Answers
1Centrifugal, helical-rotary, reciprocating, and scroll
2Air-cooled chiller advantages include lower maintenance costs, a pre- packaged system for easier design and installation, and better low-ambient operation. Water-cooled chiller advantages include greater energy efficiency (at least at design conditions) and longer equipment life.
3False. The IPLV equation was derived to provide a representation of the average part-load efficiency for a single-chiller system only.
4Three-way modulating control valve, two-way modulating control valve, and face-and-bypass dampers
5When only one chiller is operating, warm return water continues to flow through the non-operating chiller and mixes with the chilled water leaving the operating chiller. The temperature of the mixture of these two streams is higher than the desired supply-water temperature, possibly resulting in building comfort or space humidity control problems.
6Constant; variable
7Two-way modulating control valves
8Turn on
9To ensure that the water flow through the system remains above the minimum flow limit of the operating chiller(s)
10Preferential loading is typically most beneficial in the following scenarios:
nIn a system that has a high-efficiency chiller along with several standard-efficiency chillers, the high-efficiency chiller can be preferentially loaded to reduce system energy consumption.
nIn a system with a heat-recovery chiller, preferentially loading the heat-recovery chiller maximizes the amount of heat recovered, thus reducing the overall system energy consumption.
nIn a system with an alternate-fuel chiller, such as an absorption chiller, preferentially loading the alternate-fuel chiller during times of high electricity costs minimizes system energy cost.
11The swing chiller is alternated on and off between the larger chillers' operation, in order to serve as a smaller incremental step of loading. This sequence more favorably matches the capacity of the chiller plant to the system load and operates the fewest, and smallest, pieces of ancillary equipment (pumps and cooling towers) at any system load.
