TITLE.PM5

FIRST LAW OF THERMODYNAMICS 211

dharm

/M-therm/Th4-7.pm5

1. Filling a tank :
   Let m 1 = Initial mass of fluid,
   p 1 = Initial pressure,
   v 1 = Initial specific volume,
   T 1 = Initial temperature,
   u 1 = Initial specific internal energy,
   and m 2 = Final mass of fluid,
   p 2 = Final pressure,

Fig. 4.78

v 2 = Final specific volume,

T 2 = Final temperature,

u 2 = Final specific internal energy,

Also, let p′ = Entering fluid pressure,

v′ = Entering fluid specific volume,

T′ = Entering fluid temperature,

C′ = Entering fluid velocity,

u′ = Entering specific internal energy of fluid, and

h′ = Entering specific enthalpy of fluid.

The quantity of fluid entering

= m 2 – m 1

Energy of entering fluid

= (m 2 – m 1 ) ′+ ′ ′+

F ′

HG

I

KJ

upvC

2

2 ...(4.82)

= (m 2 – m 1 ) ′+

F ′

HG

I

KJ

h C

2

2 ...(4.83)

If Q = Heat transferred into the control volume, we have

(m 2 – m 1 ) ′+

F ′

HG

I

KJ

h C

2

2 + Q = m 2 u 2 – m 1 u 1 ...(4.84)