These results are similar to an analysis by Trane, which showed that varying condenser water temperature with outdoor air wet-bulb temperature resulted in lower total energy costs than the design condenser water temperature or the minimum condenser water temperature that the chiller could accept. Source data: Trane, 2000, Water System Design and Operation”, CTV-SLB005-EN. “Chilled All Variable Flow Cooling Plants Traditionally, cooling plant pumps, fans and chillers were driven with constant speed motors. Load following capability was provided by bypass, mixing, staging and on/off control. Today, load following capability can be provided by varying the flow of the pumps, fans and chillers with variable frequency drives. Variable flow control can significantly reduce energy use over traditional constant flow systems. The figure below shows an all variable-speed cooling plant. Variable-speed cooling plants have been documented to use as little as 0.5 kW/ton at high loads and 0.3 kW/ton at low loads (Erpelding, Ben, 2008, Chiller Plant “Monitoring Performance”, ASHRAE Journal, April, pp. 48-52.)
These results are similar to an analysis by Trane, which showed that varying condenser water temperature with outdoor air wet-bulb temperature resulted in lower total energy costs than the design condenser water temperature or the minimum condenser water temperature that the chiller could accept. Source data: Trane, 2000, “Chilled Water System Design and Operation”, CTV-SLB005-EN. All Variable Flow Cooling Plants Traditionally, cooling plant pumps, fans and chillers were driven with constant speed motors. Load following capability was provided by bypass, mixing, staging and on/off control. Today, load following capability can be provided by varying the flow of the pumps, fans and chillers with variable frequency drives. Variable flow control can significantly reduce energy use over traditional constant flow systems. The figure below shows an all variable-speed cooling plant. Variable-speed cooling plants have been documented to use as little as 0.5 kW/ton at high loads and 0.3 kW/ton at low loads (Erpelding, Ben, 2008, “Monitoring Chiller Plant Performance”, ASHRAE Journal, April, pp. 48-52.)