Thermodynamics and D Street


Update for 27 January 2010

 Most of the cooling appliances are designed keeping the laws of thermodynamics in mind. So a refrigerator that comprises of a compressor, copper pipes that run into a couple of meters long, filled with highly volatile compounds has the cooling chamber at the top of the insulated refrigerator box, which usually doubles up as the freezer compartment. As the freezer cools and freezes over its contents and surroundings, it also moves with the laws of physics, cooling the air within the fridge that starts its quick descent down into the rest of the refrigerator. This simple technique ensures that although the cooling exchange occurs at the top, it effectively cools everything within the confined spaces as it descends into the vegetable tray section. This principle is amply demonstrated in the room cooling appliances as well, as the air conditioning vent that blows cool air into the room is usually placed at a height within the room. It thus cools the room as the cool air leaves the vent and following the laws of thermodynamics, settles down closer to the floor pushing the warmer air upwards to effectively get cooled by the airconditioner and keeping this cycle on till the entire room is cooled.  And to prevent freeze-overs, on occasions when this cycle goes on till someone switches off the appliance, a smart inventor created the thermostat, so that at a desired temperature that is calibrated and chosen, the system shuts off and restarts when the temperatures get warmer.

The freeze-over that much of Europe and America experienced earlier this month found its way onto D Street today. The cool breeze blew in through vents that the D Boyz did not anticipate; and they were left staring at the SENSEX falling down about 150 points in the morning. And as they got busy with the day, they did know how to control the cold winds that continued to blow in. They tried covering the vents with some newspapers, but that only helped for a little while when the SENSEX moved up 50 points (still in the cold red zone); but the cold was too much to handle and thereafter the SENSEX kept plunging depths that the D Boyz could not salvage. At 350 points down, someone thought they had figured out how to control the temperature of the wind-blower and saw it work twice – but like they say, some of these devices should not be tampered with by inexperienced service-men – and so it failed and the SENSEX plumbed to depths of 540 points, before being finally placed at 490 points down at 16289. Thanks to someone using a simple technique more effective than a thermostat – a switch that could be turned off! The D Boyz are freezing, and out in the icy cold of D Street – scampering to the Tibetan woolen goods stalls in nearby Fort and swearing that they would be prepared for a freeze-over.

Interestingly, people who live in Mumbai and Chennai and other tropical seaside towns will not understand what a freeze-over is. So a converse theory could help them understand – have you sat in a closed car or taxi on a hot afternoon – and you suddenly see beads of sweat flow down your temples – that is the hot air trapped in the upper parts of the car/taxi that gets you into a sweat. Just as the cool air descends downwards, it displaces warmer air that rises higher. A neat trick to get the vehicle cooler is to lower the window to let the hot air move out and up and once you feel less sweaty, you can roll it up if your car/taxi is air conditioned – and if not, then the best idea is to keep it open!

Cheers

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