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Bench tests for the microclimate generated by the use of a heel boot indicate that heat is generally trapped explaining why the patients tend to kick them off or refuse them due to discomfort.
Engine bench tests have proved a relationship of functional performance of engine cylinder bores and 3D surface topography exists. The flatter laser textured engine surface, with pockets retaining lubricant, shows less wear then the surface manufactured by conventional honing. For a description of the wear, the material volume change in the surface was measured using 3D surface metrology. It was shown that a significant change to the surface occurs during the first hours of running of the engine. A mathematical model describing the wear-time-relationship was developed for the test engines. It was possible to determine the running-in time and the wear rates for the running-in period and the period of linear wear.
The bench test apparatus used was originally developed to study the performance of different piston ring and cylinder bore designs [1, 2] during sliding motion. In this work a transducer was mounted on one of a pair of test cylinders.
Figure 4 shows a schematic of the test bench. Two cylinders are mounted on the bench as shown. Both pistons are driven by means of a connecting rod attached to a crank on a motor. Each piston has two piston rings; one at each end. High pressure oil (Shell Tellus T32) is fed into the cavity between the two rings (as shown in figure 5) and passes over the piston rings to the low pressure oil outlets. During the tests the pressure was varied from 10 to 30 MPa.
The bench test apparatus used was originally developed to study the performance of different piston ring and cylinder bore designs by Sjödin and Olofsson (2003) during sliding motion. In this work a transducer was mounted on one of a pair of test cylinders. Figure 12.18 shows a schematic of the test bench. Two cylinders are mounted on the bench as shown. Both pistons are driven by means of a connecting rod attached to a crank on a motor. Each piston has two piston rings; one at each end. High-pressure oil (Shell Tellus T32) is fed into the cavity between the two rings (as shown in Fig. 12.19) and passes over the piston rings to the low pressure oil outlets. During the tests the pressure was varied from 10 to 30 MPa.
Simple bench tests for all the critical interfaces in the piston ring pack for a single engine have yielded a useful matrix of asperity friction coefficients and wear factors for the designer / analyst.
•
The sensitivity of the wear factor to the selection of the materials of both surfaces is clear.
•
Wear factors at the piston ring flank / piston interface are much higher than at the piston ring face / liner interface.
•
Wear for the critical top piston ring / piston groove interface was found to be the highest and increased markedly with rising temperature.
Results of bench tests, human factors studies, and clinical studies were submitted as part of the de novo application. In their summary report [20], the FDA described how the main validation study consisted of a prospective, parallel-cohort, nonrandomized, multicenter study. The participants (N=588) were split into two cohorts, those with and without a known diagnosis of atrial fibrillation. The test device was compared to a 12-lead ECG, with classification results being independently reviewed by board-certified cardiologists. Study endpoints for device performance included a sensitivity and specificity of 90% and 92% respectively when detecting AF compared to the physician-adjudicated 12-lead ECG, and production of a clinically relevant ECG trace, as adjudged by qualitative assessment by physicians. A human factors validation of the device was also carried out using a sub-set of the participants, with focus on adequate labeling for the device, such that the user can use and understand the device based solely on reading the device labels.
From laboratory bench-tests [13] it has been difficult to determine whether product lifetime will be reduced due to a change in the working fluid. Nonetheless, an extension in product lifetime as a result of this change is definitely contradictory due to the increase in the electrical power requirements observed (Table 1). Table 1 lists the CO2 contribution for the life cycle of the functional unit up to the end of its technical lifetime. The table assumes that the HFC compliant unit fails after 10 years. This 10 year period is an arbitrary value used to study the implications of premature product retirement and help highlight the fact that for a shorter product lifetime the environmental impact in the use phase drops but all other impacts gain in significance. This value was conveniently chosen to correspond to the projected direct and indirect CO2 emissions resulting from domestic refrigeration in the UK by 2010 (4.8Mt of CO2 equivalent). Hence, a percentage contribution towards these projections, as a result of a deterioration of power requirements or premature product failure, was calculated using detailed LCA. For calculation purposes, it was necessary to assume that 1.2 million HFC-134a units are sold in the UK in the year 2000. Further details of how the values in Table 2 were obtained are given in [15].
Table 1. Projection of energy consumption
Test label
Rate of change of regression curve
Projected power (W) after 500 hoursa
Lifetime electrical energy consumptionb (MJ)
Percentage difference between rated and projected values
Test 1
-0,0216
99.2
9385
-9.82
Test 2
-0.0169
101.8
9621
-7.55
Test 3
-0.0293
95.4
9026
-13.27
Test 4
-0.0788
70.6
6679
-35.82
Test 5
0.0058
112.9
10,681
+2.63
Test 6
-0.0703
74.9
7086
-31.91
Test 7
0.0106
115.3
10,908
+4.82
Test 8
-0.0669
76.6
7242
-30.36
a
ssuming a linear relationship (y = mx + c), where:y is the projected power after 500 hour (experiment duration)x is the 500 hour durationc is the stated electrical power input of the functional unit (110W)
b
at projected power for (0.2*3600*24*365*15) seconds
Table 2. Refrigerator CO2 contributions and its increase on 2010 projections
HFC-134a compliant (kg equiv.)
CFC-12 compliant (kg equiv.)
Increase in contribution for HFC unita (kg equiv.)
Contribution towards 2010 projections for CO2 equiv. emissionsb
Itemsc making up the functional unitd
666.8
663.9
Compressord
103.6
103.6
Refrigerant productione
1.4
0.9
Lubricant productionf
0.8
1.2
Lifetime of functional unitg:15 years
2525.1
1640.3
887.8
15%
10 years
1683.9
1093.6
849.8
21%
a
If premature failure of the unit does not occur, then the increase is due to the energy consumption plus the difference in dissimilar contributions at manufacturing. If failure occurs, then the contribution from the increased production of the individual items must be accounted for together with the increase in contribution due to the energy consumption over the 10 year lifetime.
b
based on the projected UK greenhouse gas emissions from domestic refrigeration
c
compressor not included and foam blower assumed to be CFC-12 (worse case scenario)
d
assuming a mixed fuel scenario for the manufacture and assembly of parts. Values obtained from LCA in [15]
e
assuming a mixed fuel scenario [15]
f
values obtained as detailed in [15]
g
for interrupted tests and assuming a low voltage electrical supply for the UK. Calculations of energy consumption and CO2 contribution were calculated as in [15]
For the completion of Table 2, four considerations were made. Firstly, it is important to note that the impact for the mineral and synthetic lubricants was included for completeness. This value assumes the production of the base oil alone and no consideration to the unknown additives in the POE was made. Therefore, this value is inaccurate but was included as it does not increase the results significantly and it is appropriate for comparison. Secondly, for the contribution throughout the use phase, the compressor electrical requirements for Test 6 and Test 7 were considered and these were assumed to stabilise just after 1000 hours of operation (Table 2). From observations made throughout this work, no indication of this assumption was given and therefore it is possible that the lifetime contributions will actually increase further for HFC-134a. Thirdly, during the time this research was carried out not enough information was obtained regarding the indirect effects of the disposal phase of a refrigerator. Undoubtedly, this would have augmented the percentages in Table 2. Finally, the percentage value obtained, albeit indicatory, does not account for any HFC-134a units manufactured prior and after the base year assumed (the year 2000) and therefore the contribution itself may be even higher.
Findings in Table 2 emphasise the importance a detailed LCA study has. Although influenced by the boundaries and assumptions set [15], this table should justify the use of the life cycle concept in quantifying the environmental burdens resulting from the use of a CFC substitute. By considering and comparing the CO2 equivalent emissions to projected emissions, this table identified a significant setback to the efforts being made by the UK (and other countries) to reduce greenhouse gas emissions from the domestic sector as a result of the Kyoto Protocol [19]. It is only through the use of this life cycle concept that the significance of such a contribution may be measured. Findings made here also emphasise the fact that, although shortening product lifetime increases the emissions pertaining to manufacturing, the environmental impact resulting from increased energy consumption is high enough to render a shorter product lifetime attractive, should new products become more efficient. It is accepted that the study does not account for indirect emissions resulting from end-of-life activities, which would increase if shorter lifetimes were experienced.
For the stationary bench test, seven different engine conditions were selected based on New European Driving Cycle (NEDC) drive mode shown in Figure 3. Seven key points listed in Table 2 represents seven most often driven conditions among various engine loads and speeds during the real driving condition. For each key point, EGR temperature was measured at each component inlet and exit, and the effect of super cooled EGR on engine performance and emission characteristics were evaluated and compared with those of typical cooled EGR system. The super cooled EGR was achieved by flowing 15 °C coolant into the EGR cooler. Three sets of experiment for each condition were carried out to reduce experimental error.
Table 2. NEDC conditions for stationary bench test
Prototypes perform similar functions to bench tests for proving out operations. Prototypes, however, tend to be more realistic because they operate in the actual operating environment with more features than units in bench tests.
Prototypes are good for field tests where you can subject an embedded system to real-world operations, realistic operator interactions, and environmental challenges. You can put prototypes through extensive laboratory tests to shake out problems and confirm design analyses and simulations; these tests can include tests for EMC, thermal cycling, mechanical shock, vibration, condensation, dust, salt spray, pressure, and vacuum.
High temperature 200°C oxidation bench test. The impact of high temperature oxidation on base depletion in the hotter regions of the engine was examined. A bench test was run for 4 hours at 200°C in the presence of air but no metal catalyst. Table 6.7 shows the TBN by the D4739 method and TAN by the D664 method of three oils at the end-of-test (EOT). Severe TBN depletion occurred with all three oils, but, like the field test, magnesium sulfonate showed the highest TBN (2.6), and also the highest TAN (2.8); the TAN/TBN ratio = 1.1. This demonstrates that the magnesium sulfonate does not neutralize acidic oxidation products as effectively as calcium phenate.