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who won the london tube cooling competition? 21 aug 2003 the nyc subway system has 230 miles of track and 207 underground stations. if each tube is 12' tall x 40' wide, and each station has ventilation holes with an equivalent cross section, we might have a thermal chimney with vent area a = 12x40x207/2 = 50k ft^2. say height h = 20 feet. with 10w/ft of lighting on both sides, a 100' platform makes 2 kw of heat, so 207 stations might use 207x2kwx24h = 10 mwh/day for lighting. if 2 million of nyc's 8 million people travel by subway for 20 minutes per day, their bodies contribute 2mx100wx20/60 = 67mwh per day to the cooling load. if a subway car holds 60 people and uses an average of 20 kw (bart cars used to idle at 20 kw), the cars add 2mx20m/60m/60px24hx20kw = 5.3 gwh/day, making the total cooling load q = 5.4 gwh/day or 225 mw or 770 mbtu/h. q = 16.6asqrt(h)dt^1.5 makes dt = 35 f. the cars contribute most of the heat in this scenario. if we could reduce their average power to 5 kw with dynamic braking and so on, q = 201m btu/h and dt = 14 f. nrel says the average july temp in nyc is 76.8 f, and the average yearly (ground) temp is 54.7... nick |