Regardless of your application requirements, understanding the major factors when sizing a cooling system is crucial to obtaining the right water chiller fit with proper cooling capacity. Pairing this information again and again can help improve efficiency, reduce frustration and even correctly re-purpose existing systems when necessary.

for example, the most important factor in choosing a cooling system is how much cooling capacity you need. And firstly you have to determine the amount of heat rejection into the cooling loop. An undersized chiller has the potential to create issues such as:

  1. The chiller will not provide fluid at the desired temperature.
  2. The system being cooled suffers in performance or experiences a catastrophic failure.
  3. Over-temperature alarms are triggered, potentially shutting down the system and process. (If over-temperature automatic shutoff is not included, the chiller can be damaged.)

Typically, the manufacturer of the equipment requiring cooling will provide the necessary specifications to size a chiller. If the information is not available, or if the process is an in-house design, then the heat load can be determined experimentally or theoretically. Experimental results are preferred for their accuracy. If experimental measurements are not practical, theoretical methods can be applied. They are inherently conservative, however, and they typically result in an oversized system.

Experimental Method. The equation is:

Q = m x CP x ΔT

Using two thermocouples, a flowmeter in combination with a cooling fluid that has known properties, and a pump (to collect inlet/outlet temperatures and flow rate data) will allow you to determine values for these variables so Q can be derived.

Theoretical Method. This method uses the first law of thermodynamics (conservation of energy). If electricity is the only form of energy entering your system, it can be conservatively assumed that all the power going into a device is being given off in the form of heat. A significant portion is consumed by equipment operation, but this is a conservative approach, limiting any potential for under-sizing.

For theoretical method, the equation is:

P = V x I


Note: For a system using three-phase power, the result must be multiplied by three.