Question

A wall has total surface area of 100 m’and consists of three distinct sections with thermal resistance values as follows: Section А Area [m²] 60 10 30 RSI (m2.°C/W] 4.58 1.06 2.82 B C a) For a period when AT = 10°C, estimate the total steady-state heat loss rate. b) Also, determine the average USI-value for the overall wall. You want to reduce the total heat loss through the wall sections, and you have some material that can improve the insulation (i.e., RSI-value) of the wall sections by 1 (m2.°C/W]. However, you only have enough material for an area = 10 m². c) Does it matter on which section the insulation material is applied first? If it does, on which section (A, B, or C) would you apply the material to get the greatest reduction in total heat loss? d) Either briefly explain the answer you provided for part c) above OR do a numerical analysis (i.e., some simple calculations) to justify your answer for part c).

Answer 1

For part C: On section B if we apply insulation, heat loss will be reduced greatly.

from the given data : - for DT = 10 c. Heat loss A DT Rsi A = Area. Total Heat loss = 60x10 + IOXID 1.06 + 30X10 2.82 4.58 watt. - 331.726 - Total heat loss Wall. (6) Average SI value overall for the Total Heat loss (Uslang - (Area) & IT (USIDAN 0.33172 w/m2 °C. (c) An insulating material, it will improve RsI-vakre I mochw. with available for 10 m² area, by it yes, valve (use) ans. Matters overall heat loss be will different ich Insulation Total is fined on C B section. A or on (d) if t insulation is fined A Section Heat Soxlo loss To fal 10x10 t. 4.58 5.58 ®, = 327.8 watt. 100 1.06 300 + 2.82 Then

if insulation is fined on Section - B. Too + 300 2082 ㅋ Total heat heat loss 4.58 2.06 9 = 285.93 Woctt. if insulation is fined Section 6. on Prien Heat loss is 300 600 4.58 + 100 1.06 + 3.82 o 8 = 303.87 watt it Evident So that, when insulation is is on apply on Section B, Heat loss (Total) is loss (To tou) is minimum and when it is Placed section. A insulation Effectiveness is minimum.