problem within the main body of the bed while a funnel flow problem within the
conical base.
Further optimization of the established model is carried out. In addition to the
investigation of the preferable wall structure, Prof. Jiang’s team has performed an
optimization study on flow-corrective insert, conical base, and discharging silo from
the reactor’s geometric perspective. The authors also contributed to the optimization of friction and flow dynamics from the mechanical perspective. The optimizations are very helpful for practical implementations and further developments
of HTGR in the nuclear industry, particularly the 600MW-HTR-PM project.
Quasi-static pebble flow in HTGR has provided numerous ideas to the solution
of non-uniformity and stagnation in the fuel cycle. In addition, heat transfer in a
pebble bed is of vital importance for the safety of the reactor.
Therefore, experiments in the full-radius-scale heat test facility measure the
effective thermal diffusivity and conductivity in four independent tests. Compared
with SANA (Secure Decay Heat Removal in German) and HTTU
(High-Temperature Test Unit in South Africa), this work expands the temperature
range of the effective thermal conductivity in the reactor and the methodology can
be applied to the measurement for temperatures up to 1600 °C, significantly contributing to the improvement of the inherent safety for HTGRs.
Numerical models of heat transfer in pebble beds of HTGRs present a comprehensive view on obtaining effective thermal conductivity. Continuum and discrete methods are adopted, and varying scales of radiation are discussed. Among
convective, conductive, and radiative heat transfers, radiation is particularly
important as the operating temperature in the reactor is about 800 °C and can reach
1600 °C in transient or severe accidents. In addition, radiation accounts for most
of the transferred heat. The Short-range Radiation Model (SRM), the improved
Short-Range Model (SRM+), the Long-range Radiation Model (LRM), the
Microscopic Scale Model (MSM), the Semi-Empirical Model (SEM), and the
Sub-Cell radiation Model (SCM) perform well under specific circumstances and
inspire the subsequent researches. Based on SRM, further improvement in coupled
CFD-DEM simulations by taking the coolant into consideration is pioneering in the
new smoothed void fraction method, which provides a brand-new view and challenge to investigate it profoundly.
I highly recommend this technical book to those who are interested in the
nuclear power industry, and also to professionals in the development of nuclear
energy, multiphase flow and heat transfer. Although Prof. Jiang’s team focused on
the complex system of helium and pebbles coupled with neutron-physics which
exists in the nuclear reactor core, the common solutions and schemes provided in
this book are indeed also applicable for the gas–particle multiphase flow and
high-temperature heat transfer systems in other research fields, e.g., the packed beds
or the spouted/fluidized beds in Engineering Thermophysics. This work not only
viii
Foreword by Hongguang Jin
conical base.
Further optimization of the established model is carried out. In addition to the
investigation of the preferable wall structure, Prof. Jiang’s team has performed an
optimization study on flow-corrective insert, conical base, and discharging silo from
the reactor’s geometric perspective. The authors also contributed to the optimization of friction and flow dynamics from the mechanical perspective. The optimizations are very helpful for practical implementations and further developments
of HTGR in the nuclear industry, particularly the 600MW-HTR-PM project.
Quasi-static pebble flow in HTGR has provided numerous ideas to the solution
of non-uniformity and stagnation in the fuel cycle. In addition, heat transfer in a
pebble bed is of vital importance for the safety of the reactor.
Therefore, experiments in the full-radius-scale heat test facility measure the
effective thermal diffusivity and conductivity in four independent tests. Compared
with SANA (Secure Decay Heat Removal in German) and HTTU
(High-Temperature Test Unit in South Africa), this work expands the temperature
range of the effective thermal conductivity in the reactor and the methodology can
be applied to the measurement for temperatures up to 1600 °C, significantly contributing to the improvement of the inherent safety for HTGRs.
Numerical models of heat transfer in pebble beds of HTGRs present a comprehensive view on obtaining effective thermal conductivity. Continuum and discrete methods are adopted, and varying scales of radiation are discussed. Among
convective, conductive, and radiative heat transfers, radiation is particularly
important as the operating temperature in the reactor is about 800 °C and can reach
1600 °C in transient or severe accidents. In addition, radiation accounts for most
of the transferred heat. The Short-range Radiation Model (SRM), the improved
Short-Range Model (SRM+), the Long-range Radiation Model (LRM), the
Microscopic Scale Model (MSM), the Semi-Empirical Model (SEM), and the
Sub-Cell radiation Model (SCM) perform well under specific circumstances and
inspire the subsequent researches. Based on SRM, further improvement in coupled
CFD-DEM simulations by taking the coolant into consideration is pioneering in the
new smoothed void fraction method, which provides a brand-new view and challenge to investigate it profoundly.
I highly recommend this technical book to those who are interested in the
nuclear power industry, and also to professionals in the development of nuclear
energy, multiphase flow and heat transfer. Although Prof. Jiang’s team focused on
the complex system of helium and pebbles coupled with neutron-physics which
exists in the nuclear reactor core, the common solutions and schemes provided in
this book are indeed also applicable for the gas–particle multiphase flow and
high-temperature heat transfer systems in other research fields, e.g., the packed beds
or the spouted/fluidized beds in Engineering Thermophysics. This work not only
viii
Foreword by Hongguang Jin