A piston-cylinder chamber contains 0.1 m3 of 10 kg R-134a in a saturated liquid-vapor mixture state at 10 °C. It is heated at constant tempe

Question

A piston-cylinder chamber contains 0.1 m3 of 10 kg R-134a in a saturated liquid-vapor mixture state at 10 °C. It is heated at constant temperature until the piston expands and the final volume of R-134a is 1 m3 . What is (a) the final pressure and (b) the total energy transferred to R-134a for this process?

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Nguyệt Ánh 1 year 2021-09-01T08:39:20+00:00 1 Answers 4 views 0

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    2021-09-01T08:40:24+00:00

    Answer:

    (A) 10132.5Pa

    (B)531kJ of energy

    Explanation:

    This is an isothermal process. Assuming ideal gas behaviour then the relation P1V1 = P2V2 holds.

    Given

    m = 10kg = 10000g, V1 = 0.1m³, V2 = 1.0m³

    P1 = 101325Pa. M = 102.03g/mol

    P2 = P1 × V1 /V2 = 101325 × 0.1 / 1 = 10132.5Pa

    (B) Energy is transfered by the r134a in the form of thw work done in in expansion

    W = nRTIn(V2/V1)

    n = m / M = 10000/102.03 = 98.01mols

    W = 98.01 × 8.314 × 283 ×ln(1.0/0.1)

    = 531kJ.

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