Accelerated Tes,ng of Membrane Heat Exchanger

Transcription

1 Accelerated Tes,ng of Membrane Heat Exchanger Julio Pulido, PhD Director Design Excellence and Reliability Engineering Philip LePoudre, PhD Principal Engineer

2 Agenda System Descrip,on System DFMEA Design of Experiments Accelerated Life Test Design Test result and Comparison to field Performance Conclusion

3 Membrane Exchanger High performance membrane Cooling loads must be drama,cally reduced when designing net zero energy buildings or other highly efficient facili,es. Advances in this area have focused primarily on reducing a building s sensible cooling loads by improving the envelope, integra,ng properly sized dayligh,ng systems, reducing unwanted solar heat gains, reducing internal heat gains, and specifying cooling equipment with high nominal efficiencies. Liquid desiccant systems have also been suggested as a way to shik latent loads to,mes when energy is cheaper and/or renewable or waste energy is abundant. Latent load shiking can be accomplished with liquid desiccant, which is a rela,vely inexpensive form of storage. Liquid desiccant systems use membranes assemblies as heat exchangers. Membrane assemblies are submimed to environmental stresses. Typically, these environmental stresses for mechanical structural HVAC components consist of vibra,on based on self- induced vibra,on with cycling temperatures between a high and low extreme.

4 Membrane Exchanger Liquid desiccants have much greater poten,al and range of applica,on when compared to solid desiccants. Desiccant wheels have several inherent disadvantages that cannot be overcome: the need to transfer solid mass between two adjacent air streams, the thermal energy bleed between the regenera,on side and the cooling side, air leakage, and maintenance requirements. Flat plate The condi,oning of air through a selec,vely permeable polymer membrane by a circula,ng fluid is something fundamental membrane this is nature s solu,on for energy exchange between a gas exchanger and a liquid in living organisms. This may well become the dominant method for condi,oning air in all occupied spaces for the foreseeable future. Membrane separation layers Liquid Air Air Heat and mass transfer Membrane

5 Test Set up Test Facility Data Acquisi,on system Ability to determine the amount of leak Bulge is calculated due to the amount of solu,on accumulated. Time to failure is measured when the leak rate is higher than an1.64 ml/day for the 10 panel exchanger and Bulge increase is higher than 0.5 mm Bulge measurement

6 Lifecycle Tes,ng Test Set up Have 20 ALT test stands Subjec,ng exchangers to accelerated stress condi,ons (high temperature, pressure, salt concentra,on) and running un,l failure We are running replicates to assess repeatability and improve confidence bounds ALT test units

7 DESIGN OF EXPERIMENTS

8 DFMEA Failure modes with high RISK were iden,fied Poten,al opera,onal profile will be test using DOE to determine factors Opera,onal profile will be used to test for ALT to find failure mechanism and failure modes.

9 Design of Experiments The analysis of the results will be used for stablishing a accelerated life test (ALT) strategy to determine the product reliability to specific failure modes under normal opera,onal condi,ons as defined by the units under field opera,on. The DOE is a two level factorial design with three factors and two responses

10 Data Analysis Strategy Analysis Sequence 1. First failure analysis for both response (Time to failure and Bulge increase) 2. ALL failures are considered in the analysis for both responses (Time to failure and bulge increase)

11 Factors and Levels A three factors full factorial was selected as the methodology for understanding response and factors Level Low Level High Pressure (Pa) Temperature ( C ) Concentration (%) Response selected from the DFMEA analysis are Bulge increase (mm) Time to failure (hours) Test methodology was considered are constant temperature since there is no understanding of the long term effects of constant temperature and concentra,on to the system. Thermal cycling effects were considered not as cri,cal during the DFMEA. Nevertheless thermal cycling test was considered for the ALT face.

12 Data Set failure Time

13 Factors Temperature and Concentra,on are cri,cal factors Temperature and concentra,on interac,ons are also cri,cal Pressure is considered for the triple interac,on Pressure alone is not considered a cri,cal factor

14 Failure Data Temperature is the largest contributor factor Interac,on effect are shown in the interac,on matrix Pressure has difference effects at high and low temperature level. This can complicate test design due to non linarites.

15 Pressure effects responses are smaller when compared to Temperature and concentra,on

16 DOE Summary DOE objectives Identify factors critical to system degradation Design of Experiments Bulge failure Mode Leak failure Mode Failure modes identified during the testing are Leaks and bulge pa is considered high for operation. Level Low Level High Pressure (Pa) Temperature ( C ) Concentration (%) Factors to be considered for Testing Temperature (Variable) Concentration (Variable) Pressure (Constant)

17 ACCELERATED LIFE TEST

18 Field Tes,ng We are undertaking an exploratory field tes,ng program to demonstrate the technology in the field, develop our controls, and assess system reliability. We have built 2 units.

19 Opera,onal Profiles Regenera,on SK CASE TEMP CONC Prop Regenera,on Miami CASE TEMP CONC Prop Supply SK temp Percent concentration Supply Miami Proportion Temp (K) Conc Opera,onal profiles from two systems are taking into considera,on for the analysis SK (Saskatoon, Canada) Cold environment Miami Florida Warm / High Humidity

20 Profiles Temperature SK Temperature Miami Concentra,on SK Concentra,on Miami Pressure is constant at 1000 Pa for SK and Miami Degrada,on is considered propor,onal at 100 hrs. interval The above will represent a average degrada,on due to the stress levels.

21 Reliability at Stress Levels in SK C4 C3 C5 C2 C1

22 Reliability at Stress Levels in Miami C4 C3 C2 C1

23 Accelerated Life Test (ALT) AF accelera,on factor LS life stress rela,onship LS Temperature AF Temperature Temperature drives degrada,on followed by concentra,on ALT findings confirm DOE findings ALT confirm field test unit results LS Concentra,on LS Pressure AF Concentra,on AF Pressure

24 Reliability to Leaks A year of opera,on is 4000 hrs. Cold Environment Warm Environment Note: Above curve represents the reliability under opera,onal condi,ons for a leak failure for a 10 panel unit

25 Membrane Assembly Reliability 100 panels Cold Environment Warm Environment The above represent the reliability for a 6 out of 10 modules system

26 High Temperature Environment (SK) 4000 hours represent a year of opera,on. A total of 0.22 units with 10 panels will have leak above the leak limit in one year in a system with 100 panels

27 High Temperature Environment (Miami) 4000 hours represent a year of opera,on. A total of 8 units of 10 panels will have leak above the leak limit in one year in a system with 10 units with 100panels

28 Conclusion The Accelerated life test was able to replicate the field performance. When new technologies are applied; Design of Experiments methodologies helped to bemer understand the cri,cal factors affec,ng the system performance. Temperature and Concentra,on are cri,cal factors to be considered when designing a Accelerated life test. Pressure levels should be considered due to the interac,on with temperature and concentra,on. Temperature is the largest cri,cal factor. Therefore it is suggested to consider low temperature effect as well as cycling effects when selec,ng your accelerated life test strategy

29 Philip LePoudre PhD, P.Eng Philip LePoudre PhD, P.Eng., is a Principal Engineer at Venmar CES and a Technology Lead in the commercializa,on of a new liquid to air membrane exchanger for evapora,ve cooling and liquid desiccant applica,ons. Venmar CES is a leader in energy recovery technologies for hea,ng, ven,la,on and cooling of commercial buildings in North America and is part of the CES Group of companies within Nortek. As a member of the CES Center of Excellence for Energy Recovery, Philip is involved in the design of world class evapora,ve cooling technologies for Data Centers, including indirect evapora,ve cooling systems, air and liquid cooling, and new advancements using the membrane exchanger technology. Philip was trained as a mechanical engineer at the University of Saskatchewan and has a doctoral degree in Applied & Computa,onal Mathema,cs from the Florida State University. His research exper,se is in Computa,onal Fluid Dynamics, Computa,onal Aeroacous,cs and High Performance Compu,ng. Before joining Venmar CES, he was a Lecturer and Research Associate at the University of Saskatchewan.

30 Julio Pulido, PhD, MBA, SE, CRE, CRP Mobile + 1 (952) Julio.pulido@nortek.com Profile: Julio Pulido is a Sr. Director Reliability Engineering at Nortek. His responsibility is to drive the capability development of Design for Reliability for consulting clients. He holds a BS from the Federal University of Bahia, Brazil; an MS from the Federal University of Rio Grande do Sul, Brazil; a PhD from the Federal University of Rio de Janeiro, Brazil; PhD Research at Duke University; MBA from Xavier University and a Certificate in Information Technology Management from the University of Chicago. His specialty is in the area of Structural Analysis, Design for Vibration, Structural Reliability, and Accelerated Testing Techniques. Dr. Pulido has 20+ years of experience as an engineering executive in Product Design and Design Assurance Organizations in medical, automotive, aerospace, HVAC and nuclear industries. He has published over 50 peer reviewed Journal and Conference papers.

31 THANK YOU