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Chambers, Terrence L.

Publications and source records attributed to Chambers, Terrence L..

Open‐source photovoltaic model pipeline validation against well‐characterized system data

Abstract All freely available plane‐of‐array (POA) transposition models and photovoltaic (PV) temperature and performance models in pvlib‐python and pvpltools‐python were examined against multiyear field data from Albuquerque, New Mexico. The data include different PV systems composed of crystalline silicon modules that vary in cell type, module construction, and materials. These systems have been characterized via IEC 61853‐1 and 61853‐2 testing, and the input data for each model were sourced from these system‐specific test results, rather than considering any generic input data (e.g., manufacturer's specification [spec] sheets or generic Panneau Solaire [PAN] files). Six POA transposition models, 7 temperature models, and 12 performance models are included in this comparative analysis. These freely available models were proven effective across many different types of technologies. The POA transposition models exhibited average normalized mean bias errors (NMBEs) within ±3%. Most PV temperature models underestimated temperature exhibiting mean and median residuals ranging from −6.5°C to 2.7°C; all temperature models saw a reduction in root mean square error when using transient assumptions over steady state. The performance models demonstrated similar behavior with a first and third interquartile NMBEs within ±4.2% and an overall average NMBE within ±2.3%. Although differences among models were observed at different times of the day/year, this study shows that the availability of system‐specific input data is more important than model selection. For example, using spec sheet or generic PAN file data with a complex PV performance model does not guarantee a better accuracy than a simpler PV performance model that uses system‐specific data.

14 SOLAR ENERGY↗

Analytical Investigation of a Reflux Boiler

A thermal model of a single Ultralight Fabric Reflux Tube (UFRT) was constructed and tested against data for an array of such tubes tested in the NASA-JSC facility. Modifications to the single fin model were necessary to accommodate the change in radiation shape factors due to adjacent tubes. There was good agreement between the test data and data generated for the same cases by the thermal model. The thermal model was also used to generate single and linear array data for the lunar environment (the primary difference between the test and lunar data was due to lunar gravity). The model was also used to optimize the linear spacing of the reflux tubes in an array. The optimal spacing of the tubes was recommended to be about 5 tube diameters based on maximizing the heat transfer per unit mass. The model also showed that the thermal conductivity of the Nextel fabric was the major limitation to the heat transfer. This led to a suggestion that the feasibility of jacketing the Nextel fiber bundles with copper strands be investigated. This jacketing arrangement was estimated to be able to double the thermal conductivity of the fabric at a volume concentration of about 12-14%. Doubling the thermal conductivity of the fabric would double the amount of heat transferred at the same steam saturation temperature.

Simon, William E.↗