Water System Designs: What Is Going On Inside My Heat Exchange System?

 

The Standard Design of a Water Cooling/Heating System:

A cooling water system absorbs heat from one area and rejects to another area.  There are many different configurations and designs, but all cooling water systems accomplish the same objective: moving heat. Billions of gallons of water are used daily in commercial and industrial applications to accomplish this objective. Industrial uses of water include air conditioning and heating systems, furnace cooling systems, plastic mold heating and cooling systems, and refrigeration, compressor and welding machine cooling systems. Regardless of the application, all cooling systems have one objective: absorb heat from one area and reject it into another area.

Heat always follows the second law of thermodynamics: matter and energy flow from a higher concentration to a lower concentration. When water encounters a hot surface, heat flows from the hot surface to the water.  When the water encounters a cooler surface, it transfers the heat to the cooler surface.

 

 

Once Through Systems vs. Recirculating Systems

In a once-through system, water circulates through the system to absorb heat only once and is then passed to the drain. As water and sewage costs increase and environmental controls on discharge into streams, ponds, rivers and lakes are tightened, many once through systems are being replaced by recirculating systems. These systems can occur in many different configurations, but the primary purpose of absorbing heat from one area and rejecting it into another remains the same. The hypothetical simple recirculating system involves water pumped from a holding tank or sump through the equipment or machinery to be heated or cooled. The water absorbs heat from the equipment and carries it back to the sump where heat is rejected into the atmosphere by natural evaporation. Through the process of evaporation, heat is rejected to the atmosphere.  

 

Closed Loop Systems

Closed recirculating systems including chilled water loops and hot water boilers are commonly used to deliver hot or cold water to air handlers for heating and air conditioning or to industrial devices which require heating or cooling. Closed loops are an integral part of most comfort cooling systems and are responsible for delivering the heat or cooling to the air handlers which make the building comfortable for its inhabitants. Closed loops are also the most efficient method to deliver very low or very high temperature water to components in industrial applications. Most closed loops consist entirely of pumps, pipes and heat exchangers, although some systems involve open sumps to allow larger volumes of water. 

The water in closed loop systems should be regularly treated to ensure the heat exchange process is efficient and cost effective. To learn more about what Chardon can offer for your closed loop system, click here!

 

Cooling Towers

A sketch of a cooling tower's inner workings.Cooling towers can vary in size from several square feet to several hundred square feet, but all cooling towers have the same basic function: to increase the surface area of the air/water interface by breaking the water into droplets or thin films. This results in more efficient evaporation of water and therefore rejection of heat from the system. Several different tower shapes and interior designs have been developed to accomplish this.

 

The induced-draft tower has one or more fans located in the air outlet from the tower and air is pulled into the tower by fans located on top of the tower. The forced-draft tower (figure 9 and 10) has one or more fans located in the air intake to the tower and air is pushed into the tower by fans located on the side of the tower. 

Cooling water containing excess heat is pumped to the top of the cooling tower where it flows into a distribution pan. The bottom of the distribution pan has many small diameter holes. Water flows out of the pan through the holes into the interior of the tower which features a complex of packing or slats referred to as fill.  The fill increases the amount of water exposed to air by providing a large surface area for the water to traverse. Air from the fan is moved across the water causing increased evaporation, resulting in greater efficiency in removing heat from the water and rejecting it to the atmosphere.

 

Another method for increasing the surface area of the water involves the spray method wherein the water is pumped into spray nozzles located inside the tower which discharge water in the form of small droplets. Air is blown across the droplets which increases evaporation and heat rejection to the atmosphere. One common application of the spray methods is the fluid cooler. In this design, process fluid containing heat is circulated through a series of tubes suspended inside the cooling tower.   Cooling tower water is sprayed over the tubes where the heat is absorbed by the cooling water and rejected to the atmosphere by the evaporation process. 

Cooling towers are a part of complex water systems that can quickly foul up and cause building-wide issues and even shutdowns. How can Chardon meet your cooling tower service needs? Find out here!

Steam Boilers

A sketch of a steamboiler.Steam boilers can be considered a special type of closed loop wherein water is heated to the boiling point. Steam boilers are manufactured in a variety of configurations, but all consist of a chamber in which water is heated to the boiling point under pressure by the combustion of fuel. Steam is delivered to heat exchangers or air handler coils where the heat flows to the material being heated.   As heat is lost during this process, steam condenses back to water and is pumped back to the boiler. 

Steam boilers that are not properly treated can cost you thousands in fuel and energy. For more information about what Chardon can offer for your boiler, click here!

 

 

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