Fundamentals

[shameem]

HI!

We are working in a pharmaceuticals project.At that project we suggest a 100TR air cool type chiller and we decide, we will use chill water directly from chiller to AHU.But engineers and consultants of that pharmaceuticals are suggesting that first take chill water to a large tank from chiller then take those water to AHU,They telling us this is more effective because at that case they will able to use chill water for other purpose and quality of chiller will be improved.Are they right? According to me and our engineers,Chill water will loose heat and AHU performance will decrease.

[Yuri B.]

Hello.
I believe they are right; the chiller's equipment would last longer as there would be less cyclings, and the chiller's work in general would be more efficient. Only the qwestion remains whether the chiller is able to also handle additional load, besides that of the AHU's.

[Brian_UK]

The buffer tank should not be an additional load as it will be well insulated.

It is required to maintain steady conditions for the chiller.

[Peter_1]

...the chiller's equipment would last longer as there would be less cyclings, and the chiller's work in general would be more efficient. Only the qwestion remains whether the chiller is able to also handle additional load, besides that of the AHU's.

I disagree this: if your chiller has capacity steps where the smallest step matches +/- the smallest load, then there will be now problem at all.
Why will it be more efficient?
Every unit is calculated with some margin and additionally for max load which rarely happens.

[Yuri B.]

I see many two-compressors Climavenetas - without or with a small water receiver, and the both compressors come in at least fifteen times an hour. This is efficiency?
Installations have been being made as cheap as possible.

[solas]

Hi

The primary reason for considering a buffer vessel is to reduce the number of times the compressor is engaged, thus prolonging the service life of the chiller.
A number of factors should be considered when designing cooling water systems and and integrating buffer vessel.

1. chiller characteristics - single stage or multi stage compressor. Singe stage invariably require buffers to inhibit cycling. multi-stage can regulate output to match load and may operate fine without a buffer.

2. systems water content - the greater the systems water content (circuit pipework & heat exchangers), the less chance a buffer is required.

Standing losses (cooling loss) for buffer vessels are normally low, providing they incorporate appropriate thermal insulation and are not oversized - They do not normally impose a load issue on the chiller.

Based on your requirements, i.e production unit cooling and possibly low water content, I would recommend a buffer help limit compressor starts/hour.

From an economic point of view, you could install many buffers for the price of replacing a single failed compressor.

I hope this helps.