. explain. 1. for one-dimensional flow, mass flow rate is the product of density, area, and velocity. 2. at steady state, conservation of mass asserts the total rate at which mass enters the control volume equals the total rate at which mass exits. 3. at steady state, conservation of energy asserts the total rate at which energy is transferred into the control volume equals the total rate at which energy is transferred out. 4. hydropower is a nonrenewable means for producing electricity. 5. as velocity decreases in a diffuser, pressure decreases. 6. compressor types include reciprocating, axial flow, centrifugal, and roots type. 7. common heat exchanger types include direct-contact, counterflow, parallel-flow, and cross-flow heat exchangers. 8. a mixing chamber is a direct-contact heat exchanger. 9. a significant increase in pressure can be achieved by introducing a restriction into a line through which a gas or liquid flows. 10. volumetric flow rate is expressed in units of m3/s or ft3/s. 11. system integration is the practice of combining components o achieve an overall objective. 12. for a control volume at steady state, mass can accumulate within the control volume. 13. factors that may allow one to model a control volume as having negligible (zero) heat transfer include (1) the outer surface of the control volume is well insulated, (2) the outer surface area of the control volume is too small to permit effective heat transfer, (3) the temperature difference between the control volume and its surroundings is so small that the heat transfer can be ignored, and (4) the working fluid passes through the control volume so quickly that there is not enough time for significant heat transfer to occur. 14. for a one-inlet, one-exit control volume at steady state, the mass flow rates at the inlet and exit are equal but the inlet and exit volumetric flow rates may not be equal. 15. flow work is the work done on a flowing stream by a paddle wheel or piston. 16. transient operation denotes a change in state with time. 17. in this book the flow at control volume inlets and exits is normally taken as one-dimensional. 18. where mass crosses the boundary of a control volume, the accompanying energy transfer is accounted for by the internal energy of the mass only. 19. a diffuser is a flow passage of varying cross-sectional area in which the velocity of a gas or liquid increases in the direction of flow. 20. the human body is an example of an integrated system. 21. when a substance undergoes a throttling process through a valve, the specific enthalpies of the substance at the valve inlet and valve exit are equal. 22. the hot and cold streams of cross-flow heat exchangers flow in the same direction. 23. the thermodynamic performance of a device such as a turbine through which mass flows is best analyzed by studying the flowing mass alone. 24. for every control volume at steady state, the total of the entering rates of mass flow equals the total of the exiting rates of mass flow. 25. an open feedwater heater is a special type of a counterflow heat exchanger. 26. a key step in thermodynamic analysis is the careful listing of modeling assumptions. 27. an automobile’s radiator is an example of a cross-flow heat exchanger. 28. at steady state, identical electric fans discharging air at the same temperature in new york city and denver will deliver the same volumetric flow rate of air.
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Category: mechanicalengineering | Author: Sagi Boris
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