Contact cleaning of polymer film solar reflectors

This paper describes the accelerated ageing of polymer film reflecting surfaces under the conditions to be found during contact cleaning of Concentrating Solar Power (CSP) collectors in the presence of dust and sand particles. In these situations, contact cleaning using brushes and water is required to clean the reflecting surfaces. Whilst suitable for glass reflectors, this paper discusses the effects of existing cleaning processes on the optical and visual properties of polymer film surfaces, and then describes the development of a more benign but effective contact cleaning process for cleaning polymer reflectors. The effects of a range of cleaning brushes are discussed, with and without the presence of water, in the presence of sand and dust particles from selected representative locations. Reflectance measurements and visual inspection shows that a soft cleaning brush with a small amount of water can clean polymer film reflecting surfaces without inflicting surface damage or reducing specular reflectance

Guidelines Accelerated Aging Testing of Aluminum Reflectors for Concentrated Solar Power

This testing guideline specifies the recommended accelerated aging conditions to reproduce realistic degradation mechanisms on aluminum reflectors, which have been observed during a 3 year outdoor exposure testing campaign at 9 exposure sites with 9 different aluminum reflector types (7 of them protected with a SiO2 based sol-gel coating, 2 of them protected by a polymeric coating). Accelerated aging parameters have been derived to simulate the exposure after 3 and 10 years at three reference outdoor scenarios: “extreme desert”, “desert” and “coastal”. The parameters have been achieved by averaging the 9 tested material types. However, if the material to be tested deviates significantly in its chemical composition, it is likely that other degradation mechanisms will be accelerated and the correlation to the outdoor reference scenarios will not apply. Fig. 1 shows the materials to be tested under the scope of this guideline. In any case, the indicated correlation to the outdoor reference scenarios can only be considered as an estimate. For some of the 9 tested materials the correlation applied better than for others. The expected uncertainty is 4.4 % (pp) specular reflectance, ρ, at a wavelength, λ, of 660 nm, an incidence angle, θi, of 15° and an acceptance angle, φ, of 12.5 mrad to simulate 3 years of exposure on the desert and coastal sites. For the “extreme desert” site the expected uncertainty is considerably higher because of the strong dependence on specific abrasion effects on site. The simulation of 10 years of exposure is based on extrapolation of the available outdoor data after 3 years

Prognostic and Predictive Value of Immune-Related Gene Expression Signatures vs Tumor-Infiltrating Lymphocytes in Early-Stage ERBB2/HER2-Positive Breast Cancer: A Correlative Analysis of the CALGB 40601 and PAMELA Trials

Càncer de mama; Expressió gènicaCáncer de mama; Expresión génicaBreast cancer; Gene ExpressionImportance Both tumor-infiltrating lymphocytes (TILs) assessment and immune-related gene expression signatures by RNA profiling predict higher pathologic complete response (pCR) and improved event-free survival (EFS) in patients with early-stage ERBB2/HER2-positive breast cancer. However, whether these 2 measures of immune activation provide similar or additive prognostic value is not known. Objective To examine the prognostic ability of TILs and immune-related gene expression signatures, alone and in combination, to predict pCR and EFS in patients with early-stage ERBB2/HER2-positive breast cancer treated in 2 clinical trials. Design, Setting, and Participants In this prognostic study, a correlative analysis was performed on the Cancer and Leukemia Group B (CALGB) 40601 trial and the PAMELA trial. In the CALGB 40601 trial, 305 patients were randomly assigned to weekly paclitaxel with trastuzumab, lapatinib, or both for 16 weeks. The primary end point was pCR, with a secondary end point of EFS. In the PAMELA trial, 151 patients received neoadjuvant treatment with trastuzumab and lapatinib for 18 weeks. The primary end point was the ability of the HER2-enriched subtype to predict pCR. The studies were conducted from October 2013 to November 2015 (PAMELA) and from December 2008 to February 2012 (CALGB 40601). Data analyses were performed from June 1, 2020, to January 1, 2022. Main Outcomes and Measures Immune-related gene expression profiling by RNA sequencing and TILs were assessed on 230 CALGB 40601 trial pretreatment tumors and 138 PAMELA trial pretreatment tumors. The association of these biomarkers with pCR (CALGB 40601 and PAMELA) and EFS (CALGB 40601) was studied by logistic regression and Cox analyses. Results The median age of the patients was 50 years (IQR, 42-50 years), and 305 (100%) were women. Of 202 immune signatures tested, 166 (82.2%) were significantly correlated with TILs. In both trials combined, TILs were significantly associated with pCR (odds ratio, 1.01; 95% CI, 1.01-1.02; P = .02). In addition to TILs, 36 immune signatures were significantly associated with higher pCR rates. Seven of these signatures outperformed TILs for predicting pCR, 6 of which were B-cell related. In a multivariable Cox model adjusted for clinicopathologic factors, including PAM50 intrinsic tumor subtype, the immunoglobulin G signature, but not TILs, was independently associated with EFS (immunoglobulin G signature–adjusted hazard ratio, 0.63; 95% CI, 0.42-0.93; P = .02; TIL-adjusted hazard ratio, 1.00; 95% CI, 0.98-1.02; P = .99). Conclusions and Relevance Results of this study suggest that multiple B-cell–related signatures were more strongly associated with pCR and EFS than TILs, which largely represent T cells. When both TILs and gene expression are available, the prognostic value of immune-related signatures appears to be superior

The design of dust barriers to reduce collector mirror soiling in CSP plants

In this work we investigate, design, and evaluate a number of dust barrier designs that would be appropriate to reduce soiling of glass mirror solar collectors in the solar field of an existing CSP plant. The principal objective was to reduce the amount of soiling (and hence the amount of cleaning water consumed) by 50% in comparison with current cleaning procedures (considering particles of size >25 µm). “Fluent” CFD software was used to model of a range of potential dust barrier shapes, sizes, and porosities. Airflows and wind loadings were analyzed in this way. A number of potential designs were then taken forward for experimental validation. Initial validation involved wind tunnel evaluation of a small number of potential designs, using a new wind tunnel specifically designed and built for this project. Larger-scale outdoor validation was carried out both at Cranfield University in the UK and at CIEMAT-PSA (Plataforma Solar de Almeria) in Spain. Initial results were independent of location and barrier shape and showed that the percentage of particles that were stopped completely or travelled less than 1m beyond the barrier was in the range 45.8 ± 5%

Equipment and methods for measuring reflectance of concentrating solar reflector materials

The proper optical characterization of solar reflector materials is a challenging task. Although several commercial instruments exist to measure reflectance, they have been developed for other applications and often do not meet all the specific requirements demanded by the solar thermal industry. In particular, the characterization of solar reflectors involve the complete solar spectral wavelength range, an incidence angle range from near normal to 70° and most importantly a very narrow acceptance angle range from near specular to 20 mrad. The accurate measurement of reflectance as a function of all the previously mentioned parameters has not been commercially implemented. This paper reviews the different alternatives to measure reflector materials, describes reflectance models used to approximate the missing information and presents current research work on prototype reflectometers to fill the gap

Equipment and methods for measuring reflectance of concentrating solar reflector materials

The proper optical characterization of solar reflector materials is a challenging task. Although several commercial instruments exist to measure reflectance, they have been developed for other applications and often do not meet all the specific requirements demanded by the solar thermal industry. In particular, the characterization of solar reflectors involve the complete solar spectral wavelength range, an incidence angle range from near normal to 70° and most importantly a very narrow acceptance angle range from near specular to 20 mrad. The accurate measurement of reflectance as a function of all the previously mentioned parameters has not been commercially implemented. This paper reviews the different alternatives to measure reflector materials, describes reflectance models used to approximate the missing information and presents current research work on prototype reflectometers to fill the gap

Identification of Soiling Properties for Different Minerals on Solar Mirrors via Artificial Soiling Setup

In order to assess the performance of solar reflectors or photovoltaic modules over their lifetime, standardized accelerated aging tests are often being applied. They are especially tailored to meet the environmental conditions where the components are going to be exposed during their service life. Already a number of standards are developed which deal with e.g. temperature and air humidity cycles, application of various chemical agents and radiation stresses. However, those accelerated durability tests do not involve the effect of soiling. Because solar industry is progressively targeting arid areas for their projects where an augmented aerosol concentration is present, efficiency losses due to soiling are gaining more an more importance in current research. The reliable and accurate laboratory simulation of this phenomenon is one of the first steps for improving O&M processes and also achieve technological progress in the development of novel components or coating systems [1]. In this work a possible artificial soiling (AS) setup to conduct such experiments is presented, its applicability is verified by the comparison to an outdoor soiling exposure. Furthermore, the setup is used to gain an understanding of the soiling properties of different minerals

Identification of Soiling Properties for Different Minerals on Solar Mirrors via Artificial Soiling Setup

In order to assess the performance of solar reflectors or photovoltaic modules over their lifetime, standardized accelerated aging tests are often being applied. They are especially tailored to meet the environmental conditions where the components are going to be exposed during their service life. Already a number of standards are developed which deal with e.g. temperature and air humidity cycles, application of various chemical agents and radiation stresses. However, those accelerated durability tests do not involve the effect of soiling. Because solar industry is progressively targeting arid areas for their projects where an augmented aerosol concentration is present, efficiency losses due to soiling are gaining more an more importance in current research. The reliable and accurate laboratory simulation of this phenomenon is one of the first steps for improving O&M processes and also achieve technological progress in the development of novel components or coating systems [1]. In this work a possible artificial soiling (AS) setup to conduct such experiments is presented, its applicability is verified by the comparison to an outdoor soiling exposure. Furthermore, the setup is used to gain an understanding of the soiling properties of different minerals

Effect of long term outdoor exposure on antisoiling coatings for solar reflectors

Results of the outdoor exposure campaign of two newly developed anti-soiling coatings for CSP mirrors are presented in this paper. Samples of coated mirrors were exposed for two years under realistic outdoor conditions and the application of two different cleaning techniques was investigated. Mirror samples were analyzed during exposure and their reflectance and cleanliness were measured. The performance of the anti-soiling coated mirror samples was compared to conventional uncoated mirrors. Depending on the selected combination of coating and cleaning technique, an advantage or disadvantage was observed over the exposure duration. One coating presented an overall cleanliness gain of 0.008 with pressurized water cleaning, due to its superior anti-soiling behavior, while presenting a negative gain of -0.009 with contact cleaning, due to its poor durability. The other coating showed a worse anti-soiling behavior, with a negative gain of -0.005 for pressurized water cleaning, due to its poor washability, and a positive gain of 0.005 with contact cleaning