Which of the following statements is false?
A. The enthalpy of the system does not appear explicitly in the generalized energy balance equation.
B. If a system is stationary, all of the kinetic energy terms in the generalized energy balance equation can definitely be set to zero.
C. If a system is stationary, the accumulation term of the energy balance equation can be simplified to dU/dt.
D. The quantity Q ? can be expressed in units of watts.
E. Flow work can be present even if the system is not expanding or contracting.
A. Incorrect. This statement is true. Enthalpy of flowing streams entering or leaving the system appears in the equation, but the accumulation of energy in the system itself is quantified through internal energy, not enthalpy.
B. Correct. Only the accumulation kinetic energy term can be set to zero. The mass flows entering or exiting the stationary system may have high velocities.
C. Incorrect. This statement is true. If the system is not moving, no change in the kinetic energy or potential energy can occur.
D. Incorrect. This statement is true. Heat flow is expressed in dimensions of energy per time, so J/s or W.
E. Incorrect. This statement is true. Flow work is not the same as work of expansion or contraction. Review section 1.4.3.
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