Trane TRG-TRC016-EN Heat-RecoveryChiller, notes, System Variations, period three, Heat Recovery

period three

System Variations

notes

nIn a system with an alternative-fuel chiller, such as an absorption chiller, preferentially loading the alternative-fuel chiller during times of high electricity costs minimizes system energy cost.

Heat-Recovery Chiller

heat-recovery condenser

standard condenser

evaporator

Figure 76

Heat Recovery

Heat recovery is the process of capturing the heat that is normally rejected from the chiller condenser and using it for space heating, domestic water heating, or another process requirement. Heat recovery has been successfully applied in virtually all types of buildings, including hotels, schools, manufacturing plants, and office buildings. It typically provides an attractive return on investment for building owners. The use of heat recovery should be considered in any building with simultaneous heating and cooling requirements, or in facilities where the heat can be stored and used at a later time. Buildings with high year-round internal cooling loads are excellent opportunities for heat recovery.

Additionally, ASHRAE/IESNA Standard 90.1–1999 (Section 6.3.2) includes restrictions on the amount of reheat that can be performed in an HVAC system unless it is recovered heat. It is therefore likely that heat recovery will be used more in the future.

Heat recovery can be applied to practically any type of water chiller. It can be accomplished either by operating at higher condensing temperatures and recovering heat from the water leaving the standard condenser, or by using a separate condenser, as shown in Figure 76 for a centrifugal chiller. In smaller chillers, heat recovery is sometimes accomplished using a device called a desuperheater. A desuperheater is a device that is connected to the refrigeration circuit between the compressor and condenser to recover heat from the hot refrigerant vapor.

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