Chat with us, powered by LiveChat

Temperature- Enthalphy Graph During Formation of Steam

 

Temperature- Enthalphy Graph During Formation of Steam” = C

 

In this case the water at A tends to have a temperature of 0°C and the different stages of it are explained as below

Induction stage- it shows the heating of water up to the boiling temperature. Sensible heat is defined  to raise the temperature of water(1 kg mass) from 0°C to boiling point . it is illustrated by  is denoted as hf” Sensible heat  = mass of water x specific heat x rise in temperature where

1 x 4.2 t s + 273- 273] = 4.2 l 5

Where specific heat of water is taken as 4.2 KJ / kg.

Warming stage- the change of the state from liquid to steam is illustrated by BC. FG is the heat absorbed during this stages and is illustrated by the latent heat of vaporization (h18).

Evaporation stage- the superheating process is shown by CD. During this stage the heat absorbed is GI,I which is known as the heat of superheat. The Line AH is a representation of the total heat that is required to go to the superheated point D

Effect of change on pressure

If the pressure bar is increased to P1, then the boiling temperature is also bound to increase.

point *B1 –the boiling temperature or saturating temperature at P1 bar.

C1- dry saturated steam

Line C1D1 shows the constant pressure process in which the steam is superheated (after C1 point).

In a similar stature, the family of curves is different for various situations. The line A- B-B1- B2 is referred to as the saturated liquid line, as it is the boundary between the water and the steam. On the other hand C2- CcC-A1, is known as dry saturated steam as it is known to formulate the boundary between the dry and the superheated steam. The pressure tends to increase the latent heat of vaporization, and this is the stage where the saturation temperature tends to decrease. It reaches a stage of  zero at E where the liquid and dry steam lines meet. At the point E is referred to as a critical point for sure. For steam, critical temperature is 374.15°C and critical pressure is 221.2 bar.

Total heat (enthalpy) of dry saturated steam (point C) is Jz8 = h1 + h/g”

where  hg = enthalpy of 1 kg of dry saturated steam

f = sensible heat of 1kg of water

fg = enthalpy of vaporisation of 1 kg of dry saturated steam = Latent heat of

steam.

The enthalpy of heating of water upto saturation temperature

f  = c pf (T sat – 273.16)

where              c  pf = 4.18 kj / kg k.

Wet steam

mg= mass of actual dry steam

m1= mass of water in suspension

m = mass of wet steam

Dryness fraction

x = mg / mg + mf

x is also called the quality of wet steam

for x = 0, it is saturated liquid

for x = 1, it is dry and saturated steam.

0 < x < 1.

Internal energy:     h = u + P f

f stands for fluid (water)

u1= hrPv1

for dry steam              u g = hg – P v g

g stands for gas (vapour).

(d) sp. enthalpy of wet steam:

h = h1+ xh fg

(e) sp. enthalpy of superheated steam:

sup = h f+ h fg + C pg U sup – t sat)

c g for steam = 2.1 KJ /kg0k.

t sup – t snt = Degree of superheat.

Specific volume: Specific volume of wet steam

v =v1+x(vg -v1)

= x vg + (1 – x) v1

Charles law when       P = C

sup / T sup = u g / T sat

(g) Specific entropy : specific entropy of wet steam

s = s1 + x (Sg – s1)

(h) Work done during evaporation

=P(vg -v1)

= Pv g as v1= negligible

(i) Work done during evaporation of a wet state

= Px vg.

(j) work done by superheated steam

‘Pv sup.

(k) specific entropy of steam:

The steam is produced at constant pressure. The entropy is assumed to be zero at 0°C.

Change m· spec1· f·1 c entropy= ds = dQ / T

(i) The heat supplied for heating 1 kg of water at constant pressure is given by

D θ = c pf dT

ds = c pf dT / T

Integrating

or                                 s = c pf in T sat / 273

(ii) The change in entropy during evaporation is given by

fg = h fg / T sat

(iii) The change in entropy during evaporation is given by

g = s f + s fg

= c pf in T sat / 273 + h fg / T sat

(iv) Entropy during superheating of steam is given by

(v) Entropy of superheated steam is given by

sup = s g + s gj

= c pf in T sat / 273 + h fg / T sat

wherecp g = sp heat of superheated steam

= 2.1 KJ/ kg° K

And                             c pf = 4.18 KJ/ kg0K.

 

Links of Previous Main Topic:-

Links of Next Mechanical Engineering Topics:-

Trustpilot

We’re rated Excellent

4.7 out of 5 based on 39 reviews

Join over 200,000+ happy students served our tutors

Take a look at independent reviews to see what users have to say about our homework help service.

4.5/5

overall rating
on LiveChat

96%

of users
recommend service

How It Works

1. Get Price Estimate.
1. Get Price Estimate.

Submit.

Send us your homework. Mention deadline & upload relevant files.

2. Pay Securely.
2. Pay Securely.

Pay.

We accept all major credit cards. Partial payments also accepted.

3. Get Solutions.
3. Get Solutions.

Delivered

Receive error-free, step-by-step solutions in your email.

FAQs

Why use Myhomeworkhelp?

We provide you with the homework help from top experienced experts. Your satisfaction is a priority to us. Get better grades or money-back. It’s that risk-free! Furthermore, everything about you is kept confidential.

How quickly can you help me with my homework?

We take pride in our 24×7 homework help services. Which means, student can approach us anytime, to get help even on short notices. As short as few hours! And yes, we provide complementary plagiarism-free report.

How much will it cost?

We do not have a monthly fees or minimum payments. Each homework task is quoted a unique price. It is based on tutor’s estimate of the time it will take them to complete your task. There are no obligations, and you are free to discuss the price quote with the tutor.
We do accept partial payment (subject to our policy) to start working on your assignment help. You can pay the remaining amount when your task gets completed. No pressure of up-front payment. No hidden costs.

Who are your tutors?

All our experts are highly qualified professionals – holding at least Master’s degree of their respective fields of expertise. We are very selective and choose only the best qualified tutors for each academic subject. All tutor applicants must provide academic transcripts for each degree they hold, and are tested and screened carefully by our staff.

I have privacy concerns. Can I trust you?

Myhomeworkhelp has completed over 250,000 homework help tasks over the last 12 years. But do not take our word for it! See our here and on Trustpilot. Furthermore, everything about you is kept confidential. Your credit card information is not stored anywhere, and use of PayPal relies on their secure payment networks. Your identity, payment and homework help are in safe hands.

Check our video

Our Reviews
Ratings