Thermal selective coatings and its enhancement characteristics for efficient power generation through parabolic trough collector (PTC)

In the field of solar power generation, concentrator systems, such as concentrator photovoltaics (CPV) or concentrated solar power (CSP), are subject of intensive research activity, due to high efficiencies in electrical power generation compared to conventional photovoltaics (PV) and low-cost energy storage on the thermal side. Even though the idea of combining the thermal and electrical part in one absorber is obvious, very few hybrid systems (i.e., concentrator photovoltaics-thermal systems (CPV-T)) are either described in literature or commercially available. This paper features the conversion of a commercial thermal parabolic trough collector to a CPV-T hybrid system using multi-junction PV cells. The design process is described in detail starting with the selection of suitable PV cells, elaborating optical and mechanical system requirements, heat sink design and final assembly. Feasibility is proven by practical tests involving maximum power point tracking as well as empirical determination of heat generation and measurement results are presented.

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SIZING A PARABOLIC TROUGH COLLECTOR FOR A MICRO SOLAR ORGANIC RANKINE CYCLE

Jurnal Teknologi ◽

10.11113/jt.v81.12304 ◽

2019 ◽

Vol 81 (2) ◽

Author(s):

Choi Yun Chai ◽

Hyung-chul Jung

Keyword(s):

Power Generation ◽

Organic Rankine Cycle ◽

Rankine Cycle ◽

Operating Conditions ◽

Working Fluid ◽

Solar Thermal Energy ◽

Parabolic Trough ◽

Tropical Country ◽

Parabolic Trough Collector ◽

Time Operation

There are many remote villages in Malaysia that are not connected to an electric grid, and are dependent on expensive diesel generator sets (gensets) in their daily activities. Malaysia, a tropical country, has the potential to promote solar power generation in these isolated areas. The organic Rankine cycle (ORC) using solar thermal energy as the heat source could be an attractive approach to off-grid power generation. In this study, a 1 kWe solar ORC with a parabolic trough collector (PTC) is proposed. The ORC utilizes R245fa as the working fluid and Therminol VP1 as the heat transfer medium between the PTC and ORC. Thermodynamic analysis of the ORC is performed, predicting the performance of the ORC and the operating conditions of the PTC. Based on the design requirements of the PTC from the power cycle analysis, process of sizing the PTC is conducted via a numerical model. Seven sets of heat collector elements (HCE) are examined. The effects of absorber tube material, selective coating on the outer surface of the absorber tube, and the absorber tube diameter on the PTC performance are presented. Simulation results show that HCE with 6 mm of SS316L absorber tube, enclosed with 11 mm of Pyrex borosilicate glass tube, has the highest collector efficiency of 62.25%. The receiver length required is 8.05 m and the aperture width of the collector is 3.54 m. Further study is recommended to select a thermal storage system for night-time operation of the ORC.

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