Document r0M300LqB1p4aydax4dRNoja

HEATING VENTILATING AIR CONDITIONING CUIDE 1942 Micron__ - V- (mu) Miles per hour.........................:.......................................................................................... ....mph Millimeter........................................... .......................................................................................mm Minute......................... ...................... --................. -.............-.................................................. min Molecular weight............................. ................................................................................. mol. wt Mol.mol Ounce----------------------- --------------------- ------------------------------------------------------------------- --oz Pound.........................-......--.................................................. ................... .............................. lb 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---------------------------------------- rpm Saturated liquid at saturation pressure and temperature, Liquid in contact with vapor______ ____________________ __________ _____________________ Subscript t Second____ ........................................... -.............. --.....-...........................-...............................sec Specific gravity.............. ...................... ........................................................................... .......sp gr Specific heat.................................... .................. ..............................................................sp ht or c Specific heat at constant pressure--........... ..................................................... .......................cD Specific heat at constant volume--------------!............... ......... ........................... ................1.......cT 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 t is used for Time in the same discussion)........................................................................J or 6 (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 conductance* (heat transferred per unit time per degree)................................ ....C r = -A- = M___ i-- cR L ti -- /, Thermal conductance per unit area. Unit conductance (heat transferred per unit time per unit area per degree).............................. ................ .............................. Ca c m JL = _L = <? _ _L a A RA A(t,-t,) L Thermal conductivity (heat transferred per unit time per unit area, and per degree per unit length)......... ............................................................. ................................ k g k= A (t\ - 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 (In general f 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 A V= h -h Terms ending ivity designate properties independent of size or shape, sometimes called specific properties. 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. 846 CHAPTER 47. TERMINOLOGY Thermal transmission (heat transferred per unit time)......................... -- Thermal resistance (degrees per unit of heat transferred per unit time) R .= ti --h __ ~ 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.. ------- ------------------------------------------------------------ ------ --------------------" 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............g Watt--........... Watthour.____ ..w ..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 Heat, Power and Work 1, t.on re,fri.geration = (I 21020,00B0tuBtu per hour Latent heat of ice I Btu 1 watthour 1 kilowatthour 1 kilowatt (1000 watts) 1000 mean calorie \ 1 kilogram calorie j 1 horsepower i1 ,bo.i,ler ,horsepower = 143.4 Btu per pound 778. 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 _-- \/ g33g,04875kwBtu per hour Weight and Volume lgal(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) I bushel 1 short ton _ / 231 cu in. - \ 0.1337 cu ft = 277.42 cu in. = / 7.48 gal \ 1728 cu in. = 62.37 lb = 59.83 lb = 8.34 lb = 71998 lb / 16 oz \ 7000 grains = 1.244 cu ft . = 2000 lb 847 i i