TITLE.PM5

FIRST LAW OF THERMODYNAMICS 159

dharm

/M-therm/Th4-4.pm5

Applying energy equation to the system, we have :

∆PE = 0 and ∆KE = 0 since these changes are negligible compared with other energies.

∴ h 1 – Q = h 2 – W ...(4.58)

4.12.6. Boiler

A boiler transfers heat to the incoming water and generates the steam. The system is
shown in Fig. 4.37.

Fig. 4.37. Boiler.

For this system, ∆Z = 0 and ∆

C 22

2

F

HG

I

KJ = 0

W = 0 since neither any work is developed nor absorbed.

Applying energy equation to the system

h 1 + Q = h 2 ...(4.59)

4.12.7. Condenser

The condenser is used to condense the steam in case of steam power plant and condense the
refrigerant vapour in the refrigeration system using water or air as cooling medium. Fig. 4.38
shows the system.
For this system :
∆PE = 0, ∆KE = 0 (as their values are very small compared with enthalpies)
W = 0 (since neither any work is developed nor absorbed)
Using energy equation to steam flow
h 1 – Q = h 2 ...[4.60 (a)]
where Q = Heat lost by 1 kg of steam passing through the condenser.