Cruet. False) For a control volume at steady state, energy cannot accumulate within the control volume
The correct answer and explanation is :
The correct answer is False.
Explanation:
In the context of thermodynamics and fluid mechanics, a control volume is a specified region in space through which fluid may flow, and the boundaries of this region can be fixed or moving. The concept of steady state refers to a condition in which the properties within the control volume do not change with time, i.e., there are no temporal changes in properties like temperature, pressure, or density within the volume.
The statement in the question implies that energy cannot accumulate within the control volume at steady state. This statement is incorrect because energy accumulation can occur within the control volume, even at steady state, as long as the system allows for energy transfer in or out of the control volume.
To elaborate, the first law of thermodynamics, which governs energy conservation, states that energy can be transferred across the boundaries of a control volume, but it does not necessarily mean that energy cannot accumulate inside the volume. At steady state, the system can still receive or expel energy in the form of heat, work, or mass flow (through the boundary of the control volume). However, if the system is in true steady state, the total energy entering the control volume must be equal to the total energy exiting (net energy flow is zero). But this does not imply that energy within the volume cannot be stored or accumulated at any moment during the process.
In practical applications, like in a steam boiler or heat exchanger, even though these systems might be in steady state with respect to mass and energy flows, energy can still accumulate temporarily in the form of internal energy, potential energy, or kinetic energy, depending on the configuration of the system and its operating conditions.
Therefore, the accumulation of energy within a control volume can occur at steady state, provided energy is flowing in and out in such a way that the system’s conditions allow for the storage of energy over time. Hence, the answer is False.