Final answer:
To determine if an adiabatic expansion process is possible, ideal, or impossible, compare the actual work done to the work done in an ideal adiabatic expansion process.
Step-by-step explanation:
An adiabatic expansion process in a piston-cylinder device refers to a process in which no heat is transferred to or from the system. In this case, the refrigerant R-134a is initially at 100 psia and in a saturated liquid state. The final pressure is 50 psia and the boundary work performed by the system is 7.623 btu/lbm. To determine if the process is possible, ideal, or impossible, we need to compare the actual work done to the work done in an ideal adiabatic expansion process.
The work done by the system in an ideal adiabatic expansion can be calculated using the formula:
W = (P1*V1 - P2*V2) / (y - 1)
where P1 and V1 are the initial pressure and volume, P2 and V2 are the final pressure and volume, and y is the specific heat ratio of the refrigerant.
If the actual work done by the system is equal to the work done in the ideal process, then the process is ideal. If the actual work done is less than the work done in the ideal process, then the process is possible but not ideal. If the actual work done is greater than the work done in the ideal process, then the process is impossible.
Using the given values and the specific heat ratio for R-134a, you can calculate the work done in the ideal process and compare it to the actual work done to determine the nature of the process.