coupled natural circulation loops with source and sink ... ·...
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Coupled Natural Circulation Loops with Source and Sink Energy Exchange and Coupling Heat Exchanger
Dan Hughes
Hughes and Associate January 2016
Abstract The steady state performance of a mathematical model of a system of two coupled Natural Circulation Loops (NCLs) is analytically determined. The loops are stacked vertically with the hot primary loop on the bottom and the cool secondary loop above. The energy source is horizontal at the bottom of the primary loop and the energy sink is horizontal at the top of the secondary loop. A horizontal Heat Exchanger (HEX) between the loops couples the loops. Two arrangements for the energy source and sink are considered. For the first case energy is supplied to the high-‐temperature primary loop from a source of constant temperature and rejected from the low-‐temperature secondary loop into a sink of constant temperature. For the second case the energy source is a constant energy supply and the sink is a HEX. The horizontal energy source and sink offers considerable simplification of the analysis. These boundary conditions have not yet been considered in the literature. Other boundary conditions are briefly considered. Additionally, only one arrangement of the direction of flows in the loops is considered, and in the coupling and sink HEXs only co-‐current conditions are considered. The number of possible arrangements of energy source and sink (horizontal and vertical), loop flow direction, and flow conditions in the HEXs is quite large. The analytical solutions of the system of four algebraic equations for the first case and five equations for the second case that describe the operating state of the system are developed. The solutions are expressed in terms of the specified boundary conditions and the thermal-‐exchange properties of the energy source and sink and coupling HEX. Application of the solutions to the physical domain requires an iterative approach. These solutions form the basis for stability analyses of the coupled NCL system, but that is not carried out in these notes. The design of such systems, also an interesting problem, is not addressed here.
Introduction Single natural circulation loops have been the subject of experimental, analytical and numerical research for several decades since the early 1950s. The literature is very extensive with investigations continuing to this day. Much of the research has been directed toward various systems of electric power generation by nuclear power plants. Coupled NCLs, on the other hand, have not been much investigated. The objectives of the present notes include development of model equations for transient and steady state flows in coupled NCLs and analytical solutions for the steady state equations.
Energy Source and Sink Temperature Specified A sketch of the system of coupled natural circulation loops is shown in Figure 1. The primary loop is at the bottom of the sketch and the secondary loop at the top. The sketch shows the loop dimensions to be the same, but that is not necessary for the analysis and is used to simplify the equation processing. The two rectangular loops are thermally coupled by convection on each side of the coupling HEX and conduction through the walls of the HEX. Energy exchange at the heater at the hot end of the primary loop, and at the cold end of the secondary loop is by convection between the fluid and the flow-‐channel wall. For the initial modeling the loops are assumed to be constant flow area and irreversible local pressure losses are ignored. These idealizations are easily removed by straightforward algebra. For the first model, the wall temperature in the regions of energy exchange is constant at Tsrc for the source at the bottom of the primary loop, and Tsnk at the top of the secondary loop. Relative to Figure 1, this assumption means that the following relationship holds for the temperatures shown in the figure Tsrc ≥Thp ≥Tp,hex ≥Ts,hex ≥Tcs ≥Tsnk (1.1)
The geometrical description as shown in Figure 1, which applies also to the second case, is summarized as follows: Vertical height of the Primary Loop
Horizontal length of the Primary Loop Horizontal length of the Energy Source at the Primary Loop Horizontal length of the Coupling Heat Exchanger Vertical height of the Secondary Loop Horizontal length of the Secondary Loop Horizontal length of the energy Sink at the Secondary Loop
Hp
LpLhexpLhexHs
LsLhexs
Energy Input
Energy Sink
Heat Exchanger
Primary Loop
Secondary Loop
Hp
Lp
Lhex
Ls
Hs
Psec
Ppri
Tsrc
Tsnk
Thp
Ths
Ths
Tcs
Tcs
Tcp
Thp Tcp
The temperature at certain locations round the loops, also indicated in Figure 1 is summarized as follows: Tsrc Temperature of the source Tcp Temperature of the cool primary fluid Thp Temperature of the hot primary fluid Tcs Temperature of the cool secondary fluid Ths Temperature of the hot secondary fluid Tsnk Temperature of the sink. The temperature of energy supply at the bottom of the primary loop, Tsrc and the energy sink at the top of the secondary loop, Tsnk are specified constants. For the second case, Tsnk is replaced by Tcin , the temperature at the inlet to the sink HEX. When referring to the fluid temperature in the loop at the boundaries of the energy exchange locations, the subscripts ‘p’ and ‘s’, for primary and secondary, respectively, will be appended to differentiate loop states from fluid states external to the loop. Some of the compound mnemonics are very frequently used in subscripts are constructed with; hex refers to the coupling HEX, shex refers to the HEX at the sink, snk refers to the sink fluid. An example symbol is Stsnk,shex , which represents the Stanton number for the fluid on the sink side of the sink HEX. A detailed list of the Nomenclature is given at the end of these notes. The flow directions shown in the figure are clockwise for the hot primary loop and counter-‐clockwise for the cool secondary loop. This flow-‐direction arrangement gives co-‐current flow conditions in the coupling HEX. Other flow directions in both loops are possible, and either of the loops in the Figure can flow in the opposite direction. Because the temperature distribution in the loops is a function of the flow directions, the analysis in these notes will consider only this case. Other cases might be considered in future notes.
Locations and Boundary Conditions The locations along the loops are measured in the direction to the right from the left-‐hand edge of the coupling HEX. A notation for the following locations and corresponding fluid temperature will simplify the equation processing. Primary Loop Description Temperature Description
ssrc,i = Lp +Hp Source Inlet Tp ssrc,i = Lp + Hp( ) = Tcp Cold Primary ssrc,o = 2Lp +Hp Source Outlet Tp ssrc,o = 2Lp + Hp( ) = Thp Hot Primary sphex,i = 0 HEX Inlet Tp sphex ,i = 0( ) = Thp Hot Primary sphex,o = Lp HEX Outlet Tp sphex,o = Lp( ) = Tcp Cold Primary
Secondary Loop Description Temperature Description sshex,i = 0 HEX Inlet Ts sshex ,i = 0( ) = Tcs Cold Secondary sshex,o = Ls HEX Outlet Ts sshex,o = Ls( ) = Ths Hot Secondary ssnk,i = Ls +Hs Sink Inlet Ts ssnk ,i = Ls + Hs( ) = Ths Hot Secondary ssnk,o = 2Ls +Hs Sink Outlet Ts ssnk ,o = 2Ls + Hs( ) = Tcs Cold Secondary
The locations and fluid states summarized above provide Boundary Conditions (BCs) for the model equations.
General Transient Model Equations The model equations for balance of mass, momentum, and energy for each loop are developed in the following discussions. This initial effort will consider only constant-‐diameter loops and all the usual assumptions and idealizations applied to natural-‐circulation loop flows. These idealizations include: (1) constant thermophysical and transport properties for the fluid, (2) uniform distributions of all flow-‐field quantities across the flow channels, (3) the fluid is thermally expandable: variations in density with pressure are neglected, (4) buoyancy forces due to fluid density variations are accounted for by the linear Bousinesq approximation, (5) conduction heat transfer characteristics of all the piping-‐wall materials can be neglected when modeling transient response, (6) axial heat conduction in the working fluids and piping materials is neglected, (7) energy losses from the outside of the piping are neglected, (8) conversion of mechanical energy into thermal energy by means of viscous dissipation is neglected, (9) pressure-‐volume work terms in the energy equation model are also neglected, and (10) parallel flow paths everywhere in the systems are not accounted for (11) the solid materials bounding the fluids are ignored (12) all hardware and engineered devices, other than the HEXs, is ignored. With these assumptions, the one-‐dimensional forms of the model equations for fluid flow are as follows: ∂∂t M + ∂
∂lW = 0 (1.2)
for conservation of mass, 1Af
∂∂tW + ∂
∂lW 2
ρAf2 = − ∂
∂l P− RwfW WρAf
2 + ρgcosθ (1.3)
for a momentum balance model, where the resistance to flow is
Rf =18 Awf fw (1.4)
for distributed wall friction, where Awf is the wetted wall area per unit volume of fluid for friction. Local irreversible losses will be included into the flow resistance as specific models are developed. Generally, the wetted wall area per unit volume is related to the equivalent hydraulic diameter by
Awf =4Dhy
(1.5)
where
Dhy =4Af
pw (1.6)
is the equivalent hydraulic diameter. Conservation of energy, written in terms of the fluid temperature, is ∂∂tAfρCpT + ∂
∂lWCpT = Af Awh ′′qwf +
∂∂tP + W
ρAf
∂∂lP + fw
2Dhy
W WρAf
2
⎡
⎣⎢⎢
⎤
⎦⎥⎥ (1.7)
where Awh is the heated wall area for heat transfer per unit fluid volume,
Awh =4Dhe
(1.8)
where
Dhe =4Af
ph (1.9)
and Dhe is the heated equivalent diameter. The wall-‐to-‐fluid heat flux, the first term on the tight-‐hand side of Eq. (1.7) is
′′qwf = hcwf Tw −T( ) (1.10)
and hcwf is the wall-‐to-‐fluid heat transfer coefficient. Special cases for the wall-‐to-‐fluid energy exchange will be considered as the analyses are developed later in these notes. The last two terms on the right-‐hand side of Eq. (1.7) are almost always neglected for applications to natural circulation flows, and we will do so. The Equation of State (EoS) returns the fluid density given the pressure and temperature
(1.11) Generally, for applications to natural circulation loops, the EoS is evaluated at a reference pressure and the fluid density taken to be a function of only the temperature
(1.12)
and is represented by a linear EoS
(1.13)
where is the coefficient of thermal expansion. For analyses of two-‐phase fluid states the independent properties used in the EoS must be other than pressure and temperature. The model equations for analyses of transients will be the subject of later analyses. The steady state forms are developed next.
Steady State Model Equations The steady state equations are ∂∂lW = 0 (1.14)
for mass conservation,
ρ = ρ P,T( )
ρ = ρ Pref ,T( )
ρ = ρ0 1−β T −T0( )⎡⎣
⎤⎦
β
∂∂lW 2
ρAf2 = −
∂∂l P− Rwf
W WρAf
2 + ρgcosθ (1.15)
for a momentum balance, and ∂∂lWCpT = Af Awh ′′qwf (1.16)
for energy conservation. Equation (1.14) indicates that the mass flow rate is everywhere the same in the loop. The flow rate is given by the solutions of the coupled momentum and energy equations. For a constant flow area, and small changes in the fluid density, the term on the left-‐hand side of the momentum balance can be neglected, and the momentum model reduces to a balance between the pressure and buoyancy and the friction losses.
Momentum Balance The fluid density is given by Eq. (1.13), and putting that equation into the momentum balance gives ∂∂lW 2
ρAf2 = −
∂∂l P− Rwf
W Wρ0Af
2 + ρ0 1−β T −T0( )⎡⎣
⎤⎦gcosθ (1.17)
Integrating the momentum balance around a loop, neglecting the momentum flux term on the left-‐hand side, gives
Af Rwf
W Wρ0Af
2 = Afρ0 1−β T −T0( )⎡⎣
⎤⎦gcosθ dl!∫ (1.18)
where variations in the fluid density are included in only the gravitational term. Evaluation of the integral around the loops requires that the temperature distribution first be evaluated so that the integral on the right-‐hand side can be evaluated. Note that the integral only has non-‐zero values in the vertical segments of the loops. This property leads to the geometric arrangement of Figure 1 that is used in these notes. The flow-‐resistance factor, Rwf , for distributed wall friction and local irreversible losses, has the general form
Rwf =18 Awf fw +
12Kllδ l − lll( )⎡
⎣⎢⎤⎦⎥ (1.19)
where the first contribution is due to distributed wall friction and the second due to local irreversible losses, and δ l − lll( ) is the Dirac-‐delta function. The wall-‐to-‐fluid friction factor can be represented in general form by fw =Cwf /Rem (1.20) where Cwf = 64.0 and m =1 for laminar flow, and Cwf = 0.3164 and m = 0.25 for lower values of the Reynolds number (Re <105 ) and Cwf = 0.184 and m = 0.20 for fully-‐developed turbulent flow (Re >105 ). The numerical value of the local loss factor, Kll , depends on the geometry of the flow channel and fluid flow rate at the location of the loss. For the fluid flow and energy exchange arrangement shown in Figure 1, the momentum balance of Eq. (1.18) gives
AfpRwfpWp Wp
ρ0 pAfp2 = Afpρ0 pβ pg Thp −Tcp( ) (1.21)
for the hot primary loop, and
AfsRwfsWs Ws
ρ0sAfs2 = Afsρ0sβsg Ths −Tcs( ) (1.22)
for the secondary loop. Neglecting the local irreversible losses and using Eq. (1.20) for the distributed wall friction factor, Eqs. (1.21) and (1.22) can be written
Rep =2Cwf
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)
Grp( )1 3−m( ) (1.23)
and
Res =2Cwf
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)
Grs( )1 3−m( ) (1.24)
where
Re =WDhy
Afµ (1.25)
is the Reynolds Number, and
Gr = Dhe3 ρ02βgµ2
Th −Tc( ) (1.26)
is the Grashof Number. The temperature difference, Thp − Tcp( ) and Ths −Tcs( ) , needed to complete the solution is developed in the flowing discussions.
Temperature Distributions The temperature distribution around the loops, necessary for integration of the momentum model, is obtained by integration of the steady-‐state energy equation around the loops. The energy equation is of interest only in the sections over which energy exchange occurs, i.e. the bottom of the hot primary loop and the top of the cool secondary loop. For all the adiabatic sections ∂∂l T = o (1.27)
and the temperature is constant at the value that the fluid attains at the exit from the energy-‐exchange sections; the primary loop energy source and the secondary loop energy sink. The distance along the loop is measured to the right from the inlet of the coupling HEX. In the coupling HEX section the distance along the loops is the same and the energy conservation model of Eq. (1.16) is
WpCp,p∂∂sTp = Afp,hexAwhp,hexUp Ts −Tp( ) (1.28)
for the primary loop, and
WsCp,s∂∂sTs = Afs,hexAwhs,hexUs Tp −Ts( ) (1.29)
for the secondary loop. Along the direction of flow the fluid temperature in the primary loop decreases, and in the secondary loop increases.
Equations (1.28) and (1.29) can be written ∂∂sTp = St p,hex Ts −Tp( ) (1.30)
and ∂∂sTs = Sts,hex Tp −Ts( ) (1.31)
respectively, where St is a Stanton Number per unit length. The initial conditions are Tp sphex,i = 0( ) = Tph for the primary side, and Ts sshex,i = 0( ) = Tsc for the secondary side. At steady state conditions, St p,hex Ts −Tp( ) = Sts,hex Tp −Ts( ) (1.32)
In the primary loop from the outlet from the coupling HEX around to the entrance to the energy source the fluid temperature, by Eq. (1.27), is Tp =Tpc (1.33) For the energy source at the bottom of the primary loop, the source temperature is taken to be constant and the energy equation model becomes
WpCp,p∂∂lp
Tp = AfpAwhphc,src Tsrc,p −Tp( ) (1.34)
or ∂∂lp
Tp = Stsrc Tsrc,p −Tp( ) (1.35)
which holds from the entrance to exit of the energy-‐source section; Lp + Hp( ) ≤ lp ≤ 2Lp + Hp( ) , and the initial condition, by Eq. (1.33), is Tp Lp +Hp( ) = Tpc (1.36)
For the first simple case considered in these notes, the length of the energy-‐source section is taken to occupy the total horizontal length of the primary loop. This is
merely for convenience, and can be assigned to be a fraction of that total length: Lsrc,p = Fsrc,pLp , for example. From the outlet of the coupling HEX in the cool secondary loop to the inlet to the energy sink section, the fluid temperature, by Eq. (1.27) is Ts = Ths (1.37) For the energy sink at the top of the secondary loop
WsCp,s∂∂lsTs = AfsAwhshc,snk Tsnk,s −Ts( ) (1.38)
or ∂∂lsTs = Stsnk Tsnk,s −Ts( ) (1.39)
which holds for (Ls +Hs )≤ ss ≤ 2Ls +Hs( )( ) , with the energy sink temperature taken to be a constant, and the initial condition by Eq. (1.37), is Ts Hs( ) = Ths (1.40)
Steady State Temperature Distribution The temperature distribution in the various sections of the loops is determined with the equation specifications in the previous section. Starting with the energy source segment, Eq. (1.35) and initial condition Eq. (1.37), integration and applying the initial condition gives the fluid temperature distribution in the energy-‐source segment
Tp = Tsrc + e− Stsrclp Tpc −Tsrc( ) (1.41)
for ssrc,i ≤ lp ≤ ssrc,o( ) . This gives the primary fluid temperature at the exit from the energy-‐source segment Thp =Tsrc + e−Stsrc Tcp −Tsrc( ) (1.42)
where
Stsrc = StLsrc (1.43) The same approach applied to the energy-‐sink segment in the secondary loop, Eqs. (1.39) and (1.40) give the secondary side fluid temperature distribution within the sink segment
Ts =Tsnk + e−Stsnkls Ths −Tsnk( ) (1.44)
which holds for ssnk,i ≤ ls ≤ ssnk,o( ) . The temperature at the exit from the energy-‐sink segment is Tcs =Tsnk + e
−Stsnk Ths −Tsnk( ) (1.45) The temperature distribution in the primary and secondary sides of the coupling HEX is obtained by solving the coupled Eqs. (1.30) and (1.31) and initial conditions Tp sphex,i = 0( ) = Tph for the primary side, and Ts sshex,i = 0( ) = Tsc . The temperature distribution in the primary side of the coupling HEX is
Tp,hex =StsThp + St pTcsSt p + Sts
+St p
St p + StsThp −Tcs( )e−(Stp+Sts )lp (1.46)
and the temperature at the outlet, lp = LHEX , is
Tp,hexo =StsThp + St pTcsSt p + Sts
+St p
St p + StsThp −Tcs( )e−(Stp+Sts )LHEX (1.47)
The temperature distribution in the secondary side of the coupling HEX is
Ts,hex =StsThp + St pTcsSt p + Sts
+ StsSt p + Sts
Tcs −Thp( )e−(Stp+Sts )ls (1.48)
and the temperature at the outlet, ls = LHEX ,
Ts,hexo =StsThp + St pTcsSt p + Sts
+ StsSt p + Sts
Tcs −Thp( )e−(Stp+Sts )LHEX (1.49)
The four equations for Thp , Tcs , Tp,hexo = Tcp , and Ts,hexo = Ths , Eqs. (1.42), (1.45), (1.47), and (1.49), respectively can be solved to obtain expressions that involve the thermal performance of the energy-‐exchange devices and the source and sink temperatures which are the boundary conditions for the system. These are mighty complex expressions. I’m considering how to display those expressions. In the meantime, the quantities needed for the momentum balance models for the primary and secondary sides, Eqs. (1.23) and (1.24) need only the temperature differences Thp −Tcp( )and Ths −Tcs( ) , respectively. So we will focus on those for the time being. Those equations contain the following common factor in the numerator
FACT = eStsrc −1( ) eStsnk −1( ) e Stp,hex+Sts,hex( ) −1⎛⎝⎜
⎞⎠⎟
(1.50)
Those equations also contain the following common expression for the denominator
DEN = Sts,hex eStsrc −1( ) eStsnk e Stp,hex+Sts,hex( ) −1⎡
⎣⎢⎤⎦⎥
+St p,hex eStsnk −1( ) eStsrce Stp,hex+Sts,hex( ) −1⎡
⎣⎢⎤⎦⎥
(1.51)
Both of the above can be re-‐arranged in a multitude of different ways. In particular the positive exponents can be converted to negative exponents and a common factor cancelled in the numerator and denominator. With Eqs. (1.50) and (1.51) the temperature difference for the hot primary loop, ΔTpri = Thp −Tcp is
ΔTpri =St p,hexDEN FACT Tsrc −Tsnk( ) (1.52)
The temperature difference for the cool secondary loop, ΔTsec = Ths −Tcs , is
ΔTsec =Sts,hexDEN FACT Tsrc −Tsnk( ) (1.53)
Putting Eqs. (1.52) and (1.53) into the momentum model solutions of Eqs. (1.23) and (1.24) gives
Rep =2Cwfp
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)Dhep3 ρ0 p2 β pgµp2 St p,hex
FACTDEN
Tsrc −Tsnk( )⎛
⎝⎜
⎞
⎠⎟
1 3−m( )
(1.54)
for the primary loop, and
Res =2Cwfs
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)Dhes3 ρ0s2 βsgµs2 Sts,hex
FACTDEN
Tsrc −Tsnk( )⎛⎝⎜
⎞⎠⎟
1 3−m( ) (1.55)
for the secondary loop. Equations (1.54) and (1.55) can be written in the usual form for these results as
Rep =2Cwfp
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)Dhep3 ρ0 p2 βpgµp2 Tsrc −Tsnk( )
⎛
⎝⎜⎜
⎞
⎠⎟⎟
1 3−m( )St p,hex
FACTDEN
⎛⎝⎜
⎞⎠⎟
1 3−m( ) (1.56)
and
Res =2Cwfs
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)Dhes3 ρ0s2 βsgµs2
Tsrc −Tsnk( )⎛
⎝⎜
⎞
⎠⎟
1 3−m( )
Sts,hexFACTDEN
⎛⎝⎜
⎞⎠⎟
1 3−m( ) (1.57)
Note that while explicit equations have been obtained application requires an iterative procedure because each of the thermal and hydrodynamic variables are dependent on all other thermal and hydrodynamic variables.
Specified, Constant, Energy Source with HEX Sink Consider the case of specified energy addition at the source with a HEX at the sink. A sketch of the system is given in Figure 2. For the flow directions indicated on the Figure both the coupling HEX and the HEX at the sink are co-‐current. In this regard, the model equations developed in the previous section will be useful. The momentum equation models of Eqs. (1.21) and (1.22) apply to this case. The energy equation model for the source, Eq. (1.41) and the temperature of the primary-‐loop fluid at the exit from the source, Eq. (1.42) also apply. The energy balance for the coupling HEX, Eqs. (1.28) and (1.29), adapted to the sink HEX also apply.
Energy Input
Energy Sink
Heat Exchanger
Primary Loop
Secondary Loop
Hp
Lp
Lhex
Ls
Hs
Psec
Ppri
Tsrc
TcinTcout
Thp
Ths
Ths
Tcs
Tcs
Tcp
Thp Tcp
Lhexs
We first look at the primary-‐loop fluid temperature. The steady state temperature distribution in the energy source segment is given by Eq. (1.16) ∂∂lp
Tp =AfpAwhpWpCp,p
′′qwp(lp ) (1.58)
which holds for Lp + Hp( ) ≤ lp ≤ 2Lp + Hp( )( ) and where the specified energy source, ′′qwp(lp ) , can be a function of the location within the source. The source will be taken
to be a constant for this first case and integration gives
Tp lp( ) = Tcp + AfpAwhpWpCpp
lp ′′qwp (1.59)
At the exit from the source segment, the fluid temperature is
Thp = Tcp +Qwfp
WpCpp (1.60)
where Qwfp = PwfpLsrc ′′qwp is the power added into the fluid across the entire source. Equation (1.60) gives the temperature difference that is the driving potential in the primary loop. The mass flow rate, Wp , however, is a function of the performance of the complete system and is not yet known. Applying the HEX energy balance of Eqs. (1.30) and (1.31) to the HEX at the sink gives
WsCp,s∂∂sTs = Afs,snkAwhs,snkUs Tsnk −Ts( ) (1.61)
for the secondary-‐loop side of the HEX, and
WsnkCp,snk∂∂sTsnk = Afsnk,snkAwhsnk,snkUsnk Ts −Tsnk( ) (1.62)
for the sink side of the HEX. The solutions for the distributions are
Ts,snk =StsnkThs + Sts,snkTcinStsnk + Sts,snk
+Sts,snk
Stsnk + Sts,snkThs −Tcin( )e−(Stsnk+Sts ,snk )lsnk ,hex (1.63)
for the secondary-‐loop fluid. The secondary side fluid temperature at the sink HEX outlet is
Tcs =StsnkThs + Sts,snkTcinStsnk + Sts,snk
+Sts,snk
Stsnk + Sts,snkThs −Tcin( )e−(Stsnk+Sts ,snk ) (1.64)
where St = StLsnk ,hex . The temperature distribution on the sink side of the sink HEX is
Tsnk =StsnkThs + Sts,snkTcinStsnk + Sts,snk
+ StsnkStsnk + Sts,snk
Tcin −Ths( )e−(Stsnk+Sts ,snk )lsnk ,hex (1.65)
and the sink coolant outlet temperature is
Tcout =StsnkThs + Sts,snkTcinStsnk + Sts,snk
+ StsnkStsnk + Sts,snk
Tcin −Ths( )e−(Stsnk+Sts ,snk ) (1.66)
Equations (1.47), (1.49), (1.60), (1.64), and (1.66) for the solutions Thp , Tp,hexo = Tcp , Ts,hexo = Ths , Tcs and Tcout .
Thp = Tcin −Qwfp
WpCpp
ℑ •( )St p,hexSts,shex
e Stp,hex+Sts ,hex( ) −1⎛⎝⎜
⎞⎠⎟−1
e Sts ,shex+Stsnk ,shex( ) −1⎛⎝
⎞⎠
−1
(1.67)
for the high temperature in the primary loop, where ℑ •( ) = ℑ St p,hex , Sts,hex , St ps,shex , Stsnk,shex ,Stp,hex ,Sts,hex ,Stps,shex ,Stsnk,shex( )
= St p,hexSts,shex e Sts,shex+Stsnk ,shex( ) −1⎛⎝⎜
⎞⎠⎟eStp,hex+Sts,hex⎛⎝
⎞⎠⎛
⎝⎜⎞
⎠⎟
+Sts,hexSts,shex eStp,hex+Sts,hex+Sts,shex+Stsnk ,shex( ) −1⎛
⎝⎜⎞⎠⎟
+Sts,hexStsnk,shexeSts,shex+Stsnk ,shex( ) e Stp,hex+Sts,hex( ) −1⎛
⎝⎜⎞⎠⎟
(1.68)
Tcp = Tcin +Qwfp
WpCpp
eStp,hex+Sts ,hex( )
−1⎛⎝⎜
⎞⎠⎟−1
+Stsnk ,shex
St p,hexSts,shex1− e− Sts ,shex+Stsnk ,shex( )( )−1⎡
⎣⎢⎢
⎤
⎦⎥⎥
+Qwfp
WpCpp
Sts,hexSt p,hex
e Stp ,hex+Sts ,hex+Sts ,shex+Stsnk ,shex( ) −1( )e Stp ,hex+Sts ,hex( ) −1( ) e Sts ,hex+Stsnk ,hex( ) −1( )
(1.69)
for the cool temperature in the primary loop,
Ths = Tcin +Sts,hexSt p,hex
Stsnk,shex + Sts,shexSts,shex
1− e− Sts,shex+Stsnk ,shex( )⎛⎝⎜
⎞⎠⎟−1 Qwfp
WpCpp (1.70)
for the high temperature in the secondary loop,
Tcs = Tcin +Sts,hexSt p,hex
Qwfp
WpCpp
Stsnk,shexSts,shex
+Stsnk,shex + Sts,shex
Sts,shexe Sts,shex+Stsnk ,shex( ) −1⎛
⎝⎜⎞⎠⎟−1⎡
⎣⎢⎢
⎤
⎦⎥⎥ (1.71)
for the cool temperature in the secondary loop, and
Tcout =Tcin +Sts,hexSt p,hex
Stsnk,shexSts,shex
Qwfp
WpCpp (1.72)
for the fluid temperature at the outlet from the sink HEX. These give the driving potential in the primary and secondary loops
ΔTp =Qwfp
WpCpp (1.73)
and
ΔTsec =Sts,hexSt p,hex
Qwfp
WpCpp (1.74)
respectively. The primary loop is not directly coupled to the secondary loop: the coupling is indirect through the effects of the mass flow rate. Plus I need to check some end conditions to see if the equations correctly produce these. Putting Eqs. (1.73) and (1.74) into the momentum model solutions of Eqs. (1.23) and (1.24) gives
Rep =2Cwfp
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)Dhep3 ρ0 p2 βpgµp2
Qwfp
WpCpp
⎛
⎝⎜⎜
⎞
⎠⎟⎟
1 3−m( ) (1.75)
and
Res =2Cwfs
⎛
⎝⎜
⎞
⎠⎟
1 (3−m)Dhes3 ρ0s2 βsgµs2
Qwfp
WpCpp
⎛
⎝⎜
⎞
⎠⎟
1 3−m( )Sts,hexSt p,hex
⎛
⎝⎜⎜
⎞
⎠⎟⎟
1 3−m( ) (1.76)
HEXs at the Source and Sink A sketch of this case is shown in Figure 3.
Energy Input
Energy Sink
Heat Exchanger
Primary Loop
Secondary Loop
Hp
Lp
Lhexp
Lhex
Ls
Hs
Psec
Ppri
Thout Thin
TcinTcout
Lhexs
Thp
Ths
Ths
Tcs
Tcs
Tcp
Thp Tcp
Conclusions Not many.
SYMBOLS AND ABBREVIATIONS
Nomenclature
A area, m2
A area per unit fluid volume, 1/m
Af flow area, m2
Cp specific heat at constant pressure,
J/kg K
D diameter, m
Dhe heated equivalent diameter, m
Dhy wetted equivalent diameter, m
fw friction factor
g gravitational body force, kg m/s2
G mass flux, kg/m2 s
Gr Grashof Number, gβΔTDhe3
υ 2
h enthalpy, J/kg
hc heat transfer coefficient, W/m2 K
hg vapor phase enthalpy, J/kg
hfg enthalpy of evaporation, J/kg
hl liquid phase enthalpy, J/kg
H vertical height, m
Kll local pressure loss factor
Subscripts
c cool, cooled, coupling
cp cool temperature primary loop
cs cool temperature secondary loop
ext external
g vapor
gs saturated vapor state
h hot, heated
hp hot temperature primary loop
hs hot temperature secondary loop
hex heat exchanger
i, in inlet
int internal
l liquid
ls saturated liquid state
lam laminar
lgs saturated liquid and vapor
ls saturated liquid state
0 reference state
o, out, outlet
p primary loop
l distance along loop, m
L horizontal length, m
M mass, kg
Npch phase change number
Nsub subcooling number
p perimeter, m
P pressure, N/m2
′′qw wall heat flux, W/m2
Q power, W
Rw flow resistance factor
Re Reynolds Number, WDhy
Afµ
St Stanton Number, hcρuCp
t time, s
T temperature, K
u speed, m/s
U overall heat transfer factor, W/m2
K
V fluid volume, m3
VSL slip velocity, m/s
W mass flow rate, kg/s
pri primary side of HEX
s secondary loop
sec secondary side of HEX
snk sink
src source
ss steady state
t total length
tur turbulent
w wall, wetted
wh wall heat
wf wall friction
Greek
α void fraction
β coefficient of thermal, 1/K
expansion
δ Dirac delta function
µ dynamic viscosity , kg/m sec
ρ density, kg/m3
υ kinematic viscosity, m2/s
Xm mass fraction
z axial direction, m
References Dipankar N. Basu, Souvik Bhattacharyya and P. K. Das, A review of modern advances in analyses and applications of single-‐phase natural circulation loop in nuclear thermal hydraulics, Nuclear Engineering and Design, Vol. 280, pp. 326-‐348, 2014. Leonardo Carlos Ruspini, Christiona Pablo Marcel and Alejandro Clausse, Two-‐phase flow instabilities: A review, International Journal of Heat and Mass Transfer, V0l. 71, pp. 521-‐548, 2014. Milan K. S. Sarkar, Abhilash K. Tilak, and Dipankar N. Basu, A state-‐of-‐the-‐art review of recent advance in supercritical natural circulation loops for nuclear applications, Annals of Nuclear Energy, Vol. 73, pp. 250-‐263, 2014. Octavio Slaazar, Mihir Sen, and Eduardo Ramos, Flow in conjugate natural circulation loops, Journal of Thermophysics, Vol. 2, pp. 180-‐183, 1988. Zhuo Wenbin, Huang Yanping, Xiao Zejun, Peng Chuanxin, and Lu Sanan, Experimental research on passive residual heat removal system of Chinese advanced PWR, Science and Technology of Nuclear Installations, Vol. 2014, Article ID 325356, 2014. S. Kim, Byoung-‐Uhn Bae, Yun-‐Je Cho, Yu-‐Sun Park, Kyoung-‐Ho Kang, and Byong-‐Jo Yun, “An experimental study on the validation of cooling capability for the passive auxiliary feedwater system (PAFS) condensation heat exchanger,” Nuclear Engineering and Design, vol. 260, pp. 54–63, 2013. P.K. Vijayan, Manish Sharma, and D.S. Pilkhwal, Steady state and stability characteristics of a Supercritical Pressure Natural Circulation Loop (SPNCL) with CO2, Bhabha Atomic Research Centre Mumbai, India Report, BARC/2013/E/003, 2013. Jin Der Lee, Chin Pan, Shaw Wen Chen, Nonlinear dynamic analysis of a two-‐phase natural circulation loop with multiple nuclear-‐coupled boiling channels, Annals of Nuclear Energy, Vol. 80, pp. 77-‐94, 2015. C. T’Joen and M. Rohde, Experimental study of the coupled thermo-‐hydraulic-‐neutronic stability of a natural circulation HPLWR, Nuclear Engineering and Design, Vol. 242, pp. 221-‐232, 2012. Dae-‐Hyun Hwang, Hyouk Kwon, and Seong-‐Jin Kim, investigation of two-‐phase flow instabilities under advanced PWR conditions, Annals of Nuclear Energy, Vol. 80, pp. 135-‐143, 2015.
A. K. Nayak and P. K. Vijayan, Flow instabilities in boiling two-‐phase natural circulation systems: A review, Science and Technology of Nuclear Installations, Volume 2008, Article ID 573192 doi: 10.1155/2008/573192, 2008. Walter Ambrosini, Lesson learned from the adoption of numerical techniques in the analysis of nuclear reactor thermal-‐hydraulic phenomena, Progress in Nuclear Energy, Vol. 50, pp. 866-‐876, 2008. Juan Carlos Ferreri and Walter Ambrosini, On the analysis of thermal-‐fluid-‐dynamic instabilities via numerical discretization of conservation equations, Nuclear Engineering and Design, Vol. 215, pp. 153-‐170, 2002. V. Chatoorgoon, A. Voodi, and D. Fraser, The stability boundary for supercritical flow in natural circulation loops Part I: H2O studies, Nuclear Engineering and Design, Vol. 235, pp. 2570-‐2580, 2005. J. C. Ferreri, Computation of unstable flows using system codes, FLUIDOS 2010: XI Meeting on Recent Advances in the Physics of Fluids and their Applications, Journal of Physics: Conference Series 296, 2011. M.R. Gartia, D.S. Pilkhwal, P.K. Vijayan, and D. Saha, Analysis of metastable regimes in a parallel channel single phase natural circulation system with RELAP5/MOD3.2, International Journal of Thermal Sciences, Vol. 46, pp. 1064-‐1074, 2007. Qiming Men, Xuesheng Wang, Xizng Zhou, and Xiangyu Meng, Heat transfer analysis of passive residual heat removal heat exchanger under natural convection condition in tank, Science and Technology of Nuclear Installations, Vol. 2014, Article ID 279791, 2014. Gonella V. Durga Prasad, Manmohan Pandey, and Manjeet S. Kalra, Review of research on flow instabilities in natural circulation boiling systems, Progress in Nuclear Energy, Vol. 49, pp. 429-‐451, 2007. Hyun-‐Sik Park, Ki-‐Yong Choi, Seok Cho, Sung-‐Jae Yi, Choon-‐Kyung Park, and Moon-‐Ki Chung, Experimental study on the natural circulation of a passive residual heat removal system for an integral reactor following a safety related event, Annals of Nuclear Energy, Vol. 35, pp. 2249-‐2258, 2008. Amit Mangal, Vikas Jain, and A. K. Nayak, Capability of the RELAP5 code to simulate natural circulation behavior in test facilities, Progress in Nuclear Energy, Vol. 61, pp. 1-‐16, 2012. G. Prasad, M. Pandley, M. Kalra, Review of research on flow instabilities in natural circulation boiling systems, Progress in Nuclear Energy, Vol. 49, (2007) pp. 429–451.
L. Tadrist, Review on two-‐phase flow instabilities in narrow spaces, International Journal of Heat and Fluid Flow, Vol. 28, (2007) pp. 54–62. A. Nayak, P. Vijayan, Flow instabilities in boiling two-‐phase natural circulation systems: A Review, Science and Technology of Nuclear Installations (2008), 1–15. S. Kakac, B. Bon, A Review of two-‐phase flow dynamic instabilities in tube boiling systems, International Journal of Heat and Mass Transfer, Vol. 51, (2007) pp. 399–433. J. March-‐Leuba, J. Rey, Coupled thermo-‐hydraulic-‐neutronic instabilities in boiling water nuclear reactors: a review of the state of the art, Nuclear Engineering and Design, Vol. 145, (1993) pp. 97–111. V. Chatoorgoon Stability of supercritical fluid flow in a single-‐channel natural-‐convection loop, International Journal of heat and Mass transfer, Vol. 44, pp. 1963-‐1972, 2001. Walter Ambrosini and Medhat Beshir Sharabi, Assessment of stability maps for heated channels with supercritical fluids versus the predictions of a system code, Nuclear Engineering and Technology, Vol. 39, pp. 627-‐636, 2007. Donghua Lu, Zejun Xiao, and Bingde Chen, A new method to derive one set of scaling criteria for reactor natural circulation at single and two-‐phase conditions, Nuclear Engineering and Design, Vol. 240. (2010) pp. 3851–3861. D. D. B. van Bragt and T. H. J. J. van der Hagen, “Stability of natural circulation boiling water reactors—II: parametric study of coupled neutronic-‐thermohydraulic stability,” Nuclear Technology, Vol. 121, pp. 52–62, 1998. IAEA, Heat Transfer Behaviour and Thermohydraulics Code Testing for SCWRs, IAEA TECDOC Series, IAEA-‐TECDOC-‐1746, 2014, September, Vienna, Austria. Free download from: http://www-‐pub.iaea.org/books/IAEABooks/10731/Heat-‐Transfer-‐Behaviour-‐and-‐Thermohydraulics-‐Code-‐Testing-‐for-‐Supercritical-‐Water-‐Cooled-‐Reactors-‐SCWRs. IAEA, “Status of advanced light water reactor designs 2004,” IAEA-‐TECDOC-‐ 1391, IAEA, Vienna, Austria, 2004. IAEA, “Natural circulation phenomena and modelling for advanced water cooled reactors,” IAEA-‐TECDOC-‐1677, Vienna, Austria, 2012. IAEA, “Status of advanced light water reactor designs 2004,” IAEA-‐TECDOC-‐ 1391, IAEA, Vienna, Austria, 2004.
IAEA, “Natural circulation phenomena and modelling for advanced water cooled reactors,” IAEA-‐TECDOC-‐1677, Vienna, Austria, 2012. International Atomic Energy Agency, Heat transfer behaviour and Thermalhydraulics code testing for supercritical water cooled reactors (SCWRs), International Atomic Energy Agency Report, IAEA-‐TECDOC-‐1746, 2014. International Atomic Energy Agency, Natural Circulation in Water cooled Nuclear Power Plants: Phenomena, Models, and Methodology for System Reliability Assessments, IAEA-‐TECDOC-‐1474, IAEA, Vienna, 2005. International Atomic Energy Agency, Passive Safety Systems and Natural Circulation in Water Cooled Nuclear Power Plants, IAEA-‐TECDOC-‐1624, IAEA, Vienna, 2009. Darrel G. Harden, Transient behavior of a natural-‐circulation loop operating near the thermodynamic critical point, Argonne National Laboratory Report, ANL-‐6710, 1963. Archie Junior Cornelius, An investigation of instabilities encountered during heat transfer to a supercritical fluid, Argonne National Laboratory Report, ANL-‐7032, 1965. Y. Zvirin, A review of natural circulation loops in pressurized water reactors and other systems, Nuclear Engineering and Design, Vol. 67, pp. 203-‐225 (1981). Y. Zvirin. P. R. Jeuck, III, C. W. Sullivan and R. B. Duffey, Experimental and analytical investigation of a natural circulation system with parallel loops, Transaction of the ASME Journal of Heat Transfer, Vol. 103, pp. 645-‐652 (1981). P. R. Jeuck, III, L. Lennert and R. L. Kiang, Single-‐phase natural circulation experiments on small break accident heat removal, EPRI Reports NP-‐2006, NP-‐81-‐18-‐LD (1981). Y. Zvirin and Y. Rabinovitz, On the behavior of natural circulation loops with parallel channels, Proc. 7th Jnt. Heat Transfer Conference, Munich, F.R.G., Vol. 2, pp. 299-‐304 (1982). A. Ronen and Y. Zvirin, The behavior of a toroidal thermosyphon at high Graetz (and Grashof) numbers, Transaction of the ASME Journal of Heat Transfer, Vol. 107, pp. 254-‐258 (1985). Y. Zvirin, The onset of flows and instabilities in a thermosyphon with parallel loops, Nuclear Engineering and Design, Vol. 92, pp. 217-‐226, 1986. Elizabeth Burroughs, Convection in a thermosyphon: Bifurcation and stability analysis, PhD Disseration, University of New Mexico, Albuquerque, NM, 2003.
E. A. Burroughs, E. A. Coutsias, and L. A. Romero, A reduced-‐order partial differential equation model for the flow in a thermosyphon, Journal of Fluid Mechanics, Vol. 543, pp. 203-‐237, 2005. L. Chen, X.-‐R. Zhang, H. Yamaguchi, H., and Z.-‐S. Liu, Effect of heat transfer on the instabilities and transitions of supercritical CO2 flow in a natural circulation loop, Int. J. Heat Mass Transfer, Vol. 53, pp. 4101–4111, 2010. Emmanuel Ampomah-‐Amoako and Walter Ambrosini, Developing a CFD methodology for the analysis of flow stability in heated channels with fluids at supercritical pressures, Annals of Nuclear Energy, Vol. 54, pp. 251-‐262, 2013. Gilles Desrayaud, Alberto Fichera, and Guy Lauriat, Two-‐dimensional numerical analysis of a rectangular closed-‐loop thermosiphon, Applied Thermal Engineering, Vol. 50, pp. 187-‐196, 2013. M. Misale, P. Ruffino, and M. Frogheri, The influence of the wall thermal capacity and axial conduction over a single-‐phase natural circulation loop: 2-‐D numerical study, Heat Mass Transfer, Vol.36, pp. 533-‐539, 2000. D.S. Pilkhwal, W. Ambrosini, N. Forgione, P.K. Vijayan, D. Saha, and J.C. Ferreri, Analysis of the unstable behavior of a single-‐phase natural circulation loop with one-‐dimensional and computational fluid-‐dynamic models, Annals of Nuclear Energy, Vol. 34, pp. 339-‐355, 2007. Ajay Kumar Yada, M. Ram Gopal, and Souvik Bhattacharyya, CFD analysis of a CO2 based natural circulation loop with end heat exchangers, Applied Thermal Engineering, Vol. 36, pp. 288-‐295, 2012a. Ajay Kumar Yada, M. Ram Gopal, and Souvik Bhattacharyya, CO2 based natural circulation loops: New correlations for friction and heat transfer, International Journal of Heat and Mass Transfer, Vol. 55, pp. 4621-‐4630, 2012b. K. Kiran Kumar and M. Ram Gopal, Steady-‐state analysis of CO2 based natural circulation loops with end heat exchangers, Applied Thermal Engineering, Vol. 29, pp. 1893-‐1903, 2009. X. Zhang, L. Chen, and H. Yamaguchi, Natural convective flow and heat transfer of supercritical CO2 in a rectangular circulation loop, International Journal of Heat and Mass Transfer, Vol. 53, pp. 4112-‐4122, 2010. L. Chen, X. Zhang, H. Yamaguchi, and Z. (Simon) Liu, Effect of heat transfer on the instabilities and transitions of supercritical CO2 flow in a natural circulation loop, International Journal of Heat and Mass Transfer, Vol. 53, pp. 4101-‐4111, 2010.
Xingtuan, Yang, Yanfei Sun, Zhiyong Liu, and Shengyao Jiang, Natural circulation characteristics of a symmetric loop under inclined conditions, Science and Technology of Nuclear Installations, Volume 2014, Aricle ID 925760, doi.org/10.1155/2014/925760, 2014. Thomas Hohne, Soren Kliem, Ulrich Rohde, and Frank-‐Peter Weiss, Boron dilution transients during natural circulation flow in PWR-‐Experiments and CFD simulations, Nuclear Engineering and Design, Vol. 238, pp. 1987-‐1995, 2008. El Hassan Ridouane, Christopher M. Danforth, and Darren L. Hitt, A 2-‐D numerical study of chaotic flow in a natural convection loop, , International Journal of Heat and Mass Transfer, Vol. 53, pp. 76-‐84, 2010. Leyuan Yu, Arita Sur, and Dong Liu, Flow boiling heat and two-‐phase flow instability of nanofluids in a minichannel, Transactions of the ASME Journal of Heat Transfer, Vol. 137, pp. 051502-‐1 thru 051502-‐11, 2015. Sami Penttila (Editor), 7th International symposium on supercritical water-‐cooled reactors, ISSCWR-‐7, March 15-‐18, 2015, Helsinki, Finland, VTT Technology Report VTT 216, 2015. Milan K. S. Sarkar, Abhilash K. Tilak, and Dipankar N. Basu, A state-‐of-‐the-‐art review of recent advances in supercritical natural circulation loops for nuclear applications, Annals of Nuclear Energy, Vol. 73, pp. 250-‐264, 2014. P. K. Vijayan, Manish Sharma, and D. S. Pilkhwal, Steady state and stability characteristics of a supercritical pressure natural circulation loop (SCNCL) with CO2, Bhabha Atomic Research Centre Report, BARC/2013/E/003. 2013. Weifeng Xu, Jiejin Cai, Shichang Liu, and Qi Tang, Analysis of the influences of thermal correlations on neutronic-‐thermohydraulic coupling calculation of SCWR, Nuclear Engineering and Design, Vol. 284, pp. 50-‐59, 2015. B. T. Swapnalee, P. K. Vijayan, M. Sharma, and D. S. Pilkhwal, Steady state flow and static instability of supercritical natural circulation loops, Nuclear Engineering and Design, Vol. 245, pp. 99-‐112, 2012. P. A. Lottes, R. P. Anderson, B. M. Hoflund, J. F. Marchaterre, M. Petrick, G. F. popper, and R. J. Weatherhead, Boiling water reactor Technology status of the art report, Argone National Laboratory Report, ANL-‐6561, 1962. Computer Simulation & Analysis, Inc., RETRAN-‐3D-‐A program for theansient thermal-‐hydraulic analysis of complex fluid flow systems. Volume 1: theory and numeric, Electric Power Research Institute Report, NP-‐7405, Volume 1, Revision 3, 1998.
Information Systems Laboratories, Inc., RELAP5/MOD3.3 Code Manual Volume I: Code structure, system models, and solution methods, United States Nuclear Regulatory Commission Report, NUREG/CR-‐5535/Rev 1-‐ Vol I, 2001. NEDE-‐32176P, Rev. 2, “TRACG Model Description,” December 1999. U. S. Rohatgi, H. S. Cheng, H. J. Khan, A. N. Mallen, and L. Y. Neymotin, RAMONA-‐4B a computer code with three-‐dimensional neutron kinetics for BWR and SBWR system transient – models and correlations, Brookhaven National Laboratory Report BNL-‐NUREG-‐52471 – Vol. 1, 1998. Alberto Escrivá, José Luis Munoz Cobo, José Melara San Roman, Manuel Albendea Darriba, and José March-‐Leuba, LAPUR 6.0 Manual Oak Ridge National Laboratory Report NUREG/CR-‐6958, 2008. S. J. Peng, M. Z. Podowski, R. T. Lahey, Jr., and M. Becker, NUFREQ -‐NP: A Computer Code for the Stability Analysis of Boiling Water Nuclear Reactors, Nuclear Science and Engineering, Vol. 88, pp. 404-‐41, 1984. J.W. Spore, M.W. Giles, G.L. Singer and R.W. Shumway, TRAC-‐BD1/MOD1: an advanced best estimate computer program for boiling water reactor transient analysis. Volume 1. Model description, Idaho National Engineering Laboratory Report, NUREG/CR-‐2178, EGG-‐2109, 1981. D. J. Richards, B. N. Hanna, N. Hobson, and K. H. Ardron, "ATHENA : A two-‐fluid code for CANDO LOCA Analysis,' Third International Topical Meeting on Reactor Thermal Hydraulics, Newport, Rhode Island, USA, Oct 15-‐18, 1985, pp . 7.E-‐1 thru 7.E-‐14. (CATHENA formerly named ATHENA), 1985. Hwang, Y.D., Yang, S.H., Kim, S.H., Lee, S.W., Kim, H.K., Yoon, H.Y., Lee, G.H., Bae, K.H., Chung, Y.J., 2005. Model description of TASS/SMR code. Korea Atomic Energy Research Institute. KAERI/TR-‐3082/2005. Hwang, Y.D., Lee, G.H., Chung, Y.J., Kim, H.C., Chang, D.J., 2006. Assessment of the TASS/SMR code using basic test problems. Korea Atomic Energy Research Institute. KAERI/TR-‐3156/2006. Soo Hyung Yang, Young-‐Jong Chung, and Keung-‐Koo Kim, Experimental validation of the TASS/SMR code for an integral type pressurized water reactor, Annals of Nuclear Energy, Vol. 35, pp. 1903-‐1911, 2008. Hyun-‐Sik Park, Byung-‐Yeon Min, Youn-‐Gyu Jung, Yong-‐Cheol Shin, Yung-‐Joo Ko, and Sung-‐Jae Yi, Design of the VISTA-‐ITL test facility for an integral type reactor of SMART and a post-‐test simulation of a SBLOCA test, Science and Technology of Nuclear Installations, Volume 2014, Article ID 840109, 14 pages, 2014.
S. Kim, Byoung-‐Uhn Bae, Yun-‐Je Cho, Yu-‐Sun Park, Kyoung-‐Ho Kang, and Byong-‐Jo Yun, “An experimental study on the validation of cooling capability for the Passive Auxiliary Feedwater System (PAFS) condensation heat exchanger,” Nuclear Engineering and Design, vol. 260, pp. 54–63, 2013. Hyun-‐Sik Park, Ki-‐Yong Choi, Seok Cho, Sung-‐Jae Yi, Choon-‐Kyung Park, and Moon-‐Ki Chung, Experimental study on the natural circulation of a passive residual heat removal system for an integral reactor following a safety related event, Annals of Nuclear Energy, Vol. 35, pp. 2249-‐2258, 2008. Qiming Men, Xuesheng Wang, Xiang Zhou, and Xiangyu Meng, Heat Transfer analysis of passive heat removal heat exchanger under natural convection condition on tank, Science and Technology of Nuclear Installations, Volume 2014, Article ID 279791, 8 Pages, 2014. Zhuo Wenbin, Huang Yanping, Xiao Zejun, Peng Chuanxin, and Lu Sansan, Experimental research on passive residual heat removal system of Chinese advanced PWR, Science and Technology of Nuclear Installations, Volume 2014, Article ID 325356, 8 Pages, 2014. Historical D.C. Hamilton, F.E. Lynch, L.D. Palmer, The nature of flow of ordinary fluids in a thermal convection harp, ORNL-‐1624, March 16, 1954. K. Garlid, N. R. Amundson and H. S. Isbin, A Theoretical Study of the Transient Operation and Stability of Two-‐Phase Natural Circulation Loops, Argonne National Laboratory Report, ANL-‐6381, 1961. R. P. Anderson, L. T. Bryant, J. C. Carter and J. F. Marchaterre, Transient Analysis of Two-‐Phase Natural-‐Circulation Systems, Argonne National Laboratory Report, ANL-‐6653, 1962. E. N. Lorenz, Deterministic non-‐periodic flow, J. Atmos. Sci., Vol. 20, pp. 130–141, 1963. H. F. Creveling and R. J. Schoenhals, Steady Flow Characteristics of a Single-‐Phase Natural Circulation Loop, Technical Report No. 15, Purdue Research Foundation, COO-‐1177-‐15, 1966. J. B. Keller, Periodic oscillations in a model of thermal convection, Journal of Fluid Mechanics, 26, Part 3, 599–606, 1967, 1966. P. Welander, On the oscillatory instability of a differentially heated fluid loop, Journal of Fluid Mechanics, vol. 29, part. 1, pp. 17-‐30, 1967.
C. D. Alstad, H. S. Isbin, and N. R. Amundson, The transient behavior of single-‐phase natural circulation water loop systems, Argonne National Laboratory Report, ANL-‐5409, 1956. Eugene H. Wissler, H. S. Isbin, and N. R. Amundson, The oscillatory behavior of a two-‐phase natural circulation loop, Presented at the Nuclear Engineering and Science Congress, Cleveland, Ohio, AIChE Preprint 59, 1955. See also American Institute of Chemical Engineers Journal, Vol. 2, pp. 157-‐162, 1956. M. Ledinegg, Instability of flow during natural and forced circulation, Die Warme, Vol. 61, pp. 891-‐898, 1938, AEC-‐tr-‐1861, 1954. Archie Junior Cornelius, An investigation of instabilities encountered during heat transfer to a supercritical fluid, Argonne National Laboratory Report, ANL-‐7032, 1965. J. A. Boure, A. E. Bergles, and L. S. Tong, Review of two-‐phase flow instabilities, National Heat Transfer Conference, Tulsa, Oklahoma, 1971. J.A. Boure, A.E ergles, L.S. Tong, Review of two-‐phase flow instability, Nuclear Engineering and Design, Vol. 25, pp. 165-‐192, 1973. B P. J. Berenson, Flow stability in multi-‐tube forced-‐convection vaporizers, Air Force Aero Propulsion Laboratory Report APL TDR 64-‐117, 1964. The 1970s and 1980s H.F. Creveling, J. F. De Paz, J.Y. Baladi and R.J. Schoenals, "Stability Characteristics of a Single-‐Phase Free Convection Loop", Journal of Fluid Mechanics, Vol. 67, part 1, pp. 65-‐84, 1975. Y. Zvirin, The effect of dissipation on free convection loops. International Journal of Heat and Mass Transfer, 22, 1539–1545, 1979. Y. Zvirin, and R. Greif, Transient behaviour of natural circulation loops: two vertical branches with point heat source and sink. International Journal of Heat and Mass Transfer, 22, 499–504, 1979. R. Greif, Y. Zvirin, and A. Mertol, "The Transient and Stability Behavior of a Natural Convection Loop", Journal of Heat Transfer, Transactions of the ASME, Vol. 101, pp. 684-‐688, 1979. A. Mertol, Heat Transfer and Fluid Flow in Thermosyphons, PHD Dissertation, Univ. of California at Berkeley, 1980.
Y. Zvirin, A review of natural circulation loops in pressurized water reactors and other systems, Nuclear Engineering and Design, Vol. 67, pp. 203-‐225, 1981. Y. Zvirin, P. R. Jeuck III, C. W. Sullivan and R. B. Duffey, Experimental and Analytical Investigations of a Natural Circulation System with Parallel Loops, Transactions ASME, Journal of heat Transfer, Vol. 103, pp. 645-‐652, 1981. H. H. Bau and K. E. Torrance, "Transient and Steady Behaviour of an Open, Symmetrically Heated, Free convection Loop", International Journal of Heat and Mass Transfer, Vol. 24, pp. 597-‐609, 1981. M. J. Gruszczynski and R. Viskanta, Heat Transfer To Water From A Vertical Tube Bundle Under Natural-‐Circulation Conditions, Argonne National Laboratory Report, NUREG/CR-‐3167, ANL-‐83-‐7, 1983. J. E. Hart, A new analysis of the closed loop thermosyphon, International Journal of Heat and Mass Transfer, Vol. 27, No. 1, pp. 125–136, 1984. J. C. Ferreri and A. S. Doval, On the Effects of Discretization in the Computation of Natural Circulation in Loops (In Spanish), Seminars of the Argentine Committee Heat & Mass Transfer, 24, pp. 181-‐212, 1984. S.J. Peng, M.Z. Podowski, R.T. Lahey, Jr., and M. Becker, "NUFREQ-‐NP: A Computer Code for the Stability Analysis of Boiling Water Nuclear Reactors", Nuclear Science and Engineering, Vol. 88, pp. 404-‐ 411, 1984. J. E. Hart, A note on the loop thermosyphon with mixed boundary conditions. International Journal of Heat and Mass Transfer, Vol. 28, No. 5, pp. 939–947, 1985. M. Sen, E. Ramos and C. Treviño, "The Toroidal Thermosyphon with Known Heat Flux", International Journal of Heat and Mass Transfer, Vol. 28, No. 1, pp. 219-‐233, 1985. K. Chen, "On the Oscillatory Instability of Closed Loop Thermosyphons", Transaction of the ASME, Journal of Heat Transfer, Vol. 107, pp. 826-‐832, 1985. Rizwan-‐uddin and Dorning, "Some Non-‐Linear Dynamics of a Heated Channel", Nuclear Engineering and Design, Vol. 93, pp. 1-‐14, 1986. S.J. Peng, M.Z. Podowski and R.T. Lahey, Jr., "BWR Linear Stability Analysis", Nuclear Engineering and Design, 93, pp. 25-‐37, 1986. March-‐Leuba, D.G. Cacuci and B. Perez, "Nonlinear Dynamics and Stability in Boiling Water Reactors: Part 1 -‐ Qualitative Analysis", Nuclear Science and Engineering, Vol. 93, pp. 111-‐123, 1986.
R. B. Duffey and J. P. Sursock, Natural Circulation Phenomena Relevant to Small Breaks and Transients, Nuclear Engineering and Design, Vol. 102, pp. 115-‐128, 1987. M. Misale, and L. Tagliafico, "The Transient and Stability Behaviour of Single-‐Phase Natural Circulation Loops", Heat and Technology, Vol. 5, No. 1-‐2, 1987. J. C. Ferreri and A. S. Doval, On the Effects of Discretization in the Time Evolution of Perturbations in a Closed Loop, presented to the Technical Committee/Workshop on Computer Aided Safety Analysis, IAEA, Poland, IAEA-‐TC-‐560.02, pp. 72-‐78, 1988. K.S. Chen and Y.R. Chang, Steady-‐state analysis of two-‐phase natural circulation loop, International Journal of Heat and Mass Transfer, Vol. 31, No. 5, pp. 931–940, 1988. The 1990s K. Svanholm and J. Friedly, “An Elementary Introduction to the Problem of Density-‐wave Oscillations”, Proc. International Workshop on BWR Stability, Holtsville NY, USA, 17-‐19 October 1990, CSNI Report 178, pp. 317-‐336, 1990. R.T. Lahey, Jr., M.Z. Podowski, A. Clausse and N. DeSanctis, "A Linear Analysis of Channel-‐to-‐ Channel Instability Modes", Chem. Eng. Communications, Vol. 93, p. 75, 1990. P. K. Vijayan and A. W. Date, Experimental and theoretical investigations on the steady-‐state and transient behaviour of a thermosyphon with throughflow in a figure-‐of-‐eight loop. International Journal of Heat and Mass Transfer, Vol. 33 No. 11, pp. 2479–2489, 1990. P. Di Marco, A. Clausse, R.T. Lahey Jr., and D.A. Drew A Nodal Analysis of Instabilities in Boiling Channels, Int. J. Heat and Technology, Vol. 8, No. 1-‐2, 1990. P.K. Vijayan and S.K. Mehta, On the steady-‐state performance of natural circulation loops, International Journal of Heat and Mass Transfer, Vol. 34, No. 9, 2219–2230, 1991. P. Di Marco, A. Clausse and R.T. Lahey, Jr., An Analysis of Non-‐Linear Instabilities in Boiling Systems, Dynamics and Stability of Systems, Vol. 6, No. 3, 1991. G. M. Grandi and J. C. Ferreri, Limitations of the use of a Heat Exchanger Approximation for a Point Heat Source", Internal Memo. CNEA, Gerencia Seg. Rad. y Nuclear, Div. Modelos Físicos y Numéricos, Argentina, 1991. F. D'Auria, G. M. Galassi, P. Vigni, and A. Calastri, Scaling of Natural Circulation Flows in PWR Systems, Nuclear Eng. and Design, Vol. 132, pp. 187-‐205, 1991.
R. B. Duffey and E. D. Hughes, Static Flow Instability Onset in Tubes, Channels, Annuli and Rod Bundles, International Journal of Heat and Mass Transfer, Vol. 34, No.10, pp. 2483-‐2496, 1991. P. K. Vijayan and A. W. Date, The limits of conditional stability for single-‐phase natural circulation with through-‐flow in a figure-‐of-‐eight loop. Nuclear Engineering and Design, Vol. 136, pp. 361–380, 1992. H. H. Bau and Y. Z. Wang, Chaos: a heat transfer perspective, in Annual Review of Heat Transfer, 4, Edited by C. L. Tien, Hemisphere Publishing Co., 1992. P. K. Vijayan and A. W. Date, The limits of conditional stability for single-‐phase natural circulation with through-‐flow in a figure-‐of-‐eight loop, Nuclear Engineering and Design, Vol. 136, pp.361-‐380, 1992. J. March-‐Leuba and J.M. Rey, "Coupled Thermo-‐Hydraulic-‐Neutronic Instabilities in Boiling Water Nuclear Reactors: A Review of The State of the Art", Nuclear Engineering and Design, Vol. 145, pp. 97-‐111, 1993. P. K. Vijayan and H. Austregesilo, Scaling laws for single-‐phase natural circulation loops, Nuclear Engineering and Design, Vol. 152, pp. 331-‐347, 1994. Cheng-‐Chi Wu and K. Almenas, RELAP5 computations of flow instabilities in a circular torodial thermosyphon, RELAP5 International User Seminar, Baltimore (Maryland), August 29-‐September 1, 1994. J. J. Velazquez, "On the Dynamics of a Closed Thermosyphon", SIAM J. Appl. Math., Vol. 54, pp. 1561-‐1593, December 1994. Raj V. Venkat, Experimental studies related to thermosyphon cooling of nuclear reactors––a review. In: Proceedings of the First ISHMT-‐ASME Heat and Mass Transfer Conference and Twelfth National Heat and Mass Transfer Conference, January 5–7, 1994, Bhabha Atomic Research Centre, Bombay, India, 1994. U. S. Rohatgi and R. B. Duffey, Natural Circulation and Stability Limits in Advanced Plants: The Galilean Law, Proceedings of the International Conference on New Trends in Nuclear System Thermal Hydraulics, Pisa, Italy, May, Vol.1, pp. 177-‐185, 1994. A. Rodriguez-‐Bernal, Attractors and inertial manifolds for the dynamics of a closed thermosyphon, J. Math. Anal. Appl. Vol. 193, pp. 942–965, 1995. P. K. Vijayan., H. Austregesilo and V. Teschendorff, Simulation of the unstable behavior of single-‐phase natural circulation with repetitive flow reversals in a
rectangular loop using the computer code ATHLET. Nuclear Engineering and Design, Vol. 155, pp. 623–641, 1995. J. C. Ferreri, W. Ambrosini and F. D'Auria, On the Convergence of RELAP5 Calculations in a Single-‐Phase, Natural Circulation Test Problem, Proceedings of X-‐ENFIR, 7-‐11th August 1995, Aguas de Lindoia, S.P., Brazil, pp. 303-‐307, 1995. R. B. Duffey and U. S. Rohatgi, Physical Interpretation of Geysering Phenomena and Periodic Boiling Instability at Low Flows, Fourth International Conference on Nuclear Engineering, ICONE 4,ASME/JSME, New Orleans, 1996. M. Frogheri, M. Misale, P. Ruffino, and F. D'Auria, "Instabilities in Single-‐phase Natural Circulation: Experiments and System Code Simulation, Proc. Of 5th UK National Conference on Heat Transfer, London, September 17-‐18, 1997. F. D’Auria (Editor) et al., "State-‐of-‐the-‐Art Report on Boiling Water Reactor Stability", NEA/CSNI/R(96)21, OCDE/GD(97)13, OECD/NEA Paris, 1997. M. Frogheri, M. Misale, and F. D’Auria, Experiments in single phase natural circulation. In: 15th UIT National Heat Transfer Conference 1997, Torino, June 19–20, 1997. F. D'Auria, et al., State-‐of-‐the-‐art report on boiling water reactor stability, NEA/CSNI/R(96)21, OCDE/GD(97)13, January 1997. W. Ambrosini and J. C. Ferreri, Numerical analysis of single-‐phase, natural circulation in a simple closed loop, Proceedings of 11th Meeting on Reactor Physics and Thermal Hydraulics, Pocos de Caldas, M.G., Brazil, August 18-‐22th 1997, pp. 676-‐681, 1997a. W. Ambrosini and J. C. Ferreri, Stability analysis of single-‐phase thermo-‐syphon loops by finite-‐difference numerical methods, Proceedings of Post SMIRT 14 Seminar 18 on 'Passive Safety Features in Nuclear Installations', Pisa, August 25-‐27th 1997, pp. E2.1-‐E2.10, 1997b. M. Frogheri, M. Misale, and F. D'Auria, "Experiments in Single-‐Phase Natural Circulation", 15th UIT National Heat Transfer Conference 1997, Torino, June 19-‐20, 1997. A.K. Nayak, P.K. Vijayan, D. Saha, V. Venkat Raj and M. Aritomi, "Adequacy of Power-‐to-‐Volume Scaling Philosophy to Simulate Natural Circulation in Integral Test Facilities", Nuclear Science and Engineering, Vol. 35, No. 10, pp. 712-‐722, 1998. A. Susanek, Analysis of flow Instabilities in a Boiling Channel by a Finite-‐Difference Numerical Method, Università degli Studi di Pisa, DCMN NT 355(98) July 1998, 'Semesterarbeit' Thesis, Tutors: P. Vigni, W. Ambrosini, P. Di Marco., 1998.
Challberg, R.C., Cheung, Y.K., Khorana, S.S., Upton, H.A., 1998. ESBWR evolution of passive features. In: 6th International Conference on Nuclear Engineering (ICONE-‐6), San Diego, USA, May 10–15, 1998. F. D'Auria and G. M. Galassi, Code Validation and Uncertainties in System Thermalhydraulics, Progress in Nuclear Energy, 33, No. 1/2, pp. 175-‐216, 1998. W. Ambrosini and J.C. Ferreri, "The Effect of Truncation Error on Numerical Prediction of Stability Boundaries in a Natural Circulation Single-‐Phase Loop", Nuclear Engineering and Design, Vol. 183, pp. 53-‐76, 1998. J. C. Ferreri and W. Ambrosini, Verification of RELAP5/MOD3 with theoretical and numerical stability results on single-‐phase, natural circulation in a simple loop, United States Nuclear Regulatory Commission, NUREG IA/151, 1999. M. Misale, M. Frogheri, and F. D’Auria, Experiments in natural circulation: influence of scale factor on the stability behavior. In: Eurotherm Seminar No. 63 on Single and Two-‐Phase Natural Circulation, September 6–8, 1999, Genoa, Italy, 1999. J.C. Ferreri, Single-‐Phase Natural Circulation in Simple Circuits -‐ Reflections on its Numerical Simulation, Invited Lecture at the Eurotherm Seminar No. 63 on Single and Two-‐ Phase Natural Circulation, September 6-‐8 1999, Genoa, Italy. J.C. Ferreri and W. Ambrosini, Verification of RELAP5/MOD3.1 with Theoretical Stability Results, NUREG-‐IA-‐0151, February 1999. P.K. Vijayan, "Experimental Observations on the General Trends of the Steady State and Stability Behaviour of Single-‐Phase Natural Circulation Loops", Invited Lecture at the Eurotherm Seminar No. 63 on Single and Two-‐Phase Natural Circulation, September 6-‐8 1999, Genoa, Italy, 1999. M. Misale, M. Frogheri and F. D'Auria, "Experiments in Natural Circulation: Influence of Scale Factor on the Stability Behavior", Eurotherm Seminar No. 63 on Single and Two-‐Phase Natural Circulation, September 6-‐8 1999, Genoa, Italy, 1999. W. Ambrosini, P. Di Marco and A. Susanek, "Prediction of Boiling Channel Stability by a Finite-‐Difference Numerical Method", 2nd International Symposium on Two-‐Phase Flow Modelling and Experimentation, Pisa, Italy, May 23-‐26, 1999. J. M. Doster and P. K. Kendall, "Stability of One-‐Dimensional Natural-‐Circulation Flows", Nuclear Science and Engineering, Vol. 132, pp. 105-‐117, 1999. J.C. Ferreri and W. Ambrosini, "Sensitivity to Parameters in Single-‐Phase Natural Circulation Via Automatic Differentiation of FORTRAN Codes", Eurotherm Seminar
No. 63 on Single and Two-‐Phase Natural Circulation, September 6-‐8 1999, Genoa, Italy. The 2000s W. Ambrosini and J.C. Ferreri, "Stability Analysis of Single-‐Phase Thermosyphon Loops by Finite Difference Numerical Methods", Nuclear Engineering and Design, Vol. 201, pp. 11-‐23, 2000. W. Ambrosini, P. Di Marco and J.C. Ferreri, "Linear and Non-‐Linear Analysis of Density Wave Instability Phenomena", Heat and Technology, Vol. 18, No. 1, 2000. W. Ambrosini and J. C. Ferreri, Stability analysis of single-‐phase thermosyphon loops by finite-‐difference numerical methods. Nuclear Engineering and Design, Vol. 201, pp. 11–23, 2000. Romney B. Duffey, Natural Convection and Natural Circulation Flow and Limits in Advanced Reactor Concepts, Paper for the IAEA Technical Committee Meeting Vienna, July 18-‐21, 2000. W. Ambrosini, F. D’Auria, A. Pennati and J.C. Ferreri, "Numerical Effects in the Prediction of Single-‐Phase Natural Circulation Stability", XIX National Heat Transfer Conference of UIT, Modena (I), June 25-‐27, 2001. W. Ambrosini, On some physical and numerical aspects in computational modelling of one-‐dimensional flow dynamics. In: 7th International Seminar on Recent Advances in Fluid Mechanics, Physics of Fluids and Associated Complex Systems (Fluidos 2001), Buenos Aires, Argentina, October 17–19, 2001. Petruzzi, F. D'Auria and M. Misale "Sensitivity Analysis on the Stability of the Natural Circulation in a Thermosyphon Loop", XIX National Heat Transfer Conference of UIT, Modena (I), June 25-‐27, 2001. M. Misale and M. Frogheri, Stabilization of a Single-‐Phase Natural Circulation Loop by Pressure Drops, Experimental Thermal and Fluid Science, Vol. 25, pp. 277-‐282, 2001. P.K. Vijayan, Experimental observations on the general trends of the steady state and stability behavior of single phase natural circulation loops, Nuclear Engineering and Design, Vol. 215, Nos. 1–2, pp. 139–152, 2002. P.K. Vijayan, Experimental observations on the general trends of the steady state and stability behaviour of single-‐phase natural circulation loops, Nuclear Engineering and Design, Vol. 215, pp. 139-‐152, 2002.
G.R. Dimmick, V. Chatoorgoon, H.F. Khartabil, and R.B. Duffey, Natural-‐convection studies for advanced CANDU reactor concepts, Nuclear Engineering and Design, Vol. 215, pp. 27–38, 2002. Y. Y. Jiang and M. Shoji, Flow Stability in a Natural Circulation Loop: Influences of Wall Thermal Conductivity,” Nuclear Engineering and Design, Vol. 222, pp. 16–28, 2003. S. K. Mousavian, M. Misale, F. D’Auria, and M. A. Salehi, 2004, Transient and Stability Analysis in Single-‐Phase Natural Circulation, Annals of Nuclear Energy, Vol. 31, pp. 1177–1198, 2004. W. Ambrosini, N. Forgione, J.C. Ferreri, M. Bucci, The effect of wall friction in single-‐phase natural circulation stability at the transition between laminar and turbulent flow, Annals of Nuclear Energy, Vol. 31, pp.1833-‐1865, 2004. S.K. Mousavian, M. Misale, F. D Auria, M.A. Salehi, Transient and stability analysis in single-‐phase natural circulation, Annals of Nuclear Energy, Vol. 31, No. 10, pp. 1177-‐1198, 2004. W. Ambrosini, N. Forgione, J. Ferreri, and M. Bucci, The effect of wall friction in single-‐phase natural circulation stability at the transition between laminar and turbulent flow, Annals of Nuclear Energy, Vol. 31, No. 16, pp. 1833–1865, 2004. IAEA, Natural Circulation in Water Cooled Nuclear power Plants, IAEA Report IAEA-‐TECDOC-‐1474, 2005. N.M. Rao, B. Maiti, P.K. Das, Pressure variation in a natural circulation loop with end heat exchangers, International Journal of Heat and Mass Transfer, Vol. 48 , pp. 1403–1412, 2005. N. M. Rao, B. Maiti, and P. K. Das, Stability Behaviour of a Natural Circulation Loop With End Heat Exchangers, ASME Journal of Heat Transfer, Vol. 127, pp. 749–759, 2005. M. Furuya, F. Inada, and T.H.J.J. Hagen, Flashing-‐induced density wave oscillations in a natural circulation BWR-‐mechanism of instability and stability map, Nuclear Engineering and Design, Vol. 235, pp. 1557–1569, 2005. Y. Malo, C. Bassi, T. Cadiou, M. Blanc, A. Messie, A. Tosselo, and P. Dumaz, Gas-‐cooled fast reactors-‐DHR systems, preliminary design and thermal-‐hydraulics studies, Nuclear Engineering and Technology Vol. 38, No. 2, pp. 129–138, 2006. M.R. Gartia, P.K. Vijayan, and D.S. Pilkhwal, A generalized flow correlation for two phase natural circulation loops, Nuclear Engineering and Design, Vol. 236, pp. 1800–1809, 2006.
N.M. Rao, Ch. C. Sekhar, B. Maiti, P.K. Das, Steady-‐state performance of a two-‐phase natural circulation loop, International Communications in Heat Mass Transfer, Vol. 33, pp. 1042–1052, 2006. Y.J. Chung, H.C. Kim, B.D. Chung, M.K. Chung, and S.Q. Zee, Two-‐phase natural circulation and the heat transfer in the passive residual heat removal system of an integral type reactor, Annals of Nuclear Energy, pp. 262–270, 2006. P.K. Vijayan, M. Sharma, D. Saha, Steady state and stability characteristics of single phase natural circulation in a rectangular loop with different heater and cooler orientations, Experimental Thermal and Fluid Science, Vol. 31, pp. 925–945, 2007. C.P. Marcel, M. Rohde, T.H.J.J.V. Hagen, Fluid-‐to-‐fluid modeling of natural circulation boiling loops for stability analysis, International Journal of Heat and Mass Transfer, Vol. 51, pp. 566–575, 2008. P.K. Vijayan, A.K. Nayak, D. Saha, M.R. Gartia, Effect of loop diameter on the steady state and stability behavior of single phase and two phase natural circulation loops, Science and Technology of Nuclear Installations, Vol. 2008, article ID: 672704, 17 pages, doi:10.1155/2008/672704. ] P.K. Vijayan, M. Sharma, D. Saha, Steady state and stability characteristics of single phase natural circulation in a rectangular loop with different heater and cooler orientation, Exp. Thermal Fluid Sci., Vol. 31, pp. 925-‐945, 2007. M. Misale, P. Garibaldi, J.C. Passos, and G.G. de Bitencourt, Experimental Thermal and Fluid Science, Vol. 31, No. 8, pp. 1111-‐1120, 2007. A.K. Nayaka, P. Dubey, D.N. Chavan, and P.K. Vijayan, Study on the stability behaviour of two-‐phase natural circulation systems using a four-‐equation drift flux model, Nuclear Engineering and Design, Vol. 237, pp. 386–398, 2007. A. K. Nayak and P. K. Vijayan, Flow Instabilities in Boiling Two-‐Phase Natural Circulation Systems: A Review, Science and Technology of Nuclear Installations, Volume 2008, 15 pages, Article ID 573192, doi:10.1155/2008/573192, 2008. N. M. Rao and P. K. Das, Steady State Performance of a Single Phase Natural Circulation Loop With End Heat Exchangers, ASME Journal of Heat Transfer, Vol. 130, 2008. Jin Ho Song, Performance and scaling analysis for a two-‐phase natural circulation loop, International Communications in Heat and Mass Transfer, Vol. 35, pp. 1084–1090, 2008.
K. Kiran Kumar, M. Ram Gopal, Steady-‐state analysis of CO2 based natural circulation loops with end heat exchangers, Applied Thermal Engineering, Vol. 29, pp. 1893-‐1903, 2009. Xin-‐Rong Zhang, Lin Chen, and Hiroshi Yamaguchi, Natural convective flow and heat transfer of supercritical CO2 in a rectangular circulation loop, International Journal of Heat and Mass Transfer, Vol. 53, pp. 4112-‐4122, 2010. B. T. Swapnalee and P. K. Vijayan, A Generalized Flow Equation for Single Phase Natural Circulation Loops Obeying Multiple Friction Laws, International Journal of Heat and Mass Transfer, Vol. xxx, pp. yyy-‐zzz, 2011. J. C. Ferreri, Engineering Judgment and Natural Circulation Calculations, Science and Technology of Nuclear Installations, Volume 2011, 11 pages, Article ID 694583, doi:10.1155/2011/694583, 2011. Jin Ho Song, Performance of a Two-‐Phase Natural Circulation in a Rectangular Loop, Nuclear Engineering and Design, Vol. 245, pp. 125-‐130, 2012. G. Angeloa, D.A. Andradea, E. Angeloa, W.M. Torresa, G. Sabundjiana, L.A. Macedoa and A.F. Silva, A Numerical And Three-‐Dimensional Analysis Of Steady State Rectangular Natural Circulation Loop, Nuclear Engineering and Design, Vol. 244, pp. 61-‐72, 2012. IAEA, Natural Circulation Phenomena and Modelling for Advanced Water Cooled Reactors, IAEA Report IAEA-‐TECODC-‐16, 2012. Amit Mangal, Vikas Jain, and A.K. Nayak, Capability of the RELAP5 code to simulate natural circulation behavior in test facilities, Progress in Nuclear Energy, Vol. 61, p. 1-‐16, 2012. M. Misale, F. Devia, and P. Garibaldi, Experiments with Al2O3 nanofluid in a single-‐phase natural circulation mini-‐loop: Preliminary results, Applied Thermal Engineering, Vol. 40, pp. 64-‐70, 2012. Ajay Kumar Yadav, M. Ram Gopal, and Souvik Bhattacharyya, CFD analysis of a CO2 based natural circulation loop with end heat exchangers, Applied Thermal Engineering, Vol. 36, pp. 288-‐295, 2012. Ajay Kumar Yadav, M. Ram Gopal, and Souvik Bhattacharyya, CO2 based natural circulation loops: New correlations for friction and heat transfer, International Journal of Heat and Mass Transfer, Vol. 55, pp. 4621–4630, 2012. W. Ambrosini, On the analogies in the dynamic behavior of heated channels with boiling and supercritical fluids. Nuclear Engineering and Design, Vol. 237, pp. 1164–1174, 2007.
W. Ambrosini, Assessment of flow stability boundaries in a heated channel with different fluids at supercritical pressure, Annals of Nuclear Energy, Vol. 38, pp. 615–627, 2011. W. Ambrosini and J. C. Ferreri, Stability analysis of single phase thermosyphon loops by finite difference numerical methods. Nuclear Engineering and Design, Vol. 201, pp. 11–23, 2000. W. Ambrosini and M. Sharabi, Dimensionless parameters in stability analysis of heated channels with fluids at supercritical pressures. Nuclear Engineering and Design, Vol. 238, pp. 1917–1929, 2008. W. Ambrosini, W., S. Bilbao y Léon, and K. Yamada, Results of the IAEA benchmark exercise on flow stability in heated channels with supercritical fluids. In: Proceedings of the 5th International Symposium on SuperCritical Water Reactors (ISSCWR5), March 13–16, Vancouver, Canada, 2011.