{"id":203,"date":"2012-06-01T20:50:29","date_gmt":"2012-06-02T01:50:29","guid":{"rendered":"http:\/\/tonykordyban.com\/?page_id=203"},"modified":"2014-04-13T20:23:16","modified_gmt":"2014-04-14T01:23:16","slug":"everything-you-know-is-wrong-march-2001","status":"publish","type":"page","link":"http:\/\/tonykordyban.com\/?page_id=203","title":{"rendered":"Everything You Know is Wrong    March 2001"},"content":{"rendered":"<p><strong>Answers to those Doggone Thermal Design Questions<\/strong><\/p>\n<p><strong>By Tony Kordyban<\/strong><\/p>\n<p>Copyright by Tony Kordyban 2001<\/p>\n<p>&nbsp;<\/p>\n<p><em>Dear TK,<\/em><\/p>\n<p><em>I got stuck with the job of getting quotes for the ventilating\/air conditioning system for the new computer room.\u00a0 It will be filled with network routers and servers and such.\u00a0 All the power for that stuff is given in watts, but all the air conditioners seem to be rated in BTUs per hour, or TONS, even!\u00a0 Where can I find the special air conditioners for computer equipment that can handle watts?<\/em><\/p>\n<p><em>Cheesed-off in Chesterton<\/em><\/p>\n<p>&nbsp;<\/p>\n<p>Dear Cheese,<\/p>\n<p>Yes, there are special air conditioners for watts.\u00a0 They are made for every country in the whole world EXCEPT theUnited States.\u00a0U.S.state and federal laws prohibit the sale and manufacture of any products that work with the metric system.\u00a0 You may have noticed that illegal drugs like heroin are the only products sold by the kilogram withinU.S.borders.\u00a0 To protect the fledglingU.S.air conditioning industry, everyone is required to use good old American units, like the BTU (British Thermal Unit), or the ton.\u00a0 The ton is based on the cooling power of a ton of melting ice.\u00a0 In the old days large public buildings were cooled by blowing air across carloads of ice cut out of lakes the previous winter.\u00a0 Now that\u2019s a standard anyone can relate to.<\/p>\n<p>For a while these laws put the electric power industry in a quandary.\u00a0 There just weren\u2019t any non-metric units for electricity.\u00a0 (Of course, there was the \u201ceel\u201d, the unit of electric power generated by an adult South American electric eel when scared by its reflection in a mirror, but it failed to catch on.)\u00a0 But they soon were able to comply with the federal laws by billing customers in kilowatt-hours, instead of the much simpler standard metric unit of energy, the Joule.<\/p>\n<p>The way I see it, you have three choices:<\/p>\n<ul>\n<li>Find some old computers that work in BTUs.\u00a0 I think ENIAC was rated that way.<\/li>\n<li>Smuggle in some Algerian or Tahitian air conditioners that work in watts.<\/li>\n<li>Implement a little-known power conversion process that I found in a mechanical engineering handbook, using a calculator if you really need to:<\/li>\n<\/ul>\n<p style=\"text-align: center;\"><strong>1 watt = 3.4121 BTU\/hour<\/strong><\/p>\n<p style=\"text-align: center;\"><strong>1 ton = 12,000 BTU\/hour<\/strong><\/p>\n<p style=\"text-align: center;\"><strong>1 ton = 3,517 watts<\/strong><\/p>\n<p>Just don\u2019t let the FBI find out you\u2019re using it.<\/p>\n<p>&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8212;&#8211;<\/p>\n<p>&nbsp;<\/p>\n<p><em>Honorable Kordyban, Sir,<\/em><\/p>\n<p><em>Attaching thermocouples to component after component seems like such a bore.\u00a0 Remember the movie \u201cRobocop\u201d?\u00a0 He could switch to Infrared Mode and see bad guys right through brick walls, because of their body heat signatures.\u00a0 I know \u201cRobocop\u201d was only science fiction (science has yet to figure out how to install a human brain in a police officer), but I have seen ads for infrared cameras specifically for testing electronic assemblies.\u00a0 They cost a bunch, but couldn\u2019t I save time by using one to snap a picture of my board while it\u2019s running inside its chassis?\u00a0 I could measure every temperature, including the inlet and exit air, with no messy wires or glue in about 10 seconds flat, and have a pretty picture for my report to boot.\u00a0 Isn\u2019t that how we should do it in the 21<sup>st<\/sup> Century?<\/em><\/p>\n<p><em>C. Kent in Metropolis<\/em><\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/ir_pcb.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft  wp-image-204\" title=\"ir_pcb\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/ir_pcb.jpg\" alt=\"\" width=\"377\" height=\"306\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/ir_pcb.jpg 897w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/ir_pcb-300x243.jpg 300w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/ir_pcb-600x486.jpg 600w\" sizes=\"auto, (max-width: 377px) 100vw, 377px\" \/><\/a>DearClark,<\/p>\n<p>Next to the watts-into-BTUs question, the one I get most frequently is, \u201cCan that infrared camera of yours see through, uh, stuff?\u201d\u00a0 And by \u201cstuff\u201d what they mean is \u201cwomen\u2019s clothes.\u201d<\/p>\n<p>Infrared cameras can be extremely useful tools for the thermal engineer.\u00a0 I use mine all the time.\u00a0 It is great for identifying hot spots on circuit boards, and can even help you find a short in a printed circuit board.\u00a0 But you are assuming that it can do a couple of things that it just can\u2019t.<\/p>\n<p>For one thing, infrared radiation, unlike X-rays, can hardly pass through anything.\u00a0 My IR camera can\u2019t image anything through a sheet of paper or window glass, let alone the aluminum, steel or plastic walls of an electronics chassis.\u00a0 It can only see the surfaces of solid objects, just like an ordinary camera.\u00a0 As Figure 2 clearly shows, it is not much good at looking through brick walls or people\u2019s clothes.\u00a0 So you won\u2019t be able to use it to measure the temperature of your components while they are mounted inside the chassis.<\/p>\n<p><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/clothes_ir.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-medium wp-image-205\" title=\"clothes_ir\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/clothes_ir-300x250.jpg\" alt=\"\" width=\"300\" height=\"250\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/clothes_ir-300x250.jpg 300w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/06\/clothes_ir.jpg 421w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><\/a>You CAN measure temperatures with the board sitting out on a bench, or if you cut a large hole in the side of your chassis so that the camera can see in.\u00a0 But then it is highly unlikely that the air flow will be the same as when the board is operating inside the chassis, so the component temperatures won\u2019t be realistic.\u00a0 You will still need thermocouples, or some other kind of sensor, to get component temperatures under realistic operating conditions.<\/p>\n<p>The other problem with your scenario is measuring air temperature.\u00a0 Air is pretty much transparent to the infrared camera.\u00a0 That is good news and bad news.\u00a0 Good, because if air were not transparent, the only thing you could see with such a camera would be the layer of air right in front of the camera lens.\u00a0 Bad, because you can\u2019t sense air temperature with it at all.\u00a0 Point your IR camera at your hot soldering iron all day.\u00a0 You will not see a red-colored plume of hot air rising from it.<\/p>\n<p>Your third premise is right on the money, though.\u00a0 Infrared cameras do produce fascinating color pictures that impress the latte right out of the MBA-types in the office.\u00a0 And that by itself makes them worth every penny of their purchase price.<\/p>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div>\n<p align=\"center\"><strong>\u00a0<\/strong><\/p>\n<p align=\"center\"><strong>Isn\u2019t Everything He Knows Wrong, Too?<\/strong><\/p>\n<p align=\"center\"><strong>\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014\u2014<\/strong><\/p>\n<p align=\"center\"><strong><a href=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/05\/tk_head_shot1.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"alignleft size-thumbnail wp-image-186\" title=\"tk_head_shot\" src=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/05\/tk_head_shot1-150x150.jpg\" alt=\"\" width=\"150\" height=\"150\" srcset=\"http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/05\/tk_head_shot1-150x150.jpg 150w, http:\/\/tonykordyban.com\/wp-content\/uploads\/2012\/05\/tk_head_shot1-200x200.jpg 200w\" sizes=\"auto, (max-width: 150px) 100vw, 150px\" \/><\/a>The straight dope on Tony Kordyban<\/strong><\/p>\n<p>Tony Kordyban has been an engineer in the field of electronics cooling for different telecom and power supply companies (who can keep track when they change names so frequently?) for the last twenty years.\u00a0 Maybe that doesn\u2019t make him an expert in heat transfer theory, but it has certainly gained him a lot of experience in the ways NOT to cool electronics.\u00a0 He does have some book-learnin\u2019, with a BS in Mechanical Engineering from the University of Detroit (motto:Detroit\u2014 no place for wimps) and a Masters in Mechanical Engineering from Stanford (motto: shouldn\u2019t Nobels count more than Rose Bowls?)<\/p>\n<p>In those twenty years Tony has come to the conclusion that a lot of the common practices of electronics cooling are full of baloney.\u00a0 He has run into so much nonsense in the field that he has found it easier to just assume \u201ceverything you know is wrong\u201d (from the comedy album by Firesign Theatre), and to question everything against the basic principles of heat transfer theory.<\/p>\n<p>Tony has been collecting case studies of the wrong way to cool electronics, using them to educate the cooling masses, applying humor as the sugar to help the medicine go down.\u00a0 These have been published recently by the ASME Press in a book called, \u201cHot Air Rises and Heat Sinks:\u00a0 Everything You Know About Cooling Electronics Is Wrong.\u201d\u00a0 It is available direct from ASME Press at 1-800-843-2763 or at their web site at http:\/\/<a href=\"http:\/\/www.asme.org\/pubs\/asmepress\">www.asme.org\/pubs\/asmepress<\/a><strong><em>,\u00a0 <\/em><\/strong>Order Number 800741.<\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>Answers to those Doggone Thermal Design Questions By Tony Kordyban Copyright by Tony Kordyban 2001 &nbsp; Dear TK, I got stuck with the job of getting quotes for the ventilating\/air conditioning system for the new computer room.\u00a0 It will be filled with network routers and servers and such.\u00a0 All the power for that stuff is [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-203","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages\/203","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=203"}],"version-history":[{"count":4,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages\/203\/revisions"}],"predecessor-version":[{"id":228,"href":"http:\/\/tonykordyban.com\/index.php?rest_route=\/wp\/v2\/pages\/203\/revisions\/228"}],"wp:attachment":[{"href":"http:\/\/tonykordyban.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=203"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}