Retrofit

Retrofitting Strategy	Conversion to primary variable flow system
	Conventional de-coupler or differential by-pass chilled water system may result in a low differential temperature difference across the chillers, especially during part load operations. Converting the chilled water system into one single loop with variable flow rate (variable primary flow) can maintain an appropriate temperature across the chillers and enhance the overall efficiency of the chillers. For de-coupler system, after conversion, it can reduce the overall system pressure due to elimination of one set of pump accessories such as strainers and valves.
	Consideration
	The converted plant will reduce space and resources for maintenance. Minimum chilled water flow for the chiller to be maintained as referred to the chiller requirement. Installation of power meter, differential pressure sensors together with the flowmeter and VSD devices for monitoring the power and W/L/s of air-conditioning pumps (Figure 2).
	Estimated Saving
	(SkW_CHWP_PRE – SkW_CHWP_POST) OPHR,yr Where S kW_CHWP_PRE = 0.605LF_SM,PRE(0.88NCHWP_SMkW_CHWP_SM + 0.12NCHWP_WN* kW_CHWP_WN) + 0.395* LF_WN,PRE (0.184NCHWP_SMkW_CHWP_SM + 0.816NCHWP_WNkW_CT_WN) SkW_CHWP_POST = 0.605LF_SM,POST(0.88NCHWP_SMkW_CHWP_SM + 0.12NCHWP_WN* kW_CHWP_WN) + 0.395* LF_WN,POST(0.184NCHWP_SMkW_CHWP_SM + 0.816NCHWP_WNkW_CHWP_WN) For CSD: LF_SM = LF_WN = 1, For VSD: LF_SM = 0.795, LF_WN = 0.562; For EC or DC-motor: LF_SM = 0.71, LF_WN = 0.38 OPHR,yr = hr/dayday/wk*52 Please click HERE to view the list of terminology.