Heat Exchanger Interface (TL)

Thermal interface between a thermal liquid and its surroundings

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Libraries:
Simscape / Fluids / Heat Exchangers / Fundamental Components

Description

The Heat Exchanger Interface (TL) block represents a liquid interface in a thermal liquid network for heat transfer with other fluids. The block models the pressure drop and temperature change between the thermal liquid inlet and outlet of a thermal interface and when combined with the E-NTU Heat Transfer block models the heat transfer rate across the interface between two fluids.

Mass Balance

The form of the mass balance equation depends on the dynamic compressibility setting. If you clear the Thermal liquid 1 dynamic compressibility checkbox, the mass balance equation is

$${\dot{m}}_A+{\dot{m}}_B=0,$$

where:

• $${\dot{m}}_A$$ and $${\dot{m}}_B$$ are the mass flow rates into the interface through ports A and B.

If you select Thermal liquid 1 dynamic compressibility, the mass balance equation is

$${\dot{m}}_A+{\dot{m}}_B=\left(\frac{dp}{dt}\frac{1}{\beta }-\frac{dT}{dt}\alpha \right)\rho V,$$

where:

• p is the pressure of the thermal liquid volume.

• T is the temperature of the thermal liquid volume.

• ɑ is the isobaric thermal expansion coefficient of the thermal liquid volume.

• β is the isothermal bulk modulus of the thermal liquid volume.

• ρ is the mass density of the thermal liquid volume.

• V is the volume of thermal liquid in the heat exchanger interface.

Momentum Balance

The momentum balance in the heat exchanger interface depends on the fluid dynamic compressibility setting. If you select Thermal liquid 1 dynamic compressibility, the momentum balance factors in the internal pressure of the heat exchanger interface explicitly. The momentum balance in the half volume between port A and the internal interface node is

$$p_A-p=\Delta p_{\text{Loss,A}},$$

while in the half volume between port B and the internal interface node it is

$$p_B-p=\Delta p_{\text{Loss,B}},$$

where:

• p_A and p_B are the pressures at ports A and B.

• p is the pressure in the internal node of the interface volume.

• Δp_Loss,A and Δp_Loss,B are the pressure losses between port A and the internal interface node and between port B and the internal interface node.

If you clear the Thermal liquid 1 dynamic compressibility checkbox, the momentum balance in the interface volume is computed directly between ports A and B as

$$p_A-p_B=\Delta p_{Loss,A}-\Delta p_{Loss,B}.$$

Pressure Loss Calculations

The exact form of the pressure loss terms depends on the Pressure loss model setting in the block dialog box. If the pressure loss model is set to Pressure loss coefficient, the pressure loss in the half volume adjacent to port A is

$$\Delta p_{Loss,A}=\{\begin{array}{ll}{\dot{m}}_A{\mu }_A{\left(CP\right)}_{Loss}{\mathrm{Re}}_L\frac{1}{4D_{h,p}{\rho }_A{S}_{Min}},\hfill & {\mathrm{Re}}_A\le {\mathrm{Re}}_L\hfill \\ {\left(CP\right)}_{Loss}\frac{{\dot{m}}_A\left|{\dot{m}}_A\right|}{4{\rho }_A{S}_{Min}^2},\hfill & {\mathrm{Re}}_A\ge {\mathrm{Re}}_T\hfill \end{array},$$

while in the half volume adjacent to port B it is

$$\Delta p_{Loss,B}=\{\begin{array}{ll}{\dot{m}}_B{\mu }_B{\left(CP\right)}_{Loss}{\mathrm{Re}}_L\frac{1}{4D_{h,p}{\rho }_B{S}_{Min}},\hfill & {\mathrm{Re}}_B\le {\mathrm{Re}}_L\hfill \\ {\left(CP\right)}_{Loss}\frac{{\dot{m}}_B\left|{\dot{m}}_B\right|}{4{\rho }_B{S}_{Min}^2},\hfill & {\mathrm{Re}}_B\ge {\mathrm{Re}}_T\hfill \end{array},$$

where:

• μ_A and μ_B are the fluid dynamic viscosities at ports A and B.

• CP_Loss is the Pressure loss coefficient parameter specified in the block dialog box.

• Re_L is the Reynolds number upper bound for the laminar flow regime.

• Re_T is the Reynolds number lower bound for the turbulent flow regime.

• D_h,p is the hydraulic diameter for pressure loss calculations.

• ρ_A and ρ_B are the fluid mass densities at ports A and B.

• S_Min is the total minimum free-flow area.

If the pressure loss model is set to Correlation for flow inside tubes, the pressure loss in the half volume adjacent to port A is

$$\Delta p_{Loss,A}=\{\begin{array}{ll}{\dot{m}}_A{\mu }_A\lambda \frac{\left(L_{press}+L_{add}\right)}{4D_{h,p}{\rho }_A{S}_{Min}},\hfill & {\mathrm{Re}}_A\le {\mathrm{Re}}_L\hfill \\ f_{T,A}\frac{\left(L_{press}+L_{add}\right)}{4D_{h,p}}\frac{{\dot{m}}_A\left|{\dot{m}}_A\right|}{{\rho }_A{S}_{Min}^2},\hfill & {\mathrm{Re}}_A\ge {\mathrm{Re}}_T\hfill \end{array},$$

while in the half volume adjacent to port B it is

$$\Delta p_{Loss,B}=\{\begin{array}{ll}{\dot{m}}_B{\mu }_B\lambda \frac{\left(L_{press}+L_{add}\right)}{4D_{h,p}{\rho }_B{S}_{Min}},\hfill & {\mathrm{Re}}_B\le {\mathrm{Re}}_L\hfill \\ f_{T,B}\frac{\left(L_{press}+L_{add}\right)}{4D_{h,p}}\frac{{\dot{m}}_B\left|{\dot{m}}_B\right|}{{\rho }_B{S}_{Min}^2},\hfill & {\mathrm{Re}}_B\ge {\mathrm{Re}}_T\hfill \end{array},$$

where:

• L_press is the flow path length from inlet to outlet.

• L_add is the aggregate equivalent length of local resistances.

• f_T,A and f_T,B are the turbulent-regime Darcy friction factors at ports A and B.

The Darcy friction factor in the half volume adjacent to port A is

$$f_{T,A}=\frac{1}{{\left[-1.8{\log }_{10}{\left(\frac{6.9}{{\mathrm{Re}}_A}+\frac{r}{3.7D_{h,p}}\right)}^{1.11}\right]}^2},$$

while in the half volume adjacent to port B it is

$$f_{T,B}=\frac{1}{{\left[-1.8{\log }_{10}{\left(\frac{6.9}{{\mathrm{Re}}_B}+\frac{r}{3.7D_{h,p}}\right)}^{1.11}\right]}^2},$$

where r is the internal surface absolute roughness.

If the pressure loss model is set to Tabulated data — Darcy friction factor vs. Reynolds number, the pressure loss in the half volume adjacent to port A is

$$\Delta p_{Loss,A}=\{\begin{array}{ll}{\dot{m}}_A{\mu }_A\lambda \frac{L_{press}}{4D_{h,p}^2{\rho }_A{S}_{Min}},\hfill & {\mathrm{Re}}_A\le {\mathrm{Re}}_L\hfill \\ f\left({\mathrm{Re}}_A\right)\frac{L_{press}}{4D_{h,p}}\frac{{\dot{m}}_A\left|{\dot{m}}_A\right|}{{\rho }_A{S}_{Min}^2},\hfill & {\mathrm{Re}}_A\ge {\mathrm{Re}}_T\hfill \end{array},$$

while in the half volume adjacent to port B it is

$$\Delta p_{Loss,B}=\{\begin{array}{ll}{\dot{m}}_B{\mu }_B\lambda \frac{L_{press}}{4D_{h,p}^2{\rho }_B{S}_{Min}},\hfill & {\mathrm{Re}}_B\le {\mathrm{Re}}_L\hfill \\ f\left({\mathrm{Re}}_B\right)\frac{L_{press}}{4D_{h,p}}\frac{{\dot{m}}_B\left|{\dot{m}}_B\right|}{{\rho }_B{S}_{Min}^2},\hfill & {\mathrm{Re}}_B\ge {\mathrm{Re}}_T\hfill \end{array},$$

where:

• λ is the shape factor for laminar flow viscous friction.

• f(Re_A) and f(Re_B) are the Darcy friction factors at ports A and B. The block obtains the friction factors from tabulated data specified relative to the Reynolds number.

If the pressure loss model is set to Tabulated data — Euler number vs. Reynolds number, the pressure loss in the half volume adjacent to port A is

$$\Delta p_{Loss,A}=\{\begin{array}{ll}{\dot{m}}_A{\mu }_A\text{Eu}\left({\mathrm{Re}}_L\right){\mathrm{Re}}_L\frac{1}{4D_{h,p}{\rho }_A{S}_{Min}},\hfill & {\mathrm{Re}}_A\le {\mathrm{Re}}_L\hfill \\ Eu\left({\mathrm{Re}}_A\right)\frac{{\dot{m}}_A\left|{\dot{m}}_A\right|}{4{\rho }_A{S}_{Min}^2},\hfill & {\mathrm{Re}}_A\ge {\mathrm{Re}}_T\hfill \end{array},$$

while in the half volume adjacent to port B it is

$$\Delta p_{Loss,B}=\{\begin{array}{ll}{\dot{m}}_B{\mu }_B\text{Eu}\left({\mathrm{Re}}_L\right){\mathrm{Re}}_L\frac{1}{4D_{h,p}{\rho }_B{S}_{Min}},\hfill & {\mathrm{Re}}_B\le {\mathrm{Re}}_L\hfill \\ Eu\left({\mathrm{Re}}_B\right)\frac{{\dot{m}}_B\left|{\dot{m}}_B\right|}{4{\rho }_B{S}_{Min}^2},\hfill & {\mathrm{Re}}_B\ge {\mathrm{Re}}_T\hfill \end{array},$$

where:

• Eu(Re_L) is the Euler number at the Reynolds number upper bound for laminar flows.

• Eu(Re_A) and Eu(Re_B) are the Euler numbers at ports A and B. The block obtains the Euler numbers from tabulated data specified relative to the Reynolds number.

Energy Balance

The energy balance in the heat exchanger interface depends on the fluid dynamic compressibility setting. If you select Thermal liquid 1 dynamic compressibility, the energy balance is

$$\frac{dp}{dt}\frac{dU}{dp}+\frac{dT}{dt}\frac{dU}{dT}={\varphi }_A+{\varphi }_B+Q_H,$$

where:

• U is the internal energy contained in the volume of the heat exchanger interface.

• ϕ_A and ϕ_B are the energy flow rates through ports A and B into the volume of the heat exchanger interface.

• Q_H is the heat flow rate through port H, representing the interface wall, into the volume of the heat exchange interface.

The internal energy derivatives are defined as

$$\frac{dU}{dp}=\left[\frac{1}{\beta }\left(\rho u+p\right)-T\alpha \right]V$$

and

$$\frac{dU}{dT}=\left[c_p-\alpha \left(u+\frac{p}{\rho }\right)\right]\rho V,$$

where u is the specific internal energy of the thermal liquid, or the internal energy contained in a unit mass of the same.

If you clear the Thermal liquid 1 dynamic compressibility checkbox, the thermal liquid density is treated as a constant. The bulk modulus is then effectively infinite and the thermal expansion coefficient zero. The pressure and temperature derivatives of the compressible case vanish and the energy balance is restated as

$$\frac{dE}{dt}={\varphi }_A+{\varphi }_B+Q_H,$$

where E is the total internal energy of the incompressible thermal liquid, or

$$E=\rho uV.$$

Heat Transfer Correlations

The block calculates and outputs the liquid-wall heat transfer coefficient value. The calculation depends on the Heat transfer coefficient specification setting in the block dialog box. If the heat transfer coefficient specification is Constant heat transfer coefficient, the heat transfer coefficient is simply the constant value specified in the block dialog box,

$$h_{L-W}=h_{Const},$$

where:

• h_L-W is the liquid-wall heat transfer coefficient.

• h_Const is the Liquid-wall heat transfer coefficient value specified in the block dialog box.

For all other heat transfer coefficient parameterizations, the heat transfer coefficient is defined as the arithmetic average of the port heat transfer coefficients:

$$h_{L-W}=\frac{h_A+h_B}{2},$$

where:

• h_A and h_B are the liquid-wall heat transfer coefficients at ports A and B.

The heat transfer coefficient at port A is

$$h_A=\frac{N{u}_A{k}_A}{D_{h,heat}},$$

while at port B it is

$$h_B=\frac{N{u}_B{k}_B}{D_{h,heat}},$$

where:

• Nu_A and Nu_B are the Nusselt numbers at ports A and B.

• k_A and k_B are the thermal conductivities at ports A and B.

• D_h,heat is the hydraulic diameter for heat transfer calculations.

The hydraulic diameter used in heat transfer calculations is defined as

$$D_{h,heat}=\frac{4S_{Min}{L}_{heat}}{S_{heat}},$$

where:

• L_heat is the flow path length used in heat transfer calculations.

• S_heat is the total heat transfer surface area.

Nusselt Number Calculations

The Nusselt number calculation depends on the Heat transfer coefficient specification setting in the block dialog box. If the heat transfer specification is set to Correlation for flow inside tubes, the Nusselt number at port A is

$$N{u}_A=\{\begin{array}{ll}{\text{Nu}}_L,\hfill & {\mathrm{Re}}_A\le {\mathrm{Re}}_L\hfill \\ \frac{\left(\raisebox{1ex}{$f_{T,A}$}\!\left/ \!\raisebox{-1ex}{$8$}\right.\right)\left({\mathrm{Re}}_A-1000\right){\mathrm{Pr}}_A}{1+12.7{\left(\raisebox{1ex}{$f_{T,A}$}\!\left/ \!\raisebox{-1ex}{$8$}\right.\right)}^{1/2}\left({\mathrm{Pr}}_B^{2/3}-1\right)},\hfill & {\mathrm{Re}}_A\ge {\mathrm{Re}}_T\hfill \end{array},$$

while at port B it is

$$N{u}_B=\{\begin{array}{ll}{\text{Nu}}_L,\hfill & {\mathrm{Re}}_B\le {\mathrm{Re}}_L\hfill \\ \frac{\left(\raisebox{1ex}{$f_{T,B}$}\!\left/ \!\raisebox{-1ex}{$8$}\right.\right)\left({\mathrm{Re}}_B-1000\right){\mathrm{Pr}}_B}{1+12.7{\left(\raisebox{1ex}{$f_{T,B}$}\!\left/ \!\raisebox{-1ex}{$8$}\right.\right)}^{1/2}\left({\mathrm{Pr}}_B^{2/3}-1\right)},\hfill & {\mathrm{Re}}_B\ge {\mathrm{Re}}_T\hfill \end{array},$$

where:

• Nu_L is the Nusselt number for laminar flow heat transfer value specified in the block dialog box.

• Pr_A and Pr_B are the Prandtl numbers at ports A and B.

If the heat transfer specification is set to Tabulated data — Colburn data vs. Reynolds number, the Nusselt number at port A is

$$N{u}_A=j\left({\mathrm{Re}}_{A,heat}\right){\mathrm{Re}}_{A,heat}{\mathrm{Pr}}_A^{1/3},$$

while at port B it is

$$N{u}_B=j\left({\mathrm{Re}}_{B,heat}\right){\mathrm{Re}}_{B,heat}{\mathrm{Pr}}_B^{1/3},$$

where:

• j(Re_A,heat) and j(Re_B,heat) are the Colburn numbers at ports A and B. The block obtains the Colburn numbers from tabulated data provided as a function of the Reynolds number.

• Re_A,heat and Re_B,heat are the Reynolds numbers based on the hydraulic diameters for heat transfer calculations at ports A and B. This parameter is defined at port A as

  $${\mathrm{Re}}_{A,heat}=\frac{{\dot{m}}_A{D}_{h,heat}}{S_{Min}{\mu }_A},$$

  and at port B as

  $${\mathrm{Re}}_B=\frac{{\dot{m}}_B{D}_{h,heat}}{S_{Min}{\mu }_B}.$$

If the heat transfer specification is set to Tabulated data — Nusselt number vs. Reynolds number and Prandtl number, the Nusselt number at port A is

$$N{u}_A=Nu\left({\mathrm{Re}}_{A,heat},{\mathrm{Pr}}_A\right),$$

while at port B it is

$$N{u}_B=Nu\left({\mathrm{Re}}_{B,heat},{\mathrm{Pr}}_B\right).$$

Hydraulic Diameter Calculations

The hydraulic diameter used in heat transfer calculations can differ from the hydraulic diameter employed in pressure loss calculations, and are different if the heated and friction perimeters are not the same. For a concentric pipe heat exchanger with an annular cross-section, the hydraulic diameter for heat transfer calculations is

$$D_{h,heat}=\frac{4\left(\pi /4\right)\left(D_o^2-D_i^2\right)}{\pi D_i}=\frac{D_o^2-D_i^2}{D_i},$$

while the hydraulic diameter for pressure calculations is

$$D_{h,p}=\frac{4\left(\pi /4\right)\left(D_o^2-D_i^2\right)}{\pi \left(D_i+D_o\right)}=D_o-D_i,$$

where:

• D_o is the outer annulus diameter.

• D_i is the inner annulus diameter.

Annulus Schematic

The difference between the outer diameter and the inner diameter depicted in orange represents the thermal liquid. The blue region within the inner diameter is the fluid that exchanges heat with the thermal liquid.

Ports

Output

C — Heat capacity rate

physical signal

Physical signal output port for the thermal capacity rate of the thermal liquid.

HC — Heat transfer coefficient

physical signal

Physical signal output port for the heat transfer coefficient between the thermal liquid and the interface wall.

Conserving

A — Thermal liquid port

thermal liquid

Thermal liquid conserving port representing the thermal liquid inlet.

B — Thermal liquid port

thermal liquid

Thermal liquid conserving port representing the thermal liquid outlet.

H — Thermal inlet temperature

thermal

Thermal conserving port associated with the thermal liquid inlet temperature.

Parameters

Minimum free-flow area — Cross-sectional area of flow channel at its narrowest point

0.01 m^2 (default) | scalar

Smallest total cross-sectional flow area between inlet and outlet. If the channel is a collection of ducts, tubes, slots, or grooves, the value of this parameter is the sum of the smallest areas at the minimum flow area point. This parameter is the area where the fluid velocity is highest. For example, if the fluid flows perpendicular to a bank of tubes, the value of this parameter is the sum of the gaps between the tubes in one cross-section where the sum of the gaps is smallest is smallest.

Hydraulic diameter for pressure loss — Diameter or equivalent diameter of channel

0.1 m (default) | scalar

Hydraulic diameter of the tubes or channels comprising the heat exchange interface. The hydraulic diameter is the ratio of the flow cross-sectional area to the channel perimeter.

Thermal liquid volume — Total volume of fluid contained in flow channel

0.01 m^3 (default) | scalar with units of length squared

Total volume of the fluid contained in the thermal liquid flow channel.

Laminar flow upper Reynolds number limit — Start of transition between laminar and turbulent regimes

2000 (default) | scalar

Start of the transition from the laminar regime to the turbulent regime. Above this number, inertial forces become increasingly dominant. The default value is given for circular pipes and tubes with smooth surfaces.

Turbulent flow lower Reynolds number limit — End of transition between laminar and turbulent regimes

4000 (default) | scalar

End of the transition from the laminar regime to the turbulent regime. Below this number, viscous forces become increasingly dominant.

Pressure loss model — Mathematical model for pressure loss due to friction

Pressure loss coefficient (default) | Correlation for flow inside tubes | Tabulated data - Darcy friction factor vs. Reynolds number | Tabulated data - Euler number vs. Reynolds number

Mathematical model for pressure loss due to friction. This setting determines which expressions to use for calculation and which block parameters to specify as input. See the Heat Exchanger Interface (TL) blocks for the calculations by parameterization.

Pressure loss coefficient — Aggregate loss coefficient for all flow resistances between the ports

0.1 (default) | scalar

Aggregate loss coefficient for all flow resistances in the flow channel, including wall friction (major losses) and local resistances due to bends, elbows, and other geometry changes (minor losses).

The loss coefficient is an empirical, dimensionless number used to express the pressure losses due to friction. It can be calculated from experimental data or obtained from product data sheets.

Dependencies

To enable this parameter, set Pressure loss model to Pressure loss coefficient.

Length of flow path from inlet to outlet — Distance traveled from port to port

1 m (default) | scalar with units of length

Total distance the flow must travel between the ports. In multi-pass shell-and-tube exchangers, the total distance is the sum over all shell passes. In tube bundles, corrugated plates, and other channels where the flow is split into parallel branches, it is the distance covered in a single branch. The longer the flow path, the steeper the major pressure loss due to friction at the wall.

Dependencies

To enable this parameter, set Pressure loss model to Correlation for flow inside tubes or Tabulated data - Darcy friction factor vs Reynolds number.

Aggregate equivalent length of local resistances — Aggregate minor pressure loss expressed in length

0.1 m (default) | scalar

Aggregate minor pressure loss, expressed as a length. The length of a straight channel results in equivalent losses to the sum of existing local resistances from elbows, tees, and unions. The larger the equivalent length, the steeper the minor pressure loss due to the local resistances.

Dependencies

To enable this parameter, set Pressure loss model to Correlation for flow inside tubes.

Internal surface absolute roughness — Mean height of wall surface variations that contribute to frictional losses

15e-6 m (default) | scalar with units of length

Average height of all surface defects on the internal surface of the pipe. The surface roughness enables the calculation of the friction factor in the turbulent flow regime.

Dependencies

To enable this parameter, set Pressure loss model to Correlation for flow inside tubes.

Laminar friction constant for Darcy friction factor — Pressure loss correction for flow cross section in laminar flow conditions

64 (default) | scalar

Pressure loss correction for laminar flow. This parameter is referred to as the shape factor, and can be used to derive the Darcy friction factor for pressure loss calculations in the laminar regime. The default value is for cylindrical pipes and tubes.

Some additional shape factors for non-circular cross-sections can be determined from analytical solutions to the Navier-Stokes equations. A square duct has a shape factor of 56, a rectangular duct with an aspect ratio of 2:1 has a shape factor of 62, and an annular tube has a shape factor of 96. A slender conduit between parallel plates also has a shape factor of 96.

Dependencies

To enable this parameter, set Pressure loss model to Correlation for flow inside tubes.

Reynolds number vector for Darcy friction factor — Reynolds number at each breakpoint in Darcy friction factor lookup table

[400, 1000, 1500, 3000, 4000, 6000, 10000, 20000, 40000, 60000, 100000, 100000000] (default) | array

Vector of Reynolds numbers at which to specify the Darcy friction factor. The block uses this vector to create a lookup table for the Darcy friction factor.

Dependencies

To enable this parameter, set Pressure loss model to Tabulated data - Darcy friction factor vs. Reynolds number.

Darcy friction factor vector — Darcy friction factor at each breakpoint in Reynolds number lookup table

[.264, .112, .071, .0417, .0387, .0268, .025, .0232, .0226, .022, .0214, .0214] (default) | array

Vector of Darcy friction factors corresponding to the values specified in the Reynolds number vector for Darcy friction factor parameter. The block uses this vector to create a lookup table for the Darcy friction factor.

Dependencies

To enable this parameter, set Pressure loss model to Tabulated data - Darcy friction factor vs. Reynolds number.

Reynolds number vector for Euler number — Reynolds number at each breakpoint in the Euler number lookup table

[50, 500, 1000, 2000] (default) | array

Vector of Reynolds numbers at which to specify the Euler number. The block uses this vector to create a lookup table for the Euler number.

Dependencies

To enable this parameter, set Pressure loss model to Tabulated data - Euler number vs. Reynolds number.

Euler number vector — Euler number at each breakpoint in the Reynolds number lookup table

[4.4505, .6864, .4791, .3755] (default) | array

Vector of Euler numbers corresponding to the values specified in the Reynolds number vector for Euler number parameter. The block uses this vector to create a lookup table for the Euler number.

Dependencies

To enable this parameter, set Pressure loss model to Tabulated data - Euler number vs. Reynolds number.

Heat transfer coefficient model — Mathematical model for heat transfer between fluid and wall

Constant heat transfer coefficient (default) | Correlation for flow inside tubes | Tabulated data - Colburn factor vs. Reynolds number | Tabulated data - Nusselt number vs. Reynolds number and Prandtl number

Parameterization used to compute the heat transfer rate between the heat exchanger fluids. You can assume a constant pressure loss coefficient, use empirical correlation for flow inside tubes, or specify tabulated data for the Colburn or Nusselt number.

Liquid-wall heat transfer coefficient — Heat transfer coefficient for convection between fluid and wall

100 W/(m^2 * K) (default) | scalar

Heat transfer coefficient between the thermal liquid and the heat-transfer surface.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Constant heat transfer coefficient.

Heat transfer surface area — Effective surface area used in heat transfer between fluid and wall

0.4 m^2 (default) | scalar with units of length squared

Aggregate surface area available for heat transfer between the heat exchanger fluids.

Length of flow path for heat transfer — Characteristic length traversed in heat transfer between fluid and wall

1 m (default) | scalar with units of length

Distance traversed by the fluid along which heat exchange takes place.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Tabulated data - Colburn factor vs. Reynolds number or Tabulated data - Nusselt number vs. Reynolds number and Prandtl number.

Nusselt number for laminar flow heat transfer — Constant assumed for Nusselt number in laminar flow

3.66 (default) | positive scalar

Proportionality constant between convective and conductive heat transfer in the laminar regime. This parameter enables the calculation of convective heat transfer rates in laminar flows. The appropriate value to use depends on component geometry.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Correlation for flow inside tubes.

Reynolds number vector for Colburn factor — Reynolds number at each breakpoint in Colburn factor lookup table

[100, 150, 1000] (default) | array

Vector of Reynolds numbers at which to specify the Colburn factor. The block uses this vector to create a lookup table for the Colburn number. The number of values in this vector must be equal to the size of the Colburn factor vector parameter to calculate tabulated breakpoints.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Tabulated data - Colburn factor vs. Reynolds number.

Colburn factor vector — Colburn factor at each breakpoint in Reynolds number lookup table

[.019, .013, .002] (default) | array

Vector of Colburn factors corresponding to the values specified in the Reynolds number vector for Colburn number parameter. The block uses this vector to create a lookup table for the Colburn factor.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Tabulated data - Colburn factor vs. Reynolds number.

Reynolds number vector for Nusselt number — Reynolds number at each breakpoint in Nusselt number lookup table

[100, 150, 1000] (default) | array

Vector of Reynolds numbers at which to specify the Nusselt number. The block uses this vector to create a lookup table for the Nusselt number.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Tabulated data - Nusselt number vs. Reynolds number and Prandtl number.

Prandtl number vector for Nusselt number — Prandtl number at each breakpoint in the Nusselt number lookup table

[1, 10] (default) | array

Vector of Prandtl numbers at which to specify the Nusselt number. The block uses this vector to create a lookup table for the Nusselt number.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Tabulated data - Nusselt number vs. Reynolds number and Prandtl number.

Nusselt number table, Nu(Re,Pr) — Nusselt number at each breakpoint in Reynolds-Prandtl number lookup table

[3.72, 4.21; 3.75, 4.44; 4.21, 7.15] (default) | array

Matrix of Nusselt numbers corresponding to the values specified in the Reynolds number vector for Nusselt number and Prandtl number vector for Nusselt number parameters. The block uses this vector to create a lookup table for the Nusselt factor.

Dependencies

To enable this parameter, set Heat transfer coefficient model to Tabulated data - Nusselt number vs. Reynolds number and Prandtl number.

Fouling factor — Increased resistance due to fouling

1e-4 m^2*K/W (default) | scalar

Empirical parameter used to quantify the increased thermal resistance due to dirt deposits on the heat transfer surface.

Effects and Initial Conditions

Thermal liquid 1 dynamic compressibility — Setting for liquid compressibility in heat exchanger

On (default) | Off | scalar

Option to model the pressure dynamics inside the heat exchanger. Setting this parameter to Off removes the pressure derivative terms from the component energy and mass conservation equations. The pressure inside the heat exchanger is then reduced to the weighted average of the two port pressures.

Thermal Liquid initial temperature — Initial temperature of thermal liquid

293.15 K (default) | scalar

Temperature of the internal volume of thermal liquid at the start of simulation.

Thermal Liquid initial temperature — Initial pressure of thermal liquid

0.101325 MPa (default) | scalar

Pressure of the internal volume of thermal liquid at the start of simulation.

Extended Capabilities

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

Version History

Introduced in R2016a