Question

In: Physics

3.19 A gas with adiabatic exponent γ is compressed adiabatically from an initial state (Pi, Vi)...

3.19 A gas with adiabatic exponent γ is compressed adiabatically from an initial state (Pi, Vi) to final state (Pf, Vf). (a) Show that the work done in this process is

W=((ViPi)/y-1)*[(Vi/Vf)^(y-1) -1]

(b) Evaluate the result numerically for one mole of helium gas initially
at P = 1.0 atm and T = 300 K compressed to half its initial volume.
(c) Compute the work done in an isothermal compression from the same
initial point to half the initial volume. Explain the difference between
the numerical results for work done in adiabatic and isothermal
compression.

Solutions

Expert Solution

As we can see the Work done results for both the processes, we can say that the Adiabatic compression work is larger than the isothermal compression work.

Because...compression lowers the volume of the system and therefore usually increases the temperature when heat exchange with the surroundings is not allowed(adiabatic compression). Whereas, Isothermal compression requires heat transfer to the surroundings to maintain constant temperature, lowering the pressure of the system and thus lowering the resistance to compression compared to the adiabatic compression (where heat exchange is not allowed).

Ask for any doubt and do upvote.


Related Solutions

A quantity of air (γ = 1.40) expands adiabatically from an initial pressure of 2 atm...
A quantity of air (γ = 1.40) expands adiabatically from an initial pressure of 2 atm and volume of 2 L at temperature 20 ° C to twice its original volume. Find: a) The final pressure b) The final temperature
An adiabatic gas turbine uses air to produce work. Air expands adiabatically from 600 kPa and...
An adiabatic gas turbine uses air to produce work. Air expands adiabatically from 600 kPa and 287 C to 90 kPa and 67 C. Take specific heats at room temperature (300 K). a) Find the isentropic efficiency of the turbine. b) Find the work produced by the turbine for a mass flow rate of 2.5 kg/s. c) If the mass flow rate of air is again 2.5 kg/s, find the entropy generation under steady conditions
15 g of nitrogen gas at STP are adiabatically compressed to a pressure of 21 atm...
15 g of nitrogen gas at STP are adiabatically compressed to a pressure of 21 atm . What is the final temperature of the gas? What is the work done on the gas? What is the heat input to the gas? What is the compression ratio Vmax/Vmin?
Air is compressed from an initial state of 1 bar and 298.15K to a final state...
Air is compressed from an initial state of 1 bar and 298.15K to a final state of 5 bar and 295.15K by three different mechanically reversible processes in a closed system: • Heating at constant volume followed by cooling at constant pressure • Isothermal compression • Adiabatic compression followed by cooling at constant volume Show these processes in a PV diagram and calculate the work required, heat transferred, and the changes in internal energy and enthalpy of the air for...
b) Ethane gas at 1 bar and 25 oC is compressed adiabatically to 55 bar in...
b) Ethane gas at 1 bar and 25 oC is compressed adiabatically to 55 bar in a steady-state flow process for which W = 10 J mol-1. Assume ethane is ideal gas at its initial state and the residual enthalpy of the gas at its final state is - 3270 J/mol, and its heat capacity is constant (CP = 4.5 R), the temperature of ethane at the final state, i.e., after compression, is i. 403.3 oC; ii. 403.3 K; iii....
An ideal gas described by Ti = 300 K, Pi = 2.00 bar, and Vi =...
An ideal gas described by Ti = 300 K, Pi = 2.00 bar, and Vi = 15.0 L is heated at constant volume until P2 = 20.0 bar. It then undergoes a reversible isothermal expansion until P3 = 2.00 bar. It is then restored to its original state by the extraction of heat at constant pressure. Depict this closed-cycle process in a P-V diagram. Calculate number of moles n ( two decimals, as 3.21) = [n]; V2 (unit L, no...
A gas confined in a piston-cylinder arrangement occupies 0.5 liters (Vi) at 4 atm (Pi) and...
A gas confined in a piston-cylinder arrangement occupies 0.5 liters (Vi) at 4 atm (Pi) and 278 K (Ti). From this initial state the gas is allowed to expand against the surrounding atmosphere which is at a constant pressure of 1 atm (Patm) and a temperature of 278 K. At equilibrium, the gas’s final volume (Vf) is 2 liters and its final temperature (Tf) is 278 K. The initial and final states are indicated in the figure below. a. In...
1 kg / s of steam is compressed in an adiabatic compressor from 200 kPa and...
1 kg / s of steam is compressed in an adiabatic compressor from 200 kPa and 200 ° C to 3000 kPa and 400 ° C. How powerful is the compressor? is this transformation possible (briefly argue)?
air is compressed in an adiabatic and isentropic compressor from 14 psia and 60F to 210...
air is compressed in an adiabatic and isentropic compressor from 14 psia and 60F to 210 psia. Determine the outlet temperature [F] and the work consumed by this compressor per unit mas of air [Btu/lbm]. Assume constant specific heats at T=100F Please explain table look ups, thank you!
R22 is compressed adiabatically and reversibly from saturated vapor at -20 deg F to 200 psia....
R22 is compressed adiabatically and reversibly from saturated vapor at -20 deg F to 200 psia. Find the final temperature and the specific work done.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT