Retrofit

Retrofitting Strategy	De-centralised chilled water distribution system with zone in-line pump
	Central chilled water systems use large central pumps to deliver chilled water to terminal devices such as air handling units (AHUs) and fan coil units (FCUs). Adequate amount of chilled water for the terminal devices is controlled by adjusting the pressure drop across the control valves. Decentralised pumping systems replace the large central pumps with small in-line pumps to the terminal devices which will pump just the right chilled water flow through it for cooling the conditioned space. It will save energy by having a lower pressure head.
	Consideration
	The converted system requires fewer resources for balancing and RCx. The conversion process is relatively complicated and should be well-planned. 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 + SkW_DCHWP_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) SkW_DCHWP_POST = 0.605LF_SM,POST(0.88NDCHWP_SMkW_DCHWP_SM + 0.12NDCHWP_WN* kW_DCHWP_WN) + 0.395LF_WN,POST(0.184NDCHWP_SM kW_DCHWP_SM + 0.816NDCHWP_WNkW_DCHWP_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 For VSD at specific speed: LF_SM = 0.88(Hz_SM/50)^1.35 +0.12(Hz_WN/50)^1.35; LF_WN = 0.184(Hz_SM/50)^1.35 +0.816(Hz_WN/50)^1.35 OPHR,yr = hr/dayday/wk52 Please click HERE to view the list of terminology.