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A 1-ft3 tank, shown in Fig. P4.136 that is initially
Chapter 4, Problem 207EUP(choose chapter or problem)
Problem 207EUP
A 1-ft3 tank, shown in Fig. P4.136 that is initially evacuated is connected by a valve to an air supply line flowing air at 70 F, 120 lbf/in.2. The valve is opened, and air flows into the tank until the pressure reaches 90 lbf/in.2. Determine the final temperature and mass inside the tank, assuming the process is adiabatic. Develop an expression for the relation between the line temperature and the final temperature using constant specific heats.
FIGURE P4.136
Questions & Answers
QUESTION:
Problem 207EUP
A 1-ft3 tank, shown in Fig. P4.136 that is initially evacuated is connected by a valve to an air supply line flowing air at 70 F, 120 lbf/in.2. The valve is opened, and air flows into the tank until the pressure reaches 90 lbf/in.2. Determine the final temperature and mass inside the tank, assuming the process is adiabatic. Develop an expression for the relation between the line temperature and the final temperature using constant specific heats.
FIGURE P4.136
ANSWER:
Solution 207EUP
Step 1 of 5:
An evacuated tank is filled with air by a line. The temperature and pressure get changed during this adiabatic process. We are going to find the final temperature and the mass of air inside the tank.
The pressure of air inside the tank P1 = 120 lbf/in2 = 827.4 kPa
The volume of the tank V = 1 ft3 = 0.0283 m3
The temperature of incoming air Ti = 70 F = 294.3 K
The final pressure P2 = 90 lbf/in2 = 620.5 kPa
The gas constant for air R = 0.287 kJ/kg.K (A.5)