vclibpy.components.heat_exchangers package

Subpackages

• vclibpy.components.heat_exchangers.heat_transfer package
  • Submodules
  • vclibpy.components.heat_exchangers.heat_transfer.air_to_wall module
    • AirToWallTransfer
      • AirToWallTransfer.calc()
      • AirToWallTransfer.calc_laminar_area_nusselt()
      • AirToWallTransfer.calc_reynolds()
    • WSUAirToWall
      • WSUAirToWall.calc_laminar_area_nusselt()
      • WSUAirToWall.calc_reynolds()
  • vclibpy.components.heat_exchangers.heat_transfer.constant module
    • ConstantHeatTransfer
      • ConstantHeatTransfer.calc()
    • ConstantTwoPhaseHeatTransfer
      • ConstantTwoPhaseHeatTransfer.calc()
  • vclibpy.components.heat_exchangers.heat_transfer.heat_transfer module
    • HeatTransfer
      • HeatTransfer.calc()
    • TwoPhaseHeatTransfer
      • TwoPhaseHeatTransfer.calc()
    • calc_reynolds_pipe()
  • vclibpy.components.heat_exchangers.heat_transfer.pipe_to_wall module
    • TurbulentFluidInPipeToWallTransfer
      • TurbulentFluidInPipeToWallTransfer.calc()
      • TurbulentFluidInPipeToWallTransfer.calc_turbulent_tube_nusselt()
  • vclibpy.components.heat_exchangers.heat_transfer.vdi_atlas_air_to_wall module
    • AirSourceHeatExchangerGeometry
      • AirSourceHeatExchangerGeometry.A
      • AirSourceHeatExchangerGeometry.A_FreieOberflaecheRohr
      • AirSourceHeatExchangerGeometry.A_Rippen
      • AirSourceHeatExchangerGeometry.A_RohrInnen
      • AirSourceHeatExchangerGeometry.A_RohrUnberippt
      • AirSourceHeatExchangerGeometry.a
      • AirSourceHeatExchangerGeometry.alpha_S()
      • AirSourceHeatExchangerGeometry.char_length
      • AirSourceHeatExchangerGeometry.d_a
      • AirSourceHeatExchangerGeometry.d_i
      • AirSourceHeatExchangerGeometry.dicke_rippe
      • AirSourceHeatExchangerGeometry.eta_R()
      • AirSourceHeatExchangerGeometry.hoehe
      • AirSourceHeatExchangerGeometry.laenge
      • AirSourceHeatExchangerGeometry.lambda_R
      • AirSourceHeatExchangerGeometry.n_Rippen
      • AirSourceHeatExchangerGeometry.n_Rohre
      • AirSourceHeatExchangerGeometry.phi
      • AirSourceHeatExchangerGeometry.t_l
      • AirSourceHeatExchangerGeometry.t_q
      • AirSourceHeatExchangerGeometry.tiefe
      • AirSourceHeatExchangerGeometry.verjuengungsfaktor
    • VDIAtlasAirToWallTransfer
      • VDIAtlasAirToWallTransfer.calc_laminar_area_nusselt()
      • VDIAtlasAirToWallTransfer.calc_reynolds()
  • vclibpy.components.heat_exchangers.heat_transfer.wall module
    • WallTransfer
      • WallTransfer.calc()

Submodules

vclibpy.components.heat_exchangers.economizer module

class vclibpy.components.heat_exchangers.economizer.VaporInjectionEconomizerNTU(**kwargs)

Bases: BasicNTU

Economizer heat exchanger which is NTU based. Used only for vapor injection cycles, as calculations are purely based for two-phase and liquid estimations.

See parent class for more arguments.

Assumptions:

• Default flow_type is counter_flow.

• Default ratio_outer_to_inner_area is 1, as

• pipes are nearly same diameter and length

• Secondary heat transfer for alpha is disabled; gas,

liquid and two-phase models are used for both sides.

calc(inputs, fs_state) -> (<class 'float'>, <class 'float'>)

Calculate the heat exchanger based on the given inputs.

The flowsheet state can be used to save important variables during calculation for later analysis.

Both return values are used to check if the heat transfer is valid or not.

Args:

inputs (Inputs): The inputs for the calculation. fs_state (FlowsheetState): The flowsheet state to save important variables.

Returns:

Tuple[float, float]:

error: Error in percentage between the required and calculated heat flow rates. dT_min: Minimal temperature difference (can be negative).

calc_alpha_secondary(transport_properties)

Calculate the secondary-medium heat transfer coefficient.

Args:

transport_properties: Transport properties for the secondary medium.

Returns:

float: The secondary-medium heat transfer coefficient.

calc_transport_properties_secondary_medium(T, p=None)

Calculate the transport properties for the selected secondary_medium.

Args:

T (float): Temperature in K. p (float, optional): Pressure to use. Defaults to None.

Returns:

media.TransportProperties: The calculated transport properties.

set_secondary_cp(cp: float)

Set primary m_flow_cp

start_secondary_med_prop()

Set up the wrapper for the secondary medium’s media properties.

property state_two_phase_inlet: ThermodynamicState

property state_two_phase_outlet: ThermodynamicState

terminate_secondary_med_prop()

To use multi-processing, MedProp can’t start in the main thread, as the object can’t be pickled.

This function terminates possible secondary med-prop classes, for instance in heat exchangers. The default component does not have to override this function.

vclibpy.components.heat_exchangers.heat_exchanger module

class vclibpy.components.heat_exchangers.heat_exchanger.HeatExchanger(A: float, wall_heat_transfer: HeatTransfer, secondary_heat_transfer: HeatTransfer, gas_heat_transfer: HeatTransfer, liquid_heat_transfer: HeatTransfer, two_phase_heat_transfer: TwoPhaseHeatTransfer, secondary_medium: str)

Bases: BaseComponent, ABC

Class for a heat exchanger.

Args:

A (float):

Area of HE in m^2 for NTU calculation

secondary_medium (str):

Name for secondary medium, e.g. water or air

wall_heat_transfer (HeatTransfer):

Model for heat transfer inside wall

secondary_heat_transfer (HeatTransfer):

Model for heat transfer from secondary medium to wall

gas_heat_transfer (HeatTransfer):

Model for heat transfer from refrigerant gas to wall

liquid_heat_transfer (HeatTransfer):

Model for heat transfer from refrigerant liquid to wall

two_phase_heat_transfer (TwoPhaseHeatTransfer):

Model for heat transfer from refrigerant two phase to wall

abstract calc(inputs: Inputs, fs_state: FlowsheetState) → Tuple[float, float]

Calculate the heat exchanger based on the given inputs.

The flowsheet state can be used to save important variables during calculation for later analysis.

Both return values are used to check if the heat transfer is valid or not.

Args:

inputs (Inputs): The inputs for the calculation. fs_state (FlowsheetState): The flowsheet state to save important variables.

Returns:

Tuple[float, float]:

error: Error in percentage between the required and calculated heat flow rates. dT_min: Minimal temperature difference (can be negative).

calc_Q_flow() → float

Calculate the total heat flow rate.

Returns:

float: The total heat flow rate.

calc_alpha_gas(transport_properties) → float

Calculate the gas-phase heat transfer coefficient.

Args:

transport_properties: Transport properties for the gas phase.

Returns:

float: The gas-phase heat transfer coefficient.

calc_alpha_liquid(transport_properties) → float

Calculate the liquid-phase heat transfer coefficient.

Args:

transport_properties: Transport properties for the liquid phase.

Returns:

float: The liquid-phase heat transfer coefficient.

calc_alpha_secondary(transport_properties) → float

Calculate the secondary-medium heat transfer coefficient.

Args:

transport_properties: Transport properties for the secondary medium.

Returns:

float: The secondary-medium heat transfer coefficient.

calc_alpha_two_phase(state_q0, state_q1, inputs: Inputs, fs_state: FlowsheetState) → float

Calculate the two-phase heat transfer coefficient.

Args:

state_q0: State at vapor quality 0. state_q1: State at vapor quality 1. inputs (Inputs): The inputs for the calculation. fs_state (FlowsheetState): The flowsheet state to save important variables.

Returns:

float: The two-phase heat transfer coefficient.

calc_secondary_Q_flow(Q_flow: float) → float

calc_secondary_cp(T: float, p=None)

Calculate and set the heat capacity rate m_flow_cp of the secondary medium.

Args:

T (float): Temperature of the secondary medium. p (float, optional): Pressure of the secondary medium. Defaults to None.

calc_transport_properties_secondary_medium(T, p=None) → TransportProperties

Calculate the transport properties for the selected secondary_medium.

Args:

T (float): Temperature in K. p (float, optional): Pressure to use. Defaults to None.

Returns:

media.TransportProperties: The calculated transport properties.

calc_wall_heat_transfer() → float

Calculate the heat transfer coefficient inside the wall.

Returns:

float: The wall heat transfer coefficient.

property m_flow_secondary: float

property m_flow_secondary_cp

start_secondary_med_prop()

Set up the wrapper for the secondary medium’s media properties.

terminate_secondary_med_prop()

To use multi-processing, MedProp can’t start in the main thread, as the object can’t be pickled.

This function terminates possible secondary med-prop classes, for instance in heat exchangers. The default component does not have to override this function.

vclibpy.components.heat_exchangers.moving_boundary_ntu module

class vclibpy.components.heat_exchangers.moving_boundary_ntu.MovingBoundaryNTU(flow_type: str, ratio_outer_to_inner_area: float, **kwargs)

Bases: BasicNTU, ABC

Moving boundary NTU based heat exchanger.

See parent classe for arguments.

iterate_area(dT_max, alpha_pri, alpha_sec, Q) → float

Iteratively calculates the required area for the heat exchange.

Args:

dT_max (float): Maximum temperature differential. alpha_pri (float): Heat transfer coefficient for the primary medium. alpha_sec (float): Heat transfer coefficient for the secondary medium. Q (float): Heat flow rate.

Returns:

float: Required area for heat exchange.

separate_phases(state_max: ThermodynamicState, state_min: ThermodynamicState, p: float)

Separates a flow with possible phase changes into three parts: subcooling (sc), latent phase change (lat), and superheating (sh) at the given pressure.

Args:

state_max (ThermodynamicState): State with higher enthalpy. state_min (ThermodynamicState): State with lower enthalpy. p (float): Pressure of phase change.

Returns:

Tuple[float, float, float, ThermodynamicState, ThermodynamicState]:

Q_sc: Heat for subcooling. Q_lat: Heat for latent phase change. Q_sh: Heat for superheating. state_q0: State at vapor quality 0 and the given pressure. state_q1: State at vapor quality 1 and the given pressure.

class vclibpy.components.heat_exchangers.moving_boundary_ntu.MovingBoundaryNTUCondenser(flow_type: str, ratio_outer_to_inner_area: float, **kwargs)

Bases: MovingBoundaryNTU

Condenser class which implements the actual calc method.

Assumptions: - No phase changes in secondary medium - cp of secondary medium is constant over heat-exchanger

See parent classes for arguments.

calc(inputs: ~vclibpy.datamodels.Inputs, fs_state: ~vclibpy.datamodels.FlowsheetState) -> (<class 'float'>, <class 'float'>)

Calculate the heat exchanger with the NTU-Method based on the given inputs.

The flowsheet state can be used to save important variables during calculation for later analysis.

Both return values are used to check if the heat transfer is valid or not.

Args:

inputs (Inputs): The inputs for the calculation. fs_state (FlowsheetState): The flowsheet state to save important variables.

Returns:

Tuple[float, float]:

error: Error in percentage between the required and calculated heat flow rates. dT_min: Minimal temperature difference (can be negative).

class vclibpy.components.heat_exchangers.moving_boundary_ntu.MovingBoundaryNTUEvaporator(flow_type: str, ratio_outer_to_inner_area: float, **kwargs)

Bases: MovingBoundaryNTU

Evaporator class which implements the actual calc method.

Assumptions: - No phase changes in secondary medium - cp of secondary medium is constant over heat-exchanger

See parent classes for arguments.

calc(inputs: ~vclibpy.datamodels.Inputs, fs_state: ~vclibpy.datamodels.FlowsheetState) -> (<class 'float'>, <class 'float'>)

Calculate the heat exchanger with the NTU-Method based on the given inputs.

The flowsheet state can be used to save important variables during calculation for later analysis.

Both return values are used to check if the heat transfer is valid or not.

Args:

inputs (Inputs): The inputs for the calculation. fs_state (FlowsheetState): The flowsheet state to save important variables.

Returns:

Tuple[float, float]:

error: Error in percentage between the required and calculated heat flow rates. dT_min: Minimal temperature difference (can be negative).

vclibpy.components.heat_exchangers.ntu module

class vclibpy.components.heat_exchangers.ntu.BasicNTU(flow_type: str, ratio_outer_to_inner_area: float, **kwargs)

Bases: HeatExchanger, ABC

Moving boundary NTU based heat exchanger.

See parent class for more arguments.

Args:

flow_type (str):

Counter, Cross or parallel flow

ratio_outer_to_inner_area (float):

The NTU method uses the overall heat transfer coefficient k and multiplies it with the outer area A (area of the secondary side). However, depending on the heat exchanger type, the areas may differ drastically. For instance in an air-to-water heat exchanger. The VDI-Atlas proposes the ratio of outer area to inner pipe area to account for this mismatch in sizes. The calculation follows the code in the function calc_k. Typical values are around 20-30.

static calc_NTU(A: float, k: float, m_flow_cp: float) → float

Calculate the Number of Transfer Units (NTU) for the heat exchanger.

Args:

A (float): Area of the heat exchanger. k (float): Overall heat transfer coefficient. m_flow_cp (float): Minimal heat capacity rates (m_flow*cp) between primary and secondary side.

Returns:

float: Number of Transfer Units (NTU).

calc_Q_ntu(dT_max: float, alpha_pri: float, alpha_sec: float, A: float) -> (<class 'float'>, <class 'float'>)

Calculate the heat transfer and overall heat transfer coefficient for the heat exchanger based on NTU.

Args:

dT_max (float): Maximum temperature differential. alpha_pri (float): Heat transfer coefficient for the primary medium. alpha_sec (float): Heat transfer coefficient for the secondary medium. A (float): Area of the heat exchanger.

Returns:

Tuple[float, float]: Heat transfer and overall heat transfer coefficient.

calc_R() → float

Calculate the R value, which is the ratio of heat capacity rates (m_flow*cp) of the primary to secondary medium.

Returns:

float: R value.

calc_eps(R: float, NTU: float) → float

Calculate the effectiveness (eps) of the heat exchanger based on NTU.

Source of implementation: EBC Lecture SimModelle.

Args:

R (float): Ratio of heat capacity rates (m_flow*cp) of the primary to secondary medium. NTU (float): Number of Transfer Units.

Returns:

float: Effectiveness (eps) of the heat exchanger.

calc_k(alpha_pri: float, alpha_sec: float) → float

Calculate the overall heat transfer coefficient (k) of the heat exchanger.

Args:

alpha_pri (float): Heat transfer coefficient for the primary medium. alpha_sec (float): Heat transfer coefficient for the secondary medium.

Returns:

float: Overall heat transfer coefficient (k).

calc_m_flow_cp_min() → float

Calculate the minimum value between the heat capacity rates (m_flow*cp) for the primary and secondary mediums.

Returns:

float: Minimum value.

set_primary_cp(cp: float)

Set the specific heat (cp) for the primary medium.

Args:

cp (float): Specific heat for the primary medium.