ENGINEERING EVALUATION 345 



Assume 



t = 75° 

 hj = (88 - 75)°" = 1.9 



0.6 (75 - 48) = 1.9(88 - 75) 

 16.3 = 24.7 



Assume 



t = 80° 

 hj = (88 - 80)°" = 1.68 



0.6(80 - 48) = 1.68(88 - 80) 

 19.2 = 13.4 



Assume 



T = 78° 

 ho = (88 - 78)°" = 1.78 



0.6(78 - 48) = 1.78(88 - 78) 

 18 = 17.8 



Therefore a good value for hj (2 in. corkboard) is 



h. = 1.79 Btu/hr-ft^-°F. 

 For 1 in. of insulation is 



0.10 X 12 ,, ,„, , ,„o ,, 



1.2(73 - 48) = 1.97(88 - 73) 

 30 = 29.6 



Therefore a good value for hj (1 in. corkboard) is 



hi = 1.98 Btu/hr-ft2-°F. 



