Answer:
a) Ql=33120000 kJ
b) COP = 5.6
c) COPreversible= 29.3
Explanation:
a) of the attached figure we have:
HP is heat pump, W is the work supplied, Th is the higher temperature, Tl is the low temperature, Ql is heat supplied and Qh is the heat rejected. The worj is:
W=Qh-Ql
Ql=Qh-W
where W=2000 kWh
Qh=120000 kJ/h
![Q_{l}=14days(\frac{24 h}{1 day})(\frac{120000 kJ}{1 h})-2000 kWh(\frac{3600 s}{1 h})=33120000 kJ](https://tex.z-dn.net/?f=Q_%7Bl%7D%3D14days%28%5Cfrac%7B24%20h%7D%7B1%20day%7D%29%28%5Cfrac%7B120000%20kJ%7D%7B1%20h%7D%29-2000%20kWh%28%5Cfrac%7B3600%20s%7D%7B1%20h%7D%29%3D33120000%20kJ)
b) The coefficient of performance is:
![COP=\frac{Q_{h} }{W}=\frac{120000 kJ/h*14(\frac{24 h}{1 day}) }{2000 kWh(\frac{3600 s}{1 h}) } = 5.6](https://tex.z-dn.net/?f=COP%3D%5Cfrac%7BQ_%7Bh%7D%20%7D%7BW%7D%3D%5Cfrac%7B120000%20kJ%2Fh%2A14%28%5Cfrac%7B24%20h%7D%7B1%20day%7D%29%20%7D%7B2000%20kWh%28%5Cfrac%7B3600%20s%7D%7B1%20h%7D%29%20%7D%20%3D%205.6)
c) The coefficient of performance of a reversible heat pump is:
![COP_{reversible}=\frac{T_{h} }{T_{h}-T_{l} }](https://tex.z-dn.net/?f=COP_%7Breversible%7D%3D%5Cfrac%7BT_%7Bh%7D%20%7D%7BT_%7Bh%7D-T_%7Bl%7D%20%20%7D)
Th=20+273=293 K
Tl=10+273=283K
Replacing:
![COP_{reversible}=\frac{293}{293-283}=29.3](https://tex.z-dn.net/?f=COP_%7Breversible%7D%3D%5Cfrac%7B293%7D%7B293-283%7D%3D29.3)
Answer:
The material will not fail
Explanation:
A rod subjected under cyclic stress will fail if the cyclic stress it is subjected to is a constant maximum value that is above the fatigue limit of the rod. but in this problem the Rod is subjected to a cyclic stress that ranges from 200 MPa(maximum stress) and 20 MPa ( minimum stress). this simply means that at all times the Rod will not experience maximum stress of 200 MPa and its Fatigue limit is also set at ~100 MPa
attached is the diagram showing the cyclic stress the rod is subjected to
Answer:
The thermal efficiency of cycle is 42.6%.
Explanation:
Given that
![T_1=300 K](https://tex.z-dn.net/?f=T_1%3D300%20K)
![P_1=100KPa](https://tex.z-dn.net/?f=P_1%3D100KPa)
mass flow rate = 6 kg/s
Compression ratio = 7
Turbine inlet temperature = 1200 K
γ=1.4
We know that thermal efficiency of Brayton cycle given as
![\eta=1-\dfrac{1}{r_p^{\frac{\gamma-1}{\gamma}}}](https://tex.z-dn.net/?f=%5Ceta%3D1-%5Cdfrac%7B1%7D%7Br_p%5E%7B%5Cfrac%7B%5Cgamma-1%7D%7B%5Cgamma%7D%7D%7D)
Now by putting the values
![\eta=1-\dfrac{1}{r_p^{\frac{\gamma-1}{\gamma}}}](https://tex.z-dn.net/?f=%5Ceta%3D1-%5Cdfrac%7B1%7D%7Br_p%5E%7B%5Cfrac%7B%5Cgamma-1%7D%7B%5Cgamma%7D%7D%7D)
![\eta=1-\dfrac{1}{7^{\frac{1.4-1}{1.4}}}](https://tex.z-dn.net/?f=%5Ceta%3D1-%5Cdfrac%7B1%7D%7B7%5E%7B%5Cfrac%7B1.4-1%7D%7B1.4%7D%7D%7D)
η=0.426
So the thermal efficiency of cycle is 42.6%.
Answer:
The factors that affect your energy of motion are speed and weight. The energy of motion increases proportionally with the increase in weight, and the energy increases proportionally with the square of the increase in speed. Traction enables your tires to grip to the road and control your vehicle.
Explanation: