Air Conditioning of a Shopping Complex

[Samarjit Sen]

I have been asked to visit an existing shopping complex in one floor. It is not a Mall or a Multiplex. There are just a number of shops selling mainly clothes etc. Since there are a large number of members who are more in Air Conditioning, could some one help me with the following .

1. How do I calculate the heat load. I take only the shop areas and not the corridoors. Am I correct.

2. Do I consider the total load or consider 80% of the total load as some of the shops would remain closed.

3. The system would be multiple chiller plants. What should be the minimum capacity of each unit.

Please let me know your advice and suggestions. In case there is some books etc on such application, please do let me know.

With all my best wishes,

[frank]

Do you intend to air condition all the individual shops?

Is it an enclosed shopping area with entrance/exit doors or just a covered walkway between the shops?

How will you deliver the conditioned air - rooftop units? Ductwork? individual fan coils?

So many questions before I can understand the layout and how you want to do the job.

[Samarjit Sen]

It is en enclosed shopping area with entrance/exit doors and walkways between the shops. There are many a row of shops.

I propose to provide individual fan coil units for each shop. There would be a central chilled water plant from where the chilled water would be recierculated through the individual fan coil units.

A seperate duct would be provided for fresh air supply to the shops.

This is my idea and would appreciate if you guide me to a better one.

[Cofreth]

It is en enclosed shopping area with entrance/exit doors and walkways between the shops. There are many a row of shops.

I propose to provide individual fan coil units for each shop. There would be a central chilled water plant from where the chilled water would be recierculated through the individual fan coil units.

A seperate duct would be provided for fresh air supply to the shops.

This is my idea and would appreciate if you guide me to a better one.

How about the common area? you are installing an AHU to cool them? What kind of floor space do you have for housing the AHU or you are also using ceiling suspended AHU?
A few units of smaller capacity chiller will be better off, no doubt, higher in installation cost, but lower maintenance and operating cost.

[lana]

Hi Samarjit Sen,

There is a book called 'HVAC equations, data and rules of thumb'. I downloaded it from some where (i think some one introduced it in this forum). This book might help you.
It is 14 MB. If you can receive it then let me know and I will mail it to you.

Cheers

[Samarjit Sen]

Hello Cofreth,

I propose to install a Chilled Water Plant with fan coil units. I shall be visiting the site and get the necessary drawings. On the basis of the heat load, I propose to install multiple Chilling Plants. As far as my guess is , it is a pretty large area

[Samarjit Sen]

Hi Lana,

It is very nice of you to offer to send the Book to me. You can upload the book at www.yousendit.com to me at my e mail address. I do not know wether you are able to utilise this facility.

Should you require my address I can have the sent to you by PM or at your address.

[US Iceman]

Why not look into thermal storage and chilled water?

Designing a system with sufficient capacity is fairly common. One aspect of delivering a good project is also the cost of operation for the client or owner.

If you investigate the cost of electricity and if you have different time periods where the power is less expensive during the night and more expensive during the day, thermal storage may provide an good option.

This can also have some first cost economies. Using ice (or ice slurry) to cool water can mean smaller pumps, piping, air handlers, fans, and duct sizes. In effect, you use a greater TD for the water and air, which translates into smaller volume flow (water or air).

If you can use a lower supply water temperature of say, 1.1°C (34°F) or slightly lower to the fan/coil units you will also be able to supply a lower RH to the stores. This helps to make the people feel more comfortable ans the stay in the stores longer, spending more money. At least this is what I have heard from an associate who did this.

If you offer options that your competitors do not, the owner may see you as more involved and interested in his project. This is always better than "who has the lowest price?"

Just some thoughts to consider...

[Lc_shi]

I think Iceman's idea is a good choice but which will depend the time period electricity cost and the initial cost. it need more place to install the storage facility.

regards
LC

[Samarjit Sen]

Good Morning Iceman,

Thank you for your suggestion. You see in our country the rates for electricity is uniform wether it is day or night. Further in certain areas there is a restriction of using electricity for commercial purpose in the night.

However your concept is good and I will make the necessary enquiry and submit the offer accordingly.

[Samarjit Sen]

Good Morning Lana,

It just occurred to me that why don't you split up the files in two parts and have the same mailed to me in two separate files or convert this into a rar file which will reduce the capacity and mail the same to me..

[US Iceman]

Hi, (I'm working late)

You see in our country the rates for electricity is uniform whether it is day or night.

OK, in that case you can still use thermal storage with a slight difference in selecting the system capacity.

For this to work you need to know the cooling loads on a per hour basis. Sum these up and divide by 24. That tells you the refrigeration system capacity per hour.

When the cooling loads in the stores decrease at night, the compressor(s) are running at 100%. They are also running at 100% during the daytime.

What this does is decrease the required system capacity. Designing the system for only chilled water would mean you have to provide a higher capacity for the maximum daytime cooling loads.

However, if you have some reasons why the power may not be used at night, then the thermal storage idea will not work. You would soon run out of capacity during the daytime as the refrigeration would then be too small.

[Samarjit Sen]

It is not that the owners would not like to run the plant in the night. In some areas due to the shortage of electricity, supply to the commercial areas are restricted in the night. I have to find out if this law applies to this particular city and the location of the project.

The shopping complex is already there and has been operating for the last 30 years. They did not have Central AC system. Some had installed Split units. Now they are interested in having the entire area provided with Central AC system.

[lana]

Hi Samarjit Sen,

I have mailed the files to your account but an error occurred.
Please check your e-mail and let me know.

Regards
LANA

[momo]

I'm not a great fan of water systems (circulation calculations and flow adjustments, chemicals, corrosion, reduced efficiency etc.) but they have some advantages:
Ice storage, simple metering of consumed cooling water and billing A/C accordingly to individual shops (helps making people conscious of energy cost) use of heat from condensing units for pre-heating hot water supply - though solar could be used in India - the A/C will operate at all times and can be incorporated in the machine room to provide for food establishments.
Also Air/wind curtains - though highly priced here - help control air flows and insects without needing doors which hinder the entry of potential customers.

[Samarjit Sen]

Hi Lana,

I recieved both your mails with the attachments of the rar files of the books. Unfortunately after downloading, it could not be occured as their were some erros.

I shall try again today.

Thank you and best wishes,

[lana]

Hi there,

I have done as promised.
It will take time but hopefully you will get it.
Cheers

[Darshi]

lana,
Hi
I can't find a link to download "HVAC equations, data and rules of thumb"

I would like to have a copy and will appreciate if you can mail it to me too.

Thanks in advance
Darshi

[lana]

lana,
Hi
I can't find a link to download "HVAC equations, data and rules of thumb"

I would like to have a copy and will appreciate if you can mail it to me too.

Thanks in advance
Darshi

The file is big and it can not be mailed. When it is split into smaller files then an .exe file must be mailed with them but as you know .exe files can not be mailed even if they are renamed.

As you may noticed I could not send it to Samarjit Sen. This is not because I don't want to but simply I cannot, sorry.

I can try and send the whole file to you but there is no guarantee that you get it.

Cheers

[Darshi]

No probs, Thanks any way , Lana
LC had your link and he transfered the file on MSN .
Thanks a lot for useful data.