6 replies to this topic

[sskumar]

Hi,
Can any body tell me whether the Pasqull's dispersion coefficients are the same for both plume and puff models or they are different? I came to know from Calpuff user's manual that there are different equations for rural and urban coefficients. Also I saw in one reference book two different nomographs for Pasquill's coefficients for plume model and puff model.
What I want know is: whether can I use same coefficients for both plume and puff models? If they are different, then can anybody suggest me where can I get the equations for Pasquill's dispersion coefficients for puff model. I got the equations for plume model.
cheers
sskumar

[mbeychok]

sskumar:

You sent me this question by the private messaging system and I responded. I don't know whether or not you received my reponse, so I will repeat it here:

It is my understanding that the CalPuff model has options for using:

(1) the standard Pasquill-Gifford rural coefficients for ground releases or releases from stacks less than 100 meters high.

(2) the Briggs rural coefficients for tall stack releases (i.e., 100 meters high or more)

(3) the McElroy-Pooler urban coefficients

(4) Internally calculated dispersion coefficients derived from various meteorological parameters.

If you want more detailed information or the specific equations, I suggest that you contact:

Mr. John Scire
Earth Tech Inc.
Phone: 508-371-4270
E-mail: jss@src.com

Earth Tech distributes and supports the CalPuff model for the U.S. EPA and John Scire is the contact person at Earth Tech.

There is a user's manual for the CalPuff model. It is the U.S. EPA publication EPA-454/B-95-006 and I assume that you can obtain a copy from Earth Tech.

[sskumar]

Mr.Milton:
Thank you very much for your response and also for the response you gave to my PM to you. This question here is little bit different from what I had asked through PM.
What I want to know is: whether can I use same dispersion coefficients for both plume and puff models. I got the equations for PG rural coefficients, Brigg's rural coefficients and McElroy-Pooler urban coefficients. Can I use these equations both for puff and plume models. Why I am asking this is that I have seen different coefficient values for puff and plume models in a reference book.
Thank you,
Regards
sskumar

[mbeychok]

sskumar:

Once again, I advise you to contact Mr. Scire at Earth Tech. He is a well-known expert on dispersion modeling in general and on puff models specifically.

[sskumar]

MILTON:

I am sorry to say that there is no response yet from the contacts given by you for my query. But I could find the equations for puff model from the following link : toxic release and gas dispersion model

You only suggested this link in some other thread. Please tell me whether these equations are reliable or not.

Thanks in advance

Regards
sskumar

[mbeychok]

sskumar:

I have just read Dr. Ludlow's Power Point presentation on "Toxic Release and Dispersion Models". I really can not pass judgement as to the reliability of his puff model dispersion coefficients. I suggest you contact him directly at campus.umr.edu/chemengr/Faculty/Prof_site/Ludlow.htm

As for my having suggested the above presentation in some other thread, that is incorrect. This is the first time that I have read it.

What I did suggest in another thread was his Power Point presentation about Flammability Limits.

[sskumar]

MILTON:

Thank you very much.

You are correct, from the suggested link in the "Flamability Limits" thread, I got the other link to dispersion coefficients.

Regards
sskumar