engineering

How to Calculate and Solve for Work of Evapouration | Enthalpy

May 27, 2022 by Loveth Idoko

The work of evapouration is illustrated by the image below.

To compute for work of evapouration, three essential parameters are needed and these parameters are Specific Volume of Dry Gas (v_g), Specific Volume of Wet Steam (v_f) and Pressure of Gas (P).

The formula for calculating work of evapouration:

W_E = P(v_g – V_f)

Where:

W_E = Work of Evapouration
v_g = Specific Volume of Dry Gas
v_f = Specific Volume of Wet Steam
P = Pressure of Gas

Given an example;
Find the work of evapouration when the specific volume of dry gas is 30, the specific volume of wet steam is 0 and the pressure of gas is 10.

This implies that;

v_g = Specific Volume of Dry Gas = 30
v_f = Specific Volume of Wet Steam = 0
P = Pressure of Gas = 10

W_E = P(v_g – V_f)
W_E = 10 x (30 – 0)
W_E = 10 x 30
W_E = 300

Therefore, the work of evapouration is 300J.

Calculating the Specific Volume of Dry Gas when the Work of Evapouration, the Specific Volume of Wet Steam and the Pressure of Gas is Given.

v_g = ^W_E / _P + v_f

Where:

v_g = Specific Volume of Dry Gas
W_E = Work of Evapouration
v_f = Specific Volume of Wet Steam
P = Pressure of Gas

Given an example;
With work of evapouration as 40, the specific volume of wet steam as 0 and the pressure of gas as 10. Find the specific volume of dry gas?

This implies that;

W_E = Work of Evapouration = 40
v_f = Specific Volume of Wet Steam = 0
P = Pressure of Gas = 10

v_g = ^W_E / _P + v_f
v_g = ⁴⁰ / ₁₀ + 0
v_g = 4

Therefore, the specific volume of dry gas is 4.

How to Calculate and Solve for Volume of Superheated Steam | Enthalpy

April 25, 2022 by Loveth Idoko

The volume of superheated steam is illustrated by the image above.

To compute for volume of superheated steam, three essential parameters are needed and these parameters are Specific Volume of Dry Steam (u_g), Superheated Temprature (t_sup) and Saturated Temprature (t_s).

The formula for calculating the volume of superheated steam:

v_sup = ^u_gT_sup / _Ts

Where:

v_sup = Volume of Superheated Steam
u_g = Specific Volume of Dry Steam
T_sup = Superheated Temprature
T_s = Saturated Temprature

Let’s solve an example;
Find the volume of superheated steam when the specific volume of dry steam is 32, the superheated temperature is 24 and the saturated temperature is 14.

This implies that;

u_g = Specific Volume of Dry Steam = 32
T_sup = Superheated Temprature = 24
T_s = Saturated Temprature = 14

v_sup = ^u_gT_sup / _Ts
vsup = ^{32 x 24} / ₁₄vsup = ⁷⁶⁸ / ₁₄vsup = 54.85

Therefore, the volume of superheated steam is 54.85 m³.

Calculating the Specific Volume of Dry Steam when the Volume of Superheated Steam, the Superheated Temperature and the Saturated Temperature is Given.

u_g = ^{v_sup x T_s} / _T_sup

Where:

u_g = Specific Volume of Dry Steam
v_sup = Volume of Superheated Steam
T_sup = Superheated Temprature
T_s = Saturated Temprature

Let’s solve an example;
Find the specific volume of dry steam when the volume of superheated steam is 10, the superheated temperature is 4 and the saturated temperature is 8.

This implies that;

v_sup = Volume of Superheated Steam = 10
T_sup = Superheated Temprature = 4
T_s = Saturated Temprature = 8

u_g = ^{v_sup x T_s} / _T_sup
u_g = ^{10 x 8} / ₄
u_g = ⁸⁰ / ₄
u_g = 20

Therefore, the specific volume of dry steam is 20 m³.

How to Calculate and Solve for Volume of Wet and Dry Steam | Enthalpy

April 25, 2022 by Loveth Idoko

The volume of wet and dry steam is illustrated by the image above.

To compute for the volume of wet and dry steam, three essential parameters are needed and these parameters are Dryness Fraction (x), Specific Volume of Dry Steam (u_g) and Specific Volume of Water (u_f).

The formula for calculating volume of wet and dry steam:

v = xu_g + (1 – x)u_f

Where:

v = Volume of Wet and Dry Steam
x = Dryness Fraction
u_g = Specific Volume of Dry Steam
u_f = Specific Volume of Water

Let’s solve an example;
Given that the dryness fraction is 22, the specific volume of dry steam is 12 and the specific volume of water is 8. Find the volume of wet and dry steam?

This implies that;

x = Dryness Fraction = 22
u_g = Specific Volume of Dry Steam = 12
u_f = Specific Volume of Water = 8

v = xu_g + (1 – x)u_f
v = 22 x 12 + (1 – 22) x 8
v = 22 x 12 + (-21) x 8
v = 264 + -168
v = 96

Therefore, the volume of wet and dry steam is 96 m³.

How to Calculate and Solve for Enthalpy of Superheated Steam | Enthalpy

April 25, 2022 by Loveth Idoko

The image above represents enthalpy of superheated steam.

To compute for enthalpy of superheated steam, five essential parameters are needed and these parameters are Constant Pressure (C_ps), Enthalpy of Water (h_f), Enthalpy of Vapourization (h_fg), Superheated Temprature (T_sup) and Saturated Temprature (T_s).

The formula for calculating enthalpy of superheated steam:

h_sup = h_f + h_fg + C_ps(T_sup – T_s)

Where:

h_sup = Enthalpy of Superheated Steam
C_ps = Constant Pressure
h_f = Enthalpy of Water
h_fg = Enthalpy of Vapourization
T_sup = Superheated Temprature
T_s = Saturated Temprature

Let’s solve an example;
Given that the constant pressure is 2, the enthalpy of water is 4, the enthalpy of vapourization is 6, the superheated temperature is 8 and the saturated temperatue is 10. Find the enthalpy of superheated steam?

This implies that;

C_ps = Constant Pressure = 2
h_f = Enthalpy of Water = 4
h_fg = Enthalpy of Vapourization = 6
T_sup = Superheated Temprature = 8
T_s = Saturated Temprature = 10

h_sup = h_f + h_fg + C_ps(T_sup – T_s)
h_sup = 4 + 6 + 2 x (8 – 10)
h_sup = 10 + 2 x (-2)
h_sup = 10 + (-4)
h_sup = 6

Therefore, the enthalpy of superheated steam is 6 J/Kg.

Calculating the Constant Pressure when the Enthalpy of Superheatred Steam, the Enthalpy of Water, the Enthalpy of Vapourization, the Superheated Temperature and the Saturated Temperature is Given.

C_ps = ^{h_sup – h_f – h_fg} / _T_sup + T_s

Where:

C_ps = Constant Pressure
h_sup = Enthalpy of Superheated Steam
h_f = Enthalpy of Water
h_fg = Enthalpy of Vapourization
T_sup = Superheated Temprature
T_s = Saturated Temprature

Let’s solve an example;
Find the Constant Pressure when the enthalpy of superheated steam is 30, the enthalpy of water is 10, the enthalpy of vapourization is 4, the superheated temperature is 8 and the saturated temperature is 2.

This implies that;

h_sup = Enthalpy of Superheated Steam = 30
h_f = Enthalpy of Water = 10
h_fg = Enthalpy of Vapourization = 4
T_sup = Superheated Temprature = 8
T_s = Saturated Temprature = 2

C_ps = ^{h_sup – h_f – h_fg} / _T_sup + T_s
C_ps = ^{30 – 10 – 4} / _{8 + 2}
C_ps = ¹⁶ / ₁₀
C_ps = 1.6

Therefore, the constant pressure is 1.6.