• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.20 no.1
• /
• pp.35-41
• /
• 2008

The radiative heat loss from a receiver of a dish solar collector is numerically investigated. The dish solar collector considered in this paper consists of a receiver and multi-faceted mirrors. In order to investigate the performance comparison of dish solar collectors, six different mirror arrays and four different receivers are considered. A parabolic- shaped perfect mirror of which diameter is 1.40 m is considered as the reference for the mirror arrays. The other mirror arrays which consist of twelve identical parabolic-shaped mirror facets of which diameter are 0.405 m are suggested for comparison. Their reflecting areas, which are 1.545 $m^{2}$, are the same. Four different receiver shapes are a conical, a dome, a cylindrical, and a unicorn type. The radiative properties of the mirror surfaces and the receiver surfaces may vary the thermal performance of the dish solar collector so that various surface properties are considered. In order to calculate the radiative heat loss in the receiver, two kinds of methods are used. The Net Radiation Method that is based on the radiation heat balance on the surface is used to calculate the radiation heat transfer rate from the inside surface of the receiver to the environment. The Monte-Carlo Method that is the statistical approach is adopted to predict the radiation heat transfer rate from the reflector to the receiver. The collector efficiency is defined as the results of the optical efficiency and the receiver efficiency. Based on the calculation, the unicorn type has the best performance in receiver shapes and the STAR has the best performance in mirror arrays except the perfect mirror.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.1
• /
• pp.29-38
• /
• 2007

In order to analyze the performance comparison of dish solar collector with mirror arrays and receiver shapes, the radiative heat flux distribution inside the cavity receiver is numerically investigated. The solar irradiation reflected by dish solar collector is traced using the Monte-Carlo method. Five different dish solar collectors and three different cavity receivers are considered. A parabolic-shaped perfect mirror of which diameter is 1.5 m is considered as a reference dish solar collector and four different arrays of twelve identical parabolic-shaped mirror facets of which diameter are 0.4 m are used. Their reflecting areas, which are $1.5\;m^2$, are the same. Three different cavity receiver shapes are dome, conical, and cylindrical. In addition, the radiative properties of the concentrating surfaces can vary the thermal performance of the cavity receiver so that variation of the surface reflectivity of each mirror is considered. Based on the calculation, the design information of dish solar collector for producing the electric power can be obtained. The results show that the dome type has the best performance in receiver shapes and the 2AND4 INLINE has the best performance in mirror arrays except perfect mirror.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.182-185
• /
• 2008

The thermal performance of air receiver with a change of flow direction for dish solar collector. This system is installed and operated in Incheon, Korea. The thermal capacity of the system is about 5 kW thermal. The aperture diameter of the cylindrical-shape receiver which is made of stainless steel is 100 mm, and the height is 210 mm. Experiments are being carried out to investigate the thermal performance variation of the receivers with several design parameters such as the shape of the receiver, the flow directions and the flow rate of air. First, air flows into the upper part of the receiver, which is the opposite side of the aperture. After the air flows through the inside receiver, that goes out of the receiver through 3 exits which are located near the aperture. Second, air flows into the backside of the receiver, Which is the forward side of the aperture. After the air flows through the inside receiver, that goes out of the receiver through 1 exit. The results show that the system efficiency and receiver efficiency increase as the volume flow rate increases as expected.

• Advances in Energy Research
• /
• v.8 no.3
• /
• pp.137-144
• /
• 2022

This study presents an experimental investigation of conventional and enhanced receiver tube performance for the application of a concentrated parabolic trough collector (CPC). The CPC system is fabricated and tested for the conventional and enhanced receiver tubes. The experiments were performed on both tubes for the change of flow rates. The temperature rise of the tube surface, as well as working fluid, were monitored for varying flow rates. The results were compared and discussed in view of enhanced CPC system performance. The results exhibited that the temperature rise of the working fluid passing through the tube was more in the case of the enhanced tube compared to the conventional receiver tube under the same flow rates.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.794-799
• /
• 2001

The simulation analyses of a solar power system with monolithic concentrator by using a stirling engine are carried out to predict the system performance in four test sites. The site has different intensities and distributions of direct solar radiation respectively. Seoul, Pusan and Cheju in Korea, and Naha in Japan are selected as test sites. To accomplish the same demand of a 25 kW output that the power level of a system has, it needs to take the matching of collector/receiver with engine/generator systems. In such a case, also, the size of the collector is sometimes adjusted. In this study, the diameter of the collector is decided by using the solar radiation of design point, which is defined as the sum of average and standard deviation $\sigma$ of maximum direct solar radiation distribution for a day during a year in the respective test site. It is found that the average power output during the system operating time in the case of slope error ${\sigma}_s=2.5$ is within the range of 9 to 13 kW.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.662-667
• /
• 2007

The thermal performance comparisons of the dish solar collector system are numerically investigated with mirror arrays and receiver shapes. In order to compare the performances of the dish solar collector systems, six different mirror arrays and four different receiver shapes are considered and the radiative heat flux distribution on the inside of the receiver is analyzed. A parabolic-shaped perfect mirror of which diameter is 1.5 m is considered as a reference of the mirror arrays. Five different mirror arrays of twelve identical parabolic -shaped mirror facets of which diameter are 0.4 m are proposed in this study. Their reflecting areas, which are 1.5 $m^2$, are the same. Four different receiver shapes are a dome, a conical, a cylindrical and a unicorn type. The solar irradiation reflected by mirrors is traced using the Monte-Carlo method. In addition, the radiative properties of the mirror surface can vary the thermal performance of the dish solar collector system so that the effects of the surface reflectivity and the surface absorptivity are considered. Based on the calculation, the design information of dish solar collector system for producing the electric power can be obtained. The results show that the dome type has the best performance in receiver shapes and the 2AND4INLINE has the best performance in mirror arrays except the perfect mirror.

• Journal of the Korean Solar Energy Society
• /
• v.27 no.4
• /
• pp.113-120
• /
• 2007

The 5kWt dish solar collector is designed and the preliminary performance test for this is carried out. The diameter of the parabolic dish is 3.2 m, and its focal length is 2 m. It consists of 10 small reflectors which have their own curvatures, and the effective reflecting area is $5.9\;m^2$, and the rim angle of the dish is $43.85^{\circ}$. The reflectivity of reflectors is 0.95, and the thermal capacity of the system is about 5 kW thermal. The aperture diameter of the cylindrical-shape receiver which is made of stainless steel is 100 mm, and the height is 210 mm. A quartz window is installed at the receiver aperture to minimize the convective heat loss and prevent air leakage. In order to increase the heat transfer area, porous materials (nickel-alloy) are inserted into the receiver. Air flows into the upper part of the receiver which is the opposite side of the aperture. After the air flows through the inside of the receiver, that goes out of the receiver through 3 exits which are located near the aperture. The volumetric flow rates of air are varied from 600 to 1200 L/min. The results show that the system efficiency and receiver efficiency increase as the volume flow rate increases.

• Solar Energy
• /
• v.12 no.1
• /
• pp.95-102
• /
• 1992

A small scale solar collector system composed of a Fresnel lens of $0.5m^2$ area as a solar concentrator and a compact fluidized-bed solar receiver was developed. Performance and temperature distribution in the fluidized bed receiver were measured using SiC for particles and air for working fluid. The maximum gas temperature was attained up to 1250K at this moment. In this study, energy efficiency achieved by the present experiment was high for the small scale solar collector system and compact receiver.

• Proceedings of the SAREK Conference
• /
• 2007.11a
• /
• pp.570-575
• /
• 2007

The thermal performance of the air receiver filled with porous material for 5kWt dish solar collector installed in Inha University, Korea, is experimentally investigated. The diameter of the parabolic dish is 3.2 m, and its focal length is 2 m. It consists of 10 small pieces of glasses which have their own curvatures, and the effective reflecting area is 5.9 m2. The reflectivity of the glass is 0.95, and the thermal capacity of the system is about 5 kW thermal. The aperture diameter of the cylindrical-shape receiver which is made of stainless steel is 100 mm, and the height is 210 mm. A quartz window is installed at the receiver aperture to minimize the convective heat loss and prevent air leakages. In order to increase the heat transfer area, porous material (nickel-alloy) is inserted into the receiver. Air flows into the upper part of the receiver, which is the opposite side of the aperture. After the air flows through the inside receiver, that goes out of the receiver through 3 exits which are located near the aperture. The volumetric flow rates of air are varied from 600 to 1200 L/min. The thermal efficiency of the receiver ranges from 82% - 92% depending upon the flow rate. The results show that the system efficiency and receiver efficiency increase as the volume flow rate increases as expected. These results from the experiment will be useful for the applications to air heating receivers and solar reactors.

• Advances in Energy Research
• /
• v.8 no.3
• /
• pp.155-163
• /
• 2022

The current study presents experimental research on a parabolic trough collector with tube and cavity receivers. The primary concentrating parabolic reflector is designed for an aperture area of 2×2 m² with mirror-polished stainless steel sheet reflectors. The cavity receiver consists of a compound parabolic secondary reflector and a copper tube. Both the conventional tube receiver and the cavity receiver tube are coated with black powder. The experiments are carried out to compare the efficiency of the cavity receiver with the tube receiver for fluid temperature rise, thermal efficiency, and overall losses. The experiments showed significantly higher fluid temperature rise and overall efficiency and lower thermal losses for the cavity receiver compared to the tube receiver within the parameters explored in this study.