Thermal-Hydraulics and Energy Systems

点击翻译按钮获取中文摘要

World energy demand will rise by 45% in 2030; however, current trends in energy supply and consumption don't satisfy environmental sustainability. Thus, maintaining economy growth and acceptable social standards, necessitates efficient energy conversion techniques. Objectives of this proposal are committed to lie on top of these requirements throughout three themes. i) Study the behaviour of water at supercritical conditions: Ten countries are collaborating (Generation-IV International Forum) to develop nuclear reactors for replacing present technologies, their main characteristics are: competitiveness, sustainability, safety and resistance to proliferation. Canada is involved on the design of a Supercritical Water-cooled Reactor (SCWR). However, the thermalhydraulics of water beyond its critical point is still unclear. Support from NSERC/NRCan/AECL and Hydro-Québec has made possible the construction of a 750 kW supercritical water loop at École Polytechnique. This loop (unique in Canada) will be used to perform supercritical water (SW) pressure drop and forced convective heat transfer experiments. Test sections will be manufactured from Hastelloy C-276 to study supercritical flows under deteriorated heat transfer regimes. These data is mandatory for designing components of SCWR's. Long-term objectives will involve modeling thermalhydraulics behaviour of SW. ii) Study CANDU moderator flow instabilities: CANDU reactors are one of the safest systems that contribute decreasing greenhouse emissions with low environmental impact. Nevertheless, since 1980, simulations indicated the existence of moderator flow instabilities. It is possible that they are triggered by competition between density driven momentum and inertia coupled to heat transfer and neutron flux distributions. Due to computational limitations, past simulations were performed using a distributed porosity model approach. This technique limits calculations to correctly represent the physics of the problem. In fact, 380 fuel channels in the calandria (approx. 6 m x 6 m cylinder), jointly with small water injectors of few cm, makes the numerical problem quite complex. Simulations based on 2D Navier-Stokes equations necessitate at least 3.5 million elements. In this project, we will implement a 3D CFD model to be solved with the Québec high performance computing network using "Code-Saturne" software and 100 million elements. CFD simulations will be coupled with neutron simulations. Numerical data will permit us to understand the phenomena and characterize the flow based on dimensionless numbers. In long-term, valuable models for the nuclear industry will be developed. iii) Exergy modeling and optimization of integrated energy systems: Environmental impact of energy consumption decreases with increasing performance of energy conversion units. Better use of energy resources can be achieved by integrating different sources and technologies. Integration increases the difficulty to determine optimal equipment operation that must satisfy external constrains (weather.) System analyses cannot be performed using only the first law of thermodynamics. In a short-term, first and second laws (exergy) will be applied to create models and optimization tools. Matrix and graphic representations of distributed exergy sources and destruction sinks in integrated systems will be developed. In a long-term, superstructure matrix implementations within stochastic algorithms will be used for optimization. We have more than 30 years of experience working in nuclear and conventional energy areas. Outcomes from this program should have direct impact on nuclear, thermal, solar and geothermal technologies, and thus contribute to the industrial and economical wellbeing of Canada.