Jordan Ruff is product line manager, Monitoring and Controls for Xylem Inc. He holds a Bachelor of Science degree in mechanical engineering from Duke University and completed the Advancing Business Acumen Program at the University of Pennsylvania – The Wharton School. For more information, visit www.bellgossett.com.
System optimization is the process of evaluating pump systems to identify opportunities for improvements that will reduce energy consumption and increase reliability. Improving a single component—like installing a more efficient motor—will do little to improve overall system efficiency. Engineers seeking to design mechanical systems for commercial buildings that lower energy consumption, reduce maintenance and extend the life of system components must evaluate how all pump components work together to ensure they are selecting the most efficient pumps for the application.
Greater pump system efficiency achieved through system optimization will improve reliability and lower operating costs by reducing wear and tear. It will also decrease downtime and costs associated with lost production, maintenance and repairs, while extending equipment life. Here are three ways to boost pump system optimization.
1. Use Multiple Pumps
When multiple pumps operate as part of a parallel pumping system, there can be opportunities for significant energy savings. Multiple pumps in parallel are well suited for systems with high static head.
Some advantages of multiple pump arrangements are flexibility and the ability to meet changing flow needs efficiently in systems with high static head. Another advantage is system redundancy. One pump can fail or be taken offline for maintenance while the other pumps support system operation. When identical parallel pumps are used, the pump curves should remain matched. Therefore, operating hours should be the same for each pump, and reconditioning should be done at the same time for all pumps.
With a series of identical pumps placed in parallel, the number of operating pumps can be changed according to system demands. Because the pumps are the same size, they can operate together, serving the same discharge header. If the proper pumps are selected, each pump can operate closer to its highest efficiency point. An added flow control benefit of parallel pumps is that a system curve remains the same whether one or several pumps are operating. What changes is the operating point along this system curve.
2. Switch to Smart Pumping
While installing drives and controls on existing pump systems can deliver improvements in efficiency and reliability, the emergence of pumps with embedded intelligence is a critical step forward in the evolution of performance management and pump system optimization.
Intelligent pump controllers can automatically configure a system with the optimal settings for the application, taking the guesswork out of the process.
Systems can be customized with pump protections and for multiple pump operation. Curve control technology relies on pump-specific algorithms, which can accurately predict where a pump operates on its curve. Using speed, torque and power data to know where the pump operates on the curve, sensorless pump controllers can be set up to take action based on those factors.
Area control uses physical sensors to embed the actual pump curves into controllers, giving the controller an unprecedented view of the pumps and the system and how it is performing. Now, the controller is not just responding to the need for additional flow, but it can also look at that the pumps in the arrangement to decide the most efficient way to get that extra flow.
Embedded electronic drives expand the efficiency island of the pump, which is the area where the pump is operating within its preferred operating range. This maximizes flexibility and enhances system performance as the pump system adapts to user needs in real time, ensuring optimum performance at all times. The drive also enables the size of the motor to be reduced, resulting in a more compact footprint.
Electronically commutated motors (ECMs) are another variable to consider for pump system optimization. ECMs can reduce energy consumption by as much as 80 percent without sacrificing performance.
Today’s ECM circulators use a permanent magnet motor design and variable speed technology to adapt automatically to system demand. Infinitely variable speeds means optimized system performance while drawing the least amount of energy possible.
When paired with technologically advanced drives and controls, pumps with ECM technology enable designers to optimize hydronic systems for the lowest total energy use.
3. Access Advanced Selection Tools
Proper system design is critical to minimizing life-cycle costs and reducing a system’s power consumption.
Online selection tools that enable designers to choose all system components within a single integrated tool ensure the most efficient hydronic system design.
Advanced selection tools include intuitive features to assist in system design. One market feature allows users to search pumps by constant or variable speed to discover and select products that will deliver optimal performance within a hydronic heating, ventilation and air conditioning (HVAC) or plumbing system. Variable speed technology allows the pump to adjust operating speed and respond smoothly and efficiently to fluctuations in demand.
The online system selection tool is also the only one available that includes part load efficiency value (PLEV) selection criteria, a calculation that helps system designers gauge true pump performance by measuring the efficiency of the pump at partial flow rates.
Flow requirements fluctuate constantly based on the heating and cooling needs of a building at any given time.
However, with the traditional pump selection approach, industry professionals select pumps at 100 percent load conditions, although a pump only operates there 1 percent of the year.
When combining efficient pumps with selections based on PLEV, system designers can maximize operational performance while realizing energy cost savings.