To be able to solve problems involving force, moment, velocity, and time by applying the principle of impulse and momentum to ri
gid bodies. The principle of impulse and momentum states that the sum of all impulses created by the external forces and moments that act on a rigid body during a time interval is equal to the change in the linear and angular momenta of the body during that time interval. In other words, impulse is the change in momentum. The greater the impulse exerted on a body, the greater the body’s change in momentum. For example, baseball batters swing hard to maximize the impact force and follow through to maximize the impact time. This principle holds true for both linear and angular impulse and momentum. For a rigid-body’s planar motion, the equations for the linear impulse and momentum in the x–y plane are given by m(vGx)1+∑∫t2t1Fxdt=m(vGx)2 m(vGy)1+∑∫t2t1Fydt=m(vGy)2 Similarly, the equation for the principle of angular impulse and momentum about the z axis, which passes through the rigid-body’s mass center G, is given by IGω1+∑∫t2t1MGdt=IGω2
2 answers:
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Answer:
The mass flow rate of refrigerant is 0.352 kg/s
Explanation:
Considering the cycle of an ideal heat pump, provided in the attachment, we first find enthalpy at state B and D. For that purpose, we use property tables of refrigerant R134a:
<u>At State A</u>:
From table, we see the enthalpy and entropy value of saturated vapor at 0.2 MPa. Therefore:
ha = 244.5 KJ/kg
Sa = 0.93788 KJ/kg.k
<u>At State B</u>:
Since, the process from state A to B is isentropic. Therefore,
Sb = Sa = 0.93788 KJ/Kg
From table, we see the enthalpy value of super heated vapor at 1 MPa and Sb. Therefore:
hb = 256.85 KJ/kg (By interpolation)
<u>At State C</u>:
From table, we see the enthalpy and entropy value of saturated liquid at 1 MPa. Therefore:
hc = 107.34 KJ/kg
Now, from the diagram it is very clear that:
Heat Loss = m(hb = hc)
m = (Heat Loss)/(hb - hc)
where,
m = mass flow rate = ?
Heat Loss = (180,000 Btu/hr)(1.05506 KJ/1 Btu)(1 hr/3600 sec)
Heat Loss = 52.753 KW
Therefore,
m = (52.753 KJ/s)/(256.85 KJ/kg - 107.34 KJ/kg)
<u>m = 0.352 kg/s</u>
Answer:
a) , b)
, c)
Explanation:
A turbine is a steady-state devices which transforms fluid energy into mechanical energy and is modelled after the Principle of Mass Conservation and First Law of Thermodynamics, whose expressions are described hereafter:
Mass Balance
Energy Balance
Specific volumes and enthalpies are obtained from property tables for steam:
Inlet (Superheated Steam)
Outlet (Liquid-Vapor Mix)
a) The mass flow rate of the steam is:
b) The exit velocity of steam is:
c) The power output of the steam turbine is: