This month we will be discussing the fundamentals of thermal energy storage (TES) systems.
At the functional core of any HVAC system design is the necessity to move heat in to or out of the system. Mechanical condensers, heat pumps, and evaporative cooling towers all serve the same purpose of moving heat from inside of the system to outside of the system or vice versa. The energy it takes to move heat in and out of the system, as well as the energy contained in the heat itself is effectively lost as most designs have little to no ability to capture the waste heat energy removed from the system for use when needed. This is the economical, environmental and efficiency argument for thermal energy storage systems. Such systems are designed to capture, store, and make available the energy contained in waste heat. DARCO has designed, constructed, and delivered several systems that take advantage of waste heat generation. These systems are designed to store heat removed from the system in the form of hot water stored in large, DARCO spec, direct bury fiberglass tanks. The stored hot water is then available as heat energy to be moved back into the system as needed.
The following two examples are indicative of the type of systems with which DARCO has some experience. Please see our website for additional information on products and applications as well as contact information for our sales and technical team.
Example #1 – Rural Public High School in NW United States
This system was part of a newly constructed high school in a small town in NW Oregon. The climate of the Willamette valley is temperate with high temperatures rarely exceeding the mid-eighties and freezing temperatures occurring infrequently and rarely for extended periods of time. Due to the proximity to the Pacific coast, daily temperature changes can be quite wide. It is not uncommon to find temperatures in the forties at dawn and in the mid-eighties by the afternoon. This kind of temperature swing is ideal for a heat pump systems that can boost the effectiveness and efficiency of an HVAC system responsible for heating a building at night and cooling the building during the day. The system design for this project consists of a large 50,000 gallon DARCO direct bury fiberglass tank buried under the gymnasium. The tank acts as a thermal reservoir. Cold water stored in the tank from the night time heating of the building is used to boost the efficiency of the daytime cooling period. As the building is cooled throughout the day, heat is drawn out of the system and stored in the tank to be used to boost the effectiveness and efficiency of the night time heating period.
Example #2 – Large Hotel and Casino resort in the Great Lakes Region
This system was designed to boost the efficiency of an existing photovoltaic (PV) solar power array as well as capture waste heat for use in the resort and hotel. Solar panels have an optimal temperature range at which they operate most efficiently. This temperature is easily exceeded in large arrays and therefore water cooling of the arrays is a common practice. This is another example of waste heat being lost from the system. DARCO was able to partner with the mechanical systems engineers to provide a 40,000 gallon DARCO direct bury fiberglass tank to capture the heat drawn off of the PV array. The captured hot water is used through heat exchangers to preheat domestic water supply for the hotel and casino as well as provide ice and snow melting capabilities for the sidewalks and driveways of the resort campus.
DARCO is looking forward to future projects and applications for thermal energy storage systems. Please contact us with your TES needs and allow us to collaborate on storage solutions