(1a). The 1st law of thermodynamics cannot be applied to: (A) (B) (C) Control vo
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(1a). The 1st law of thermodynamics cannot be applied to: (A) (B) (C) Control volume system as the mass can cross the boundary. A steady operation steam turbine. An unsteady operation system such as a pressure cooker which continuously loss steam from its pressure controlling device. Diffuser, which has different inlet and exit area. None of above (D) (E) (1b). Circle the invalid statement (s) about the control volume: ; me I (A) Both the mass and the energy can cross the boundary of a control volume. (B) Under the steady-flow condition, the volume, mass and energy contents of a control volume A) remain constant (C) Under the steady-flow condition, the fluid properties at an inlet or exit always remain constant (do not change with time). (D) Under the steady-flow condition, the intensive properties of the substance contained m homogeneous (uniform) everywhere in a control volume. (E) Gas turbines, throttling valves, nozzles and diffusers operated under steady condition can be treated as the steady-flow control volume system. (1c). Circle the valid statements regarding heat exchangers: (A) Heat exchangers are devices where two moving fluid streams are mixed together. (B) Heat exchangers are devices where two moving fluid streams exchange mass. (C) Heat exchangers are devices where two moving fluid streams exchange heat (thermal energy) without mixing together. (D) Heat exchangers are devices where two moving fluid streams exchange mechanical work (E) (1d). Circle the invalid statement (s) regarding a steady-flow device. without mixing together There is no heat transfer between the two fluids of an insulated heat exchanger. (A) (B) (C) (D) The mass within the control volume always remains constant The energy within the control volume always remains constant The fluid properties may change with location over the cross section of the inlets or exits. The fluid flow at any point of any inlet and exit must be uniform and steady and the fluid properties do not change with time or location over the cross section of an inlet or exit None of the above (E)Explanation / Answer
1a) E- None of above
first law of thermodynamics is valid to all types of processes irrespective of steady and unsteady process, reversible or irreversible process. The only difference is that we have to calculate heat transfer and work depend on types of the process being used.
1b) D
under steady flow condition, the substance need not be homogeneous everywhere in the control volume.
1c) C
The heat exchanger is a device which is used to exchange the heat between two moving fluid without mixing together through walls or surfaces.
1d) D
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