Case Study #1

University of Arizona Student Recreation Center: Combined Solar HVAC and Pool Heating Plant with Central Plant District Cooling and Heating

A 140 ton solar thermal air conditioning project was completed in April 2011 at University of Arizona Student Recreation Center, Tucson Arizona. This project has received a significant amount of national attention, including a cover story in the October 2011 issue of PM Engineer Magazine

Tucson Electric Power (TEP) serves electricity to the campus. Time of use electric rates apply. Because solar thermal energy can be stored in insulated tanks, in combination with the absorption chiller, it offsets peak electric rates and demand charges. The campus central plant supplies chilled water to multiple buildings, classrooms, laboratories, a hospital, and dormatories. The peak cooling demand can reach 30,000 tons. The project helps the campus save electricity and natural gas. It also helps TEP in meeting renewable portfolio standards.

The absorption chiller is manufactured by Broad and is rated at 140 tons. Solar thermal collectors are SUNDA SEIDO 2-16 vacuum tube direct flow type. 346 solar thermal collectors are staged over the roof of the Student Recreation Center. Pressurized hot water is collected in an insulated vertical; tank (10,000 gallons / 37,850 liters) staged next to the absorption chiller. The maximum allowed temperature at the solar hot water tanks is 230°F (110°C).

The condensing loop of the absorption chiller is directed to a heat exchanger set up to heat the Olympic size pool next to the Student Recreation Center. The energy management system regulates the opertion of the absorption chiller and pool heating system. Consequently, the solar thermal energy concurrently displaces the electricity supplying chilled water via the condensing loop of the absorption chiller. The absorption chiller only operates when the solar hot water is adequately high. The pool heating system has gas burning heaters as a backup.

The condensing loop of the absorption chiller operates at 93°F (34°C).

Summary of features:

• Solar thermal collectors staged over Student Recreation Center Building

• 30,000 ton campus peak cooling load

• 140 tons absorption chiller capacity

• 346 solar thermal collectors (5,336 tubes)

• One 10,000 gallon capacity insulated solar hot water storage tank

• Daily storage discharge cycle

Case Study #2

Central Plant District Cooling and Heating on Los Angeles College Campus

Click here to download Los Angeles Valley Community College case study...

Case Study #3

University of New Mexico: Mechanical Engineering Building

Click here to learn more about the UNM project, which features 40 Sunda Seido 1-16 vacuum tube solar collectors and engineering assistance from SunChiller

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