Research into improving hydronic solar panels
Background
California State University – Dominguez Hills has been actively working to reduce energy consumption and prevent greenhouse gas emissions from campus equipment. This has led to numerous energy saving initiatives: installing LED lighting, replacing their direct-fired natural gas coolers with electric ones, installing a 4 mWh “behind the meter” battery for clean energy during peak demand, and installing smart lighting controls , based sensors and smart valves on air handling units.
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“It's a combination of a lot of things,” said Kenny Seeton, central plant manager at CSUDH. “I always look at how things are intertwined and work together. How can we get the best bang for our buck from these new devices? We push the boundaries of technology.”
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CSUDH has a history of testing cutting-edge technologies and has received statewide recognition for its efforts. Studies published by the California Energy Commission have used their campus buildings as models of what energy efficiency best practices look like in the real world.
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Seeton and the rest of the CSUDH campus facilities team are constantly looking for new ways to increase efficiency and reduce their reliance on natural gas for heating and cooling.
Challenge
Hydronic solar panels are among these emerging technologies that Seeton has tested. “We started playing with solar thermal energy,” he says, “which allows us to make hot water from the sun.” He started a beta test for a group of hydronic solar panels that would serve part of the hot water loop at CSUDH. Initially, the panels operated on a 30% glycol mixture, a standard mixture of heat transfer fluids found in a traditional hydronic system. The panel array produced a certain amount of Btu, but not as much as they predicted. Facility management has explored new technologies to make this cycle more efficient, including upgrades to the solar panels and more efficient heat transfer fluids. When they heard about Hydromx, it seemed like a natural fit. “We heard about Hydromx and wanted to try it out,” says Seeton. “It seemed like a great opportunity to change the fluid. It's not very much, and we had all the measurements on board [for data reporting].” ​
Solution
CSUDH started beta testing Hydromx in their hydronic solar panels in February 2022.
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Results
The solar panels experienced almost immediate efficiency gains once the loop was running on Hydromx. “The data showed that productivity increased when we changed fluids,” Seeton reports. ​
While running on glycol, the maximum capacity of each solar panel was approximately 105 Btu. With Hydromx, the capacity of the panels was immediately increased to 120 Btu. ​
The rate of heat transfer also improved with Hydromx. As the data shows [Table 1], Hydromx increased the delta T of the system as the amount of solar radiation increased. This means that the panels produced higher leaving fluid temperatures with a simple fluid change. K assumes the cost savings of the original 35% ethylene glycol together with the initial glycol installation work.
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The campus now uses less electricity than in 2017, despite the addition of 300,000 m2 of construction space. ​
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