initial commit / add all books

23 files changed, 476 insertions, 0 deletions

diff --git a/1073/CH4/EX4.1/4_1.sce b/1073/CH4/EX4.1/4_1.sce
new file mode 100755
index 000000000..2ed8935ed
--- /dev/null
+++ b/1073/CH4/EX4.1/4_1.sce
@@ -0,0 +1,9 @@
+clc;

+clear;

+//Example 4.1

+e=0.9   //[Emissivity]

+sigma=5.67*10^-8    //[W/m^2.K^4]

+T1=377  //[K]

+T2=283  //[K]

+Qr_by_a=e*sigma*(T1^4-T2^4) //[W/sq m]

+printf("Heat loss by radiation is %d W/sq m",round(Qr_by_a));

diff --git a/1073/CH4/EX4.10/4_10.sce b/1073/CH4/EX4.10/4_10.sce
new file mode 100755
index 000000000..ebde4488c
--- /dev/null
+++ b/1073/CH4/EX4.10/4_10.sce
@@ -0,0 +1,20 @@
+clc;

+clear;

+//Example 4.10

+e1=0.05

+e2=e1

+A1=0.6944;

+A2=1;

+T1=293  //[K]

+T2=90   //[K]

+sigma=5.67*10^-8    //[W/m^2.K^4]

+D=0.3   //Diameter in [m]

+

+F12=1/(1/e1+(A1/A2)*(1/e2-1))

+Q_by_A=sigma*F12*(T1^4-T2^4)    //[W/sq m]

+Q=Q_by_A*%pi*(D^2)  //[kJ/h]

+Q=Q*3600/1000   //[kJ/h]

+lambda=21.44    //Latent heat in [kJ/kg]

+m_dot=Q/lambda    //kg/h

+printf("\n The liquid oxygen will evaporate at %f kg/h",m_dot);

+

diff --git a/1073/CH4/EX4.11/4_11.sce b/1073/CH4/EX4.11/4_11.sce
new file mode 100755
index 000000000..51514e282
--- /dev/null
+++ b/1073/CH4/EX4.11/4_11.sce
@@ -0,0 +1,22 @@
+clc;

+clear;

+//Example4.11

+sigma=5.67*10^-8    //W/(m^2.K^4)

+e1=0.3;

+e2=e1;

+D1=0.3  //[m]

+D2=0.5  //[m]

+T1=90   //[K]

+T2=313  //[K]

+A1=%pi*D1^2 //Area in [sq m]

+A2=%pi*D2^2//Area in [sq m]

+Q1=sigma*A1*(T1^4-T2^4)/(1/e1+(A1/A2)*(1/e2-1))  //[W]

+Q1=abs(Q1); //Absolute value in [W]

+printf("\n Rate of heat flow due to radiation is %f W",Q1);

+//When Aluminium is used

+e1=0.05

+e2=0.5

+Q2=sigma*A1*(T1^4-T2^4)/(1/e1+(A1/A2)*(1/0.3-1))  //[W]

+Q2=abs(Q2) //Absolute value in [W]

+Red=(Q1-Q2)*100/Q1  //Percent reduction

+printf("\n Reduction in heat flow will be %f percent ",Red);

diff --git a/1073/CH4/EX4.12/4_12.sce b/1073/CH4/EX4.12/4_12.sce
new file mode 100755
index 000000000..0f0667341
--- /dev/null
+++ b/1073/CH4/EX4.12/4_12.sce
@@ -0,0 +1,22 @@
+

+clc;

+clear;

+//Example 4.12

+sigma=5.67*10^-8    //[W/sq m.K^4]

+T1=77   //[K]

+T2=303  //[K]

+D1=32   //cm

+D1=D1/100   //[m]

+D2=36   //[cm]

+D2=D2/100   //[m]

+A1=%pi*D1^2 //[sq m]

+A2=%pi*D2^2 //[sq m]

+e1=0.03;

+e2=e1;

+Q=sigma*A1*(T1^4-T2^4)/(1/e1+(A1/A2)*(1/e2-1))  //[W]

+Q=Q*3600/1000   //[kJ/h]

+Q=abs(Q);   //[kJ/h]

+lambda=201  //kJ/kg

+m_dot=Q/lambda  //Evaporation rate in [kg/h]

+printf("\n Nitrogen evaporates at %f kg/h",m_dot);

+

diff --git a/1073/CH4/EX4.13/4_13.sce b/1073/CH4/EX4.13/4_13.sce
new file mode 100755
index 000000000..062059f3d
--- /dev/null
+++ b/1073/CH4/EX4.13/4_13.sce
@@ -0,0 +1,22 @@
+

+clc;

+clear;

+//Example 4.13

+D1=250  //Inner sphere idameter[mm]

+D1=D1/1000  //Outer diameter [m]

+D2=350  //[mm]

+D2=D2/1000  //[m]

+sigma=5.67*10^-8    //W/(sq m.K^4)

+A1=%pi*D1^2 //[sq m]

+A2=%pi*D2^2 //[sq m]

+T1=76   //[K]

+T2=300  //[K]

+e1=0.04;

+e2=e1;

+Q=sigma*A1*(T1^4-T2^4)/((1/e1)+(A1/A2)*((1/e2)-1))   //[W]

+Q=-2.45     //Approximate

+Q=abs(Q)    //[W]

+Q=Q*3600/1000   //[kJ/h]

+lambda=200  //kJ/kg

+Rate=Q/lambda   //[kg/h]

+printf("\n Rate of evaporation is %f kg/h(approx)",Rate);

diff --git a/1073/CH4/EX4.15/4_15.sce b/1073/CH4/EX4.15/4_15.sce
new file mode 100755
index 000000000..062f44275
--- /dev/null
+++ b/1073/CH4/EX4.15/4_15.sce
@@ -0,0 +1,19 @@
+clc;

+clear;

+//Example 4.15

+sigma=5.67*10^-8    //[W/(m^2.K^4)]

+e1=0.4

+e3=0.2

+T1=473  //[K]

+T3=303  //[K]

+Q_by_a=sigma*(T1^4-T3^4)/((1/e1)+(1/e3)-1)  //[W/sq m]

+//Q1_by_a=sigma*(T1^4-T2^4)/((1/e1)+(1/e2)-1)=sigma*A*(T2^4-T3^4)/((1/e2)+(1/e3)-1) //[W/sq m]

+e2=0.5

+//Solving we get

+T2=((6/9.5)*((3.5/6)*T3^4+T1^4))^(1/4)  //[K]

+Q1_by_a=sigma*(T1^4-T2^4)/((1/e1)+(1/e2)-1) //[W/sq m]

+red=(Q_by_a-Q1_by_a)*100/Q_by_a

+printf("\nHeat transfer rate per unit area(WITHOUT SHIELD) due to radiation is %f W/sq m\n",Q_by_a);

+printf("\nHeat transfer rate per unit area(WITH SHIELD) due to radiation is %f W/sq m\n",Q1_by_a);

+printf("\nReduction in heat loss is %f percent",red);

+

diff --git a/1073/CH4/EX4.16/4_16.sce b/1073/CH4/EX4.16/4_16.sce
new file mode 100755
index 000000000..8c9a68af0
--- /dev/null
+++ b/1073/CH4/EX4.16/4_16.sce
@@ -0,0 +1,27 @@
+clc;

+clear;

+//Example 4.16

+//In steady state,we can write:

+//Qcd=Qdb

+//sigma(Tc^4-Td^4)*/(1/ec+1/ed-1)=sigma(Td^4-Tb^4)/(1/ed+1/eb-1)

+// i.e Td^4=0.5*(Tc^4-Tb^4)

+//Given:

+Ta=600  //[K]

+eA=0.8;

+eC=0.5;

+eD=0.4;

+sigma=5.67*10^-8        //For air

+//(600^4-Tc^4)/2.25=(Tc^4-Td^4)/3.5

+//1.56*(600^4-Tc^4)=Tc^4-Td^4

+//Putting value of Td in terms of Tc

+//1.56*(600^4-Tc^4)=Tc^4-0.5*(Tc^4-300^4)

+function y=f(Tc)

+  y=1.56*(600^4-Tc^4)-Tc^4+0.5*(Tc^4-300^4)

+endfunction

+Tc=fsolve(500,f);           //[K]

+//or

+Tc=560.94       //[K] Approximate after solving

+Td=sqrt(sqrt(0.5*(Tc^4-300^4)))         //[K]

+Q_by_a=sigma*(Ta^4-Tc^4)/(1/eA+1/eC-1)      //[W/sq m]

+printf("\nRate of heat exchange per unit area=%f W/m^2",Q_by_a);

+printf("\nSteady state temperatures,Tc=%f K,and Td=%f K",Tc,Td);

diff --git a/1073/CH4/EX4.17/4_17.sce b/1073/CH4/EX4.17/4_17.sce
new file mode 100755
index 000000000..d73d598fe
--- /dev/null
+++ b/1073/CH4/EX4.17/4_17.sce
@@ -0,0 +1,27 @@
+clc;

+clear;

+//Example 4.17

+sigma=5.67*10^-8    //[W/(sq m.K^4)]

+e=0.8

+T1=673;  //[K]

+T2=303;  //[K]

+Do=200   //[mm]

+Do=Do/1000  //[m]

+L=1      //Let [m]

+A1=%pi*Do*L //[m^2/m]

+//CAse 1: Pipe to surrundings

+

+Q1=e*A1*sigma*(T1^4-T2^4)   //[W/m]

+Q1=5600     //Approximated

+//Q1=5600         //[W/m] approximated in book for calculation purpose

+//Concentric cylinders

+e1=0.8;

+e2=0.91;

+D1=0.2  //[m]

+D2=0.4  //[m]

+Q2=sigma*0.628*(T1^4-T2^4)/((1/e1)+(D1/D2)*((1/e2)-1))   //[W/m] length

+Red=Q1-Q2   //Reduction in heat loss

+

+printf("\nDue to thermal radiaiton,Loss of heat to surrounding is %d W/m\n",round(Q1));

+printf("\nWhen pipe is enclosed in 1 400 mm diameter brick conduit,Loss of heat is %d W/m\n",round(Q2));

+printf("\n Reduction in heat loss is %d W/m\n",round(Red));

diff --git a/1073/CH4/EX4.18/4_18.sce b/1073/CH4/EX4.18/4_18.sce
new file mode 100755
index 000000000..894eb30a8
--- /dev/null
+++ b/1073/CH4/EX4.18/4_18.sce
@@ -0,0 +1,16 @@
+

+

+clc;

+clear;

+//Example 4.18

+

+

+sigma=5.67*10^-8 ;   //[W/(sq m.K^4)]

+T1=813;  //[K]

+T2=473;  //[K]

+e1=0.87;

+e2=0.26;

+D1=0.25 ;//[m]

+D2=0.3; //[m]

+Q_by_a1=sigma*(T1^4-T2^4)/(1/e1+(D1/D2)*(1/e2-1))   //[W/ sqm]

+printf("\n Heat transfer by radiaiton is %d W/sq m",Q_by_a1);

diff --git a/1073/CH4/EX4.19/4_19.sce b/1073/CH4/EX4.19/4_19.sce
new file mode 100755
index 000000000..97c6bcd66
--- /dev/null
+++ b/1073/CH4/EX4.19/4_19.sce
@@ -0,0 +1,11 @@
+

+clc;

+clear;

+//Example 4.19

+sigma=5.67*10^-8    //[W/sq m.K^4]

+A1=0.5*1    //[sq m]

+F12=0.285

+T1=1273 ///[K]

+T2=773  //[K]

+Q=sigma*A1*F12*(T1^4-T2^4)    //[W]

+printf("\n Net radiant heat exchange between plates is %d W",Q);

diff --git a/1073/CH4/EX4.2/4_2.sce b/1073/CH4/EX4.2/4_2.sce
new file mode 100755
index 000000000..c01af8bd2
--- /dev/null
+++ b/1073/CH4/EX4.2/4_2.sce
@@ -0,0 +1,9 @@
+clc;

+clear;

+//Example 4.2

+e=0.9   //Emissivity

+T1=393  //[K]

+T2=293  //[K]

+sigma=5.67*10^-8    //[W/sq m.K]

+Qr_by_a=e*sigma*(T1^4-T2^4) //W/sq m

+printf("\n Rate of heat transfer by radiation is %f W/sq m",Qr_by_a);

diff --git a/1073/CH4/EX4.20/4_20.sce b/1073/CH4/EX4.20/4_20.sce
new file mode 100755
index 000000000..4ca535724
--- /dev/null
+++ b/1073/CH4/EX4.20/4_20.sce
@@ -0,0 +1,35 @@
+clc;

+clear;

+//Example 4.20

+sigma=5.67*10^-8    //[W/sq m.K^4]

+T1=750  //[K]

+T2=500  //[K]

+e1=0.75;

+e2=0.5;

+//Heat transfer without shield :

+

+Q_by_a=sigma*(T1^4-T2^4)/((1/e1)+(1/e2)-1)  //[W/sq m]

+

+//Heat transfer with shield:

+R1=(1-e1)/e1    //Resistance 1

+

+F13=1;

+R2=1/F13        //Resistance 2

+

+e3=0.05

+R3=(1-e3)/e3    //Resistance 3

+

+R4=(1-e3)/e3    //Resistance 4

+

+F32=1;

+R5=1/F32        //Resistance 5

+

+R6=(1-e2)/e2       //Resistance 6

+

+Total_R=R1+R2+R3+R4+R5+R6   //Total resistance

+

+Q_by_as=sigma*(T1^4-T2^4)/Total_R   //[W/sq m]

+

+Red=(Q_by_a-Q_by_as)*100/Q_by_a     //Reduciton in heat tranfer due to shield 

+

+printf("\n Reduction in heat transfer rate as a result of radiaiotn shield is %f percent",Red);

diff --git a/1073/CH4/EX4.21/4_21.sce b/1073/CH4/EX4.21/4_21.sce
new file mode 100755
index 000000000..7c91c8dec
--- /dev/null
+++ b/1073/CH4/EX4.21/4_21.sce
@@ -0,0 +1,24 @@
+clc;

+clear;

+//Example 4.21

+e1=0.3

+e2=0.8

+//Let sigma*(T1^4-T2^4)=z=1(const)

+z=1;    //Let

+Q_by_A=z/(1/e1+1/e2-1)  //W/sq m

+

+//Heat transfer with radiation shield 

+e3=0.04

+F13=1;

+F32=1;

+//The resistances are:

+R1=(1-e1)/e1

+R2=1/F13

+R3=(1-e3)/e3

+R4=R3

+R5=1/F32

+R6=(1-e2)/e2

+R=R1+R2+R3+R4+R5+R6     //Total resistance

+Q_by_As=z/R //where z=sigma*(T1^4-T2^4) //W/sq m

+red=(Q_by_A-Q_by_As)*100/Q_by_A    //Percent reduction in heat transfer

+printf("\n The heat transfer is reduced by %f percent due to shield",red)

diff --git a/1073/CH4/EX4.22/4_22.sce b/1073/CH4/EX4.22/4_22.sce
new file mode 100755
index 000000000..c6cb26c81
--- /dev/null
+++ b/1073/CH4/EX4.22/4_22.sce
@@ -0,0 +1,43 @@
+

+clc;

+clear;

+//Example 4.22

+sigma=5.67*10^-8;

+T1=1273 //[K]

+T2=773  //[K]

+T3=300  //[K]

+A1=0.5  //[sq m]

+A2=A1;  //[sq m]

+F12=0.285;

+F21=F12;

+F13=1-F12;

+F23=1-F21;

+e1=0.2;

+e2=0.5;

+//Resistance in the network are calculated as:

+R1=1-e1/(e1*A1)

+R2=1-e2/(e2*A2)

+R3=1/(A1*F12)

+R4=1/(A1*F13)

+R5=1/(A2*F23)

+R6=0    //Given (1-e3)/e3*A3=0

+//Also

+Eb1=sigma*T1^4  //W/sq m

+Eb2=sigma*T2^4   //[W/sq m]

+Eb3=sigma*T3^4 //[W/sq m]

+

+//Equations are:

+//(Eb1-J1)/2+(J2-J1)/7.018+(Eb3-J1)/2.797=0

+//(J1-J2)/7.018+(Eb3-J2)/2.797+(Eb2-J2)/2=0

+

+//On solving we get:

+J1=33515    //[W/sq m]

+J2=15048    //[W/sqm]

+J3=Eb3  //[W/sq m]

+Q1=(Eb1-J1)/((1-e1)/(e1*A1))        //[W/sq m]

+Q2=(Eb2-J2)/((1-e2)/(e2*A2))        //[W/sq m]

+Q3=(J1-J3)/(1/(A1*F13))+(J2-J3)/(1/(A2*F23))    //[W/sq m]

+printf("\n Total heat lost by plate 1 is %f W/sq m\n",Q1);

+printf("\n Total heat lost by plate 2 is %f W/sq m\n",Q2);

+printf("\nThe net energy lost by both plates must be absorbed by the room,\n %f=%f",Q3,Q1+Q2)

+

diff --git a/1073/CH4/EX4.23/4_23.sce b/1073/CH4/EX4.23/4_23.sce
new file mode 100755
index 000000000..be2dd7a03
--- /dev/null
+++ b/1073/CH4/EX4.23/4_23.sce
@@ -0,0 +1,22 @@
+clc;

+clear;

+//Example 4.23

+sigma=5.67*10^-8    //[W/sq m.K^4]

+e1=0.7;

+e2=0.7;

+T1=866.5    //[K]

+T2=588.8    //[K]

+Q_by_A=sigma*(T1^4-T2^4)/((1/e1)+(1/e2)-1)  //[W/sq m]

+e1=0.7;

+e2=e1;

+e3=e1;

+e4=e1;

+e=e1;

+//Q with n shells =1/(n+1)

+n=2

+Q_shield=1/(n+1);

+es1=e1;

+es2=e1;

+Q_by_A=sigma*(T1^4-T2^4)/((1/e1)+(1/e2)+2*(1/es1+1/es2)-(n+1))  //[W/sq m]

+printf("\n New Radiaiton loss is %f W/sq m",Q_by_A);

+

diff --git a/1073/CH4/EX4.24/4_24.sce b/1073/CH4/EX4.24/4_24.sce
new file mode 100755
index 000000000..62dd800f6
--- /dev/null
+++ b/1073/CH4/EX4.24/4_24.sce
@@ -0,0 +1,38 @@
+clc;

+clear;

+//Example 4.24

+//1.WITHOUT SHIELD

+sigma=5.67*10^-8        

+e1=0.12;

+e2=0.15;

+T1=100  //[K]

+T2=300  //[K]

+r1=0.015    //[m]

+r2=0.045    //[m]

+L=1         //[m]

+A1=2*%pi*r1*L   //[sq m]

+Q_by_L=2*%pi*r1*sigma*(T1^4-T2^4)/(1/e1+(r1/r2)*(1/e2-1))   //[W/m]

+//-ve saign indicates that the net heat flow is in the radial inward direction

+//2.WITH CYLINDRICAL RADIATION SHIELD

+e3=0.10;

+e4=0.05;

+r3=0.0225   //[m]

+Qs_by_L=2*%pi*r1*sigma*(T1^4-T2^4)/(1/e1+r1/r2*(1/e2-1)+(r1/r3)*(1/e3+1/e4-1))  //[W/sq m]

+red=(abs(Q_by_L)-abs(Qs_by_L))*100/abs(Q_by_L)  //percent reduction in heat gain

+

+//Radiation network approach

+A3=2*%pi*r3     //[sq m]

+A2=2*%pi*r2     //[sq m]

+F13=1;

+F32=1;

+R1=(1-e1)/(e1*A1)

+R2=1/(A1*F13)

+R3=(1-e3)/(e3*A3)

+R4=(1-e4)/(e4*A3)

+R5=1/(A3*F32)

+R6=(1-e2)/(e2*A2)

+

+Qs=sigma*(T1^4-T2^4)/((1-e1)/(e1*A1)+1/(A1*F13)+(1-e3)/(e3*A3)+(1-e4)/(e4*A3)+1/(A3*F32)+(1-e2)/(e2*A2))        

+printf("\n With cylindrical radiaiton shield Heat gained by fluid per 1 m lengh of tube is %f W/m\n",Qs_by_L);

+printf("\nPercent reduction in heat gain is %f percent\n",red);

+printf("\nWith radiaiton network approach %f W/sqm ",Qs);

diff --git a/1073/CH4/EX4.3/4_3.sce b/1073/CH4/EX4.3/4_3.sce
new file mode 100755
index 000000000..340e0eec3
--- /dev/null
+++ b/1073/CH4/EX4.3/4_3.sce
@@ -0,0 +1,16 @@
+

+clc;

+clear;

+//Example 4.3

+L=1; //[m]

+e=0.8  ; //Emissivity

+sigma=5.67*10^-8 ;   //[m^2.K^4]

+T1=423;  //[K]

+T2=300;  //[K]

+Do=60;   //[mm]

+Do=Do/1000;  //[m]

+A=%pi*Do*L  //[sq m]

+A=0.189     //Approx in book [m^2]

+Qr=e*sigma*A*(T1^4-T2^4)    //[W/m]

+printf("\n Net radiaiton rate per 1 metre length of pipe is %d W/m",round(Qr));

+

diff --git a/1073/CH4/EX4.4/4_4.sce b/1073/CH4/EX4.4/4_4.sce
new file mode 100755
index 000000000..69d78cd61
--- /dev/null
+++ b/1073/CH4/EX4.4/4_4.sce
@@ -0,0 +1,17 @@
+clc;

+clear;

+//Example 4.4

+e=0.9   //Emissivity

+L=1 //[m]

+Do=50   //[mm]

+Do=Do/1000  //[m]

+sigma=5.67*10^-8    //[W/(m^2.K^4)]

+T1=415  //[K]

+T2=290  //[K]

+dT=T1-T2    //[K]

+hc=1.18*(dT/Do)^(0.25)  //[W/sq m.K]

+A=%pi*Do*L  //Area in [sq m]

+Qc=hc*A*dT //Heat loss by convection W/m

+Qr=e*sigma*A*(T1^4-T2^4)    //Heat loss by radiation per length W/m

+Qt=Qc+Qr    //Total heat loss in [W/m]

+printf("\n Total heat loss by convection is %f W/m",Qt);

diff --git a/1073/CH4/EX4.5/4_5.sce b/1073/CH4/EX4.5/4_5.sce
new file mode 100755
index 000000000..00ba6c238
--- /dev/null
+++ b/1073/CH4/EX4.5/4_5.sce
@@ -0,0 +1,17 @@
+clc;

+clear;

+//Example 4.5

+e=0.85

+sigma=5.67*10^-8    //[W/sq m.K]

+T1=443  //[K]

+T2=290  //[K]

+dT=T1-T2    //[K]

+hc=1.64*dT^0.25     //W/sq m.K

+Do=60   //[mm]

+Do=Do/1000  //[m]

+L=6 //Length [m]

+A=%pi*Do*L  //Surface area of pipe in [sq m]

+Qr=e*sigma*A*(T1^4-T2^4)    // Rate of heat loss by radiaiton W

+Qc=hc*A*(T1-T2) // Rate of heat loss by convection [W]

+Qt=Qr+Qc    //Total heat loss  [W]

+printf("\n Total heat loss is %d W",round(Qt))

diff --git a/1073/CH4/EX4.6/4_6.sce b/1073/CH4/EX4.6/4_6.sce
new file mode 100755
index 000000000..9f41ff8cb
--- /dev/null
+++ b/1073/CH4/EX4.6/4_6.sce
@@ -0,0 +1,18 @@
+

+clc;

+clear;

+//EXample 4.6

+sigma=5.67*10^-8    //[W/m^2.K^4]

+e1=0.79;

+e2=0.93;

+T1=500 ; //[K]

+T2=300 ; //[K]

+D=70    //[mm]

+D=D/1000    //[m]

+L=3 //[m]

+W=0.3   //Side of conduit [m]

+A1=%pi*D*L  //[sq m]

+A1=0.659        //Approximate calculation in book in [m^2]

+A2=4*(L*W)  //[sq m]

+Q=sigma*A1*(T1^4-T2^4)/(1/e1+((A1/A2)*(1/e2-1)))    //[W]

+printf("\n Heat lost by radiation is %f W",Q);

diff --git a/1073/CH4/EX4.7/4_7.sce b/1073/CH4/EX4.7/4_7.sce
new file mode 100755
index 000000000..34f1a17cc
--- /dev/null
+++ b/1073/CH4/EX4.7/4_7.sce
@@ -0,0 +1,10 @@
+clc;

+clear;

+//Example 4.7

+sigma=5.67*10^-8    //[W/sq m.K^4]

+T1=703  //[K]

+T2=513  //[K]

+e1=0.85 

+e2=0.75

+Q_by_Ar=sigma*(T1^4-T2^4)/(1/e1+1/e2-1) //[W/sq m]

+printf("\n Net radiant interchange per square metre is %d W/sq m",round(Q_by_Ar));

diff --git a/1073/CH4/EX4.8/4_8.sce b/1073/CH4/EX4.8/4_8.sce
new file mode 100755
index 000000000..10ad30c9d
--- /dev/null
+++ b/1073/CH4/EX4.8/4_8.sce
@@ -0,0 +1,13 @@
+clc;

+clear;

+//Example 4.8

+L=3 ;//[m]

+A=L^2   //Area in [sq m]

+sigma=5.67*10^-8;    //[W/sq m.K^4]

+T1=373;  //[K]

+T2=313;  //[K]

+e1=0.736;

+e2=e1;

+F12=1/((1/e1)+(1/e2)-1)

+Q=sigma*A*F12*(T1^4-T2^4)   //[W]

+printf("\n Net radiant interchange is %d W",round(Q));

diff --git a/1073/CH4/EX4.9/4_9.sce b/1073/CH4/EX4.9/4_9.sce
new file mode 100755
index 000000000..887a1f7c4
--- /dev/null
+++ b/1073/CH4/EX4.9/4_9.sce
@@ -0,0 +1,19 @@
+clc;

+clear;

+sigma=5.67*10^-8    //[W/sq m.K^4]

+e1=0.05 

+e2=0.05

+//A1=A2=1 (let)

+A1=1;

+A2=A1;

+F12=1/(1/e1+(A1/A2)*(1/e2-1))   

+T1=368  //[K]

+T2=293  //[K]

+Q_by_A=sigma*F12*(T1^4-T2^4)    //Heat loss per unit Area  [W/sq m]

+printf("\nRate of heat loss when of silvered surface is %f W/sq m",Q_by_A);

+//When both the surfaces are black

+e1=1;

+e2=1;

+F12=1/(1/e1+(A1/A2)*(1/e2-1))   

+Q_by_A=sigma*F12*(T1^4-T2^4)    //[W/sq m]

+printf("\n When both surfaces are black,Rate of heat loss  is %d W/sq m",round(Q_by_A));