From b1f5c3f8d6671b4331cef1dcebdf63b7a43a3a2b Mon Sep 17 00:00:00 2001
From: priyanka
Date: Wed, 24 Jun 2015 15:03:17 +0530
Subject: initial commit / add all books

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 2873/CH12/EX12.2/Ex12_2.sce |  55 ++++++++++++++++++++++++++++++++++++++++++++
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+// Display mode
+mode(0);
+// Display warning for floating point exception
+ieee(1);
+clear;
+clc;
+disp("Engineering Thermodynamics by Onkar Singh Chapter 12 Example 2")
+h1=40;//average heat transfer coefficient at inner surface in KJ/m^2 hr oc
+h6=50;//average heat transfer coefficient at outer surface in KJ/m^2 hr oc
+deltax_steel=2*10^-3;//mild steel sheets thickness in m
+deltax_wool=5*10^-2;//thickness of glass wool insulation in m
+k_wool=0.16;//thermal conductivity of wool in KJ/m hr
+k_steel=160;//thermal conductivity of steel in KJ/m hr
+T1=25;//kitchen temperature in degree celcius
+T6=5;//refrigerator temperature in degree celcius
+disp("here thermal resistances are")
+disp("R1=thermal resistance due to convection between kitchen air and outer surface of refrigerator wall(T1 & T2)")
+disp("R2=thermal resistance due to conduction across mild steel wall between 2 & 3(T2 & T3)")
+disp("R3=thermal resistance due to conduction across glass wool between 3 & 4(T3 & T4)")
+disp("R4=thermal resistance due to conduction across mild steel wall between 4 & 5(T4 & T5)")
+disp("R5=thermal resistance due to convection between inside refrigerator wall and inside of refrigerator between 5 & 6(T5 & T6)")
+disp("overall heat transfer coefficient for one dimentional steady state heat transfer")
+disp("(1/U)=(1/h1)+(deltax_steel/k_steel)+(deltax_wool/k_wool)+(deltax_steel/k_steel)+(1/h6)")
+disp("so U=1/((1/h1)+(deltax_steel/k_steel)+(deltax_wool/k_wool)+(deltax_steel/k_steel)+(1/h6))in KJ/m^2hr oc")
+U=1/((1/h1)+(deltax_steel/k_steel)+(deltax_wool/k_wool)+(deltax_steel/k_steel)+(1/h6))
+U=2.8;//approx.
+disp("rate of heat transfer(Q)=U*A*(T1-T6)in KJ/m^2 hr")
+disp("wall surface area(A) in m^2")
+A=4*(1*0.5)
+Q=U*A*(T1-T6)
+disp("so rate of heat transfer=112 KJ/m^2 hr ")
+disp("Q=A*h1*(T1-T2)=k_steel*A*(T2-T3)/deltax_steel=k_wool*A*(T3-T4)/deltax_wool")
+disp("Q=k_steel*A*(T4-T5)/deltax_steel=A*h6*(T5-T6)")
+disp("substituting,T2=T1-(Q/(A*h1))in degree celcius")
+T2=T1-(Q/(A*h1))
+disp("so temperature of outer wall,T2=23.6 oc")
+disp("T3=T2-(Q*deltax_steel/(k_steel*A))in degree ")
+T3=T2-(Q*deltax_steel/(k_steel*A))
+disp("so temperature at interface of outer steel wall and wool,T3=23.59 oc")
+disp("T4=T3-(Q*deltax_wool/(k_wool*A))in degree celcius")
+T4=T3-(Q*deltax_wool/(k_wool*A))
+disp("so temperature at interface of wool and inside steel wall,T4=6.09 oc")
+disp("T5=T4-(Q*deltax_steel/(k_steel*A))in degree celcius")
+T5=T4-(Q*deltax_steel/(k_steel*A))
+disp("so temperature at inside of inner steel wall,T5=6.08 oc")
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-- 
cgit