Using chilled air to cool water

In summary, the group is looking for a way to cool a large volume of seawater in their aquaculture facility. They are considering using chilled air instead of ambient air and are seeking an equation to calculate the amount of chilled air needed. However, it is suggested that using chilled water or evaporative cooling would be more efficient and cost-effective. The water temperatures reach 23C and can reach up to 40C during the day, while night temperatures can be as low as 10C. The use of heat exchangers has been deemed too expensive, but the idea of using cold air for aeration has been brought up as a potential option. However, it is noted that this may not be as effective as other methods and
  • #1
saseafoods
2
0
We are looking to chill large volumes of seawater using chilled air. Does anyone know of an equation that may help us work out how much chilled air would be required to cool the water?

To give you some background to the project, we are an aquaculture facility pumping approx 800L/sec of water throughout the farm. We are trialling the use of compressors and diffusers to increase oxygen levels in the water. However, we would also like to reduce our water temperatures by 1-2C during the middle of summer. One thought was to use chilled air (-20C) instead of ambient air.

Does this sound feasible? Any suggestions?

Cheers,

Ben
 
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  • #2
Welcome to PF.

It would be more efficient to use chilled water and heat exchangers to chill the water. But it would be even more efficent to use evaporative cooling (cooling towers) to do it.

What are the initial water temperature and night-time air temperature and humidity?
 
  • #3
Thanks.

Peak water temperatures reach 23C, although there is very little fluctuation throughout the day (1C max). Daytime air temperatures can reach 40C with night temperatures as cool as 10C.

Heat exchangers have been investigated but are cost-prohibitive for the volume of water we are using. As we are aerating the water in this trial, the idea of using cold air instead of ambient was one that was thrown up as a cheap way of possibly cooling the water. Do you think this would work?
 
  • #4
if you use air blowing, the primary cooling would be from increased evaporation rates instead of heat transfer from water to air, so cooled air should not have significant advantages over ambient air while being significantly more expensive.
 
  • #5


I would recommend using the specific heat capacity equation to calculate the amount of chilled air needed to cool the water. The equation is Q = mcΔT, where Q is the amount of heat transferred, m is the mass of the water, c is the specific heat capacity of water, and ΔT is the change in temperature. You can use this equation to determine the amount of chilled air needed to cool the water by 1-2C.

However, I would also suggest considering other factors such as the heat transfer coefficient and the temperature difference between the air and water. These factors can affect the efficiency of the cooling process and the amount of chilled air needed.

In terms of feasibility, using chilled air to cool large volumes of seawater is definitely possible. It is commonly used in industrial processes and aquaculture facilities. However, it is important to carefully consider the cost and energy consumption of using compressors and diffusers to generate chilled air. You may also want to explore alternative methods of cooling, such as using a heat exchanger or a cooling tower.

Additionally, I would recommend consulting with experts in the field of aquaculture and heat transfer to ensure the most effective and efficient method of cooling is chosen for your specific facility and needs. Good luck with your project!
 

1. How does using chilled air to cool water work?

Using chilled air to cool water involves passing cold air over the surface of the water to lower its temperature. This is typically done using a heat exchanger, which allows for the transfer of heat between the air and the water. As the cold air passes over the water, it absorbs heat from the water, lowering its temperature.

2. What are the benefits of using chilled air to cool water?

There are several benefits to using chilled air to cool water. First, it is a more energy-efficient method compared to traditional methods of cooling, such as using refrigerant or water chillers. Second, it is a more cost-effective solution, especially for smaller-scale applications. Finally, using chilled air can also help improve the quality and taste of the water by reducing the growth of bacteria and algae.

3. Can chilled air be used to cool any type of water?

Yes, chilled air can be used to cool various types of water, including drinking water, industrial process water, and wastewater. The method of using chilled air to cool water is versatile and can be adapted to different systems and applications.

4. Are there any limitations to using chilled air to cool water?

While using chilled air to cool water has many advantages, there are also a few limitations to consider. One limitation is the temperature differential between the air and the water. The greater the difference, the more efficient the cooling process will be. Additionally, the humidity and airflow rate of the chilled air can also impact the cooling efficiency.

5. Is using chilled air to cool water environmentally friendly?

Yes, using chilled air to cool water can be considered an environmentally friendly method of cooling. It does not use harmful refrigerants or chemicals and is more energy-efficient compared to other cooling methods. Additionally, using chilled air can also help reduce water usage, making it a more sustainable solution in the long term.

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