Trane SYS-APM001-EN manual Retrofit Opportunities, Applications Outside the Chiller’s Range

System Issues and Challenges

Retrofit Opportunities

A tremendous retrofit opportunity can be realized if the low-flow concepts discussed in the chapter “System Design Options” on page 27 are utilized. Building owners may need to increase the capacity of an existing system, for example, in response to a building addition. In many of these buildings, the condenser water system (piping, pump, and tower) is in good condition, but is considered to be too small. By changing from traditional design conditions, the existing infrastructure can often be used while still providing additional capacity. A detailed discussion of this starts on page 37.

Applications Outside the Chiller’s Range

Designers may wish to use chillers to provide cooling for which the flow rate or temperature requirements are not within the allowable ranges of a particular chiller, even though the chiller has adequate capacity. This often occurs with manufacturing processes. Let’s look at two examples showing system designs that can satisfy the desired conditions.

Flow rate out of range

A plastic injection molding process requires 80 gpm [5.1 L/s] of 50°F [10°C] water and returns that water at 60°F [15.6°C]. The selected chiller can operate at these temperatures, but has a minimum flow rate of 120 gpm [7.6 L/s]. The following system in Figure 51 can satisfy the process. Decoupling the chiller from the process load allows the water flow to be different, ensuring that the flow through the chiller is within acceptable limits. With a single chiller system, one pump and a three-way valve gives the same results.

Figure 51. Flow rate out of range for equipment

50°F [10°C]

80 gpm [5.1 L/s]

50°F [10°C] 120 gpm [7.6 L/s]

Bypass

Pipe

Chiller

56.7°F [13.7°C]

120 gpm [7.6 L/s]

Constant Volume Pump
50°F [10°C]	Process
40 gpm [2.3 L/s]	Load
60°F [15.6°C]
80 gpm [5.1 L/s]

Constant Volume Pump 120 gpm [7.6 L/s]

84 Chiller System Design and Control SYS-APM001-EN