Background

The Facilities Management team at the University of Nebraska-Lincoln (UNL) is continually exploring means to improve operational efficiency through technology adoption, workflow adjustment, and benchmarking. During a collaboration event at the 2018 Big Ten and Friends Conference team members attended a technical presentation given by the University of Virginia on the effectiveness of the Helios Tube Cleaning System® in UVA’s operations.
The results reported by UVA were compelling, and UNL began investigating how the Helios TCS™ could benefit their central plant operations.

Use Case

As is frequently the case, a Helios-equipped chiller would be compared with an identical “control” chiller operating without a tube cleaning system.  Both chillers had to be operating in close-proximity and under the same environmental factors, to enable the best-possible measurement & verification (M&V) protocols.

UNL structured the M&V evaluation to include a high degree of qualitative and quantitative measures. While data-based measurement of the energy savings was the highest priority, also closely considered was how the new system affected the workflow culture in the organization.

Specifically, UNL planned to measure:

• Effects on chiller energy efficiency – Quantitative.
• Workflow requirements associated with Helios Tube Cleaning System operation – Qualitative.
• Manual Chiller Tube cleaning requirements after Helios installation – Qualitative and Quantitative.

Successfully Integrating the new technology was one of UNL’s highest priorities to ensure the system was operated to its highest potential. To assist with the Helios integration, Innovas Technologies worked closely for the first year with the UNL operators and maintenance personnel, ensuring they were well-versed on managing the Helios operation. Specifically, Innovas Technologies personnel made bi-monthly visits to assist in ball change efforts and system inspection. This provided ample opportunity to train the operations and maintenance personnel to self-reliance in operating the Helios system.

Method of Analysis

The method of analysis involved two approaches. In the first method, Trend Condenser Approach Temperature would be measured. This is the simplest way to measure heat transfer efficiency of a heat exchanger.

The second method would simultaneously consider multiple factors affecting chiller efficiency including load, chilled water supply and entering condenser water temperature, and tube fouling. Data would then be plotted along performance curves at identical operating conditions to see how curves to shifted over time.

Results

From April 2018, the condenser served by the Helios TCS ceased to experience increases in condenser approach temperatures. The untreated chiller continued on the cycle of fouling-related inefficiency.

The approach temperature of the chiller equipped with the Helios Tube Cleaning System®  saw a dramatic improvement in approach temprature.  The chiller operated with condenser approach temperatures at or below the design values for the both the 2019 and 2020 cooling seasons. Additionally, the chiller was never opened for manual tube cleaning after Helios installation.

The control chiller, the one without a Helios system installed, continued to experience elevated condenser approached temperatures in the 2019 and 2020 cooling seasons. Additionally, the condenser required opening, and the tubes had to be manually brushed between each cooling season.

The energy savings and cleaning-related labor savings are compelling and stand on their own merits. Added to this, though, is the change in maintenance flows in the plant. University of Nebraska – Lincoln is now able to focus their highly-trained maintenance personnel on higher priority tasks rather than the manual cleaning of chillers throughout the cold weather season.

Most importantly, the detailed evaluation of the Helios Tube Cleaning System impact on plant efficiency has led UNL to proceed with continued technology adoption. A Helios® system has already been procured for and an additional implementation is being planned for other chillers in the district cooling system.