ENERGY SYSTEM & COMPONENT DESIGN
Generating electricity is getting more important in modern society. To meet the needs, safer and efficient power plant systems are extensively investigated. Since the basic components of the energy power plant system are thermodynamic cycles, improving each component such as heat exchangers for boiler and condenser, compressors, and turbines is also an issue in the field. Based on the understanding of thermodynamic cycles and heat & fluid dynamics, we are working on optimizing energy components to design the whole energy layout for future energy systems.
Printed Circuit Heat Exchanger (PCHE) design
PCHE is one of compact heat exchanger which can sustain high pressure and high temperature conditions due to the structural rigidity. They are widely chosen as a heat source and sink for a compact supercritical Brayton cycle power conversion system. The densely-stacked structure allows high compactness, and the diffusion-bounded junctions enable high rigidity. However, the optimized channel designs for PCHE is not yet determined. Therefore, we are actively working on understanding what phenomena happen in PCHE and find out the best channel designs for energy system applications.
Using low temperature heat for power generation
To mitigate environmental effects of coal-burning power plant, natural gas is regarded as a promising energy resource of clean energy because there is a little emission of CO2 and sulfur oxides compared with conventional coal power plant (however, still natural gas power plant emits global warming gas such as methane [the main element of natural gas] and some dust). Due to the large volume of natural gas, Liquefied Natural Gas (LNG) is actively used in actual industries and power plants. The thing is that the regasification process is required for actual use, and the regasification process used about 830 kJ/kg, which is waste energy called ‘cold energy’. To use low temperature energy for generating electricity, various energy layouts are considered, and we are investigating the optimized energy layout for Organic Rankine Cycle (ORC).
Sodium Fast Reactor (SFR) energy system layout design
A Sodium Fast Reactor (SFR) is a fast neutron reactor cooled by liquid sodium. Since the potential to use current Light Water Reactor (LWR) nuclear waste as nuclear fuel with the reprocessing procedure, SFR is considered as one solution to handle current nuclear waste problems. However, the detail layout of SFR is not yet fixed. Our group is actively working on to consider safety components preventing water-sodium reaction and to design actual SFR energy system layout. including heat exchanger as well as turbomachinery.
Hydrogen producttion - Two-step thermochemical water splitting method
Hydrogen is a promising energy carrier due to its abundance and high energy per mass content. Considering the climate emergency, a global problem, green hydrogen production without carbon dioxide emission is compromising. The two-step thermochemical water splitting method is one of the candidates for the massive green hydrogen production method. The method uses a two-step cycle using the non-stoichiometry of the metal oxides. As the non-stoichiometry is determined based on the condition (temperature, oxygen partial pressure), the system efficiency depends on the operating condition and system lay-out. Therefore, we are actively working on finding the optimal system lay-out and operating conditions. We also focus on the high temperature heat recuperations (solid-solid heat recuperator, fluid-fluid heat recuperator).
Heat pipe cooled micro-reactor design
A heat pipe cooled micro-reactor is a system that transfers heat transfer rate generated from nuclear fuel to the Power Conversion System (PCS) by using it as an intermediate medium for heat pipe. The heat pipe cooled micro-reactor has significant progress due to many advantages, which are a strong negative feedback, low power density, independent emergency control rod shutdown system and passive heat removal. But, the research on the detailed design of the PCS in micro-reactor remains insufficient. Our group is working on a detailed design for each component of a micro-reactor PCS including volume and boundary conditions, which is a key element for the micro-reactor to be transported to remote areas.