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Enthalpy change, symbolized as \( \Delta H \), is a key concept in thermodynamics. It represents the heat energy transfer in a chemical process at constant pressure. In our case of a heat exchanger, knowing the enthalpy change of ammonia is crucial. For ammonia entering as a mixture and leaving as saturated vapor, the enthalpy change is determined using thermodynamic tables.
\[ h_1 = h_f + x(h_fg) \]
Here, \( h_1 \) is the initial specific enthalpy, \( h_f \) is the specific enthalpy of the fluid, \( h_fg \) is the specific enthalpy of vaporization, and \( x = 0.35 \) is the quality. The final enthalpy \( h_2 \) is the saturated vapor enthalpy. The energy balance helps us calculate the enthalpy change, which is essential for further calculations.

Entropy production is a measure of the irreversibility of a process. It quantifies the generation of entropy within the system due to factors like friction, unrestrained expansion, heat transfer through a finite temperature difference, etc. In the context of the heat exchanger, we calculate the entropy production to understand how much disorder is generated.
The entropy changes for both air and ammonia must be calculated, then summed to find the total entropy production:
\[ \dot{S}_{\text{gen}} = \dot{m}_{\text{air}} C_p \ln\left(\frac{T_{out}}{T_{in}}\right) + \frac{Q}{T_{out}} \]
For ammonia:
\[ \dot{S}_{\text{NH}_3} = \dot{m}_{NH3} \left( \frac{h_2 - h_1}{T_{sat}} \right) \]
Each term in these equations allows us to trace the entropy change contributions of air and ammonia streams, ensuring a comprehensive analysis of the system’s efficiency.

Steady-state energy balance is used to ensure that the energy flowing into and out of a system is balanced when the system is in a steady state, meaning its properties do not change over time. For the heat exchanger, the steady-state assumption helps simplify our equations. Since there's no heat transfer from the system's outer surface:
\[ \dot{m}_{\text{NH}_3} (h_2 - h_1) = \dot{m}_{\text{air}} C_p (T_{in} - T_{out}) \]
Here, \( \dot{m}_{\text{NH}_3} \) is the mass flow rate of ammonia, and \( \dot{m}_{\text{air}} \) is the mass flow rate of air, with \( C_p \) representing the specific heat capacity of air. Applying this balance helps determine the mass flow rate required for ammonia to match the energy transferred between both streams.

Specific heat capacity, denoted as \( C_p \), is the amount of heat required to raise the temperature of a unit mass of a substance by one degree Celsius. For the given problem, the specific heat capacity of air is necessary to relate the temperature change of air to the heat exchanged:
\[ q = C_p \dot{m}_{\text{air}}(T_{in} - T_{out}) \]
Working with specific heat capacities, particularly at different temperatures, provides insight into the thermal behaviors of substances. For ammonia, the specific heat capacities for liquid and vapor phases are also considered to evaluate enthalpy changes and analyze heat transfer efficiently.

Thermodynamic tables are indispensable tools for engineers and scientists, providing properties of substances at various temperatures and pressures. In this calculation, tables for ammonia include values like specific enthalpy (\( h_f \) and \( h_g \)), specific heat capacities, and entropies at specific states.
By referring to these tables, we accurately determine properties such as enthalpies at different qualities and states. Thermodynamic tables ensure precision, making complex calculations more manageable and ensuring reliability in results. Working with them is essential for validating the theoretical aspects of thermodynamics in practical applications, like our heat exchanger problem.