The document discusses concepts related to thermodynamics including the first law of thermodynamics. It includes 10 sections that describe energy changes in systems and control volumes, how kinetic energy relates to fluid velocity, the functions of nozzles and diffusers, throttling valves and how they cause pressure drops, enthalpy remaining constant during throttling but internal and flow energies converting, heat transfer in heat exchangers, different forms of work in pipe/duct flow, a schematic for an example problem, and a typical freezing curve for a food item.

1. CHAPTER
4
The First Law of
Thermodynamics

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FIGURE 4–7
The energy change of a
system during a process
is equal to the net work
and heat transfer
between the system and
its surroundings.
4-1

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FIGURE 4-22
Under steady-flow conditions,
the mass and energy contents
of a control volume remain
constant.
4-2

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FIGURE 4-28
At very high velocities,
even small changes in
velocities may cause
significant changes in
the kinetic energy of
the fluid.
4-3

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FIGURE 4-30
Nozzles and diffusers
are shaped so that they
cause large changes in
fluid velocities and thus
kinetic energies.
4-4

6. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
FIGURE 4-35
Throttling valves are
devices that cause large
pressure drops in the
fluid.
4-5

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FIGURE 4-37
During a throttling process, the
enthalpy (flow energy + internal
energy) of a fluid remains constant.
But internal and flow energies may be
converted to each other.
4-6

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FIGURE 4-42
The heat transfer associated with a heat
exchanger may be zero or nonzero
depending on how the system is
selected.
4-7

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FIGURE 4-46
Pipe or duct flow may
involve more than one
form of work at the
same time.
4-8

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FIGURE 4-53
Schematic for Example 4–17.
4-9

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FIGURE 4-59
Typical freezing curve
of a food item.
4-10