Indirect evaporative systems can make summer peak electrical demands go away
Throughout western US, particularly in the southwest and California, peak electrical demands during hot summers are extremely expensive for utilities and customers. These peaks are primarily driven by conventional air conditioning which drops in efficiency just when relief from the heat is most needed.
In positive contrast, indirect evaporative systems operate more efficiently the hotter and dryer it gets going beyond wet bulb temperature approaching dew point. Tested by UC Davis Western Cooling Energy Center (WCEC) three years ago, two indirect evaporative systems provided EERs of 44.3 and 45.2 in Bakersfield California.
Figure 1. Indirect Evaporative System Diagram
SMUD has tested Seeley Internationals Climate Wizard in a manufacturing setting and on the roof of an office/data center both in Sacramento. Tri Tool, the manufacturer, had moved into an IRS building designed to store documents not for manufacturing. In summers they would run the 90 ton Trane RTU full blast and could not adequately cool the manufacturing area while using terminal re-heat in the offices to keep from freezing. The EER at Tri Tool was mean 29 and maximum 60. See Table 1 below.
Table 1. Summary of Climate Wizard performance characteristics.
SMUD monitored the heat gain of the manufacturing; the Trane RTU and the terminal re-heat circuits during the peak of summer heat before this project. The data from this monitoring helped management to decide to go ahead with the installation of the indirect evaporative system.
The Climate Wizard with an associated exhaust fan solved air quality and cooling challenges for Tri Tool. Cooling of manufacturing was decoupled from the offices; the Trane unit is dedicated to the offices eliminating the need for the terminal re-heat saving a great deal of energy and cost.
In addition to this project SMUDs R&D Department has conducted several lighting and lighting control projects in the building and in the parking lot. The Facility Manager pointed out that each project was to solve a problem and had the added benefit of reducing electrical operating costs, in total, by one third.
L&H Air Co is the first distributor for Seeley in the US is a controls company in Rocklin, CA. In their installations of Climate Wizard they use Allerton Controls to enable the system to be monitored and controlled via the internet on a PC.
Figure 2. Climate Wizard 24,000 ft3/min cooling unit.
Figure 3. Interior Duct Work Delivering Cool, Non-Humidified Air to Tri Tools Manufacturing Area.
The Climate Wizard installed at Tri Tool was the first of its size installed in the US. Several others of this size have been installed in Mexico in manufacturing operations too.
Environmental Synectics Inc. (Synectics) provides environmental services and information technology services to federal environmental government agencies as well as commercial companies. Their largest customer is the US Army Corps of Engineers. In an effort to walk their talk and to demonstrate progressive environmental standards, Synectics acquired a warehouse in Sacramentos downtown redevelopment area adjacent to the confluence of the American and Sacramento Areas to repurpose it to an energy efficient attractive office.
Figure 4: Climate Wizard installed at Synectics.
With the proximity to the two rivers the few times in the summer when it is moderately hot and cloudy, the higher humidity required a hybrid solution with the indirect evaporative system. Four Climate Wizards are in a hybrid configuration with conventional cooling and one unit for the datacenter utilizes indirect evaporation without the conventional back up.
The monitoring of these two projects was conducted by ADM under contract to SMUD. Daniel J. Chapman was ADMs principal investigator.
SMUD is also beginning to monitor a Munters indirect cooling system which has been installed on Whole Foods of Sacramento as part of a major energy efficiency retrofit project.
It should also be noted that Seeley International recently acquired Coolerado. Key Coolerado employees reported this acquisition and their excitement with this new direction.
Water consumption of evaporative systems in the hot dry part of the country has been addressed by the WCEC. To address this concern they determined the most expensive method of producing additional water is by desalinization. They determined that even if customers had to pay for water produced by destalinization their cost savings would still be 5 to 1.
In summary, conventional compressor based air conditioning is the primary cause of peak electrical demands throughout the Southwest US, and indirect evaporation widely deployed is a big part of the answer to this challenge. EERs of 29, 44 and 45 are amazing and without adding any humidity,