Document 8RJrxR2dgvB40vQMkj12wjy3y

r ! / 294 CHAPTER 15 1946 Guide Combined Normal and Solar Radiation Transmission: Surface S Wall.......... W Wall Roof.............. Total: Dimensions (30 ft x 12 ft) - 155 (60 ft x 12 ft) - 321 60 ft x 30 ft Area Sq Ft 205.. 399 1800 Btu per (Hour) (Sq Ft) 2 x 1.2 2 x 1.2 m Btu per ' Hour 490 960 15,300 16,750 Solar Radiation Through Glass: South Hs = 155 ,X (18 X 0.9) X 0.25 = 625 ` . . ' West Hz = 321 X (193 X 0.9) X 0.25 = 13,930 .t"iuat,on 2) Occupants: 50 X 431 = 21,550 Btu per hour. 50 X 0.198 = 9.90 lb water evaporated per hour. Infiltration and Outside Air: H= (ho -- Ap (Equation 3) _ _ _ v = 13.33 cu ft per pound dry air (infiltration, and outside air required for ventir * lation may be considered in terms of Standard. Air). . . (jl = per cent saturation at 95 F dry-bulb and 75F wet-bulb * 38.4 per cent (by calculation, Chapter 3). ho = hi + yhas (Equation 5, Chapter 3). h* '= specific enthalpy of dry air at .95 F = 22.827 Btu per pound (Table 1, Chapter 3). ;haa =. difference between enthalpy of saturated mixture and specific, enthalpy.of dry air at'95 F = 40.49 Btu per. pound .(Table 1, Chapter 3).. ho -- 22.80 -f (0.384 X 40.49) = 38.26 Btu per pound dry air. . . (i at 80 Fdry-bulb and 67 F wet-bulb -- 50.2 per cent (by calculation, Chapter 3). hi = ha + tAas = 19.221 + (0.5Q2:X 2447) = 31.50 Btu per pound dry.air (Table <-- . 1, Chapter 3). - ' .* . . ' Ian v fin' ' ; <* H (infiltration) =--13 33--(38.26 -- 31.50) = 4,270'Btu per hour.' B (outside) = (^17^>)6 (38.26 - 31.50) = 10,950 Btu per hour. Wo =.humidity ratio of outside air at 95 F dry-bulb and 75 F wet-bulb = 0.384 X . . 0.03673 = 0.01410 lb water per pound dry air. (Equation 3, Chapter 3.) Wi = humidity ratio of inside air at 80 F dry-bulb and 67 F wet-bulbi = 0.502 X. 0.02233 = 0.01121 lb water per pound dry air. (Equation 3, Chapter 3.) Weight of water.to be removed from infiltration air =~ (W0 -- Wi) (Equation.4) , v; (0.01410 - 0.01121) - .1.82 lb per hour. ' .. ,\ Lights:! 14200 X 3.413 = 14,335 Btu per hour. Cnoling -Load 29S, Summary: Components of Load' Combined Normal and Solar Radiation Transmission...:.---- ----------- Liehts plus Heat Equivalent of that Proportion of the Power Load Used in Air Conditioning System Which Adds Heat to the Air.... Total Room Load (Sensible and Latent Heat Gain)---------- :............. Btu per Hour 11,438 16,750 - 14,555 21,550 4,270 -' 14,335 82,898 10,950 . 93,848 Determination of Apparatus Dew-Point: First, determine the water added as a part of the room load as follows: Occupants.__1.......-..9.9 lb water per hour Infiltration..............1.82 lb water per hour 11.72 lb water per hour . The condition line for this application may be determined' from Equation 11 in' Chapter 3 by taking the ratio of room total load to pounds water per hour released in the room = 82,898 -s- 11.72 .= 7075 Btu per pound of water. In this case, it crosses the saturation curve at.a temperature for which the enthalpy kg and the humidity ratio. Ws satisfy the equation, 31.50 - hs 0.01121 - WB = 7075 The required apparatus dew-point may be determined graphically from the Mollier, chart or by cut and try from Table 1, Chapter 3, as 57.9 F. Air Quantity and Refrigeration Load: Assuming 100 per cent saturation efficiency for the air conditioning apparatus, the air will leave the dehumidifier saturated. The thermodynamic properties involved in cal culating the air quantity are: . - Inside Air After Cooling t 80.0 57.9 k 31.50 ' 25.06 W 0.01121 (0.01030 Vapor -f 0.00091 Liquid) The cooling effect is 31.50 - 25.06 = 6.372 Btu per pound dry air. The total outside and recirculated dry air through the air conditioning apparatus is: 6.44 X 60 = 2860 cfm (Standard Air) The refrigeration may be assumed equal to the grand total load; that is. 93,848 7.82 tons 12,000 1 REFERENCES -, .= A.S.H.V.E. Research Report No. 1147--Heat Gain Through Glass Blocks by Solar Radiation and ' Transmittance, by F. C. Houghten, David Shore, H. T. Olson and Bait Guast (A.S.H.V.E. Transactions, Vol. 46. 1940. p. 83). - . v. l~A,S.H,V.E. Research Report No. 923--Heat Transmission as Influenced by Heat Capacity and, Solar Radiation, by F. C. Houghten, J. L. Blackshaw, E. M. Pugh and Paul McDermott (A.S.H.V.E.. Transactions. Vol. 38, 1932, p. 231). Effect of Heat Storage and Variation in Outdoor Temperature.and Solar Intensity on Heat Transfer Through Walls, by J. S. Alford, J. E. Ryan and F. O. Urban (A.S.H.V.E. Transactions, VoL 45, 1939. p. 369).' Periodic Heat Flow in Building Walls Determined by Electrical Analogy Method, by Victor Paschkis (A.S.H.V.E. Transactions, VoL 48, 1942, p. 75). 'Summer Comfort Factors as Influenced by the Thermal Properties of Building Materials, by C. O. Mackey and L. T. Wright, Jr. (A.S.H.V.E. Transactions, Vol. 49, 1943, p. 148). /- 1