Critical thickness of insulation

It is basic information about what is critical thickness and why we should we know this. Then there is critical thickness formula for cylindrical pipe and spherical shell.

1. CRITICAL THICKNESS OF INSULATION CRITICAL THICKNESS OF INSULATION PRESENTED TO: Mr. KAPIL NAHAR PRESENTED BY: MD NOORUDDIN B.TECH(MECH.),5 TH SEM MUR1800575

2. CONTENTS WHY WE NEED INSULATION? CRITICAL THICKNESS OF INSULATION FOR CYLINDRICAL PIPE FOR SPHERICAL SHELL CONCLUSION

3. WHY WE NEED INSULATION? Let r i = 80mm, r o = 110mm, T i = 320 o C, T o = 237 o C k = 58 W/m o C So and r O r i T i T o

4. WHY WE NEED INSULATION? Let thickness x= 50mm, T 1 =40 o C r 1 = (110+50)mm = 160mm, k1 = 0.18 W/m o C So and r O r i T i r 1 T 1 T o x

5. WHY WE NEED INSULATION? Q without insulation Q with insulation 95000 W 843 W r O r i T i r 1 T 1 T o x r O r i T i T o

6. CRITICAL THICKNESS OF INSULATION Critical thickness of insulation means maximum heat loss with minimum thermal resistance. It is useful when surface area of the base object increases with the insulation i.e., cylindrical and spherical systems. The thickness up to which heat flow increases and after which heat flow decreases is termed as Critical thickness . In case of cylinder and sphere it is also called Critical radius .

7. 1. For Cylindrical Pipe : Critical radius of insulation depends on the thermal conductivity of the insulation ‘k’ and the external convection heat transfer coefficient ‘h’. CRITICAL THICKNESS OF INSULATION r O r i r cr k h x

8. 2. For Spherical Shell : CRITICAL THICKNESS OF INSULATION r O r cr k h x

9. CONCLUSION CONCLUSION

10. THANK YOU