air conditioning principles steps please A more delailed dis

air conditioning principles

steps please

A more delailed discussion energy consers. tion in HVAC system design will be presented Chapter 15. n ovides a n. Some PROBLEMS A6 A building with a 120 ft by 80 ft roof, lokaed the in Cincinnati, Ohio, has a rool constructed d 1 in. wood with R-5.5 insulation and a sus- ign DB pended ceiling. The inside design oondilion is 78 F. Determine the net rok cooling load 8-80 F A. September 21 at noon yst B. Time of peak roof heat gain for 6.2 A southeast facing wall of a building located

Solution

A) Area of roof top = 120*80 = 9600ft² = 1.3824*10⁶ in²

Thermal conductivity of R-5.5 = K_R-5.5 = 0.00217 Btu/in h ^oF

Thermal conductivity of Wood = K_w = 0.00816 Btu/in h ^oF

Let us consider thickness of insulation =x₁ = 1 inch

According to Fourier\'s law of heat conduction,

Q = [A*(T_o - T_i)]/[(x₁/ K_R-5.5)+(x₂/K_w)]

T_o = 87.8^oF .......(Ambient temperature at noon on september 21)

T_i = 78 ^oF

So, net roof coolin load, Q = 23222.521 Btu.

B) Time of peak roof heat gain is from noon to 5 pm.