Document XO3LN8wqQRok1xkvNENYq6XQd

r' . HEATING VENTILATING AIR CONDITIONING GUIDE 1940 ./ Ounce... ....................................................... ..... ...................................... .... ..............02 Power, Horsepower, Work per unit time._____________ _________ Pressure, Absolute pressure, Gage pressure, Force per unit area_ Quantity (total) of fluid, water, gas, heat; Quantity by volume; Total quantity of heat transferred.. -Q Quality of steam. Pounds of dry steam per pound of mixture.. ~x Revolutions per minute..................... ................................. ________________________ ___ rpm Saturated liquid at saturation pressure and temperature, Liquid in contact with vapor:Subscript f Specific gravity---------- ------------------------- ---------------------------------------------------------------sp gr * Specific heat...sp ht or c Specific heat at constant pressurecp Specific heat at constant volume.. Specific volume, Volume per unit weight, Volume per unit mass.. Square foot____________________________ _______________________ _______ :____ sq ft Square inch.. ____________sq in. Temperature (ordinary) F or C. ( Theta is used preferably only when l is used for Time in the same discussion)tor 0 (theta) Temperature (absolute) F abs or K. (Capital theta is used preferably only when small theta is used for ordinary temperature)T or 0 (capital theta) Thermal conductance5 (heat transferred per unit time per degree)C r1 R kA q L ti -- ti Thermal conductance per unit area, Unit conductance (heat transferred per unit time per unit area per degree)Ca r ---- g a = A ~ RA = A(.t, - t,) h_ L Thermal conductivity (heat transferred per unit time per unit area, and per degree per unit length).........................................................................................................k g k = __d__ ~ h) L Surface coefficient of heat transfer, Film coefficient of heat transfer. Individual . coefficient of heat transfer (heat transferred per unit time per unit area per degree)--............................................................................................. ........................... ./* " g A ~ t, - t, (In general / is not equal to k/L, where L is the actual thickness of the fluid film.) Over-all coefficient of heat transfer, Thermal transmittance per unit area (heat transferred per unit time per unit area per degree over-all) .. ....................... ............V g 6Terms ending icily designate properties independent of size or shape, sometimes called specific proper ties. Examples: conductivity, resistivity. Terms ending once designate quantities depending not only on the material, but also upon size and shape, sometimes called total quantities. Examples: conductance, transmittance. Terms ending ion designate rate of heat transfer. Examples: conduction, transmission. 784 CHAPTER 46. TERMINOLOGY Thermal transmission (heat transferred per unit time).. ----------- q Thermal resistance (degrees per unit of heat transferred per unit time)______________ R Thermal resistivity.______________________________________________________ ________1/k Vaporization values at constant pressure, Differences between values for saturated vapor and saturated liquid at the same pressure__________________ ____ Subscript fg Velocity;.............................................................................................................................. V Volume (total)____ __________________________________________ V Volume per unit time, Rate at which quantity of material passes through a . machine, Quantity ofheat per unit time, Quantity of heat per unit weightq Watt____________________________________________________ w Watthour.____________________________________________________________________ __ whr Weight of a major item, Total weight................................ W Weight rate, Weight per unit of power. Weight per unit of time____ __ _____________ v> Work (total)............................................................... W CONVERSION EQUATIONS Heat, Power and Work 1 ton refrigeration Latent heat of ice 1 Btu 1 watthour 1 kilowatthour 1 kilowatt (1000 watts) 1000 mean calorie 1 1 kilogram calorie / 1 horsepower 1 boiler horsepower Weight and Volume ( 12,000 Btu per hour \ 200 Btu per minute 143.5 Btu per pound 778 ft-lb 0.293 whr 252 mean calories 2,655 ft-lb 3.413 Btu 3600 joules 860 mean calories 3.413 Btu 3.517 lb water evaporated from and at 212 F 1.341 hp 56.88 Btu per minute 44,253 ft-lb per minute 3.969 Btu 3087 ft-lb 1.1627 whr 0.746 kw 42.42 Btu per minute 33,000 ft-lb per minute 550 ft-lb per second / 33,475 Btu per hour \ 9.808 kw 1 gal (U. S.) 1 British or Imperial gallon 1 cu ft 1 cu ft water at 60 F 1 cu ft water at 212 F 1 gal water at 60 F 1 gal water at 212 F 1 lb (avdp) 1 bushel 1 short ton -{ 231 cu in. 0.1337 cu ft = 27' 7.42 cu in. -{ 7.48 gal 1728 cu in. 62.37 lb 59.83 lb 8.34 lb 7.998 lb / 16 oz \ 7000 grains = 1.244 cu ft = 2000 lb 785