modelHotWaterStorage_L2

Information

Purpose of model

Hot water storage without spatial discretisation (based on analytic solution for output temperature at steady state). Thermodynamic properties are calculated in dependence on the thermodynamic state with the fluid models of the TIL media. The model can be used to determine the average temperature of the heat storage in operation. Moreover, the heat losses of the storage are calculated.

Level of detail, physical effects considered, and physical insight

Level L2 (defined in the Coding Conventions)

• consideration of heat losses
• two static mass balances, the circuits of the heat generation and consumption are decoupled
• static momentum balances for both circuits
• assumption of a constant pressure loss
• a simple dynamic energy balanced based on the stored energy

Interfaces

GenIn: inlet from heat generator

GenOut: outlet to heat generator

ConIn: inlet from heat consumer

ConOut: outlet to heat consumer

Q_flow_gen: output for the generated heat flow [W]

T_Stor: output for temperature in heat reservoir in K [K]

Governing Equations

Mass balances:

Generator: GenIn.m_flow + GenOut.m_flow =0

Consumer: ConIn.m_flow + ConOut.m_flow =0

Heat losses to environment: Q_flow_loss=k*A*(T_stor-T_amb)

Energy balance: dE_stor/dt=-Q_flow_gen-Q_flow_loss-Q_flow_con

Impulse balances:

GenIn.p - GenOut.p = dp (constant pressure loss)

ConIn.p - ConOut.p=dp (constant pressure loss)

Remarks for Usage

The circuits for generation and consumption are decoupled. Therefore, when using the storage model a pressure should be defined by the hydraulic grids in BOTH circuits. Look at the test model for an example how to connect the fluid ports.

Validation

The model was tested in the test model:

TransiEnt.Storage.Heat.HotWaterStorage_L2.Check.Check_HotWaterStorage_L2

Version History

Created by Inken Knop (inken.knop@tuhh.de), Jun 2015

Edited by Pascal Dubucq (dubucq@tuhh.de), Aug 2015

Revised by Lisa Andresen (andresen@tuhh.de), Dec 2016

Modified by Anne Senkel (anne.senkel@tuhh.de), Dec 2017

Parameters

Connectors

Components

Contents