98 ENGINEERING THERMODYNAMICS
Dharm
\M-therm/th3-2.p65
- With the increase in pressure
(a) boiling point of water increases and enthalpy of evaporation increases
(b) boiling point of water increases and enthalpy of evaporation decreases
(c) boiling point of water decreases and enthalpy of evaporation increases. - With increase in pressure
(a) enthalpy of dry saturated steam increases
(b) enthalpy of dry saturated steam decreases
(c) enthalpy of dry saturated steam remains same
(d) enthalpy of dry saturated steam first increases and then decreases. - Dryness fraction of steam is defined as
(a) mass of water vapour in suspension/(mass of water vapour in suspension + mass of dry steam)
(b) mass of dry steam/mass of water vapour in suspension
(c) mass of dry steam/(mass of dry steam + mass of water vapour in suspension)
(d) mass of water vapour in suspension/mass of dry steam. - The specific volume of water when heated at 0°C
(a) first increases and then decreases (b) first decreases and then increases
(c) increases steadily (d) decreases steadily. - Only throttling calorimeter is used for measuring
(a) very low dryness fraction upto 0.7 (b) very high dryness fraction upto 0.98
(c) dryness fraction of only low pressure steam (d) dryness fraction of only high pressure steam. - Heat of superheated steam is given by
(a)hsup = hf + hfg + cps logeT
Tssup (b)h
sup = hf + xhfg(c)hsup = hf + hfg (d)hsup = hf + xhfg + cps loge 273 Ts.- Volume of wet steam (per kg) with dryness fraction x is given by
(a)x^3 vg (b) xvf
(c)x^2 (vg – vf) (d)x^2 vg
(e) none of the above. - Internal latent heat is given by
(a)hfg –
pv
J
g (b)h
g –pv
Jg(c)hsup – pvJf (d)hfg + pvJg
(e) none of the above.- Entropy of 1 kg of water at T K is given by
(a)cpw loge 273 T (b)cpw logeT
T2
1
(c)cpw log 10 273 T (d)cpw loge 273 T^2
(e) none of the above.- Entropy of wet steam (1 kg) is given by
(a)sf +
xh
Tfg
s
(b)sg +xh
Tfg
s
(c)sf +
h
Tfg
s
(d)sf + cps logeT
Tsup
s
(e) none of the above.