Back-of-the-envelope calculation I'm going to look at a column of air of volume V -- with area A ... and a height H sufficient to hold 1-second's worth of 1MW of heat. This has to be vented in 1 second.
1MW is 1000 kJ /second. Q = 1000 kJ in one second Specific heat of air at 100C is 1 kJ / (kg K) Density of air at 100C is r = 1kg/m^3 http://www.engineeringtoolbox.com/air-properties-d_156.html Ambient air is 20C, heated air is 100C dK = 80 Q = S * dK * M Mass = 1kg * r * V = r * V Q = S * dK * r * V Solve for V : V = Q / ( S * dK * r ) = 1000 / ( 1. * 80 * 1.) = 12.5 m^3 per SECOND = 750 m^3 per MINUTE = 26,486 CFM (Cubic Feet per Minute) That's a teeny tiny little fan! http://www.industrialfansdirect.com/wall-ventilation.html?&gclid=CIb8x7zb68wCFQEJaQodk4AMnQ From: "Alan Fletcher" <a...@well.com> To: "vortex-l" <vortex-l@eskimo.com> Sent: Saturday, May 21, 2016 10:37:55 AM Subject: Re: [Vo]:1 MW of heat in a 6,500 sq. ft. facility without industrial ventilation would be fatal This chimney sizing link doesn't really apply --- it's for natural draft up a chimney of a given height and diameter -- WITHOUT a fan. (The longer the chimney the higher velocity of the draft, so a given diameter can exhaust more heat. They recommend " The velocity of air and flue gas in a smaller furnace should not exceed 2 m/s . " -- so I presume that the charts are based on this, and not the maximum 10m/s. ). I haven't put a ruler on the aerial photos of the vents on the roof ... but it looks like they could easily be 22 inches. Since a 22-inch vent WITHOUT a fan at a velocity of 2 m/s can handle 1MW, it seems likely that a vent WITH a fan could also do so. There's probably a vent/fan sizing chart somewhere, but this isn't it. From: "Jed Rothwell" <jedrothw...@gmail.com> To: "vortex-l" <vortex-l@eskimo.com> Sent: Saturday, May 21, 2016 9:16:31 AM As I said, 1 MW in this space would be like running 16 space heating furnaces continuously without thermostats. To remove that much heat, you need a 22" vent and a large fan. An expert from I.H. would have to confirm this ventilation equipment is installed and working to confirm the claim. 1 MW of heat release calls for at least at 22" vent: http://www.engineeringtoolbox.com/chimney-sizing-d_175.html
