Heat Exchanger

Intercooler or exhaust gas recirculation (EGR) cooler

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  • Powertrain Blockset / Propulsion / Combustion Engine Components / Fundamental Flow

Description

The Heat Exchanger block models a heat exchanger, for example, an intercooler or exhaust gas recirculation (EGR) cooler. The inlet (port C) connects to an engine flow component (flow restriction, compressor, turbine, or engine block). The outlet (port B) connects to a volume (control volume or environment). Based on the upstream temperature, heat exchanger effectiveness, and cooling medium temperature, the block determines the heat transfer rate and downstream temperature.

For the heat exchanger effectiveness and cooling medium temperature, you can specify either a constant value or an external input. For example, if you specify a heat exchanger effectiveness that is:

  • Equal to 1, the downstream temperature is equal to the cooling medium temperature.

  • Equal to 0, there is no heat transfer to the cooling medium. The downstream temperature is equal to the upstream temperature.

The block assumes no pressure drop. To model pressure losses, use a Flow Restriction block.

Equations

The Heat Exchanger block implements equations that use these variables.

Tupstr

Upstream temperature

Tdnstr

Downstream temperature

Tcool

Cooling medium temperature

Tcool,cnst

Constant cooling medium temperature

Tcool,input

External input cooling medium temperature

ε

Heat exchanger effectiveness

εcnst

Constant heat exchanger effectiveness

εinput

Input heat exchanger effectiveness

cp

Specific heat at constant pressure

qht

Heat exchanger heat transfer rate

pflw,in

Pressure at inlet

pvol,out

Pressure at outlet

Tvol,out

Temperature at outlet

hvol,out

Specific enthalpy at outlet

qin

Heat flow rate at inlet

qout

Heat flow rate at outlet

m˙

Heat exchanger mass flow rate

Tflw,in

Temperature at inlet

Tin

Heat exchanger inlet temperature

Tout

Heat exchanger outlet temperature

hin

Inlet specific enthalpy

Heat Exchanger Effectiveness

Heat exchanger effectiveness measures the effectiveness of heat transfer from the incoming hot fluid to the cooling medium:

ε=TupstrTdnstrTupstrTcool

In an ideal heat exchanger, the downstream temperature equals the cooling temperature. The effectiveness is equal to 1.

Tdnstr=Tcoolε=1

The Heat Exchanger block uses the effectiveness to determine the downstream temperature and heat transfer rate.

Tdnstr=Tupstrε(TupstrTcool)qht=m˙cp(TupstrTdnstr)

Fluid Flow

Since the block assumes no pressure drop, Pflw,in=Pvol,out.

The flow component connection to the heat exchanger inlet determines the direction of the mass flow. Based on the mass flow rate direction, these temperature and heat flow equations apply.

Fluid FlowMass Flow RateTemperatures and Heat Flow

Forward — From engine flow component to outlet volume

m˙0

Tupstr=Tflw,inTin=TupstrTout=Tdnstrqout=m˙cpTdnstr

Reverse — From outlet volume to engine flow component

m˙<0

Tupstr=Tvol,outTin=TdnstrTout=Tvol,outhin=cpTdnstrqout=m˙hvol,out

Power Accounting

For the power accounting, the block implements these equations.

Bus Signal DescriptionEquations

PwrInfo

PwrTrnsfrd — Power transferred between blocks

  • Positive signals indicate flow into block

  • Negative signals indicate flow out of block

PwrHeatFlwIn

Heat flow rate at port C

qin

PwrHeatFlwOut

Heat flow rate at port B

-qout

PwrNotTrnsfrd — Power crossing the block boundary, but not transferred

  • Positive signals indicate an input

  • Negative signals indicate a loss

PwrHeatTrnsfr

Heat transfer rate to cooling medium

-qht

PwrStored — Stored energy rate of change

  • Positive signals indicate an increase

  • Negative signals indicate a decrease

Not used

Ports

Input

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Bus containing the heat exchanger:

  • MassFlwRate — Mass flow rate at inlet, m˙, in kg/s

  • HeatFlwRate — Heat flow rate at inlet, qin, in J/s

  • Temp — Temperature at inlet, Tflw,in, in K

  • MassFrac — Inlet mass fractions, dimensionless.

    Specifically, a bus with these mass fractions:

    • O2MassFrac — Oxygen

    • N2MassFrac — Nitrogen

    • UnbrndFuelMassFrac — Unburned fuel

    • CO2MassFrac — Carbon dioxide

    • H2OMassFrac — Water

    • COMassFrac — Carbon monoxide

    • NOMassFrac — Nitric oxide

    • NO2MassFrac — Nitrogen dioxide

    • NOxMassFrac — Nitric oxide and nitrogen dioxide

    • PmMassFrac — Particulate matter

    • AirMassFrac — Air

    • BrndGasMassFrac — Burned gas

Bus containing the heat exchanger:

  • Prs — Pressure at outlet, pvol,out, in Pa

  • Temp — Temperature at outlet, Tvol,out, in K

  • Enth — Specific enthalpy at outlet, hvol,out, in J/kg

  • MassFrac — Outlet mass fractions, dimensionless.

    Specifically, a bus with these mass fractions:

    • O2MassFrac — Oxygen

    • N2MassFrac — Nitrogen

    • UnbrndFuelMassFrac — Unburned fuel

    • CO2MassFrac — Carbon dioxide

    • H2OMassFrac — Water

    • COMassFrac — Carbon monoxide

    • NOMassFrac — Nitric oxide

    • NO2MassFrac — Nitrogen dioxide

    • NOxMassFrac — Nitric oxide and nitrogen dioxide

    • PmMassFrac — Particulate matter

    • AirMassFrac — Air

    • BrndGasMassFrac — Burned gas

Heat exchanger effectiveness, εinput.

Dependencies

To create this port, select External input for the Effectiveness model parameter.

Cooling medium temperature, Tcool,input.

Dependencies

To create this port, select External input for the Cooling medium temperature input parameter.

Output

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Bus signal containing these block calculations.

SignalDescriptionUnits

InletTemp

Heat exchanger inlet temperature

K

OutletTemp

Heat exchanger outlet temperature

K

HeatTrnsfrRate

Heat exchanger heat transfer rate

J/s

PwrInfo

PwrTrnsfrd

PwrHeatFlwIn

Heat flow rate at port C

W

PwrHeatFlwOut

Heat flow rate at port B

W

PwrNotTrnsfrd

PwrHeatTrnsfr

Heat transfer rate to cooling medium

W

PwrStored

Not used

Bus containing the heat exchanger:

  • Prs — Pressure at inlet, pflw,in, in Pa

  • Temp — Temperature at inlet, Tin, in K

  • Enth — Specific enthalpy at inlet, hin, in J/kg

  • MassFrac — Inlet mass fractions, dimensionless.

    Specifically, a bus with these mass fractions:

    • O2MassFrac — Oxygen

    • N2MassFrac — Nitrogen

    • UnbrndFuelMassFrac — Unburned fuel

    • CO2MassFrac — Carbon dioxide

    • H2OMassFrac — Water

    • COMassFrac — Carbon monoxide

    • NOMassFrac — Nitric oxide

    • NO2MassFrac — Nitrogen dioxide

    • NOxMassFrac — Nitric oxide and nitrogen dioxide

    • PmMassFrac — Particulate matter

    • AirMassFrac — Air

    • BrndGasMassFrac — Burned gas

Bus containing the heat exchanger:

  • MassFlwRate — Mass flow rate at outlet, m˙, in kg/s

  • HeatFlwRate — Heat flow rate at outlet, qout, in J/s

  • Temp — Temperature at outlet, Tout, in K

  • MassFrac — Outlet mass fractions, dimensionless.

    Specifically, a bus with these mass fractions:

    • O2MassFrac — Oxygen

    • N2MassFrac — Nitrogen

    • UnbrndFuelMassFrac — Unburned fuel

    • CO2MassFrac — Carbon dioxide

    • H2OMassFrac — Water

    • COMassFrac — Carbon monoxide

    • NOMassFrac — Nitric oxide

    • NO2MassFrac — Nitrogen dioxide

    • NOxMassFrac — Nitric oxide and nitrogen dioxide

    • PmMassFrac — Particulate matter

    • AirMassFrac — Air

    • BrndGasMassFrac — Burned gas

Parameters

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Block Options

Type of model to calculate the heat exchanger effectiveness.

Dependencies

  • Selecting External input creates the Effct port.

  • Selecting Constant enables the Heat exchanger effectiveness, ep_cnst parameter.

Cooling medium temperature input.

Dependencies

  • Selecting External input creates the CoolTemp port.

  • Selecting Constant enables the Cooling medium temperature, T_cool_cnst parameter.

Block icon color:

  • Intercooler for blue, to indicate an intercooler

  • EGR cooler for red, to indicate exhaust-gas-recirculation (EGR) cooling

Constant heat exchanger effectiveness, εcnst.

Dependencies

To enable this parameter, select Constant for the Effectiveness model parameter.

Constant cooling medium temperature, Tcool,cnst, in K.

Dependencies

To enable this parameter, select Constant for the Cooling medium temperature input parameter.

Specific heat at constant pressure, cp, in J/(kg*K).

References

[1] Eriksson, Lars and Nielsen, Lars. Modeling and Control of Engines and Drivelines. Chichester, West Sussex, United Kingdom: John Wiley & Sons Ltd, 2014.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Introduced in R2017a