A Discussion of Peltier Cooling Compared to Chilled Air Cooling and 4 mm DSR Results (and related issues)

Transcription

1 A Discussion of Peltier Cooling Compared to Chilled Air Cooling and 4 mm DSR Results (and related issues) Gerald Reinke MTE Services Binder ETG, May 3, 2017 Ames, IA

2 STATEMENT OF PROBLEM In the course of working with a laboratory trying to implement the 4 mm DSR comparative testing between MTE and that lab was performed The laboratory was using a DSR with a Peltier temperature control system MTE DSR uses a chilled air system Significant variation in results when testing the same binder samples Investigation into factors causing the variation

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6 RHEA C 1649, D, PAV, 4mm, HR3-4 RHEA C 1649, D, PAV, 4mm, HR3-2 Critical temps based on 4 mm DSR test Critical temps based on 4 mm DSR test m, m, TEMP G)t) creep Log(G(t) TEMP G)t) creep Log(G(t) Critic al value s slope intercept Critical values critical temps critical temps ΔTc slope intercept G(t) 3 critical m 6 critical Std Dev ΔTc Std dev COV ΔTc G(t) critical m 5critical ΔTc COV Average ΔTc Avg T m-critical T S- Critical 0.4% 4.% T S-Critical T m- Critical 0.4% T m-critical

7 Data at RHEA C Peltier cooling PAV - C 0_02 #1 Critical temps based on 4 mm DSR test TEMP G)t) m, creep Log(G(t) Critical values slope intercept critical temps ΔTc T S-Critical T m-critical

8 SUMMARY PG PAV COOLING TYPE ΔT S-critical ΔT m-critical ΔTc PELTIER CHILLED AIR Δ(ΔT S-critical ) Δ(ΔT m-critical ) Δ(ΔTc)

9 PG 5-2 PAV Residue Peltier relative to Air Results Relative to BBR Results Limiting Grade ΔT S-critical ΔT m-critical ΔT S-critical ΔT m-critical Test Device T S-critical T m-critical ΔTc Δ(ΔTc) BBR mm DSR using chilled air system mm Peltier circulator at mm Peltier circulator at DSR Unit T S-Critical T m-critical ΔTc HR HR Average

10 COMPLEX MODULUS: PG C reference Temp Chilled Air 1.0E+10 & Peltier COMPLEX MODULUS, G*, Pa 1.0E E+0 1.0E E E E-0 1.0E E E E E E E E E E E E E E E+07 REDUCED FREQUENCY, rad/sec Chilled Air C 1649, E, 64-2 PAV, 4mm, HR to -6 Peltier C NH 64-2 PAV 1 - reduced NF, compliance 0.2 Peltier Cooled C HN 64-2 PAV - compliance 0.3

11 COMPLEX MODULUS: PG C reference Temp Chilled Air 1.0E+10 & Peltier COMPLEX MODULUS, G*, Pa 1.0E E+0 1.0E E E E E E E E E E E E E E E E+0 1.0E E E+11 REDUCED FREQUENCY, rad/sec Chilled Air C 1649, E, 64-2 PAV, 4mm, HR3-4 Peltier C NH 64-2 PAV 1 - reduced NF, compliance 0.2 Peltier C HN 64-2 PAV - compliance 0.3

12 COMPLEX MODULUS: Comparison PG -30 C of G* mastercurve for 1.0E+10 Peltier & Chilled Air Cooled DSR 1.0E E+0 COMPLEX MODULUS, G*, Pa 1.0E E E E E E E E E E E E E E E E E E+05 REDUCED FREQUENCY, rad/sec Peltier C MN 5-2 PAV Chilled Air C 1649, B, 5-2 PAV, 4mm, HR3-4

13 COMPLEX MODULUS: -1 C of G* mastercurve for Peltier & 1.0E+10 Chilled Air Cooled DSR 1.0E E+0 COMPLEX MODULUS, G*, Pa 1.0E E E E E E E E E E-0 1.0E E E E E E E E+0 REDUCED FREQUENCY, rad/sec Peltier C MN 5-2 PAV Chilled Air C 1649, B, 5-2 PAV, 4mm, HR3-4

14 COMPLEX MODULUS: -12 C & 0 C of G* mastercurve for Peltier 1.0E+10 & Chilled Air Cooled DSR 1.0E E+0 COMPLEX MODULUS, G*, Pa 1.0E E E E E E E E E E E E E E E E E E E+11 REDUCED FREQUENCY, rad/sec Peltier C MN 5-2 PAV Chilled Air C 1649, B, 5-2 PAV, 4mm, HR3-4 Peltier C MN 5-2 PAV Chilled Air C 1649, B, 5-2 PAV, 4mm, HR3-4

15 1.00E+09 MODULUS, Pa CHLLED AIR -27 C CHILLED AIR -24 C PELTIER COOL -30 C AIR refers to Chilled Air cooling via external chiller 1.00E Frequency, radians/sec AIR -30 C AIR -30 C PELTIER -30 AIR -27 AIR -24 AIR -21

16 1.00E+09 AIR -24 C MODULUS, Pa PEL -27 C AIR -21 C PEL -24 C AIR -1 C, 2 tests, 2 DSR AIR refers to Chilled Air cooling via external chiller 1.00E FREQUENCY, RADIANS/SEC CHILLED AIR -24 CHILLED AIR -21 CHILLED AIR -24 PELTIER -24 PELTIER -27 CHILLED AIR -1 CHILLED AIR -1

17 7.00E+0 PEL -27 C MODULUS, Pa PEL -24 C AIR refers to Chilled Air cooling via external chiller PEL -12 C, 2 test, 1 DSR 7.00E FREQUENCY, RADIANS/SEC AIR -1 C AIR -1 PELTIER -24 PELTIER -27 PELTIER -1 AIR -12 AIR -12 PELTIER -12 PELTIER COOLED -1 C 1 mm gap PELTIER COOLED -12 C 1 mm gap

18 1.00E+0 AIR -6 C, 2 tests, 2 DSR MODULUS, Pa PEL -6 C, 2 tests. 1 DSR AIR 0 C, 2 tests, 2 DSR AIR refers to Chilled Air cooling via external chiller PEL 0 C 1.00E FREQUENCY, RADIANS/SEC AIR -6 AIR -6 PELTIER -6 AIR 0 AIR 0 PELTIER 0 C PELTIER COOLED -6 C 1 mm gap

19 COMPLIANCE CORRECTION Compliance correction is essential for obtaining accurate results at low temperatures If the temperature is wrong the compliance correction can t fix that issue Depending on the machine compliance correction importance diminishes at around 0 C for the 4 mm test

20 2016 International Symposium on Asphalt Emulsion Technology II. FACTORS AFFECTING 4 mm DSR TEST and RESULTS--COMPLIANCE 1.2x , H, STH 169, B4 Scrub Seal, 1SB, Top layer, Rec AC, 4mm, HR3-2 complianc COMPARISON OF G* AT -30 C BETWEEN RESULT WITH COMPLIANCE CORRECTION AND SAME FILE WITH NO COMPLIANCE CORRECTION DIFFERENCE IN MODULUS AT 10 RADIANS/SEC IS 107 MPa 1.1x x10 9 Complex modulus (Pa) 9.0x10.0x rad/s,.76175e Pa COMPLIANCE = 0 7.0x10 6.0x Angular frequency (rad/s)

21 2016 International Symposium on Asphalt Emulsion Technology II. FACTORS AFFECTING 4 mm DSR TEST and RESULTS--COMPLIANCE 1.2x , H, STH 169, B4 Scrub Seal, 1SB, Top layer, Rec AC, 4mm, HR3-2 complianc 1.1x x10 9 TEMP = -30 C rad/s,.76175e Pa COMPLIANCE = 0 9.0x10 Complex modulus (Pa).0x10 7.0x10 6.0x10 5.0x10 4.0x10 3.0x10 Note: As frequency decreases the compliance correction decreases. Torques are lower and so are displacements. More on this coming up Angular frequency (rad/s)

22 2016 International Symposium on Asphalt Emulsion Technology II. FACTORS AFFECTING 4 mm DSR TEST and RESULTS--COMPLIANCE 1.2x , H, STH 169, B4 Scrub Seal, 1SB, Top layer, Rec AC, 4mm, HR3-2 complianc Complex modulus (Pa) 1.0x10 9.0x10 6.0x10 4.0x10 TEMP = -30 C rad/s,.76175e Pa COMPLIANCE = 0 When the test temp reaches 0 C the compliance correction is negligible even at 100 rad/sec. Why is this when the binder stiffness is still quite high? It really comes down to the relationship between torque and angular displacement 2.0x10 0.0x Angular frequency (rad/s)

23 2016 International Symposium on Asphalt Emulsion Technology II. FACTORS AFFECTING 4 mm DSR TEST and RESULTS--COMPLIANCE IMPACT OF TORQUE & ANGULAR DISPLACEMENT AT DIFFERENT TEMPERATURES ON THE LEVEL OF COMPLIANCE CORRECTION Temperature, C Angular Displacement, θ, radians Compliance Correction, mrad/n m Displacement correction due to torque, radians Percent of displacement due to correction 10 rad/sec, µn m E E % E E-06 7.% E % E % To paraphrase the ads for stock market investments Individual results may vary Compliance Correction is machine and geometry dependent

24 Summary Comment s The solution to the issue of uniform and accurate Peltier temperatures must be addressed by the DSR manufacturers Not an asphalt issue, but an equipment issue A reliable method of temperature calibration needed down to -40 C Peltier appears to have unique issues with respect to uniformity of temperature between lower plate and upper geometry Chilled air or LN2 provides uniformity of cooling (calibration still important) The BBR result is still the basis of comparison

25 Summary Comment s An uniform method of data analysis needs to be developed and used WRI and MTE have used Abatech RHEA software as have a few others The relationship of 300 MPa BBR S(t) = 143 MPa G(t) and BBR slope value = -0.2 or mm slope has been used successfully Uniformity of data analysis method is needed, there can t be multiple relationships between BBR and 4 mm

26 IMPACT OF MINOR CHANGES IN THE SLOPE CRITICAL VALUE When BBR m-value = and 4 mm m-value = Test Device S Critical Temp m Critical temp ΔTc Δ(ΔTc) LT PG Grade BBR mm HR WHAT IF THE 4 mm m-value target slope is rather than Test Device S Critical Temp m Critical temp ΔTc Δ(ΔTc) LT PG Grade BBR mm HR WHAT IF The BBR m-value target slope is rather than Test Device S Critical Temp m Critical temp ΔTc Δ(ΔTc) LT PG Grade BBR mm HR These are good results, but they are not exceptional results especially for typical 20 hour PAV residues. However the sensitivity of the 4 mm to minor slope variations and the basic use of the BBR to determine whether or not a given binder meets a given low temperature grade on the basis of just one test temperature make it unlikely that the 4 mm test will replace the BBR for the standard grading of PG binders

27 10 9 Log Relaxation Modulus, G(t) Log Reduced Time G(t) plot at -1C ref temp PG 5-2 PAV G(t) plot at -24C ref temp PG 5-2 PAV slope at -1C = C = C = C =

28 9. Log Relaxation Modulus, Pa sec sec Inaccurate test temperatures will result in incorrect relaxation moduli and as this plot shows very slight changes in the slope determination will impact the determination of the final binder grade This issue is also true for the BBR, where temperature control and mechanical factors will affect the BBR slope value 9. sec sec Log Reduced Time G(t) plot at -1C ref temp PG 5-2 PAV G(t) plot at -24C ref temp PG 5-2 PAV slope at -1C = C = C = C =

29 Summary Comment s Compliance correction is needed for the lowest temperatures At 0 C and warmer compliance correction appears negligible Validation of Peltier data against a chilled air or LN2 cooled system is recommended until such time as reliable Peltier temperatures can be obtained

30 Summary Comments Important at low temperatures where displacements are low and torques can be high Becomes negligible at 0 C and above (at least for our machines) 4 mm is a valuable tool for forensic analysis, thin film emulsion residue testing, material screening May not be suitable for everyone I don t see it as a replacement for BBR for routine PG QC testing

31 Questions or Comments

32 RHEA C 1649, A, MIA PG 5-2 PAV, , pooled PAV residues, 4mm, HR3-3 Critical temps based on 4 mm DSR test RHEA C 1649, A, MIA PG 5-2 PAV, , pooled PAV residues, 4mm, HR3-2 Critical temps based on 4 mm DSR test TEMP G)t) m, creep Log(G(t) -24 TEMP G)t) m, creep Log(G(t) Critical values Critical values slope critical intercept temps ΔTc slope intercept critical temps ΔTc - G(t) - -G(t) critical critical m critical m critical Std Dev ΔTc Std dev COV ΔTc COV Average ΔTc Avg T S-Critical T S-Critical -0.1% T S-Critical T m-critical T m-critical -0.% T m-critical