Document dQr3mpYngXK9kZBXQO9RLEGVe

American Society of Heating and Ventilating Engineers Guide, 1934 I nch-pound........ -.................................................................................................................in-lb Indicated horsepower--............................................................................................. -.... ihp Indicated horsepower-hour.--------------- :.........................................................-............. ihp-hr Internal energy, Intrinsic energy. (The capital should be used for any weight and the small letter for unit weight).... :................................................._................... U or u Kilogram........................ kg Kilowatt.................................................................................................................................. kw Kilowatthour................................................................................... kwhr Length of path of heat flow, thickness.................. L Load, total............................................................................................................................... W Mass.......................................................................................................................................... Mechanical efficiency...................................................-.....................................--................ m Mechanical equivalent of heat.__......................................................................... J Melting point........................................ mp Meter......................................................................................................................................... m Micron.................................................................................................. -......................... V- (mu) Miles per hour......... :..............................................................................;........................... mph Minute.................................. -........................ ....................................................-................ m'n Molecular weight.................. -................................. ...... ............. --....................... .....mol. wt MoL.................................................................... mol Ounce...............................................-----................................................... .--......... .............. oz Power, Horsepower, Work per unit time............................................................................-P Pressure, Absolute pressure, Gage pressure, Force per unit area....................................... p 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......... .................... -............. * Revolutions per minute..... ...................................................... -........................................ rpm Saturated liquid at saturation pressure and temperature, Liquid in contact with vapor........................................................................................................Subscript i Specific gravity............ ............................ ..........................................................................sp gr Specific neat...................... ............................ -.............................................-......... -~sp ht or c Specific heat at constant pressure......................................................................................... tp Specific heat at constant volume..................................... .................................................... Specific volume, Volume per unit weight, Volume per unit mass...................................... v Square foot...-...... ......................... ..... ............... -............. -.........-........................... -......vsq ft Squarelnch.............................................._........................................................................ in. sq Temperature (ordinary) F or C. (Theta is used preferably only when t is used for Time in the same discussion)....... ... ;............. :................................ -...... t or 0 (theta) Temperature (absolute) F abs or K. (Capital theta is used preferably only when small theta is used for ordinary temperature)____________ ___ T or (capital theta) Thermal conductance4 (heat transferred per unit time, per degree)................................. C C=-- =-- = ? R L ti -- ti Thermal conductance per unit area, unit conductance (heat transferred per unit time per unit area, per degree)................................................................... ...... C* A RA A (It -- ti) L Thermal conductivity (heat transferred per unit time per unit area, and per degree per unit length).................................................................... -------- --------- g A . k = (ti -- <>) L 4Terms ending ivity designate properties independent of size or shape, sometimes called specific proper ties. Examples are--conductivity and resistivity. Terms ending once designate, quantities depending not only on the material, but also upon size and shape, sometimes called total quantities. Examples are-- conductance and transmittance. Terms ending ton designate rate of heat transfer. Examples are--con duction and transmission. 598 Chapter 42^--Heating and Ventilating Standard Terms 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 it -- /* (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)..................................... U g U= A t, - t. 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 of heat per unit time, Quantity of heat per unit weight........... q Watt.............................. ,.........................................................................................................w Watthour....... ............... ............................ ;......................................................................... whr Weight of a major item, Total weight................................................................................. W Weight rate. Weight per unit of power, Weight per unit of time................... ................. w Work (total)............................................................................................................................ W CONVERSION EQUATIONS Fahrenheit degrees = 9/5 centigrade degrees 32. Centigrade degrees = 5/9 (Fahrenheit degrees -- 32). Absolute temperature, expressed in Fahrenheit degrees = Fahrenheit degrees + 459.6. In heating and ventilating work, 460 is usually used. Absolute temperature, expressed in centigrade degrees = centigrade degrees + 273.1. Powers and Work 1 ton refrigeration Latent heat of ice 1 Btu 1 watthour 1 mean calorie 200 Btu per minute 143.33 Btu per pound 777.5 ft-lb 0.293 watthours 252.02 mean calories ( 2,655.2 ft-lb I 3.415 Btu | 3600 joules { 860.648 mean calories f 0T003968 Btu \ 3.085 ft-lb ( 0.0011619 watthours 599