Retrofit

Retrofitting Strategy	Supply and return chilled water temperature differential control with zone control valve
	The installation of the automatic valves can improve the low Delta-T syndrome (small temperature difference between supply and return chilled water across terminal devices) and ultimately reduces energy consumption.
	Consideration
	Pump energy can be reduced as the flow will be automatically driven by demand. Installation of power meter, temperature differential sensors together with the flowmeter and VSD devices for monitoring the power and W/L/s of air-conditioning pumps (Figure 2). It can also reduce the need for system balancing and enhance the temperature control of the terminal devices. Installation of power meter, temperature sensors, and flowmeter or differential pressure sensors for monitoring the power, cooling energy and COP of chiller (Figure 1).
	Estimated Saving
	For Chillers [(DT_POST – DT_PRE)QBLDG / 5.5] 1/COP_CH Where COP_CH = 0.605COP_CH_SM + 0.395COP_CH_WN COP_CH_SM = (COPa_SM + COPb_SM)/2; COP_CH_WN = (COPa_WN + COPb_WN)/2 QBLDG = 0.605[0.77(0.88NCH_SMQCH_SM + 0.12NCH_WNQCH_WN)] + 0.395[0.596(0.184NCH_SMQCH_SM + 0.816NCH_SMQCH_SM)] For VSD CHWP circuit (SkW_CHWP_PRE – SkW_CHWP_POST) OPHR,yr Where SkW_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_CHWP_WN) SkW_CHWP_POST = (DT_PRE/DT_POST)^1.35S kW_CHWP_PRE 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/wk52 Please click HERE to view the list of terminology.