Which equation is used with the heat transfer equation to monitor heat exchanger performance?

Which equation is used with the heat transfer equation to monitor heat exchanger performance?

• A. General Energy Equation
• B. Continuity Equation
• C. Bernoulli Equation
• D. Fourier's Law

Answer: (A)

In heat exchanger performance analysis, you apply an energy balance to the control volume that includes the exchanger. The general energy equation is used because it encapsulates conservation of energy: energy entering and leaving the system, plus any work and changes in the energy stored in the fluids, must balance. When you analyze a steady-state exchanger, this framework lets you connect the heat transferred to the temperature changes and the flow rates of both streams. For example, the energy balance for each stream relates m_dot c_p (T_out − T_in) to the heat transferred, and that heat transfer rate is also described by the overall heat transfer relation Q = U A ΔT_lm. Fourier's law would only cover conduction in solids, while the continuity and Bernoulli equations handle mass conservation and fluid dynamics (not the energy exchange) respectively. So the general energy equation is the appropriate tool to monitor exchanger performance because it ties together the heat transfer with the fluid energy changes in a coherent, comprehensive way.

In heat exchanger performance analysis, you apply an energy balance to the control volume that includes the exchanger. The general energy equation is used because it encapsulates conservation of energy: energy entering and leaving the system, plus any work and changes in the energy stored in the fluids, must balance. When you analyze a steady-state exchanger, this framework lets you connect the heat transferred to the temperature changes and the flow rates of both streams. For example, the energy balance for each stream relates m_dot c_p (T_out − T_in) to the heat transferred, and that heat transfer rate is also described by the overall heat transfer relation Q = U A ΔT_lm. Fourier's law would only cover conduction in solids, while the continuity and Bernoulli equations handle mass conservation and fluid dynamics (not the energy exchange) respectively. So the general energy equation is the appropriate tool to monitor exchanger performance because it ties together the heat transfer with the fluid energy changes in a coherent, comprehensive way.