Document 3eQKav2BQ1eyradOJp3wNd4za

T American Society of Heating and Ventilating Engineers Guide, 1925-26 245 259.7 112.6 D O PC UEOa>, o t5 N ts otO 2a 5 to 4 o> s H l- oto 8et 2 8 h- 6CO tCoO CtoS u Cto* O 2O 3 s H 2 00 O oDObDas) fiu s to 38 OH O No tO a> I1 *tv0HT0fOlSO0*'O00V'Oi0N<I S5.f0Oifel`oOooaOo^oO*>-0O'^wONfOo'to*O->oOo'OoOofCOO' '0- '0,-.i`V0o- "O`Ow- t^J>-"^.v-n.---f.S053^'r----0^-o-W0o--Oo3-rO04o\-0o0toro-'-o*^t0--'-o'Oi^oiNOOf^oJN0t<--Tefj<^srOQi0'cv0O'2Or''fOoo Nitofl^\ciSOooO^o*mO,ooSOo'O-^cOO'4Oi'oOoOvi^O^O,QtrQ'?O2iiO,O''"'NfQ^lQOr'5QN!^N0!2O!MflOOJO'-2' 'OiOiO^,^'OfOM'H0 trrVN0o0-UrOi)0.^a`O0H'.'O<'OOl.,t^O-/i-,>ff^OO^.-oNWrO'-ON^O-T>}0O-,-'o,0fOlO-O50fQ-^oOO\0oNo'OirQ>^*v'0O5'0iOo''N^io0f'pi^0OCTNNi*mO*i0OOrrQ)'vOP'tOrf^^t `ftOOOOOOOOOO'ftOOO'flOOOOQ'n r-v5 -- ooTt<C'jm--C'J--|eC?>-;^0OC7'CNr----;C') -loo^'OMflt^O'^r'Noo^'Oooo^^'O'HOOioN - i'"i . . . - - i - -OOoO*'-'OiOTt`T*fOfOf5 OtOUO'^J'rnrOCS*-->*--'O 00000O,0,flOOOO0OQOQOp r0-v*cr0>0-r0M^000r^t*^5Tt0`0^0r*--0\^Q|iO^\Ov^et^iOp'Ori"*--<^'5-c-s*'^^io^^ ---------- -00 oO vO o fO f*) t*5 lOt^Tf^tOrOfN*--'O 0 0000000*00 0n0 0p0"j0 0 tot*3-HTroo55t,Mto,*'>*Ne>`4oto^^o - - . ------ -Ov OOt- ** O w> to ** m ro *> lJOo^^*bc\n^i1t0<oNj--Jo0o6fo60^6ooot"o6t-^"'0C 5Pkfc-_-ioon2^toch'4.tN--i-^*-'0*to0-'W*ooOtO*','0-*0,4)0t^ 110 140 170 c5 s oto 0o > < 2Os VM o N 1 u tn tSo Mtn u z U Abs. to 3 2 oJ o 3 e K E H 0 fO PO tO *5 OooNr^*^^o)o0-'000towes^to'ooioto^c>ioo o^^-o<rfO-oPo-OoCp-so-eoMo-^---F-*H-^-c^^CoKoo5Ocrj^-Pt--r2'o3t!ots2^2PgOif2OSfOJSCS Luo OOOQOOOOOOOOOOO OOOOOO <-<go ^^<^tor-t^fO'--<0'oocMPO^ focs0'o6i^-rj*e^o6`0-'N^OvO^i^^'OOJ ++++++fnfn^NNNMNN^*^^ | I ( o_-? *? ^ ^ *? *? I I I II I I I I I I ;_J i-J U J S 5 m4 iS - ,3 ~h cm n *h fo ^ tj* o to to PO CS *-* 236 American Society of Heating and Ventilating Engineers Guide, 1925-26 operate too close to the freezing point, either brine must be sprayed or a low temperature cannot be carried without submerged coil surface as well as extra coils in the spray chamber. When the sprayed water hits the cooling coil it does not have a ten dency to stick to the coil. The result is that a lower total volume of water will be flowing over the total coil surface and less total cooling will be secured per foot of surface used. If the cost of a larger spray chamber, extra coil surface in the spray chamber, and the submerged coils required and the other factors are favorable, the coils may be used in the upper spray chamber with satis factory results in some installations. For some duties a return bend arrangement may be used passing the air through the upper chamber and then down and back through the lower coil chamber. The coils are covered by a film of running water at a lower temperature than the air and as some air will come in contact with the cold water and other cooled surfaces a limited amount of extra cooling may be secured. There is one important point which is a problem for the refrigerating engineer, but which has sometimes been overlooked. This is the matter of control of the refrigeration. Almost all air conditioning installations, whether with .automatic or hand control, give a varying refrigerating load. Systems have been operated using many tons of refrigeration and this load has suddenly been removed owing to changing requirements. Meanwhile the ammonia compressor may be operating, and freezing of the system with accompanying damages results if carried far enough. Ammonia lines in a plant cannot be tapped and valves turned on and off quite as readily as in a steam line. The refrigerating engineer should be fully advised regarding the varying of the air conditioning refrigerating load. With the accompanying charts no one should have difficulty in checking a layout or making preliminary approximate estimates of the part of an air conditioning unit using refrigeration. It is impossible to give here all the factors governing the use of refrigeration and the allowance to make for different conditions such as coils that are dirty or oily on the inside, coils with poor outside surfaces, the element of time in changing condi tions of air treatment, structural considerations' and particularly the action of the water when it is sprayed in the coil chamber in contact with the air. It is not suggested by the author that those unfamiliar with the details of such work use these charts except as a source of general information as to the factors governing the design of such equipment. Estimates as shown by the dotted lines on the charts are made as follows: 1. Total heat load--4,000 B.t.u. per minute 20 tons refrigeration 2. Design and conditions allow 6 deg. rise in water temperature 3. Average water temperature 44 deg. i 4. Average ammonia temperature 10 deg. 5. Difference ammonia and water 34 deg. 6. Gallons handled per ft. of trough ljJ 7. Standard unit available allows 8 ft. long troughs 237