Document NGOyGVVEz2dXNBo69nm8Dp38R
Heating Ventilating Air Conditioning Guide 1939
Table 1. Pressure Losses in Dichlorodifluoromethane Discharge or Hot Gas Lines
Capacity BTU pbb Hour
10,000 15,000 20,000
25,000 30,000 40.000
50,000 60,000 70,000
80,000 90,000 100,000
125,000 150,000 175,000
200,000 250,000 300,000
400,000 500,000 600,000
800.000 1,000,000 1,250,000
1,500,000 2,000,000
Pressure Dkop m Pounds pbb Square Inch per 100 Fib
X
2.3 4.9 8.5
Lxnb Sizes, Inches
X
1.0 2.0 3.4
5.3 7.5
.X
0.6 1.0 1.7
2.6 3.6 6.4
9.8
IX m IX 2X
0.6
0.9 1.2 2.1
0.5 0.7
3.1 4.4 6.0
1.0 1.3 1.9
0.5 0.7 0.9
8.0 10.2
2.5 3.1 3.8
1.1 1.4 1.7
0.5
6.0 8.5 11.6
2.6 3.8 5.1
6.7 ip.4
0.7 1.0 1.3
1.7 2.6 3.7
6.7 10.5
2X
0.6 0.9 1.2 2.2 3.5 5.0 9.0
3X W
--
~
0.5
0.9 1.5 2.1
3.8 5.8 9.5
0.7 1.0
1.8 2.9 4,4
6.4 11.3
*Soft annealed copper tubing up to and including H in. outside diameter. Hard copper pipe H in. outside diameter and larger.
bLength of tubing includes the average number of fittings.
unit capacity may be reduced by using back pressure regulating valves, by-pass valves, or variable speed compressors.
Another method of providing for economy of operation is to have storage capacity which can be utilized during the peak period. _ The refrigerating system can be operated for a longer period at maximum efficiency with tanks to store cold water or brine for supplementing the actual output of the refrigerating equipment. However,-storage tanks require space and extra apparatus, which increase the cost of the entire system, and further, it is difficult to determine the exact size of the compressor because of the other variables which enter the problem. Depending upon the availability of storage space, the compressor may be designed for any reasonable percentage of the maximum load. On this basis of selection, the smaller the compressor, the larger the storage space, and vice versa.
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Chapter 23. Cooling and Dehumidification Methods
Table 2. Pressure Losses in Dichlorodifluoromethane Liquid Refrigerant Lines
--
Pressure Drop m Pounds per Square Inch per 100 Ft*
Capacttt BTtJ pen Hour
Pipe Sizes, Inches
X IX IX IX
---- '
100,000
0.6
125.000
0.9
150,000
1.3
175,000
1.8
200,000
2.3
0.6
225,000 250,000 275,000 300,000
2.9 3.6 4.3 5.1
0.8 1.0 1.2 1.4
325,000 350,000 375,000 400,000
5.9 . 6.9
7.9 9.0
1.6 1.8 2.1 2.3
0.8
450,000 500,000 550,000
2.9 3.5 4.3
1.0 1.3 1.5
0.7
600,000 700,000 800,000
5.0 6.7 8.7
1.8 2.4 3.1
0.8 1.1 1.4
900,000 1,000.000 1,200,000
3.9 4.7 6.7
1.7 2.1 3.0
1,400,000 1,600,000 1,800,000
9.0
4.0 5.1 6.3
2,000,QOO 2,200,000
7.9 9.2
Length of tubing includes the average number of fittings.
There is a further method of controlling the compressor output which is particularly adaptable. to the centrifugal type of machine. This is accomplished by varying the amount of condensing water used with the fluctuation in load demand. Bemuse of the characteristics of the cen trifugal type of apparatus, as the condensing water quantity is reduced and the condensing temperature consequently raised, the discharge pressure of the centrifugal machine rises correspondingly and the horse power input to the machine drops proportionately. While this reduces the total power input to the machine, it does not necessarily reduce the power input per ton of refrigeration developed, as the power input does "ot drop with a rising discharge pressure as fast as the refrigerating effect is reduced.
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