Develop and Test Protocols for Evaporative Pre-Coolers for RTU Retrofit Initiative

Develop test protocol for uniformly evaluating performance of AC unit condenser air evaporative pre-coolers. The purpose of this project is to establish a nationally-recognized performance standard for the different types of technologies designed to pre-cool AC unit condenser air, using water evaporation. This standard will be designed to allow stakeholders to compare the effectiveness of these technologies. The protocol will be tested in the laboratory on three different manufacturers to validate the protocol.

In order to understand the energy benefits associated with evaporative pre-coolers, the American Society for Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) formed a Standard Project Committee (SPC-212P) chaired by Mark Modera of the Western Cooling Efficiency Center (WCEC) to develop a Method of Test for “Determining Energy Performance and Water-Use Efficiency of Add-On Evaporative Pre-Coolers for Unitary Air Conditioning Equipment”. This report describes laboratory testing of five evaporative condenser air pre-cooler products on a packaged roof top unit and provided feedback to the ASHRAE SPC-212P. Evaporative pre-coolers evaporate water into the air stream that cools the condenser coil of an air conditioning system. The evaporated water reduces the sensible temperature of the air stream, increasing the overall air conditioning system efficiency. There are a large numbers of manufacturers offering evaporative pre-coolers as retrofits to existing RTUs and the methods of pre-cooling air vary. The design of the pre-cooler will impact its performance and the resulting energy and demand savings of the air conditioning system. While various field studies have been conducted, an objective laboratory test protocol is needed to quantify both the energy savings and the associated water use of the pre-cooler. The objectives of this project as described in the scope of work were to: 1. Laboratory test five evaporative pre-cooler technologies (results to include energy and water impacts). Evaluate the impact of wind speed and direction on one technology. 2. Continue to move the Method of Test through the ASHRAE standards committee. As part of objective 1, the decision was made by the ASHRAE committee to abort the wind speed tests after the lab determined they were too difficult to conduct and accurately reproduce between laboratories.