sizing system suction/ventilation stall

[TommasoFacciorusso]

save Tutti;as from title, I would need community support for sizing of a suction/ventilation system for a zootechnical stall, then proceed, but only in a second moment, at air filtration and air conditioning.

I am at the end of the three-year course in engineering, and I find myself stuck in the development of the thesis; ahimè, I thought the work was easier, but comparing with reality I realized that I lack some skills to deal with this issue.

In particular, I would like to see if there are some GuidelinesOf the standard, or even only of manuals or theory books who can study to understand how realize the design, even far from the application reality and therefore ideal, route me in the right direction.

Moreover, I would also like to know if there were software (computational fluid dynamics) that allow to simulate how much studied, giving evidence of the results, and perhaps that allow to automate the sizing (if you could automate, I would have solved much of the difficulties).

It's my first post, so I hope to have followed the rules and to be expressed clearly; However, if further details are needed, do not hesitate to ask.

Of course. Thank you very much, and in advance, all colors that will read and give me a hand Just give me a few minutes.

Have a good day!

 

[Mito125]

I can't help you, but I remember this discussion that's pretty similar to yours, maybe there are a couple of tips to take note of:

PROGETTAZIONE VENTILATORE

Buongiorno a tutti. Vi spiego il mio problema. Devo realizzare il dimensionamento di un ventilatore centrigugo collegato ad un tubo di uscita alto max 5 mt e di una data sezione che posso decidere io.( Restando max in 1 mt ^2) Il mio problema è che poi l'aria deve andare a scaricarsi in ambiente...

www.cad3d.it

you probably don't have to make the fan but just check the pipelines, so it becomes much easier. for the cfd you can use ansys (from university you can access the student version). I follow to learn something new about the imperative.

 

[TommasoFacciorusso]

Thank you. @mito125!

I immediately give an eye to the link, and I begin to take confidence with the software.

 

[Mito125]

ansys is not that simple, I cfd never made it... I tried to see in some manual that I had if there was something dedicated but I didn't find anything to help you more specifically, I don't have any plant size... the maximum would be to find a plant already realized and understand how who before you came to the solution. . Unfortunately I can't do more...

 

[+forte]

buy this book you study it and you are affixed

https://www.amazon.it/impianti-termotecnici-openschool-tecnici-espansione/dp/8820378876

 

[TommasoFacciorusso]

buy this book you study it and you are affixed

https://www.amazon.it/impianti-termotecnici-openschool-tecnici-espansione/dp/8820378876

I find everything I need in one book?

 

[+forte]

Yes.
there is a lot of practice
there are many tables and exercises carried out

 

[paulpaul]

@tommasofacciorusso in addition to all the tips that have given you others, I would impose the work as follows:

1. determine how much air flow you need to recirculate: I am not an expert of stables, but perhaps there are applicable norms or rules, which you may find on the net in the form of a minimum number of hourly air exchanges, from which - knowing or hypothesized the volume of the stable - traces to the reach. this is the very first necessary data of each air circulation system;

2. build the load losses curve: You don't need a cfd, but a simple sw 1d that you can develop in excel by implementing the basic relationships of distributed and concentrated load losses. you have to hypothesize your air path, with lengths, curves, filters, etc., and go to see the loss coefficients of each (in literature you find a lot of data, but also in the sites of filter manufacturers for example). to build the curve you need to calculate the load loss for two values of any size: knowing that it is parabolic and passes by zero, you build the whole curve (there are also sw online or trial version that you can use for calculating losses);

3. individuals a fan (stiavelli, buds, etc.) with a curve such as to overlap to the previous about in the flow point referred to in point 1, verifying that the fan works in a correct area (result acceptable, manufacturers usually give the maps) of the curve.

This approach is rather simple and scholastic, but includes the fundamental steps for the sizing of a ventilation system: If your purpose is just to locate the commercial fan, I don't think you need any cfd.

Hi.

 

[TommasoFacciorusso]

Your emails Thank you very much for the answer.

1. determine how much air flow you need to recirculate: I am not an expert of stables, but perhaps there are applicable norms or rules, which you may find on the net in the form of a minimum number of hourly air exchanges, from which - knowing or hypothesized the volume of the stable - traces to the reach. this is the very first necessary data of each air circulation system;

On the first point we are perfectly in agreement, I will be myself to hypothesize a structure, or to refer to existing structures (avoiding to document me on rural buildings).

2. build the load losses curve: You don't need a cfd, but a simple sw 1d that you can develop in excel by implementing the basic relationships of distributed and concentrated load losses. you have to hypothesize your air path, with lengths, curves, filters, etc., and go to see the loss coefficients of each (in literature you find a lot of data, but also in the sites of filter manufacturers for example). to build the curve you need to calculate the load loss for two values of any size: knowing that it is parabolic and passes by zero, you build the whole curve (there are also sw online or trial version that you can use for calculating losses);

As far as the second point is concerned, it is the one on which I have greater difficulty.
Can you tell me one of the literature you can see? and maybe some of the computing software?
That's where I have the greatest knowledge. . .
I would have used the cfd to simulate the project... but, given the difficulty already existing, perhaps it is better to avoid putting another "flesh on the fire".

3. individuals a fan (stiavelli, buds, etc.) with a curve such as to overlap to the previous about in the flow point referred to in point 1, verifying that the fan works in a correct area (result acceptable, manufacturers usually give the maps) of the curve.

For the third point, developed the first two, there should be no problem: it will be to compare technical data sheets with the results obtained. confirm?

Thanks again for the support!

 

[ian3d]

to completion of point 1 and in anticipation of the conditioning system that you should develop at a later time, you should also take into account the following aspects:
- the stable is a unique place or if there are some separate
- number of animals present
- external environmental conditions and environmental conditions
- any internal heat sources, such as machines present, which should be disposed of or compensated

I am not an expert in hvac systems, but I think the ventilation and air conditioning system should be developed in parallel. if you size your plant only on the necessary air exchanges by law, then risk having to review it if you find out, for example, that to get a good environmental conditioning you need a lot more air or different points of diffusion

also with regard to the suction system, you should check whether the current legislation requires the passage through a filter or if the air can be discharged directly into the atmosphere. this depends on what you are aspiring and any impurities present

 

[paulpaul]

As far as the second point is concerned, it is the one on which I have greater difficulty.
Can you tell me one of the literature you can see? and maybe some of the computing software?

try to look at sf pressure drop. try to do research on duct google (hvac calculation, air losses, etc.): I tried and found several results. one of the most important features that must have a designer is knowing how to quickly find information, and the internet is a mine.. .
However, from your course of studies you should know the basic formulas for both calculation of concentrated and distributed losses (which apply to any fluid), and you should have all the tools to throw down two simple formulas: number of reynolds, hydraulic diameter, faciality, friction coefficients and concentrated load loss. If you don't have to be clear these basics...I see it hard without restudying them! few software could help you!

For the third point, developed the first two, there should be no problem: it will be to compare technical data sheets with the results obtained. confirm?

exact, it is about overlapping the curves of the fans at the curve of the plant resistors, and check the working point of the first.

 

[Mito125]

@tommasofacciorusso How are you? I would like to follow your progress and if possible then read your thesis

 

[TommasoFacciorusso]

@tommasofacciorusso How are you? I would like to follow your progress and if possible then read your thesis

ciao @mito125, thanks to the interest
I am proceeding with a first draft of theory (presumptions, motivations, etc...), a very rough draft, but for the design of the plant they are still far away.

In the meantime I'm looking for more literature, who knows the situation unblocks.
You can be sure I'll update you anyway!

 

[TommasoFacciorusso]

- the stable is a unique place or if there are some separate
- number of animals present
- external environmental conditions and environmental conditions
- any internal heat sources, such as machines present, which should be disposed of or compensated

- being the first work of this nature, and considering that the ideal way is to be preferred to the real and close to reality, surely it will be realized by hypothesize the stable as the only local; in fact, however, there are different environments, more or less communicating between them.
- As for the number of animals, we agree. It is an indispensable fact to quantify the gas mixture to aspire and filter.
- about the environmental, internal and external conditions, touch a sore button .. in the sense that, if I worked ideally, hiring them null, I would facilitate the work that, at a later time, could be perfected; If I wanted to consider them immediately, I would significantly complicate the job and I don't know if I can be able to do it independently.
Consider that, in most cases, the stables are open on the hips: imagine the air currents from the outside. They are a very important factor to consider in order to realize a real job, one of many others that however they would very much complicate the project, as I mentioned before.
- the same applies to whole plants/machines at the premises. theoretically, assuming a single environment would not exist, but if I extended the project also to the milking room, for example, I should consider all the equipment present.

I am not an expert in hvac systems, but I think the ventilation and air conditioning system should be developed in parallel. if you size your plant only on the necessary air exchanges by law, then risk having to review it if you find out, for example, that to get a good environmental conditioning you need a lot more air or different points of diffusion

I also agree on designing simultaneously and in parallel ventilation and possible conditioning. . I just have to decide whether to include it in work, or leave it out to not put too much meat on fire.

about air exchanges required by law, do you know where they can find legal and/or technical standards?
It's one of the hitches I'm seeing.

also with regard to the suction system, you should check whether the current legislation requires the passage through a filter or if the air can be discharged directly into the atmosphere. this depends on what you are aspiring and any impurities present

theoretically, considering how I said before many stables are open, filtering should not be provided by law... However it is one of the focus of the work, so I think I will insert filtering devices.
If you have suggestions, they are well accepted.

Thank you so much for all the support!

 

[TommasoFacciorusso]

try to look at sf pressure drop. try to do research on duct google (hvac calculation, air losses, etc.): I tried and found several results. one of the most important features that must have a designer is knowing how to quickly find information, and the internet is a mine.. .

thanks for the straights, I will look for immediately.
internet is a real mine, you are perfectly right; But, in fact, you must know how to look and know well what to look for.

However, from your course of studies you should know the basic formulas for both calculation of concentrated and distributed losses (which apply to any fluid), and you should have all the tools to throw down two simple formulas: number of reynolds, hydraulic diameter, faciality, friction coefficients and concentrated load loss. If you don't have to be clear these basics...I see it hard without restudying them! few software could help you!

you are giving me so many important straights that I couldn't easily get on my own... in my cdl you do not study all these themes. .
Of course, they may also be my gaps, but I do not think I remember some of the knowledge indicated.

Thank you so much!

 

[ian3d]

if you are still looking for standards or regulations, you can check on the website of ashrae (American). There is a section on guidelines and regulations, I don't know if even in the field of your interest and how they are followed in Italy

doing an internet search with “ahrae italia” you will find some Italian associated entities that take back the standards

 

[TommasoFacciorusso]

Thank you. @an3d

 

[Mito125]

I tried to look at a method to solve your problem but I think I have some difficulty. I used the book "mechanical plants for the industry" of pareschi to come to head, having a chapter dedicated to ventilation systems. Something's not coming back, I hope someone can make me understand better.

It tells me that for the renewal of the air it is necessary to consider the only volume for a recommended number of air exchanges for that specific environment. from the values in the book table, using as a pigeon environment, I get a value between 6-10. This value multiplied by the volume of the environment returns me the volumetric flow of air v.

If we want to achieve a cooling of the environment without introducing a real conditioning, we must consider the thermal power produced in the environment q. I couldn't give a value to this q, excluding every machine and every operator and considering only animals, from the ashrae I found 2.5kw for each cow. So I should know how many cows are inside. summer is the worst season, because it drastically reduces milk production, so I should consider the maximum summer temperatures in the area where the stable is located. the internal temperature I want that always stays around the 24°C as always indicated on ashrae. the thermal power entering from the walls expressed in kw should depend on how the structure is made, but I could not calculate it.

with this data, I can calculate the v range and choose the suitable fan. with the due approximations I can obtain:
♪[ V \approx \frac{Q-Q_d}{\rho c_p (t_i-t_e)} \]in the summer season, we put q_d equal to zero. But then I don't consider the thermal indents anymore?

now comes the least clear part for me. I have to choose how to make the extraction. for simplicity and cost reduction, we lower a ceiling extraction plant. but where do I make the suction channels? How do I know what is the most loaded branch? in the book talks about the sizing of the pipelines a little fast, half page without even an example, I can't follow it.

We end up with the choice of the fan. note the flow rate (the v found above) and the required prevalence (where do I find the prevalence?), I go to choose a fan with adequate prevalence capacity. but nothing is specified.

It's the first time I've been trying to look at a plant like this, I've definitely made some mistakes, but I'd like to get something out.

 

[TommasoFacciorusso]

I tried to look at a method to solve your problem

Thank you. I don't know how to get rid of me.
I have to try to recover this book, although to what I understand it is very reductive somewhere... but it is already material from which to start!

maybe some other user can propose other manuals, maybe on the part of the sizing of the extraction plant.If you join them, something should come out.

volumetric flow of air v.

therefore the flow to be desired for the right environmental comfort, if so we can say, is easy.. Do I understand?

the minimum volume of the environment, at least that, should be defined in some technical norm relating to "animal welfare", always to be observed on the basis of the number of heads present in the breeding.
being that I can hypothesize everything freely, also this data should come easy.. If only I found the norm?

the thermal power produced in the environment q [...] excluding every machine and every operator and considering only animals [...] the thermal power entering from the walls expressed in kw should depend on how the structure is made, but I could not calculate it.

I'm trying, but I think I'm wearing... unless it works as a refrigeration plant.

Ideally, hoping not to say nonsense, I think it would be enough to consider the temperature difference between external and internal, the surface of thermal exchange (alias walls, floor and roof) and construction materials (their thermal conductivity, for accuracy). We are speculating that there are no doors to open and close, so a really ideal structure, does not enter and exit people, machinery, there are no lights or other heat sources. . .

In order to neglect everything, animals must be considered necessarily ?: safe are a beautiful source of heat, first for breathing.

from the ashrae I found 2.5kw for each cow [...] the internal temperature I want that always stays around the 24°C as always indicated on ashrae.

Would you tell me the exact rule you refer to?
I've been reading literature and documents for days now, and my brain has melted. . .
even the easiest notions to find escape my hinges.

in the summer season, we put q_d equal to zero. But then I don't consider the thermal indents anymore?

qd What is that? I couldn't understand. . .
and why do you put it zero in summer?

I ask you again, isn't it a fact that we can get with a reverse formula? I think you can have all the other variables from your reasoning. . .

now comes the least clear part for me. I have to choose how to make the extraction. for simplicity and cost reduction, I choose an extraction plant to the ceiling. but where do I make the suction channels? How do I know what is the most loaded branch? in the book talks about the sizing of the pipelines a little fast, half page without even an example, I can't follow it.

on this part planting helmet own... All I can do is hope in your directions.

extraction is the thing that's driving me crazy. I don't even know what shape to give the aspiring hoods, as well as where to place them.

We end up with the choice of the fan. [...] choose a fan with adequate prevalence capacity.

As long as we find the prevalence, and any other necessary data, I believe here we can proceed as it pointed out Your emails

3. individuals a fan (stiavelli, buds, etc.) with a curve such as to overlap to the previous about in the flow point referred to in point 1, verifying that the fan works in a correct area (result acceptable, manufacturers usually give the maps) of the curve.

Last... I think we're underestimating something important: the internal fluid to the stable is a mixture of gas, which will have to be subsequently filtered.
definitely coco2, ch4, n2o, o, h, n, etc.

Does this complicate things further?
If so, how much?

 

[Mito125]

the first v refers to the necessary air change for each environment. It's the air change with ideal temperatures, a kind of reservoir for always breathing air. always on the ashrae hvac applications you find that for each cow it is ideal to have a 5/7 square meters per animal. so you can decide how many items you have inside based on your structure. this is the minimum area for each animal.

you can avoid in my opinion considering the transient type openings and closing doors, and then consider (if correct) the value of 2.5kw for each cow (I am hypothesized cows). this value is always reported inashrae hvac applications .

q_d is the lost heat, the cows do not have winter problems, but the heat reduces the amount of milk produced and creates serious problems (always in the ashrae book you find a very discourse part that will surely be useful to stretch the thesis). I put it equal to zero because in summer you have no heat lost (in the book of pareschi says to put it equal to zero and it explains everything better, check your library to have access to everything).

for the hoods always look on the book of pareschi, choose the one with the spiovente roof with in the center the aspirator, simple and economic. I found nothing on the conduits. I'm stuck. We have to wait for someone who can move in this field.

I for now only looked at ventilation, on pareschi there is also part of air treatment but I didn't look at it since I still have the base to move on.