HO H,O P1 = 2bar Rigid pressure vessel P2 = 10bar X1 = 0.1 containing H20 Qhot hot W1-2 W2-1 Reversed heat engine Heat Engine 2 cold Qcold Tcold = 270K Tcold = 270K (a) At state point one heat supply is started. (b) At state point two heat extraction is started. Figure Q2. Reversible heat engine used for heating and work (i.e., Qhot and W2-1).1-2 A reversed reversible heat engine extracts heat O from a cold reservoir at temperature 7, ,, = 270K to supply heat Q,\" to a rigid pressure vessel filled with a system of wet steam of mass m=10kg. The arrangement is depicted in Fig. Q2, where heat supplied by the reversed engine causes the pressure of the system to rise from p, =2 bar at state point 1 to p, =10 bar at state point 2. Subsequently, the reversed engine is reversed, and heat is extracted from the steam to produce work Hf ', which returns the system back to state point 1, i.e., the system undergoes a cycle. Information recorded at the state points depicted in the figure is as follows: State point 1: dryness fraction x, =0.1 and pressure p, =2 bar. State point 2: p, =10 bar. Assume that the only transfers of heat to take place are those labelled in Fig. Q2, i.e., O,, O.., O,/ and O . Additionally, assume that the role of the rigid pressure vessel is solely limited to containment, so that any changes to its temperature can be reasonably neglected. The shaft work supplied to the reversed engine during process 1to 2 is W'* =3000kJ. (a) Determine the specific internal energy , and specific volume v, of the system of steam at state point 1. [16 marks] (b) Determine the specific internal energy u, and dryness fraction x, of the system of steam at state point 2. [16 marks] (c) Determine the coefficient of performance of the reversed heat engine and hence determine the temperature of a hot reservoir that could reasonably replace the system of steam. [12 marks] (d) Determine the thermal efficiency of the heat engine. [6 marks]