Ammonia refrigeration compressors produce high-temperature, high-pressure gaseous ammonia, which then goes to the condenser (with cooling water) to be cooled – what is its state at that point?

Why is it high pressure? The pressure can also change after cooling down, right? Could it be because of the connection between the compressors?

After compression, there is also a turbine – has this been taken into consideration? If the gas is only cooled after passing through the compressor, what results is high-pressure nitrogen gas, which then needs to be depressurized and liquefied

Liquid ammonia is used to cool the chilled water; after coming out of the compressor, it goes to a cooling tower for cooling. There is no such thing as liquefaction through pressure reduction – pressure reduction is achieved in the evaporator via a throttle valve

This post was last edited by ylb913 on 2016-7-31 07:13. One of our former ammonia compressors had an ammonia temperature of around 150 degrees Celsius after compression (the temperature at the compressor inlet usually did not reach 10 degrees), with a pressure of 1.3–1.5 MPa (I’m referring to gauge pressure). When condensed to below 40 degrees, it becomes liquid ammonia, with a pressure of approximately ~1.4 MPa. The pressure of liquid ammonia depends on its temperature; it is around 1.4 MPa at its highest in summer, while in winter it is below 0.7 MPa here. Table of saturated vapor pressure of liquid ammonia vs. temperature
Temperature °C | Vapor pressure MPa(a)
--- | ---
-40 | 0.072
-20 | 0.190
0 | 0.429
20 | 0.857
40 | 1.554
-38 | 0.079
-18 | 0.208
2 | 0.462
22 | 0.913
42 | 1.642
-36 | 0.089
-16 | 0.226
4 | 0.497
24 | 0.972
44 | 1.734
-34 | 0.098
-14 | 0.247
6 | 0.534
26 | 1.034
46 | 1.830
-32 | 0.109
-12 | 0.268
8 | 0.574
28 | 1.099
48 | 1.929
-30 | 0.120
-10 | 0.291
10 | 0.615
30 | 1.167
50 | 2.033
-28 | 0.132
-8 | 0.315
12 | 0.658
32 | 1.237
52 | 2.140
-26 | 0.145
-6 | 0.341
14 | 0.704
34 | 1.311
54 | 2.252
-24 | 0.159
-4 | 0.369
16 | 0.752
36 | 1.389
56 | 2.368
-22 | 0.174
-2 | 0.398
18 | 0.804
38 | 1.470
58 | 2.489

I agree with the statement that there is a relationship between the pressure and temperature of liquid ammonia; if the cooling effect in the condenser is good, the temperature of the liquid ammonia will be low, and consequently the pressure will also be low!

After cooling, the pressure will decrease, but it will still be much higher than that at the inlet of the ice machine! Due to circulating water cooling, it is not possible to condense all of the gaseous ammonia; the saturated vapor pressure of liquid ammonia at 30°C can be used as a reference

It really is a matter of perspective – different people have different views~~ I’ve learned*e*e

High-temperature and high-pressure gaseous ammonia, after being condensed and cooled, does not see a decrease in pressure; only a phase change occurs, don’t you think? . . . . .

Why isn’t the pressure reduced? Shouldn’t it be reduced? Is it related to the saturated vapor pressure of liquid ammonia mentioned above?