Temperature Control Of Processing Water

Eh?

There isn't a food grade chemical that can be used to do this. A refrigeration plant is required!

http://en.wikipedia.org/wiki/Refrigeration

I am not aware of any chemical that can do this cost-effectively. You can use nitrogen but that's expensive.

We use heat exchangers for cooling our process liquids. The cooling medium is chilled water which we cool to around 8°C.

Have you thought about using CO² bubbled through the water? Relatively cheap and can be introduced via a stainless steel diffuser at the bottom of the tank which will aerate the water while mixing it and the temperature can be monitored near the top of the tank. You might even be able to automate the system by a feedback control to the CO² inlet valve.

CO₂ will not aerate the water, it will carbonate it instead. The pH will drop, and the agitated water will achieve the wet-bulb temperature of the surrounding air, over time, howsoever the agitation is provided.

Wasn't this question, posed as an answer to the fish delivery, holding tank question; just two weeks ago?

Wswrwbwm

When you talk about processed water in a food plant & bringing down its temperature from 49-15 deg Centigrade with the help of addition of chemicals or injection of gases such as Nitrogen , CO2 as such might affect the water quality ,Hence I suggest you to check your actual demand and install a pump in series with a heat exchanger in case chilled water is available. The system can be designed to reduce the temperature it can be open loop or a closed loop system depending upon your requirement .Or the other way you can install a pump in series with a chiller/cooler can be designed to reduce the temperature it can be open loop or a closed loop system depending upon your requirement

Hope this will be helpful

Ayub.A.Ismail

I would be very hesitant to use any sort of chemical to cool down water that I used in a food plant. CO2 addition will make the water acidic and you will be replacing everything that comes into contact with it shortly after that. Direct addition of nitrogen will cool it down but again, I wouldn't do that either. Why not install an exchanger downstream of the holding tank and cool your water that way? Put a closed loop on the other side that uses a nitrogen chilling tower or a mechanical refrigeration unit. Note that neither of these will be free and mechanical refrigeration units consume power and usually some other sort of medium to condense the refrigerant.

...refrigeration unit...

Quite.

http://www.dhmo.org/facts.html

You could accomplish your goal of using a chemical by adding ice water or dry ice.

Assuming the ice is at 0degC and ignoring, for illustrative purposes, the energy change upon ice melting, it would need 34 parts of ice to every 15 parts of water to achieve the temperature required simply by mixing. Either:

• The tank is going to need to be 49/15 larger, or
• only 15/49 of the incoming water needs to be processed in the same tank and 34/49 goes to waste.

In either case, chemical treatment costs to produce a food-grade water will go up by a factor of 49/15, unless the ice is made from the food-grade water. Hmmmmmmm.

Dry ice will carbonate the water, it being solid CO₂ [#3 and #4 above]. The proportions will be different, as the temperature and thermal capacity of CO₂ is different from water, and the resulting CO₂ vapour will need to be exhausted safely somewhere, as it is an asphyxiant. Hmmmmmmmmm.

Oh, and how is the ice/dry ice to be produced? Hmmmmmmm.

A refrigeration system still looks a good bet!

I agree here and most chemicals that react with water are not food grade and are exothermic.

You gave us: 60 m3 of water at 49 °C that needs to cool down to 15 °C.

Q = m Cp ΔT

Where:

Q = energy required

m = mass of water

Cp = specific heat of water

ΔT = change in temperature

Find a text book on thermodynamics.

In order to provide you with the energy required to cool the water, we would need to know the rate of water flow into the tank or is this a batch operation where you just fill the tank, cool the water, dump the water, and repeat?

Stephan