Total Energy Recovery Wheel Contaminant Transfer Study. Report

Transcription

1 Total Energy Recovery Wheel Contaminant Transfer Study Report Total Energy Recovery Wheel Contaminant Transfer Study Submitted to SEMCO LLC 1800 East Pointe Drive Columbia, MO Prepared by Charlene W. Bayer, PhD 610 Village Trace, # HYGIEIA SCIENCES LLC August 31, 2011

2 Total Energy Recovery Wheel Contaminant Transfer Study Report Introduction Research has shown that the potential for contaminants carry-over by total energy recovery wheels during the latent energy transfer process varies as a function of the contaminant properties, the construction of the total energy wheel, and the desiccant utilized. Several manufacturers are now using molecular sieve desiccants, both 3Å and 4Å pore sizes. Although the angstrom pore sizes among different molecular sieves may be reported to be identical, the molecular sieves and their potential to transfer pollutants across various wheels may differ. According to research reported by SEMCO, there are substantial differences between various grades of the 3Å desiccant powders available, and there may be changes to the molecular sieve cation properties during the wheel coating process. The binders used to adhere the desiccants to the wheel matrix, and the wheel matrix properties may degrade the ability of the 3Å wheel product to limit contaminants transfer. If found to be true, this would be problematic for building owners since new products, marketed as 3Å desiccant wheels are assumed to perform identically with the SEMCO product but, to date, there is limited data to substantiate these claims. According to SEMCO, the only other independent study to investigate the transfer of contaminants by total energy recovery wheels has been completed by researchers at the School of Mechanical Engineering at the Kanazawa University in Japan (1). This study included the testing of a 3Å wheel product marketed in Asia in addition to an alternative technology employing an ion exchange resin. The carry-over data measured by Kanazawa University for the 3Å wheel tested has been included within the final summary graphic (Figure 2) and Table 3 of this report for comparison. To verify the SEMCO and the Kanazawa University data, we performed a research investigation examining the transfer across two different 3Å total energy wheels. The first 3Å total energy wheel, manufactured by SEMCO, was tested on three previous occasions by the Georgia Tech Research Institute (1991, 1999 and 2004) (2,3,4). This wheel was not retested, but the previously collected data was included in this study. The second 3Å total energy wheel was an unidentified 3Å wheel that is currently marketed in the US. The testing of the unidentified wheel was completed under the supervision of Dr. Charlene Bayer of Hygieia Sciences at the SEMCO testing facility in Columbia, MO and at the request of SEMCO using the same chemicals, velocities, pressures, wheel speed, purge setting and other key design parameters used previously for the testing completed by the Georgia Tech Research Institute. 1

3 Technical Approach The SEMCO testing facility was operating according to the requirements of ASHRAE Standard The conditions used were matched to the 1991 and 1999 testing conditions to allow for data comparisons (Table 1). The actual operating conditions are shown in Figure 1. A range of challenge gases were selected to simulate compound classes to which the wheel may be exposed in typical indoor air and laboratory environments. The challenge gases chosen were: propane, carbon dioxide (CO 2 ), methyl isobutyl ketone (MIBK), isopropyl alcohol (IPA), xylene, acetaldehyde, methanol (MeOH), and acetic acid (HOAc). The system was also challenged by sulfur hexafluoride (SF 6 ) to determine purge efficiency and seal leakage as described within ASHRAE Standard This allows for the differentiation between any recirculated air and desiccant-based transfer of contaminants. Samples were obtained from the outside, supply, and return air streams by simultaneous collection into clean Tedlar sampling bags and analyzed by a B&K photoacoustical monitor equipped with the appropriate filters for the target gases. Ten samples from each bag were analyzed and averaged to calculate percent carry-over for each challenge compound. Table 1. Testing Parameters Test face velocity as per past two tests by GTRI 400 ft/min Supply and exhaust flow based on face velocity Pounds of air/min Grams of air/min Goal for challenge concentrations Detection limit for TVOC as propane 1at05 cfm 141 lb/min 64,082 g/min ppm 0.02 ppm 50 1% carry-over 0.25 ppm % carry-over ppm Pressure differential between supply and return Purge angle at full 10 degrees Wheel rpm inches 10 degrees 20 rpm 2

4 Figure 1. Actual operating conditions during testing. Results The averaged test results of challenge compounds for each sampling location for the 2011 testing of the undisclosed 3Å wheel are listed within Table 2. As shown, contaminant transfer ranging from % depending on the challenge analyte was observed for the undisclosed 3Å molecular sieve recovery wheel. Table 3 summarizes and compares the measured contaminant carry-over percentage associated with the SEMCO wheel, the undisclosed 3Å wheel marketed in the US and the undisclosed 3Å wheel marketed in Asia tested only by Kanazawa University. As shown, the carry-over in both non-semco 3Å wheels was greater for all compounds than with the SEMCO 3Å wheel (Table 3 and Figure 2), with a range of carry-over percentage of % for the tested challenge compounds. Both undisclosed 3Å molecular sieve wheels showed transfer of some or most contaminants. The difference in the measured data suggests that the two undisclosed 3Å wheels tested might be either from different manufacturers or reflect variations in product quality from the same manufacturer. 3

5 Table 2. Concentration of challenge gases at each sampling location. Concentration (ppm) Compound Return (challenge) Outdoor Supply Carryover (%) Sulfur Hexafluoride (SF 6 ) % Propane % Carbon Dioxide (CO 2 ) % Methyl Isobutyl Ketone (MIBK) % Isopropyl Alcohol - IPA % Xylene % Acetaldehyde % Methanol (MeOH) % Acetic Acid (HOAc) % Table 3. Carryover percentage for each 3Å wheel tested. Carryover (%) Compound 3Å SEMCO (1999) 3Å non-semco (2011) 3Å non-semco (Kanazawa University Study) Sulfur Hexafluoride (SF 6 ) 0.04 % 0.31 % NA Propane Not detected 0.20 % 4.00 % Carbon Dioxide (CO 2 ) Not detected 4.20 % 2.00 % Methyl Isobutyl Ketone (MIBK) Not detected 2.51 % 13.0 % Isopropyl Alcohol (IPA) Not detected 3.86 % 12.0 % Xylene Not detected 13.1 % 19.0 % Acetaldehyde Not detected 17.4 % 35.0 % Methanol (MeOH) Not detected 11.3 % NA Acetic Acid (HOAc) Not detected (1) 35.9 % NA Note: Contamination carry-over percentage is defined by ASHRAE as follows: = (Supply Air Concentration Outdoor Air Concentration)/(Return Air Concentration Outdoor Air Concentration) 4

6 Figure 2. Comparison of carry-over percentage for all tested 3Å wheels. Conclusions The SEMCO 3Å wheel tested by the Georgia Tech Institute in 1991 and 1999 resulted in no detectable carryoverr for the challenge analytes; however, the other two undisclosed 3Å wheels did result in carry-over for most of the challenge analytes, with a range of carry-over by SEMCO, both of the percentage of % for the tested challenge compounds. As reported undisclosed 3Å molecular sieve wheels are marketed as products capable of limiting the transfer of airborne chemical contaminants inferring equality to the SEMCO product performance. Based on the resultss of this research, the undisclosed products do not exhibit the ability to limit all detectable contaminant transfer. Thesee results highlight the need for all manufacturers of energy recovery devices to have their products independently ested using contaminants of concern eliminating technology misapplication. Hygieia Sciences (5) has both the expertise and facilities in its laboratories necessary to perform this type of contaminant carry-over testing for manufacturers, engineers or end users and offers these services for all energy recovery product types as an independent third party tester. The testing performed under this reported project was completed under the supervision of Hygieia Sciences in the SEMCO testing facilities (not at the Hygieia Sciences laboratory) at the request of SEMCO. 5

7 Bibliography: 1) Kodama, Akio, Cross Contamination Test of the Seibu-Giken Hi-PANEX-Ion Enthalpy Wheel, School of Mechanical Engineering, College of Science and Engineering, Kanazawa University. Ishikawa, Japan. 2) Bayer, Charlene W and Downing, Chris. Results of Chemical Cross-contamination Testing of a Total Energy Recovery Wheel Phase I, The Georgia Tech Research Institute, Atlanta Georgia, ) Bayer, Charlene W and Hendry, Robert. The Importance of the Desiccant in Total Energy Wheel Cross-contamination, The Georgia Tech Research Institute, Atlanta Georgia, ) Bayer, Charlene W and Hendry, Robert. Total Recovery Desiccant Wheel Pollutant Contaminant Challenge: Ventilation Effectiveness Comparison - The Importance of the Desiccant in Total Energy Wheel Cross-contamination, The Georgia Tech Research Institute, Atlanta Georgia, ) Hygieia Sciences Dr. Charlene Bayer, Chairman and Chief Science Officer Dr. Bayer Dr. Bayer founded HYGIEIA in 2008 building on her extensive research and management experience from years of experience at the Georgia Tech Research Institute (GTRI) of the Georgia Institute of Technology (GT). Her primary focus at HYGIEIA is to provide advanced technological solutions to commercial, governmental, and institutional clients challenges for providing healthier and greener indoor environments. 6