1. Fundamentals a. b. c. How can mass flowrate be determined from the velocity?

Question

1. Fundamentals a. b. c. How can mass flowrate be determined from the velocity? What is the area of a circle? Express in terms of both radius and diameter. Beginning with the 'equation' at the beginning of section 4.4.1, derive equation 4.15 d. Do you use the internal energy (u) for the energy of a flowing mass? Why e. What does it mean for a system to be in steady state? How does equation f. Suppose a device has 2 inlets (states 1&2) and 2 exits (states 3&4) and is g. Show that the kinetic and potential energy terms (v'/2 and gz) in equation or why not? 4.15 change for a system in steady state? operating in steady state. Write the appropriate form of equation 4.15 with all summations expanded. 4.15 have units of energy/mass. What must you do in order to make the units of the kinetic and potential energy terms in equation 4.15 match that of the enthalpy in the tables? What is the purpose of a heat exchanger? What is an example of a heat exchanger in your everyday life? What is the purpose of a pump? What is an example of a pump in your everyday life? h. i. j. What is the difference between a pump and a compressor? k. What is the purpose of a turbine? List 2 places where they are used I. What do nozzles do? How do they work m. What is an example of a throttling device in your house/everyday life? On what types of thermodynamic devices is it used? What effect does it have on a fluid? Often kinetic energy can be ignored. For which components can you never ignore kinetic energy? Why is heat transfer assumed to be negligible for many compopents? n. o.

Explanation / Answer

a)mass flow rate = (cross-section area)×(velocity)×(density of fluid)

b)Area of circle = (×R2), now because diameter D = 2× Radius(R)

Area of circle = D2/4

c) *equation needed.

d)Flow of mass contains internal energy as well as flow energy (PV)

So for flow of mass, internal energy can not be used.

e)When the system is Time independent ie: it's property does not change with time.

f) *Equation needed.

g) kinetic energy is given by = mv2/2

So for mv2/2/m = energy/mass.

Potential energy is given by = m×g×h

So potential energy /mass = g×h.

Enthalpy is also energy so its unit will be equal to potential and kinetic energy ie: joule.

h) Heat exchanger is a used for heat transfer from high temperature to low temperature. Example one of heat exchanger are refrigerator, air-conditioner etc.

i)pump is used to transfer incompressible fluid from one place to other..hydrolic pump used in water tanks are example of pump.

j)pump is mainly a transmission device which transfer fluids by developing pressure.

Compressure is used to increase pressure of compressible fluids.

k) Turbine is work developing device which is used to rotate generator to produce power.They are used in power dams and jet engine.

l) nozzle is used to increase the velocity of fluids substantially. Nozzle have mainly three sections converging, throat and diverging section. From converging section velocity of fluid is increased and from diverging section smooth outlet flow is achieved.

m) common use of throttling device is refrigeration. It is use in closed system devices. It have heating or cooling effect on fluid.

n) Whichever component, if velocity is substantially high then kinetic energy should not be ignored. In nozzle kinetic energy can never be neglected.

o) Usually component have insulation and the process is very fast so there is little heat transfer so it is often neglected.

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