Chiller Technical Information 3-1. Types and characteristics of cooling water
3-1. Types and characteristics of cooling water
This section describes the types and characteristics of the cooling water used in standard heat exchangers.
An introduction to the types of heat exchangers available was given in “2-2. Liquid-cooled heat exchanger (liquid to liquid)”. When using a liquid-cooled heat exchanger, water with a good heat exchange efficiency can usually be obtained as a cooling medium. This section describes the types and characteristics of the cooling water.
Advantages and disadvantages of each cooling water
| Advantages | Disadvantages | |
|---|---|---|
|
Well water
|
・No usage fee or cheaper compared to tap supply. ・Water temperature is stable throughout the year ・Easy to secure a large flow rate |
・Drilling, pump installation and other initial costs are incurred ・Bacteria and algae breed easily ・Water volume and water quality vary depending on the location |
|
Tap water
|
・Water quality is constant throughout the year ・Easy to secure a constant flow rate throughout the year |
・Cost is high ・Water temperature varies with the season |
|
Cooling tower
|
・Saves water resources, lowering costs ・Low running cost because it used the vaporization heat of water ・Large-scale cooling of one whole building etc. is possible |
・Scales tend to occur because water evaporates and condenses into circulating water ・Algae and bacteria grows easily, causing slime ・Water temperature varies greatly depending on the season ・Flow rate decreases in summer when cooling is often used. |
|
Chiller water
|
・Saves on water bills and electricity bills ・Constant water volume and water quality ・Temperature and flow rate can be controlled according to the equipment ・Size can be selected according to the facility and operation
|
・Construction takes time and money during implementation ・Exhaust heat is generated when an air-cooled machine is installed indoor |
Classification by water quality
| Tap water |
Tap water is strictly controlled by the Water Works Act. The water quality must meet 51 standards. |
| Well water | Groundwater is pumped up for use as industrial water. The variance in the water quality may be large depending on the location where it is drawn. The water contains fungi and bacteria as the water quality is not treated like tap water, so algae and slime may occur easily. |
| Pure water | Almost all salts and residual chlorine are removed, and based on how the impurities are removed, the water may be known as RO water (water passing through a reverse osmosis membrane) or deionized water (water win the ions removed by an ion exchange resin, etc.) and so on. |
| Ultra-pure water | Ultra-high purity water that is theoretically close to 100% pure water in which organic substances, element particles and gases etc. that cannot be removed by the production methods of pure water are removed via a variety of processes. Known also as hungry water, it has a high capacity to dissolve substances, so it is used to wash silicon wafers in the semiconductor manufacturing processes of ultra-LSI etc., and the manufacture of pharmaceuticals and so on. |
Water quality problems that you may want to take note of
| Scales |
Scales adhering to and deposited inside the piping are insoluble components in the water. Scales are mainly inorganic materials such as calcium, silica, and iron rust etc., which either cause local corrosion when left untreated, or reduce the heat transfer rate and increase the operating costs when attached to the heat transfer surface of the tube inside the heat exchanger. |
| Slime | Chiller circulating water tends to become breeding grounds for the growth of microorganisms due to the water temperature and the loss of residual chlorine during circulation, allowing algae, bacteria and fungi (mold) etc. to breed in the water. These microorganisms and the viscous organic matter secreted from them are the causes of slime formation. Blockage caused by algae and slime can cause odors and health hazards. |
Previous item: 2-3. Direct cooling by chiller
Next item: 4-1. When there is a water path to the cooling object
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