[Self Practice] 10.38 (2nd Edition), 14.21 (3rd Edition) Modified: The building in Problem 10.36 (2nd Edition), 14.20 (3rd Edition) can be cooled either by the specified chiller or by three chillers, each capable of meeting one-third of the load (use three 300-ton chillers by manufacturer A). Since the large chiller has more capacity than needed most of the time, it may use more energy than the small chillers operating more closely to their full capacity. Rework Problem 10.36 (2nd Edition), 14.20 (3rd Edition) using the three-chiller strategy. For simplicity, assume that the lead chiller (the first one to be operated) operates up to full capacity before the second is activated; the same strategy is used to operate the third chiller relative to the second. [Self Practice] 10.36 (2nd Edition), 14.20 (3rd Edition) Modified: A commercial building has the weather and cooling load data as shown in the table below. The performance of a single, large centrifugal chiller with a capacity of 925 tons (3250 kW) is to be evaluated. It is the unit made by manufacturer A (0.692 kW/ton) in the online HCB software of the chiller PLR table (also shown below). What is the annual energy consumption (kWh) and the annually averaged COP for this chiller? Bin Temperature (F) Bin Hours (hrs) Cooling Load (BTU/hr) 57.5 622 656250 62.5 615 1968750 67.5 687 3281250 72.5 805 4593750 77.5 512 5906250 82.5 362 7218750 87.5 222 8531250 92.5 97 9843750 Identification Capacity Efficiency A B C 925 tons 0.625 kW/ton 0.204 0.626 0.149 Manufacturer A 925 tons 0.692 kW/ton 0.201 0.555 0.221 300 tons 0.673 kW/ton 0.201 0.602 0.185 900 tons 0.624 kW/ton 0.092 0.804 0.098 Manufacturer B 900 tons 0.673 kW/ton 0.092 0.802 0.104 Manufacturer C 900 tons 0.622 kW/ton 0.170 0.239 0.589