Document 6RovR7QdYexzQM7Q24DY0ZLVE

902 CHAPTER 43 1950 Guide oC0O0 . 550 580 1020 910 950 720 750 1170 1210 1530 1300 1400 M odern A ir Conditioning, Heating and V entilating,.by W . H . Carrier, R. C. Cheme and W . A. Grant (Pitman Publishing Carp. 1940, p. 73). 1290 970 535 620 620 570 1060 760 800 830 740 880 770 810 330 330 310 .470 370 380 440 400 410 980 1790 1280 1330 1650 1420 1530 . 700 ' 720 840 750 780 1020 890 940 W ash in g t o n D.C, St . L ouis 640 420 450 450 430 650 500 oo O fUaid ,< 5g in M o o ga | N ew 2tt -a s04 o w D etroit i& C hicago foogH 2o >< ao s 2 -S afo O Qs J uD. ----------- 1 H r Open FOR A t l a n t a B oston 1 B usiness Los Anceles Okla homa C ity jORLBANS 1280 1010 650 720 720 1080 830 940 840 660 610 610 580 0901 068 098 089 2100 1630 950 1060 099 069 ' 8o O 00 .o So ClON 1500 1010 700 750 750 720 1080 850 860 670 850 620 620 680 900 0691 099 O U 099 069 . 0S6 800 590 1510 820 930 940 870 ooCO oCtoO 1 M 600 006 0601 ' 0015. D O' w CO waca !i j j | i j O X O WH X <a CD O *W J] to I IJAoCZO . (n Sr= flj ccead r 8Q 1:st 0! W O i1 j t0 | S4e9) ' 8e.d!i11 t U O Jt0S: ceS 3 3 c4a> XJ0bcao' 9Cs 3 J3 S i -.mOCbC "3 JS O X t* a <CU1uA . 'mS. (jas-- JsZ H Owning and Operating Costs 903 SERVICE COSTS Service costs include the costs for power, water, steam, coal, oil, etc., consumed to operate the system. From the selected equipment and type of installation, it is possible to segregate the relatively constant power loads and the total brake horse power. Annual power cost can then be figured from the following formula: where annual power cost 0.746 (blip) g R V (1) bhp -- Brake horsepower. H = Annual operating hours. R *= Power rate, dollars per/kwhr. ?! = Motor efficiency (decimal). In using Equation 1 it must be pointed out that the electric rate, R must reflect the proper combination of energy and demand rates. These vary widely between the utility companies, and sometimes the rate struc ture is such that it is largely the demand charge which determines the proper value of R to use in Equation 1. Refrigerating-Equipment Operating Cost In an air conditioning system, the refrigerating equipment is usually the largest power-consuming item to be considered. Also, the prediction of operating cost is more complex, since the power required for summer cool ing is affected by many factors which are .of a variable nature. Among these are solar radiation, temperature difference between outside and in side, sensible and latent heat brought in with outside air, sensible and latent heat from people, heat released by electric lights, and, in some cases motor-driven equipment, cooking devices, and other equipment used in the conditioned spaces. Some of these factors vary with the weather, while others are substantially independent of it. The relative proportion of each factor varies widely even among installations of the same application, depending on building layout and location, the size and quality of the establishment, the personal idiosyncracies of the owner, and other items. In a strict sense, it is necessary to evaluate the effect of all such factors in order to predict the operating cost of a refrigeration plant. In most cases this procedure will prove to be too tedious, or it may not be possible because the exact breakdown of load data is unknown. The use of a simplified semi-rational formula, Equation 2, which takes into account for each application the number of hours open for business and the geographical location, will provide a value of H which may be used in Equation 3 to determine the Season Power Cost. where H. = m (6 + cf) (2) = Equivalent full load operating hours of refrigeration equipment used for . summer cooling during period May IS to October 15. m -- Total hours, during period May 15 to October 15 that the establishment is open for business. b -- Fraction of maximum load from internal heat under average operating con ditions.