Specific Dissipation Heat Transfer

A simple model of heat transfer between two ordinary liquids.

blockType: EngeeFluids.HeatExchangers.SpecificDissipation.Interfaces.HeatTransfer

Path in the library:

/Physical Modeling/Fluids/Heat Exchangers/Fundamental Components/Specific Dissipation Heat Transfer

Description

Block Specific Dissipation Heat Transfer simulates heat transfer between two liquids, with only minimal data on the parameters of the components. The liquids are controlled by signals that determine the mass flow rate at the inlet and the isobaric specific heat for each of them. Non-directional heat-related ports set the temperature of the liquids at the inlet.

The heat transfer rate is calculated based on the relative heat transfer value, a parameter presented in tabular form as a function of the mass flow rate at the inlet. The relative magnitude of heat transfer determines the amount of heat transferred between liquids per unit of time with an inlet temperature difference of one degree.

Pressure losses and other aspects of fluid mechanics are not taken into account. To account for such effects, use the interface blocks of heat exchangers presented in the same library. Combine the heat transfer and heat exchanger units to simulate a non-standard heat exchanger.

Heat transfer rate

Heat is transferred from a warmer liquid to a cooler one at a rate proportional to the temperature difference of the liquids at the inlet. The value of the heat flow is positive if the temperature of liquid 1 is higher than the temperature of liquid 2, and therefore heat is transferred from liquid 1 to liquid 2.:

where — inlet liquid temperatures determined by the conditions in the non-directional ports H1 for liquid 1 and H2 for liquid 2. — the relative value of heat transfer obtained from the indicated tabular data at specified mass flow rates:

where — inlet mass flow values set via directional ports M1 for liquid 1 and M2 for liquid 2. The relative heat transfer value can be calculated for a set of inlet mass flow rates taking into account the experimental values of the heat transfer rate and the corresponding temperature difference at the inlet:

Maximum heat transfer rate

The heat transfer rate is limited so that the relative heat transfer value used in the calculations never exceeds the maximum value.:

where — indicators of the heat capacity of controlled liquids, each of which is defined as

where denotes the isobaric specific heat capacity of a liquid, set through directional ports CP1 for liquid 1 and CP2 for liquid 2. The limit on the maximum heat transfer rate is implemented as a piecewise function:

A warning is issued whenever the heat flow rate exceeds the maximum value. if for the parameter Check if violating maximum specific dissipation the value is set Error.

Ports

Conserving

# H1 — inlet temperature of the controlled liquid 1
warmth

Details

Inlet temperature of the controlled liquid 1.

Program usage name

thermal_port1

# H2 — inlet temperature of the controlled liquid 2
warmth

Details

Inlet temperature of the controlled liquid 2.

Program usage name

thermal_port2

Input

# CP1 — isobaric specific heat capacity of the controlled liquid 1
scalar

Details

Isobaric specific heat capacity of the controlled liquid 1.

Data types	`Float64`
Complex numbers support	I don’t

# CP2 — isobaric specific heat capacity of the controlled liquid 2
scalar

Details

Isobaric specific heat capacity of the controlled liquid 2.

Data types	`Float64`
Complex numbers support	I don’t

# M1 — inlet mass flow rate of the controlled liquid 1
scalar

Details

Input mass flow rate of the controlled liquid 1. Positive values correspond to the flow entering the heat exchanger. Negative values correspond to the flow coming out of the heat exchanger.

Data types	`Float64`
Complex numbers support	I don’t

# M2 — inlet mass flow rate of the controlled liquid 2
scalar

Details

The input mass flow rate of the controlled liquid 2. Positive values correspond to the flow entering the heat exchanger. Negative values correspond to the flow coming out of the heat exchanger.

Data types	`Float64`
Complex numbers support	I don’t

Parameters

# Fluid 1 mass flow rate vector, mdot1 — the input mass flow rate at which it is necessary to specify data on the relative value of heat transfer
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)

Details

An array of mass flow values at the inlet for the controlled liquid 1. Each value corresponds to a row in the search table with data on the relative value of heat transfer. Positive values indicate the flow entering the heat exchanger, while negative values indicate the flow leaving the heat exchanger.

Units	`kg/s` \| `N*s/m` \| `N/(m/s)` \| `lbf/(ft/s)` \| `lbf/(in/s)`
Default value	`[0.3, 0.5, 0.6, 0.7, 1.0, 1.4, 1.9, 2.3] kg/s`
Program usage name	`mdot1_vector`
Evaluatable	Yes

# Fluid 2 mass flow rate vector, mdot2 — the input mass flow rate at which it is necessary to specify data on the relative value of heat transfer
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)

Details

An array of mass flow values at the inlet for the controlled liquid 2. Each value corresponds to a row in the search table with data on the relative value of heat transfer. Positive values indicate the flow entering the heat exchanger, while negative values indicate the flow leaving the heat exchanger.

Units	`kg/s` \| `N*s/m` \| `N/(m/s)` \| `lbf/(ft/s)` \| `lbf/(in/s)`
Default value	`[0.3, 0.5, 1.0, 1.3, 1.7, 2.0, 2.6, 3.3] kg/s`
Program usage name	`mdot2_vector`
Evaluatable	Yes

# Specific dissipation table, SD(mdot1, mdot2) — the values of the relative heat transfer value corresponding to the specified mass flow
kW/K

Details

A matrix of relative heat transfer values corresponding to the specified arrays of mass flow values for controlled liquids 1 and 2. The unit uses tabular data to calculate heat transfer under simulated operating conditions.

If the heat transfer coefficients are specified in the technical data sheet of your heat exchanger, multiply the indicated heat transfer coefficients by the surface area to calculate the relative amount of heat transfer.

Units	`kW/K`
Default value	`[0.324 0.3533 0.404 0.4253 0.4333 0.4373 0.4453 0.4533; 0.3813 0.424 0.496 0.5307 0.544 0.5547 0.5693 0.5787; 0.4267 0.4827 0.5813 0.6173 0.6413 0.6573 0.672 0.6827; 0.4613 0.528 0.64 0.6987 0.7267 0.7467 0.7707 0.7853; 0.5533 0.6467 0.8227 0.928 0.9853 1.0187 1.0653 1.0973; 0.58 0.688 0.8853 1.0147 1.08 1.124 1.176 1.2147; 0.624 0.7467 0.992 1.148 1.244 1.304 1.3773 1.4267; 0.656 0.7907 1.0667 1.26 1.376 1.452 1.548 1.612] kW/K`
Program usage name	`specific_dissipation_matrix`
Evaluatable	Yes

# Mass flow rate threshold for flow reversal — the mass flow rate below which numerical data needs to be smoothed
kg/s | N*s/m | N/(m/s) | lbf/(ft/s) | lbf/(in/s)

Details

The mass flow rate, below which there is a smooth change in the flow direction to prevent discontinuities in the simulation data.

Units	`kg/s` \| `N*s/m` \| `N/(m/s)` \| `lbf/(ft/s)` \| `lbf/(in/s)`
Default value	`0.001 kg/s`
Program usage name	`mdot_threshold`
Evaluatable	Yes

# Check if violating maximum specific dissipation — the possibility of warning if the relative value of heat transfer exceeds the maximum allowable value
None | Error

Details

The possibility of warning if the relative value of heat transfer exceeds the maximum value specified in the description of the unit.

Values	`None` \| `Error`
Default value	`None`
Program usage name	`Q_assert_action`
Evaluatable	Yes