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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigation of Machine Learning Regression Techniques to Predict Critical Heat Flux

Helmryd Grosfilley, Emil January 2022 (has links)
A unifying model for Critical Heat Flux (CHF) prediction has been elusive for over 60 years. With the release of the data utilized in the making of the 2006 Groeneveld Lookup table (LUT), by far the largest public CHF database available to date, data-driven predictions on a large variable space can be performed. The popularization of machine learning techniques to solve regression problems allows for deeper and more advanced tools when analyzing the data. We compare three different machine learning algorithms to predict the occurrence of CHF in vertical, uniformly heated round tubes. For each selected algorithm (ν-Support vector regression, Gaussian process regression, and Neural network regression), an optimized hyperparameter set is fitted. The best performing algorithm is the Neural network, which achieves a standard deviation of the prediction/measured factor three times lower than the LUT, while the Gaussian process regression and the ν-Support vector regression both lead to two times lower standard deviation. All algorithms significantly outperform the LUT prediction performance. The neural network model and training methodology are designed to prevent overfitting, which is confirmed by data analysis of the predictions. Additionally, a feasibility study of transfer learning and uncertainty quantification is performed, to investigate potential future applications.

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