First I want to thank you both for the answer. Yes, I concluded that it was supposed to use the efficiency and I was given Th being Tc the temperature at the bottom. It's done!
Homework Statement
A haet engine works based on the difference of the temperature at the top and bottom of the ocean. The machine is solar powered and the average solar irradiance is 240W/m^2 and the temperature at the surface of the water is 25ºC. Calculate the temperature at the bottom of...
Homework Statement
A compressor processes 1.5kg/min of air in ambient conditions (1 bar and 20ºC). The compressed air leaves at 10bar and 90ºC. It is estimated that the heat losses trough the walls of the compressor are of 25kJ/min. Calculate:
a) The power of the compressor
b) The...
Homework Statement
Calculate the variation of entropy in the following processes:
a) Heating of 18 kg of water from 15 to 40ºC at ambient pressure.
b) Compression of 9 kg of water from ambient pressure to 7atm at the temperature of 15ºC.
Homework Equations
ΔS=Cp*ln(T_final/T_initial)...
I have the specific heat in (kJ/kgK). I got it from this website http://www.engineeringtoolbox.com/carbon-dioxide-d_974.html.
But with that how do I do the m∫CpdT part? The integral is between the two temperatures but I have two Cp's according to that table.
I also found this table, could be...
For a) I have the specific heat at 300K and 800K. H=mCpT where m is the mass, Cp the specific heat and T the temperature in F? For the mass I have the molar mass(139.7405) and number of moles(3175,2) so I just need to multiply them to get the mass right?
Best Regards
For a) and b) I have the property tables of ideal gases, for c) I have that expression. I'm finding it hard because I don't really know which table to use and because I'm having trouble calculating the ΔU. The only thing the problem says is to use the property tables of ideal gases.
Homework Statement
Calculate the variation of ΔH in Btu for the following processes:
a) Heating of 7Ibmol of carbon dioxide from 77 to 1000ºF at 1atm using property tables for ideal gases.
b) Cooling of 22Ibmol of benzene from it's normal boiling point(80.1ºC) to 77ºF at 1atm.
c)...
I've corrected the units, I think. Converted 4.937ft^3/lb to Btu. 1ft^3=1.027Btu. It gave me 5.070299.
So, instead of using the 1atm I'll use the 14.7 psi and the specific volume I calculate it from the density you gave me to use in the (ΔPV) part? But I still don't get it how will I found the...
Homework Statement
Liquid water at 212ºF and 1atm has a specific internal energy of 180.02Btu/lbm. The water is transformed into steam at 400ºF and the pressure of 100psi where it's specific volume is 4.937ft^3/lb and it's specific enthalpy is 1228.4Btu/lb. Determine the variation of internal...