رفتار سازه ماکروسکوپی در مقیاس کوچک نمونه اولیه PHE تحت شرایط آزمون درجه حرارت بالا

PHE (Process Heat Exchanger) is a key component to transfer the high temperature heat generated from a VHTR (Very High Temperature Reactor) to the chemical reaction for massive production of hydrogen. Korea Atomic Energy Research Institute established a small-scale gas loop for the performance test of VHTR components and manufactured a PHE prototype in order to test in the small-scale gas loop. In this study, in order to investigate the macroscopic structural characteristics and behaviour of the PHE prototype under the test condition of the small-scale gas loop, we carried out high-temperature structural analysis modelling, thermal analysis, and an elastic/elastic-plastic structural analysis for the PHE prototype under the loop test conditions as a precedent study prior to the performance test in the small-scale gas loop. The results obtained in this study will be compared with the performance test results in the near future.

Hydrogen is considered a promising future energy solution because it is clean, abundant and storable and has a high energy density. One of the major challenges in establishing a hydrogen economy is how to produce massive quantities of hydrogen in a clean, safe, and economical way. Among the various hydrogen production methods, hydrogen production using the high temperature heat from nuclear energy has been the focus of recent research [1]. Researches demonstrating the massive production of hydrogen using a VHTR (Very High Temperature Reactor) designed for operation up to 950

To discover the high-temperature structural integrity of the PHE prototype prior to the actual performance test, FE modeling, thermal analysis, and high-temperature elastic and elastic-plastic structural analyses were carried out under the test conditions of the small-scale gas loop established at KAERI. As a result of these analyses, we drew the following conclusions. 1. Under temperature/pressure, the maximum stress at the pressure boundary of the PHE prototype from the elastic structural analysis is much higher than the yield stress of Hastelloy-X. Thus, a way to strengthen the structural integrity of the PHE prototype should be discovered. 2. Under temperature/pressure, the maximum equivalent plastic strain at the pressure boundary of the PHE prototype from the elastic-plastic structural analysis is very high, even if most of the PHE pressure boundary remains in the elastic region. Therefore, a way to modulate the creep-fatigue damage of the PHE prototype should be ascertained. 3. Temperature is a far more influential on the structural integrity of the PHE prototype than pressure. Therefore, thermal expansion and thermal stress are very important for the structural integrity evaluation of the PHE prototype in the small-scale gas loop.