Document 7xrqapXYrnjqQkNnQ76kJoOR

American SociETr of Heating and Ventilating Engineers Guide, 1935 Head.......... ................................................................--,............................................. \...... II or h Heat content, Total heat, Enthalpy. (The capital should be used for any weight and the small letter for unit weight.)...:............................. ......................................H or A-* Heat content of saturated liquid. Total heat of saturated liquid, Enthalpy of ' saturated liquid, sometimes called heat of the liquid.................._.............................hf - Heat content of dry saturated vapor, Total heat of dry saturated vapor, Enthalpy of dry saturated vapor......................................................... ............................. .............. :.hz Heat of vaporization at constant pressure......................................................... .... L or hfg Horsepower.................................................................................. hp Horsepower-hour.................................................................................................................... hp-hr Inch......................................................................................... ................................ ;...............:in. Inch-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.................................. :.................................................................................................. .lew Kilowatthour.................................................................................................... kwhr Length of path of heat flow, thickness--.............. ......,....:...................................................... JL Load, total.................. W Mass............ ....................................................................................................... ..;...........;............m Mechanical efficiency......... ...................... em Mechanical equivalent of heat--............................................................. J Melting point............................................ ................................. ........................................i......mp Meter........................................................................... ..................................................... -.......;..m Micron.............. ................................................................................................ ................... p. (mu) Miles per hour................. mph Minute.--......................................................................................................... :......................... min 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..,................................... ........x- Revolutions per minute_____________ _______ .1.................. ................................................rpm Saturated liquid at saturation pressure and temperature, Liquid in contact with vapor..................... .................................................. ..................... ..............Subscript [ Specific gravity............................... ....................... .................................... ______________ sp gr Specific heat..................................................... ...............................................................sp ht or c Specific heat at constant pressure............................ ...........1.................................................... cv' Specific heat at constant volume.............. ........................................................................ .......cv . Specific volume, Volume per unit weight, Volume per unit mass...... .......................... .......v Square foot........ .......................................................................................................................sq ft Square inch................. ......................................... ........................................ ........................ sq in. Temperature (ordinary) F or C. (Theta is used preferably only when f 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 8 (capital theta) ' Thermal conductance* (heat transferred per unit time per degree)......... :................ .........C r = J_ = M = 1 R L h - t. Thermal conductance per unit area, Unit conductance (heat transferred per unit time per unit area per degree)...................................................................... Ca . C_ = _i_ = q = A RA A(t,~l,) L <Terms ending iviiy 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 ion designate rate of heat transfer. Examples are--con duction and transmission. 698 Chapter 41--Terminologv Thermal conductivity (heat transferred per unit time per unit area, and per degree per unit length)............................................................................................... . -k = ___------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)........................................................................................-..............-..................... / A___ f " 11 - /. (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 _9 A U = <i - t, Thermal transmission (heat transferred per unit time)........................................................ q Thermal resistance (degrees per unit of heat transferred per unit time)............ .............R R= L_ kA Thermal resistivity.......................,................ ...................-................. -.......-................... -...... 1/* Vaporization values at constant pressure, Differences between values for saturated vapor and saturated liquid at the same pressure........ ................................. Subscript fg Velocity--................................... -............................................................. .................................... Y Volume (total).........................-................................................................-..........................-......' 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.........................................-............................................................ ............................. Weight of a major item, Total weight..........................---.........;........................ .................. w Weight rate, Weight per unit of power, Weight per unit of time...........................-......... vi Work (total)........_............. -............................:.........~...............-................................ ..............^ 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. Power, Heal, and Work , ,. . 1 ton refrigeration Latent heat of ice (12,000 Btu per hour \200 Btu per minute = 143.33 Btu per pound 699