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Receiver Accumulator (2P)

Tank with liquid and vapor volumes of variable proportion
具有可变比例的液体和蒸汽体积的罐

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  • Receiver Accumulator (2P) block

Libraries: 图书馆：
Simscape / Fluids / Two-Phase Fluid / Tanks & Accumulators
Simscape / 流体 / 两相流体 / 储罐和蓄能器

Description 描述

The Receiver-Accumulator (2P) block represents a tank with fluid that can undergo phase change. The liquid and vapor phases, referred to as zones, are modeled as distinct volumes that can change in size during simulation, but do not mix. The relative amount of space a zone occupies in the system is called a zone fraction, which ranges from 0 to 1. The vapor-liquid mixture phase is not modeled.
接收器-蓄能器 （2P） 模块代表一个装有可以发生相变的流体的罐。液相和气相（称为区域）被建模为不同的体积，这些体积在仿真过程中可能会改变大小，但不会混合。一个区域在系统中占据的相对空间量称为区域分数，其范围从 0 到 1 。未对气液混合相进行建模。

In an HVAC system, when this tank is placed between a condenser and an expansion valve, it acts as a receiver. Liquid connections to the block are made at ports AL and BL. When the tank is placed between an evaporator and a compressor, it acts as an accumulator. Vapor connections to the block are made at ports AV and BV. A fluid of either phase can be connected to either port, however the fluid exiting from a V port is in the vapor zone and an L port is in the liquid zone. There is no mass flow through unconnected ports.
在 HVAC 系统中，当该水箱放置在冷凝器和膨胀阀之间时，它充当接收器。在端口 AL 和 BL 处与模块进行液体连接。当罐放置在蒸发器和压缩机之间时，它充当蓄能器。在端口 AV 和 BV 处与模块进行蒸汽连接。任何一相的流体都可以连接到任一端口，但是从 V 端口流出的流体位于蒸汽区，L 端口位于液体区。没有质量流通过未连接的端口。

The temperature of the tank walls are set at port H.
罐壁的温度设置在端口 H 处。

The liquid level of the tank is reported as a zone fraction at port L. If the liquid level reports 0, the tank is fully filled with vapor. The tank is never empty.
储罐的液位报告为端口 L 处的区域分数。如果液位报告 0 ，则罐中充满蒸汽。油箱永远不会是空的。

Heat Transfer 传热

The total heat transfer, QH, is the sum of the heat transfer in the liquid and vapor phases:
总传热 Q H 是液相和气相传热的总和：

QH=QL+QV.

The portion of the heat transfer that goes to the liquid volume, QL, accounts for the heat transfer between the liquid and the wall and between the liquid and the vapor,
传热到液体体积的部分 Q L 表示液体与壁面之间以及液体与蒸汽之间的传热，

QL=(Sc+zLSs)αL(TH−TL)+ScαLV(TV−TL)

where: 哪里：

  • zL is the liquid volume fraction of the tank.
    z L 是储罐的液体体积分数。

  • Sc is the Tank cross sectional area parameter.
    S c 是储罐横截面积参数。

  • Ss is surface area of the tank side, which the block calculates from the volume and tank cross-sectional area.
    S s 是储罐侧的表面积，块根据体积和储罐横截面积计算得出。

  • αL is the Liquid heat transfer coefficient parameter.
    α L 是液体传热系数参数。

  • TH is the temperature of the tank wall.
    T H 是罐壁的温度。

  • TL is the temperature of the liquid.
    T L 是液体的温度。

The block calculates the heat transfer coefficient between the liquid and the vapor as
该模块将液体和蒸汽之间的传热系数计算为

αLV=11αL+1αV.

The portion of the heat transfer that goes to the vapor volume, QV, accounts for the heat transfer between the vapor and the wall and between the liquid and the vapor,
传热到蒸气体积的部分 Q V 考虑了蒸气与壁面之间以及液体与蒸气之间的热传递，

QV=(Sc+(1−zL)Ss)αV(TH−TV)+ScαLV(TL−TV),

where: 哪里：

  • αV is the Vapor heat transfer coefficient.
    α V 是蒸汽传热系数。

  • TV is the temperature of the vapor.
    T V 是蒸汽的温度。

The liquid volume fraction is determined from the liquid mass fraction:
液体体积分数由液体质量分数确定：

zL=fM,LνLfM,LνL+(1−fM,L)νV,

where: 哪里：

  • fM,L is the mass fraction of the liquid.
    f M,L 是液体的质量分数。

  • νL is the specific volume of the liquid.
    ν L 是液体的比体积。

  • νV is the specific volume of the vapor.
    ν V 是蒸气的比体积。

Energy Flow Rates Due To Phase Change
相变引起的能量流速

When the liquid specific enthalpy is greater than or equal to the saturated liquid specific enthalpy, the mass flow rate of the vaporizing fluid is:
当液体比焓大于等于饱和液体比焓时，汽化流体的质量流量为：

˙mVap=ML(hL−hL,Sat)/(hV−hL,Sat)τ.

where: 哪里：

  • ML is the total liquid mass.
    M L 是液体总质量。

  • τ is the Vaporization and condensation time constant parameter.
    τ 是汽化和冷凝时间常数参数。

  • hL is the specific enthalpy of the liquid at the internal node.
    h L 是液体在内部节点处的比焓。

  • hL,Sat is the saturated liquid specific enthalpy at the internal node.
    h L,Sat 是内节点处的饱和液体比焓。

  • hV is the specific enthalpy of the vapor.
    h V 是蒸气的比焓。

  • hV,Sat is the saturated vapor specific enthalpy.
    h V,Sat 是饱和蒸气比焓。

The energy flow associated with vaporization is:
与汽化相关的能量流为：

ϕVap=˙mVaphV,Sat,

When the liquid specific enthalpy is lower than the saturated liquid specific enthalpy, no vaporization occurs, and ṁVap = 0.
当液体比焓低于饱和液体比焓时，不发生汽化，ṁ Vap =0。

Similarly, when the vapor specific enthalpy is less than or equal to the saturated vapor specific enthalpy, the mass flow rate of the condensing fluid is:
同样，当蒸汽比焓小于或等于饱和蒸汽比焓时，冷凝流体的质量流量为：

˙mCon=MV(hV−hV,Sat)/(hV−hL,Sat)τ.

where MV is the total vapor mass.
其中 M V 是总蒸气质量。

The energy flow associated with condensation is:
与冷凝相关的能量流为：

ϕCon=˙mConhL,Sat,

When the vapor specific enthalpy is higher than the saturated vapor specific enthalpy, no condensation occurs, and ṁCon = 0.
当蒸气比焓高于饱和蒸气比焓时，不发生冷凝，ṁ Con =0。

Mass Balance 质量平衡

The total tank volume is constant. Due to phase change, the volume fraction and mass of the fluid changes. The mass balance in the liquid zone is:
油箱总容积是恒定的。由于相变，流体的体积分数和质量会发生变化。液体区的质量平衡为：

dMLdt=˙mL,In−˙mL,Out+˙mCon−˙mVap,

where: 哪里：

  • ˙mL,In is the inlet liquid mass flow rate at all L and V ports.
    L,In 是所有 L 和 V 端口的入口液体质量流量。

  • ˙mL,Out is the outlet liquid mass flow rate:
    L,Out 是出口液体质量流量：

    ˙mL,Out=−(˙mAL+˙mBL),

  • ˙mCon is the mass flow rate of the condensing fluid.
    Con 是冷凝流体的质量流量。

  • ˙mVap is the mass flow rate of the vaporizing fluid.
    Vap 是汽化流体的质量流量。

The mass balance in the vapor zone is:
蒸气区的质量平衡为：

dMVdt=˙mV,In−˙mV,Out−˙mCon+˙mVap,

where: 哪里：

  • MV is the total vapor mass.
    M V 是总蒸气质量。

  • ˙mV,In is the inlet vapor mass flow rate at all L and V ports.
    V,In 是所有 L 和 V 端口的入口蒸汽质量流量。

  • ˙mV,Out is the outlet vapor mass flow rate:
    V,Out 是出口蒸汽质量流量：

    ˙mV,Out=−(˙mAV+˙mBV).

If there is only one zone present in the tank, the outlet mass flow rate of the fluid is the sum of the flow rate through all of the ports:
如果储罐中只有一个区域，则流体的出口质量流量是通过所有端口的流量之和：

˙mphase,Out=−(˙mAL+˙mBL+˙mAV+˙mBV).

where  哪里˙mphase,Out is   phase,Out 是˙mL,Out if the fluid is entirely liquid, and
L,Out 如果流体完全是液体，并且˙mV,Out if the fluid is entirely vapor.
V,Out 如果流体完全是蒸汽。

Energy Balance 能量平衡

The fluid can heat or cool depending on the heat transfer between the tank and wall, which is set by the temperature at port H.
流体可以加热或冷却，具体取决于罐和壁之间的热传递，该热传递由端口 H 的温度设定。

The energy balance in the liquid zone is:
液体区的能量平衡为：

MLduLdt+dMLdtuL=ϕL,In−ϕL,Out+ϕCon−ϕVap+QL.

where: 哪里：

  • uL is the specific internal energy of the liquid.
    U L 是液体的比内能。

  • ϕL,In is the inlet liquid energy flow rate at all L and V ports.
    φ L,In 是所有 L 和 V 端口的入口液体能量流率。

  • ϕL,Out is the outlet liquid energy flow rate:
    φ L,Out 是出口液体能量流速：

    ϕL,Out=−(ϕAL+ϕBL).

  • ϕCon is the energy flow rate of the condensing vapor.
    φ Con 是冷凝蒸汽的能量流动速率。

  • ϕVap is the energy flow rate of the vaporizing liquid.
    φ Vap 是汽化液体的能量流速。

  • QL is the heat transfer between the tank wall and the liquid.
    Q L 是罐壁与液体之间的传热。

The energy balance in the vapor zone is:
蒸气区的能量平衡为：

MVduVdt+dMVdtuV=ϕV,In−ϕV,Out−ϕCon+ϕVap+QV.

  • uV is the specific internal energy of the vapor.
    u V 是蒸气的比内能。

  • ϕV,In is the inlet vapor energy flow rate at all L and V ports.
    φ V,In 是所有 L 和 V 端口的入口蒸汽能量流速。

  • ϕV,Out is the outlet vapor energy flow rate:
    φ V,Out 是出口蒸汽能量流量：

    ϕV,Out=−(ϕAV+ϕBV).

  • QV is the heat transfer between the tank wall and the vapor.
    Q V 是罐壁与蒸汽之间的传热。

If there is only one zone present in the tank, the outlet energy flow rate is the sum of the flow rate through all of the ports:
如果储罐中只有一个区域，则出口能量流量是通过所有端口的流量之和：

ϕphase,Out=−(ϕAL+ϕBL+ϕAV+ϕBV).

where ϕphase,Out is ϕL,Out if the fluid is entirely liquid, and ϕV,Out if the fluid is entirely vapor.
L,Out 其中，如果流体完全是液体，则φ φ， V,Out 如果流体完全是蒸汽， phase,Out 则φ。

Momentum Balance 动量平衡

There are no pressure changes modeled in the tank, including hydrostatic pressure. The pressure at any port is equal to the internal tank pressure.
在储罐中没有模拟压力变化，包括静水压力。任何端口的压力都等于罐内压力。

The Receiver Accumulator block models the vapor and liquid volumes separately. If you input vapor or liquid quickly, the block may compress the vapor volume and the pressure may rise faster than expected. The pressure rises because when there is a high vapor or liquid mass flow rate input, the temperature rise due to compression is faster than the heat transfer that cools the vapor. If you add the vapor slowly, the heat transfer between the vapor and the liquid brings the vapor temperature down, which allows it to condense into liquid, and the pressure will not spike. Additionally, if you wait until the block achieves equilibrium, adding vapor or liquid shifts the mass fraction and does not cause pressure spikes.
Receiver Accumulator 模块分别对蒸汽和液体体积进行建模。如果快速输入蒸汽或液体，块可能会压缩蒸汽体积，并且压力上升速度可能比预期的要快。压力升高是因为当输入高蒸汽或液体质量流速时，由于压缩引起的温度升高比冷却蒸汽的传热更快。如果缓慢添加蒸汽，蒸汽和液体之间的热传递会降低蒸汽温度，从而使其能够凝结成液体，并且压力不会飙升。此外，如果等到块达到平衡，添加蒸汽或液体会改变质量分数，并且不会导致压力峰值。

Assumptions and Limitations
假设和限制

  • Pressure must remain below the critical pressure.
    压力必须保持在临界压力以下。

  • Hydrostatic pressure is not modeled.
    未对静水压力进行建模。

  • The container wall is rigid, therefore the total volume of fluid is constant.
    容器壁是刚性的，因此流体的总体积是恒定的。

  • The thermal mass of the tank wall is not modeled.
    未对罐壁的热质量进行建模。

  • Flow resistance through the outlets is not modeled. To model pressure losses associated with the outlets, connect a Local Restriction (2P) block or a Flow Resistance (2P) block to the ports of the Receiver-Accumulator (2P) block.
    未对通过出口的流动阻力进行建模。要对与出口相关的压力损失进行建模，请将局部限制 （2P） 模块或流量阻力 （2P） 模块连接到接收器-蓄能器 （2P） 模块的端口。

  • A liquid-vapor mixture is not modeled.
    未对液-蒸气混合物进行建模。

Examples 例子

Refrigeration Cycle (Air Conditioning)

Refrigeration Cycle (Air Conditioning)
制冷循环（空调）

A refrigeration cycle for a home air conditioning system. See Model a Refrigeration Cycle for the recommended steps to build this model in the two-phase fluid domain.
家用空调系统的制冷循环。请参阅对制冷循环建模，了解在两相流体域中构建此模型的推荐步骤。

Open Model
Electric Vehicle Thermal Management

Electric Vehicle Thermal Management
电动汽车热管理

Model the thermal management system of a battery electric vehicle.
对纯电动汽车的热管理系统进行建模。

Open Model

Ports

Output

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Liquid level in the tank. Use this port to monitor the amount of liquid remaining inside.

Conserving

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Opening for the fluid to flow into or out of the tank. Both liquid and vapor can enter through this port. However, only vapor can exit through it—until the tank is depleted of vapor, in which event liquid too can flow out through this port.

Opening for the fluid to flow into or out of the tank. Both liquid and vapor can enter through this port. However, only vapor can exit through it—until the tank is depleted of vapor, in which event liquid too can flow out through this port.

Opening for the fluid to flow into or out of the tank. Both liquid and vapor can enter through this port. However, only liquid can exit through it—until the tank is depleted of liquid, in which event vapor too can flow out through this port.

Opening for the fluid to flow into or out of the tank. Both liquid and vapor can enter through this port. However, only liquid can exit through it—until the tank is depleted of liquid, in which event vapor too can flow out through this port.

Thermal boundary between the fluid volume and the tank wall. Use this port to capture heat exchanges of various kinds—for example, conductive, convective, or radiative—between the fluid and the environment external to the tank.

Parameters

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Main

Aggregate volume of liquid and vapor phases in the tank.

Cross-sectional area of the tank.

Area normal to the direction of flow at port AV.

Area normal to the direction of flow at port BV.

Area normal to the direction of flow at port AL.

Area normal to the direction of flow at port BL.

Select what happens when the block has volume fractions lower than the Minimum liquid volume fraction parameter or higher than the Maximum liquid volume fraction parameter. Select Warning to be notified when the volume fraction crosses a specified range. Select Error to stop simulation at such events.

Lower bound of the valid range for the liquid volume fraction in the tank. Fractions below this value will trigger a simulation warning or error (depending on the setting of the Liquid volume fraction out of range block parameter.

Dependencies

This parameter is active when the Liquid volume fraction out of range block parameter is set to Warning or Error.

Upper bound of the valid range for the liquid volume fraction in the tank. Fractions above this value will trigger a simulation warning or error (depending on the setting of the Liquid volume fraction out of range block parameter.

Dependencies

This parameter is active when the Liquid volume fraction out of range block parameter is set to Warning or Error.

Volume fraction of either phase below which to transition to a single-phase tank—either subcooled liquid or superheated vapor. This parameter determines how smooth the transition is. The larger its value, the smoother the transition and therefore the faster the simulation (though at the cost of lower accuracy).

Heat Transfer

Coefficient for heat exchange between the vapor zone and its section of the tank wall. This parameter serves to calculate the rate of this heat exchange.

Coefficient for heat exchange between the liquid zone and its section of the tank wall. This parameter serves to calculate the rate of this heat exchange.

Effects and Initial Conditions

Thermodynamic variable in terms of which to define the initial conditions of the component.

The value for Initial fluid energy specification limits the available initial states for the two-phase fluid. When Initial fluid energy specification is:

  • Temperature — Specify an initial state that is a subcooled liquid or superheated vapor. You cannot specify a liquid-vapor mixture because the temperature is constant across the liquid-vapor mixture region.

  • Liquid mass fraction— Specify an initial state that is a liquid-vapor mixture. You cannot specify a subcooled liquid or a superheated vapor because the liquid mass fraction is 0 and 1, respectively, across the whole region. Additionally, the block limits the pressure to below the critical pressure.

  • Liquid volume fraction— Specify an initial state that is a liquid-vapor mixture. You cannot specify a subcooled liquid or a superheated vapor because the liquid volume fraction is 0 and 1, respectively, across the whole region. Additionally, the block limits the pressure to below the critical pressure.

  • Specific enthalpy — Specify the specific enthalpy of the fluid. The block does not limit the initial state.

  • Specific internal energy — Specify the specific internal energy of the fluid. The block does not limit the initial state.

Pressure in the tank at the start of simulation, specified against absolute zero.

Temperature in the tank at the start of simulation, specified against absolute zero.

Dependencies

This parameter is active when the Initial fluid energy specification option is set to Temperature.

Mass fraction of liquid in the tank at the start of simulation.

Dependencies

This parameter is active when the Initial fluid energy specification option is set to Liquid mass fraction.

Volume fraction of liquid in the tank at the start of simulation.

Dependencies

This parameter is active when the Initial fluid energy specification option is set to Liquid volume fraction.

Specific enthalpy of the fluid in the tank at the start of simulation.

Dependencies

This parameter is active when the Initial fluid energy specification option is set to Specific enthalpy.

Specific internal energy of the fluid in the tank at the start of simulation.

Dependencies

This parameter is active when the Initial fluid energy specification option is set to Specific internal energy.

Characteristic time to equilibrium of a phase-change event taking place in the tank. Increase this parameter to slow the rate of phase change or decrease it to speed up the rate.

Extended Capabilities

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

Version History

Introduced in R2018b

See Also

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