{'fraction_non_alphanumeric': 0.01858736059479554, 'fraction_numerical': 0.003304419661296985, 'mean_word_length': 5.131645569620253, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
C / SiC HX Thermal and Mechanical Analysis

This report summarizes UCB’s initial results and methods on C/SiC heat exchanger thermal and mechanical analysis for high temperature heat transfer under support from DOE National Hydrogen Initiative program (NHI) through UNLV HTHX project, as a part of efforts for nuclear hydrogen production. The intermediate heat exchanger (IHX) transfers heat from high temperature high pressure helium to a liquid salt intermediate loop which couples to hydrogen production loops. The IHXs operates at temperature from 600°C to 1000°C and pressure difference up to 8 MPa. The operating conditions are extremely challenging for metals to function in, while it is not challenging for carbon and silicon carbide composites. To be economically viable for hydrogen production, ceramic heat exchangers must have costs under a few tens of dollars per thermal kilowatt. Plate-type ceramic heat exchanger with relatively small flow channels provide a good candidate approach for this purpose, because they can obtain high power densities and low mechanical stresses with thin heat transfer surfaces and small amounts of material. Thermal and stress analysis are carried out to identify optimal designs for core heat transfer unit, inlet and outlet manifolds, distribution channels, and channel dividers. Finding detailed stress distribution in a complete heat exchanger with direct FEM (Finite Element Method) requires an order of billion FEM computation units and million hours PC computing time. Therefore, it is not practical to analyze the entire heat exchanger design directly. We propose an alternative method to obtain approximate stresses that only requires several days to finish in a fast PC. The methods are composed of three steps. First, the heat exchanger is broken down into several regions. Unit cell models are built based on each region that captures all of the most important features of that region. The effective mechanical and thermal properties for each unit cell are then founded through FEM simulations. Second, average stress distribution in an overall model composed of various unit cell regions is computed by using the effective mechanical and thermal properties. Third, these average stress values are then applied to the unit cells to find localized points of high stresses. Pro/Mechanica module (Pro/M) in the Pro/E Wildfire Edition is used for FEM stress analysis.