Step 5: Secondary Side

Complete input file for this step: 05_secondary_side.i

Figure 1: Model diagram

In this step, we will add the secondary side of the heat exchanger and set up the inlet mass flow rate boundary condition as a function of time.

Heat Exchanger

We will define the following heat exchanger parameters:


# heat exchanger parameters
hx_dia_inner = ${units 10. cm -> m}
hx_wall_thickness = ${units 5. mm -> m}
hx_dia_outer = ${units 50. cm -> m}
hx_radius_wall = ${fparse hx_dia_inner / 2. + hx_wall_thickness}
hx_length = 1       # m
hx_n_elems = 10

m_dot_sec_in = 1    # kg/s

We also define second fluid that we will be using on the secondary side:

[water]
  type = StiffenedGasFluidProperties
  gamma = 2.35
  cv = 1816.0
  q = -1.167e6
  p_inf = 1.0e9
  q_prime = 0
[]

Components

To define the heat exchanger block, we will use the syntax for grouping components together.

The general syntax is:


[group]
  [component1]
  []
  [component2]
  []
[]

Then, individual components can be referred to as group/component1 and group/component2.

note

Note: It is possible to define parameters within the group. Good candidates would be hx_length and hx_n_elems.

We will take advantage of this feature and set our heat exchanger as follows:

[hx]
  [pri]
    type = FlowChannel1Phase
    position = '1 0 2'
    orientation = '0 0 -1'
    length = ${hx_length}
    n_elems = ${hx_n_elems}
    A = '${fparse pi * hx_dia_inner * hx_dia_inner / 4.}'
    D_h = ${hx_dia_inner}
  []

  [ht_pri]
    type = HeatTransferFromHeatStructure1Phase
    hs = hx/wall
    hs_side = inner
    flow_channel = hx/pri
    Hw = 0.97
  []

  [wall]
    type = HeatStructureCylindrical
    position = '1 0 2'
    orientation = '0 0 -1'
    length = ${hx_length}
    n_elems = ${hx_n_elems}
    widths = '${hx_wall_thickness}'
    n_part_elems = '3'
    materials = 'steel'
    names = '0'
    inner_radius = '${fparse hx_dia_inner / 2.}'
  []

  [ht_sec]
    type = HeatTransferFromHeatStructure1Phase
    hs = hx/wall
    hs_side = outer
    flow_channel = hx/sec
    P_hf = '${fparse 2 * pi * hx_radius_wall}'
    Hw = 36
  []

  [sec]
    type = FlowChannel1Phase
    position = '${fparse 1 + hx_wall_thickness} 0 2'
    orientation = '0 0 -1'
    length = ${hx_length}
    n_elems = ${hx_n_elems}
    A = '${fparse pi * (hx_dia_outer * hx_dia_outer / 4. - hx_radius_wall * hx_radius_wall)}'
    D_h = '${fparse hx_dia_outer - (2 * hx_radius_wall)}'
    fp = water
    f = 0.075
  []
[]

Then, we connect the inlet boundary condition to the secondary side flow channel:

[inlet_sec]
  type = InletMassFlowRateTemperature1Phase
  input = 'hx/sec:out'
  m_dot = 0
  T = 300
[]

And then, the outlet boundary condition for the same channel:

[outlet_sec]
  type = Outlet1Phase
  input = 'hx/sec:in'
  p = ${press}
[]

This is the same as what we did in step 1 of this tutorial.

Inlet Mass Flow Rate

To set up the inlet boundary condition as a function of time, we first need to define a time-dependent function in the top-level [Functions] block:

[m_dot_sec_fn]
  type = PiecewiseLinear
  xy_data = '
      0    0
      100 ${m_dot_sec_in}'
[]

In the [ControlLogic] block, we bring the function value in using the GetFunctionValueControl block:

[m_dot_sec_inlet_ctrl]
  type = GetFunctionValueControl
  function = m_dot_sec_fn
[]

And then we feed this value back into the system:

[set_m_dot_sec_ctrl]
  type = SetComponentRealValueControl
  component = inlet_sec
  parameter = m_dot
  value = m_dot_sec_inlet_ctrl:value
[]

Alternative Solution

An alternative solution to this is to use a convenience block called TimeFunctionComponentControl which combines these two ControlLogic blocks into one. It takes three parameters component, parameter, and function.

The equivalent syntax would look like this:


[set_m_dot_sec_ctrl]
  type = TimeFunctionComponentControl
  component = inlet_sec
  parameter = m_dot
  function = m_dot_sec_fn
[]

note

Note: This should be your preferred setup when you want to use time-dependent component parameters.

Previous Next

(modules/thermal_hydraulics/tutorials/single_phase_flow/05_secondary_side.i)

T_in = 300.         # K
m_dot_in = 1e-4     # kg/s
press = 1e5         # Pa

# core parameters
core_length = 1.    # m
core_n_elems = 10
core_dia = ${units 2. cm -> m}
core_pitch = ${units 8.7 cm -> m}

# pipe parameters
pipe_dia = ${units 10. cm -> m}

tot_power = 100     # W

# heat exchanger parameters
hx_dia_inner = ${units 10. cm -> m}
hx_wall_thickness = ${units 5. mm -> m}
hx_dia_outer = ${units 50. cm -> m}
hx_radius_wall = ${fparse hx_dia_inner / 2. + hx_wall_thickness}
hx_length = 1       # m
hx_n_elems = 10

m_dot_sec_in = 1    # kg/s


[GlobalParams]
  initial_p = ${press}
  initial_vel = 0
  initial_T = ${T_in}
  initial_vel_x = 0
  initial_vel_y = 0
  initial_vel_z = 0

  rdg_slope_reconstruction = full
  closures = simple_closures
  fp = he
  f = 0.4
[]

[Functions]
  [m_dot_sec_fn]
    type = PiecewiseLinear
    xy_data = '
      0    0
      100 ${m_dot_sec_in}'
  []
[]

[Modules/FluidProperties]
  [he]
    type = IdealGasFluidProperties
    molar_mass = 4e-3
    gamma = 1.67
    k = 0.2556
    mu = 3.22639e-5
  []

  [water]
    type = StiffenedGasFluidProperties
    gamma = 2.35
    cv = 1816.0
    q = -1.167e6
    p_inf = 1.0e9
    q_prime = 0
  []
[]

[Closures]
  [simple_closures]
    type = Closures1PhaseSimple
  []
[]

[HeatStructureMaterials]
  [steel]
    type = SolidMaterialProperties
    rho = 8050
    k = 45
    cp = 466
  []
[]

[Components]
  [total_power]
    type = TotalPower
    power = ${tot_power}
  []

  [core_chan]
    type = FlowChannel1Phase
    position = '0 0 0'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}
    A = ${fparse core_pitch * core_pitch - pi * core_dia * core_dia / 4.}
    D_h = ${core_dia}
    f = 1.6
  []

  [core_hs]
    type = HeatStructureCylindrical
    position = '0 0 0'
    orientation = '0 0 1'
    length = ${core_length}
    n_elems = ${core_n_elems}

    names = 'block'
    widths = '${fparse core_dia / 2.}'
    materials = 'steel'
    n_part_elems = 3
  []

  [core_heating]
    type = HeatSourceFromTotalPower
    hs = core_hs
    regions = block
    power = total_power
  []

  [core_ht]
    type = HeatTransferFromHeatStructure1Phase
    flow_channel = core_chan
    hs = core_hs
    hs_side = outer
    P_hf = ${fparse pi * core_dia}
    Hw = 1.36
  []

  [jct1]
    type = JunctionParallelChannels1Phase
    position = '0 0 1'
    connections = 'core_chan:out up_pipe:in'
    volume = 1e-3
  []

  [up_pipe]
    type = FlowChannel1Phase
    position = '0 0 1'
    orientation = '0 0 1'
    length = 1
    n_elems = 10
    A = ${fparse pi * pipe_dia * pipe_dia / 4.}
    D_h = ${pipe_dia}
  []

  [jct2]
    type = VolumeJunction1Phase
    position = '0 0 2'
    connections = 'up_pipe:out top_pipe:in'
    volume = 1e-3
  []

  [top_pipe]
    type = FlowChannel1Phase
    position = '0 0 2'
    orientation = '1 0 0'
    length = 1
    n_elems = 10
    A = ${fparse pi * pipe_dia * pipe_dia / 4.}
    D_h = ${pipe_dia}
  []

  [jct3]
    type = VolumeJunction1Phase
    position = '1 0 2'
    connections = 'top_pipe:out hx/pri:in'
    volume = 1e-3
  []

  [hx]
    [pri]
      type = FlowChannel1Phase
      position = '1 0 2'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      A = ${fparse pi * hx_dia_inner * hx_dia_inner / 4.}
      D_h = ${hx_dia_inner}
    []

    [ht_pri]
      type = HeatTransferFromHeatStructure1Phase
      hs = hx/wall
      hs_side = inner
      flow_channel = hx/pri
      Hw = 0.97
    []

    [wall]
      type = HeatStructureCylindrical
      position = '1 0 2'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      widths = '${hx_wall_thickness}'
      n_part_elems = '3'
      materials = 'steel'
      names = '0'
      inner_radius = ${fparse hx_dia_inner / 2.}
    []

    [ht_sec]
      type = HeatTransferFromHeatStructure1Phase
      hs = hx/wall
      hs_side = outer
      flow_channel = hx/sec
      P_hf = ${fparse 2 * pi * hx_radius_wall}
      Hw = 36
    []

    [sec]
      type = FlowChannel1Phase
      position = '${fparse 1 + hx_wall_thickness} 0 2'
      orientation = '0 0 -1'
      length = ${hx_length}
      n_elems = ${hx_n_elems}
      A = ${fparse pi * (hx_dia_outer * hx_dia_outer / 4. - hx_radius_wall * hx_radius_wall)}
      D_h = ${fparse hx_dia_outer - (2 * hx_radius_wall)}
      fp = water
      f = 0.075
    []
  []

  [jct4]
    type = VolumeJunction1Phase
    position = '1 0 1'
    connections = 'hx/pri:out down_pipe:in'
    volume = 1e-3
  []

  [down_pipe]
    type = FlowChannel1Phase
    position = '1 0 1'
    orientation = '0 0 -1'
    length = 1
    n_elems = 10
    A = ${fparse pi * pipe_dia * pipe_dia / 4.}
    D_h = ${pipe_dia}
  []

  [jct5]
    type = VolumeJunction1Phase
    position = '1 0 0'
    connections = 'down_pipe:out bottom_b:in'
    volume = 1e-3
  []

  [bottom_b]
    type = FlowChannel1Phase
    position = '1 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${fparse pi * pipe_dia * pipe_dia / 4.}
    D_h = ${pipe_dia}
  []

  [pump]
    type = Pump1Phase
    position = '0.5 0 0'
    connections = 'bottom_b:out bottom_a:in'
    volume = 1e-3
    A_ref = ${fparse pi * pipe_dia * pipe_dia / 4.}
    head = 0
  []

  [bottom_a]
    type = FlowChannel1Phase
    position = '0.5 0 0'
    orientation = '-1 0 0'
    length = 0.5
    n_elems = 5
    A = ${fparse pi * pipe_dia * pipe_dia / 4.}
    D_h = ${pipe_dia}
  []

  [jct6]
    type = VolumeJunction1Phase
    position = '0 0 0'
    connections = 'bottom_a:out core_chan:in'
    volume = 1e-3
  []

  [inlet_sec]
    type = InletMassFlowRateTemperature1Phase
    input = 'hx/sec:out'
    m_dot = 0
    T = 300
  []

  [outlet_sec]
    type = Outlet1Phase
    input = 'hx/sec:in'
    p = ${press}
  []
[]

[ControlLogic]
  [set_point]
    type = GetFunctionValueControl
    function = ${m_dot_in}
  []

  [pid]
    type = PIDControl
    initial_value = 0
    set_point = set_point:value
    input = m_dot_pump
    K_p = 250
    K_i = 0.5
    K_d = 0
  []

  [set_pump_head]
    type = SetComponentRealValueControl
    component = pump
    parameter = head
    value = pid:output
  []

  [m_dot_sec_inlet_ctrl]
    type = GetFunctionValueControl
    function = m_dot_sec_fn
  []

  [set_m_dot_sec_ctrl]
    type = SetComponentRealValueControl
    component = inlet_sec
    parameter = m_dot
    value = m_dot_sec_inlet_ctrl:value
  []
[]

[Postprocessors]
  [m_dot_pump]
    type = ADFlowJunctionFlux1Phase
    boundary = core_chan:in
    connection_index = 1
    equation = mass
    junction = jct6
  []

  [core_T_out]
    type = SideAverageValue
    boundary = core_chan:out
    variable = T
  []

  [hx_pri_T_out]
    type = SideAverageValue
    boundary = hx/pri:out
    variable = T
  []

  [hx_sec_T_in]
    type = SideAverageValue
    boundary = inlet_sec
    variable = T
  []

  [hx_sec_T_out]
    type = SideAverageValue
    boundary = outlet_sec
    variable = T
  []
[]

[Executioner]
  type = Transient
  start_time = 0

  [TimeStepper]
    type = SolutionTimeAdaptiveDT
    dt = 1
  []
  dtmax = 100
  end_time = 50000

  line_search = basic
  solve_type = NEWTON

  nl_rel_tol = 1e-5
  nl_abs_tol = 1e-5
  nl_max_its = 5
[]

[Outputs]
  exodus = true

  [console]
    type = Console
    max_rows = 1
    outlier_variable_norms = false
  []
  print_linear_residuals = false
[]

Heat Exchanger
Components
Inlet Mass Flow Rate

Install MOOSE

New Users

Examples and Tutorials

Application Usage

Physics and Syntax

Application Development

Framework Development

MOOSEDocs

Infrastructure

Questions

Information and Tools

INL Applications and Remote Access

Step 5: Secondary Side

Heat Exchanger

Components

Inlet Mass Flow Rate

Alternative Solution