Cutting Energy Consumption in the Tropics with NI LabVIEW and Compact FieldPoint

For two decades, Thirumalaichelvam “Thiru” Subramaniam, chief technical officer of Chiller Energy Management System (CEMS) Engineering in Malaysia, has been pursuing his dream of energy conservation for the facilities he manages. In the last three years, he developed a breakthrough approach for improving the quality and energy efficiency of commercial air conditioning systems in the tropics including those located in office buildings, factories, and hospitals. He has saved his clients up to 30 percent of their air conditioning energy costs in tropical countries in which cooling costs typically consume 45 to 60 percent of building energy expenses.

Thiru’s Quest: Making an Entire Manufacturing Plant Energy Efficient

Thiru is a third-generation Malaysian who studied engineering in the U.K. He began his career working in aircraft maintenance in Malaysia but quickly “became bored with it.” He then turned to mechanical engineering in the U.S. in the 1980s to specialize in the design and operation of process manufacturing plants.

Thiru noticed that while engineers specialized in particular manufacturing processes, few seemed to focus on the overall efficiency of the plant, particularly in energy use. “This really hit me when I returned to Malaysia and began to work in process manufacturing,” he said. After his return in 1989, Thiru became involved in the design and operation of a calcium carbonate processing plant. This plant was one of the first to implement roller mill technology, a technique used to reduce the size of certain materials, and Thiru was unclear about how to optimize its operation.

“I realized that I needed to build a model of how the entire plant operated end-to-end and quickly understood that the operations of the plant were not economically feasible. The energy costs were too high, even in Malaysia where energy costs were largely subsidized by the government at the time.”

After building a model of the plant’s operations, Thiru began to take raw data readings and mechanical observations and enter them into a database to study the characteristics of the inputs and outputs and model the plant operations. He reduced the plant’s energy bill by 20 percent, making it feasible to operate.

After this first success, Thiru worked with a number of multinational manufacturing companies, continuing to model their plants and study and refine their energy consumption. “There was no such thing as an energy consultant back then. I was simply applying my training as an engineer to model and monitor the plant processes.”

Commercial Air Conditioning: Huge Energy Consumers in the Tropics

By 1995, Thiru began specializing in chilling systems. He began working with an American company to build hospitals in Malaysia and realized that the water cooling systems they installed in the hospitals were not well-tuned for the tropical climate because the temperature fluctuates – hot during the day and cool at night.

To cool a large area, commercial and industrial centralized air conditioning systems, like the ones used in Malaysian hospitals, traditionally consist of multiple machines known as chillers. These machines control air temperature by removing heat from water through vapor compression or an absorption-refrigeration cycle. Each air conditioning plant typically contains four to six large chillers, and each chiller is operated independently to produce a return water temperature at a particular setpoint.

The typical approach to cooling a building is to determine how much energy is required to cool a particular building to a desired temperature and then set each chiller to produce chilled water at the same setpoint. The calculations are usually based on the worst-case condition – the one or two hottest days of the year – which leads to inefficient energy use and hard-to-control building temperatures.

Real-Time Sensing, Analysis, and Dynamic Control

Thiru realized that they needed a way to manage the temperature of the chill water in real time, taking into account the spikes in the external temperature and the time lags, and to optimize loads across different chillers. He began looking for technology to implement real-time data acquisition and temperature management across multiple chillers. “That’s when I discovered National Instruments, the Compact FieldPoint programmable automation controller (PAC), and LabVIEW running on an industrial PC,” he said.

He attended a seminar with NI demonstrations on ways to handle motion control using sensors and real-time analysis. Thiru said that the solution seemed to be able to handle the real-time acquisition of data coming from multiple sources in parallel, analyze those signals in real time, and send signals to control various motion controllers. Thiru thought he could use this same approach to manage chill water temperature in real time and started exploring this idea with NI about five years ago. “The engineers were very helpful,” Thiru said.  He also explained that when NI engineers in Malaysia could not answer his questions, they turned to Singapore. If they were stumped in Singapore, they talked to the engineers in Austin, Texas. “I was very well supported,” he added.

Launching a Project to Design a Chiller Energy Management System

Even though Thiru’s job was to simply run the hospitals’ cooling systems, he undertook the energy management project on his own initiative. He started hooking up sensors, putting them indoors and outdoors and looking at elements such as temperature, humidity, water flow, and electricity consumption.

Then he began to think about the program he needed to analyze the data and control the heat transfer. He wanted to capture the outside air temperature and the water parameters in real time and conduct a dynamic analysis of the chilled water compared to the desired building temperature. Next, he wanted to synchronize the operation of the chillers, which may have come from different manufacturers, and their associated components and operate them as one thermal system.

Building a Team of Environmental Programmers and Engineers

With support from investors and a $1 million grant from the Malaysian government, Thiru hired four engineers and began to train them in the LabVIEW programming language to model the system he envisioned.

Thiru wrote the requirements for the basic program using HP calculators because he did not know a lot about programming with LabVIEW. His team spent about a year programming all of the modules, and then spent another year refining and optimizing them. They have since added modules and continue to optimize those.

Thiru’s programming team is growing by recruiting engineering students, just one or two years out of school, and training them on the principles of energy management and how to use NI tools. “We now have a great team of young engineers who work day and night and love their jobs very much because they believe their work will prolong mankind on earth through their methods of energy conservation.”

Thiru requires his engineers to take courses on LabVIEW, but stresses the importance of learning through practice. “When you start writing programs you make amateur mistakes, but it’s really easy once you learn it,” he said. “With the graphical environment of LabVIEW you see the inputs and the outputs – the means and the ends. When you view the module and look at the output, you can tell if it is wrong.”

Using Genetic Algorithms to Create a DNA Footprint of Each System

The CEMS basic program is quite sophisticated. Users acquire real-time input data directly from sensors outside, on the chillers, and in the buildings. Thiru’s team conducts a series of variance calculations of the real-time input data with proportional-integral-derivative (PID) control loops, and then uses this data to determine and send new operating instructions to the chillers using small electrical signals. There are no moving parts and the operating instructions are determined using a series of genetic algorithms that combine heat transfer principles, thermodynamics, and advanced mathematical predictions, creating a “DNA footprint” of the entire system.

CEMS Team Monitors Multiple Facilities in Multiple Locations via the Internet

With the graphical interface, users can literally see the heat flow coming into and out of each building. Another benefit of this graphical real-time monitoring approach, Thiru explained, is that his firm can cost-effectively handle its clients’ energy management remotely.

 “We make it easy for our customers to do their jobs and conserve energy,” Thiru said. “The facility manager for a hospital or the plant manager for a manufacturing plant is responsible for the entire facility. These people are experts in different trades and concerned about efficient production and making sure nothing breaks down. Although they are being pressured to reduce costs through energy savings, they don’t have the time or the experience to monitor energy usage and conserve energy. Centralized chillers are the largest power consumer in a facility. Statistically, 45 to 60 percent of operations costs come from the centralized air conditioning, and 40 percent of that is from the chillers alone. We handle the energy conservation for the chillers.”

After the systems are installed, CEMS engineers implement real-time monitoring from their offices to monitor and control systems anywhere in the world. CEMS modulates the chillers according to the change of internal and external load at 10-second intervals, automatically controlling the chiller loads. By benchmarking the average consumption of the chillers for each day, the plant managers can see drastic changes in consumption when CEMS is in savings mode. All necessary data is recorded and reported to plant managers to verify the amount of savings made in chiller consumption.

In the event of a mechanical problem, CEMS engineers can alert the facilities manager or the plant manager to switch over to their standby system while they make arrangements to make on-site repairs. CEMS monitors the number of hours each chiller has been running, and schedules preventive maintenance based on the manufacturers’ specifications for each chiller type and condition.

Extending the CEMS Platform to Other Forms of Energy Conservation

Thiru is looking forward to adapting his firm’s energy management systems to many other kinds of energy management, ranging from electrical power quality management, to decreasing the levels of diesel fuel consumption for boiler systems, to reducing electrical energy consumption through industrial air compressor optimization.

Learn more about the development of the CEMS. 

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Potential CEMS Navy Use
Has CEMS been evaluated for U.S. Navy chiller applications?
- James Winward, U.S. Navy. james.winward@navy.mil - Aug 3, 2009