August 07, 2009

Ammonia Vapor Pressure & Temperature Equations

In the series of physical properties calculation methods, I am now covering Ammonia P & T correlations which are frequently used in refrigeration system design calculations. Or they may be used for designing of heat pumps - yes may be I don't know at this stage if one can use ammonia for heat pump service or not.

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Saturation Pressure vs Temperature.

This equation is valid for t = -75 to 70°C. I have limited this equation to this range for better accuracy of calculated data vis a vis comparison with published data.

Pv = A x T^5 + B x T^4 + C x T^3 + D x T^2 + E x T + F

where Pv = vapor pressure in Kg/cm2
T is temperature in Kelvin.

A = -4.5864778 x 10^-11
B = 9.85099347 x 10^-8
C = - 5.7526544 x 10^-5
D = 1.4773233 x 10^-2
E = -1.7847943
F = 83.3895705

Saturation Pressure vs Temperature for t > 70°C.

Pv = 89875.92511 exp (-2706.64791 / T)

where units are same as above.

Saturation Temperature Vs Pressure for P = 0 to 34 Kg/cm2.

T = A x y^5 + B x y^4 + C x y^3 + D x y^2 + E x y + F

A = 0.13493672
B = 0.380555
C = 2.13810444
D = 10.058439
E = 45.5972648
F = 239.1719874

T is in Kelvin

List of other property estimation methods on this Blog.

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Anonymous said...

Do you have any information on the ACES21 urea production process? I need some information on the reactor and vacuum concentrators. thanks

profmaster said...

Dear I do not have any Info on ACES process.

Anonymous said...

Could anyone please give me the steps how to calculate the polytropic efficiency of a screw compressor used to liquify ammonia vapour in 10000 T atmospheric liq ammonia tank. What I need is to find out how efficient is the compressor to do the job

Anonymous said...

The equation for calculating temperature, when pressure is known is incorrect. The equation for calulating pressure is working correctly though. Please explain, as I need to program this into my electronic expansion valve.

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