficiency of the solar collector is 69.47%. The average exergy efficiency of the receiver is found to be 5.88% with a peak value of 10.35%. A peak exergy factor of 0.152 is obtained for the receiver. Experiments are also conducted with flow rates of 1, 1.5 and 2 LPM in addition to the flow rate of 2.5 LPM and the receiver showed better performance for 2.5 LPM.

Performance investigation on solar thermal conversion of a conical cavity receiver employing a beam-down solar tower concentrator

Development of a beam-down solar tower (BST) with strong wind-resistance heliostats is a particular topic of active research. A BST system, equipped with three linear Fresnel heliostat modules, corresponding beam-down concentrators, and a central cavity receiver with a spiral tube, has been introduced, experimentally investigated and theoretically analyzed in this paper. The elaborate derivation process of sun-tracking formulas for the BST collector has been implemented. In addition, detailed numerical models for thermal behaviors of the conical cavity receiver with the spiral tube, on the basis of three-dimensional Computing Finite Dynamics (CFD) method, have been developed and validated with experimental data. The objective of this paper is to report test results of the conical receiver equipped the BST concentrator, and to numerically evaluate conversion performance of the solar thermal process including the heat flux distribution on the absorber surface, heat losses, as well as instantaneous thermal efficiencies, thereby providing useful data for the optimization of the cavity receiver. Experimental results and numerical prediction indicate that instantaneous thermal efficiencies of about 60% and 39% can be reached at differences of 81K and 181K between inlet and ambient temperatures under water and Therminol VP-1 flow rates of 0.5l/s, respectively. The operational volume flow rates of 0.25l/s and 0.35l/s are respectively suggested to the conical cavity receiver using water and Therminol VP-1 under the geometry and operational conditions in this paper. The optimal conical angle of 100° has a minimum heat loss leading to obtain a maximum thermal efficiency.

Theoretical and experimental analysis on efficiency factors and heat removal factors of Fresnel lens solar collector using different cavity receivers

The efficiency and heat removal factors are useful parameters for evaluating the thermal performance of concentrating solar collectors. In this work, the efficiency factors and heat removal factors of Fresnel lens solar collectors using different kinds of point-focus cavity receivers were obtained both theoretically and experimentally. An experimental unit was built, whereby eight kinds of cavity receivers, namely: conical, spherical, cylindrical, hemispherical, positive cone frustum, reverse cone frustum, heteroconical and domical, were tested and analyzed. It is found that the theoretical results agree well with the test results. For the point-focus Fresnel lens solar collector, the conical cavity receiver showed the best thermal performance, with a highest theoretical heat removal factor of 0.868. Effect of conical cavity parameters on the efficiency and heat removal factors were studied. Results showed that under given operation conditions, the optimum aperture diameter of the cavity, the optimum inside diameter of the receiver tube and the optimum vertex angle of the cross section through the symmetric axis of the receiver are 80mm, 15mm and 60°, respectively. For better thermal performance, the geometrical concentration ratio of the studied Fresnel lens solar collector should be more than 500.

The Numerical Investigation on Optical Efficiency and Heat Flux Distribution of Conical Cavity Receiver

Optical efficiency analysis of conical cavity receiver is introduced in this receiver. Monte-Carlo ray tracing codes was developed to analyze the optical efficiency and heat flux distribution of conical cavity receiver with aperture radius variation. Besides, the impact of slope error variation on the optical efficiency and heat flux distribution are also investigated. The numerical results show that inverted conical cavity receiver with optimized aperture radius has the highest optical efficiency.