Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector
In order to increase the overall solar energy gain of evacuated tube collectors, rear-side reflectors are used. In this way, the otherwise unused incident radiation between the tubes can be reflected back to the absorber, and the performance of the collector can be improved. In this paper, the use o...
| Main Authors: | , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-12-01
|
| Series: | Energies |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1996-1073/14/24/8209 |
| _version_ | 1797505152806027264 |
|---|---|
| author | Julian Schumann Bert Schiebler Federico Giovannetti |
| author_facet | Julian Schumann Bert Schiebler Federico Giovannetti |
| author_sort | Julian Schumann |
| collection | DOAJ |
| description | In order to increase the overall solar energy gain of evacuated tube collectors, rear-side reflectors are used. In this way, the otherwise unused incident radiation between the tubes can be reflected back to the absorber, and the performance of the collector can be improved. In this paper, the use of a low-cost, diffusely reflecting, trapezoidal roof covering made from a galvanized metal sheet is investigated and compared to a high-quality, specularly reflecting plane reflector made of aluminum. For this purpose, ray-tracing analysis and TRNSYS simulations were carried out. In the ray-tracing analysis, the experimentally determined zero-loss collector efficiency η<sub>0</sub> as well as the incident angle modifiers for each reflector can be reproduced with an error lower than 7.5%. Thermal system simulations show that the performance of both reflectors is comparable. The use of the low-cost reflector leads to an increase in annual collector output of around 30% compared to an increase with the specular reflector of around 33%. Considering a typical domestic hot water system, both reflectors enable an increase in the solar annual yield of approx. 11%. |
| first_indexed | 2024-03-10T04:14:32Z |
| format | Article |
| id | doaj.art-e37f0a871ba84451ab432dcdae432c99 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-10T04:14:32Z |
| publishDate | 2021-12-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-e37f0a871ba84451ab432dcdae432c992023-11-23T08:04:04ZengMDPI AGEnergies1996-10732021-12-011424820910.3390/en14248209Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse ReflectorJulian Schumann0Bert Schiebler1Federico Giovannetti2Institute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, GermanyInstitute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, GermanyInstitute for Solar Energy Research Hamelin (ISFH), Am Ohrberg 1, 31860 Emmerthal, GermanyIn order to increase the overall solar energy gain of evacuated tube collectors, rear-side reflectors are used. In this way, the otherwise unused incident radiation between the tubes can be reflected back to the absorber, and the performance of the collector can be improved. In this paper, the use of a low-cost, diffusely reflecting, trapezoidal roof covering made from a galvanized metal sheet is investigated and compared to a high-quality, specularly reflecting plane reflector made of aluminum. For this purpose, ray-tracing analysis and TRNSYS simulations were carried out. In the ray-tracing analysis, the experimentally determined zero-loss collector efficiency η<sub>0</sub> as well as the incident angle modifiers for each reflector can be reproduced with an error lower than 7.5%. Thermal system simulations show that the performance of both reflectors is comparable. The use of the low-cost reflector leads to an increase in annual collector output of around 30% compared to an increase with the specular reflector of around 33%. Considering a typical domestic hot water system, both reflectors enable an increase in the solar annual yield of approx. 11%.https://www.mdpi.com/1996-1073/14/24/8209solar thermalevacuated tube collectordiffuse reflectorspecular reflectorTRNSYSray tracing |
| spellingShingle | Julian Schumann Bert Schiebler Federico Giovannetti Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector Energies solar thermal evacuated tube collector diffuse reflector specular reflector TRNSYS ray tracing |
| title | Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector |
| title_full | Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector |
| title_fullStr | Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector |
| title_full_unstemmed | Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector |
| title_short | Performance Evaluation of an Evacuated Tube Collector with a Low-Cost Diffuse Reflector |
| title_sort | performance evaluation of an evacuated tube collector with a low cost diffuse reflector |
| topic | solar thermal evacuated tube collector diffuse reflector specular reflector TRNSYS ray tracing |
| url | https://www.mdpi.com/1996-1073/14/24/8209 |
| work_keys_str_mv | AT julianschumann performanceevaluationofanevacuatedtubecollectorwithalowcostdiffusereflector AT bertschiebler performanceevaluationofanevacuatedtubecollectorwithalowcostdiffusereflector AT federicogiovannetti performanceevaluationofanevacuatedtubecollectorwithalowcostdiffusereflector |