Temperature
Correction Factor for Reverse Osmosis Membranes
Performance of the
reverse osmosis membrane element is affected by two key factors;
temperature of the feed water and the net driving pressure across the
element. These two factors must be taken into account before comparing or
evaluating the performance of a membrane element or a reverse osmosis
system.
The following
information is provided to assist you in roughly calculating the affects
of the temperature factor.
For information on pressure correction,
please click here.
The water
temperature is one of the key factors in the pe5rformance of the reverse
osmosis membrane element. The higher the temperature, the more the
product flow and vice versa. All reverse osmosis membrane elements and
systems are rated at 77º Fahrenheit (25ºCelsius).
To find the membrane permeate rate at a different temperature, follow
these steps:
Find the
temperature correction factor (TCF) from the table
Below.
Divide the rated
permeate flow at 77 degrees Fahrenheit by the temperature correction
factor. The result is the permeate flow at the desired temperature.
|
Feed
Water Temperature |
Correction Factor |
|
ºC |
ºF |
|
5 |
41.0 |
2.58 |
|
6 |
42.8 |
2.38 |
|
7 |
44.6 |
2.22 |
|
8 |
46.4 |
2.11 |
|
9 |
48.2 |
2.00 |
|
10 |
50.0 |
1.89 |
|
11 |
51.8 |
1.78 |
|
12 |
53.6 |
1.68 |
|
13 |
55.4 |
1.61 |
|
14 |
57.2 |
1.54 |
|
15 |
59.0 |
1.47 |
|
16 |
60.8 |
1.39 |
|
17 |
62.6 |
1.34 |
|
 |
|
Feed
Water Temperature |
Correction Factor |
|
ºC |
ºF |
|
18 |
64.4 |
1.29 |
|
19 |
66.2 |
1.24 |
|
20 |
68.0 |
1.19 |
|
21 |
69.8 |
1.15 |
|
22 |
71.6 |
1.11 |
|
23 |
73.4 |
1.09 |
|
24 |
75.2 |
1.04 |
|
25 |
77.0 |
1.00 |
|
26 |
78.8 |
0.97 |
|
27 |
80.6 |
0.94 |
|
28 |
82.4 |
0.91 |
|
29 |
84.2 |
0.88 |
|
30 |
86.0 |
0.85 |
|
EXAMPLE
Question
For a thin-film membrane permeate rate at 77 degrees Fahrenheit = 1800
gallons/day. What is the permeate rate at 59 degrees Fahrenheit?
Answer
Temperature correction factor (from table) = 1.47
Permeate flow at 59 degrees Fahrenheit = 1800÷1.47
= 1224 gallons/day
Please
Note: For
systems, more detailed calculations are necessary to take into account the
effect of pressure drop and variation in total dissolved solids (TDS)
throughout the system. For more information, please contact us. |
