2 replies to this topic

[Monkichi]

Hi,

 

I have read a few threads regarding sizing for fluid in the supercritical region but was unable to find the particular answer. When sizing for a fluid in the supercritical region I followed both "Rigorously Size Relief Valves for Supercritical Fluids" by Ouderkirk and "A calculation of relieving requirements in the critical region" by Shakelton. 

 

Both method used yielded similar mass flow rates but once I reach the initial "high" flow rate, it begins to drop. However, as the temperature increases the mass flow-rate begins to increase again and exceeds the initial "high" flow rate. I don't think this is supposed to happen but I am not sure.

 

Does anyone have experience working with these methods? I have copied an example of the results below. As the rate reaches 3406.7 KG / H it starts to go back down but then it goes back up again.

 

KG/H

2304.0 2336.7 2412.1 2470.5 2530.4 2610.2 2684.1 2770.8 2863.3 2965.1 3406.7 2911.2 3371.3 3561.6 3790.4

 

Assuming the values are correct, would I take the rate of 3406.7 KG / H to size for supercritical fluid?

Edited by Monkichi, 28 October 2015 - 07:24 AM.

[PaoloPemi]

there is a detailed discussion (and a Excel page showing how to solve the problem) in this thread

 

"http://www.cheresour...g-temperature/"

 

the procedure is not too different from that described in this paper

 

"http://people.clarks...n/reliefv2.pdf"

 

as alternative you can solve directly the critical condition (the method included in Prode Properties)  for different models (HEM, HNE, NHNE etc.)

[AlertO]

Hi Monkichi

 

See my answer to your question below.

 

1. It is fine if you have the second peak flow. It depends on your fluid.

 

2. You should check the required area for each step. Sometimes the maximum flow does not present the maximum area due to the difference on fluid properties.

 

Hope this helps.