A pistoncylinder device contains 5 kg of R134A at 800 kPa an

A piston-cylinder device contains 5 kg of R-134A at 800 kPa and 70°C. The refrigerant is now cooled isobarically (at constant pressure) until it exists as a compressed liquid at 15°C. Determine the heat loss in kJ and show the process on a T-v diagram with respect to saturation lines (vapor dome).

Solution

sol:

Assume final condition is a saturated liquid.

Use energy balance for closed system.
U = Q - W
Q = U + W
Q = m* [u2-uf + P(v2-vf)], remember h = u+pv
Q = m* [h2-hf]
Q = 5 * [305.50 - 70.6]
Q = 1174.5 kJ