.TAeZoSysPro.HeatTransfer.BasesClasses.PartialHeatExchanger

Information

This components contains partial equation describing a generic adiabatic heat exchanger using the effetiveness method. The advantage of the effetiveness method regarding the mean logarithmic method is to avoid a non linear equation where oulet temperature are unknown(see explainations in the theoretical note). The system of equations describing an heat exchanger derives:

Where:

• Qc is the thermal flow rate unit.m_flow and cp being the mass flow rate and the specific heat capacity
• Cr is the ration of the thermal flow rate units
• NTU is the number of transfer unit
• h_global is the global heat exchange coeffcient
• A is generally the maximal exchange surface (if exchange surfaces for both fluid are different )
• Eff is the effectiveness of the exchanger
• Q_flow is the exchanged power. It is defined as positive when the fluid A is cooled
• Q_flow_max is the maximal exchangeable power for an infinite exchanger
• T_A is temperature of the fluid A (T_B for fluid B).

An heat exchanger is a complex object that can have various configurations such as:

• counter, cross or parallel flow
• single or multi passes
• etc

Therefore, it has been chosen to develop a partial heat exchanger containing the common equations to all kind of exchanger whatever its configuration. For a specific exchanger the user just have to inherit this partial model and give the specific missing equations for:

• The relation between the effectiveness and geometrical and flow configuration: Eff = f(Cr, NTU, ...)
• The thermal flow rate: Qc_A and Qc_B
• The inlet temperature: T_A_in, T_B_in
• The global heat exchange coefficient: K_global