Effect of temperature, flow rate and contamination on hydraulic filtration

Abstract

The performance of a mechanical filter is an implicit function of many variables pertinent to fluid condition, flow variables, filter element condition and operational parameters. This paper presents the details and results of a parametric study that examined the effect of oil temperature, contamination level and flow rate on the performance of a hydraulic filter through laboratory experiments. A 5 μm rated commercial filter with glass fiber made element that had an effective surface area of 0.154 m2 through 57 pleats was used to filter VG32 hydraulic oil. The filtrate was supplied with the contaminant of ISO medium test dust at four gravimetric levels - 2, 5, 8 and 10 mg/L of oil. The tests were conducted at the flow rates of 40 and 120 L/min for different oil viscosities, corresponding to the temperatures of 30, 40, 50 and 60o C. As the temperature increases, the oil viscosity decreases due to weakened cohesive forces, which leads to increased filtration rates and hence more time to build the pressure, upstream of the element. On the other hand, the pressure on upstream of filter bed builds up at higher rate when the filtrate has higher level of contamination loading. An extensive investigation on the effect of flow variables and oil condition parameters on the pressure drop across the element would therefore give a better knowledge about filter element lifetime.

Full text

Effect of temperature, flow rate and contamination
on hydraulic filtration
The 24th International Conference on Hydraulics and Pneumatics
Sep 12-14, 2018
Prague, Czech Republic
J.M.R. Gorle, V-M. Heiskanen, S. Nissi, M. Majas
Hydraulic & Industrial Process Filtration EMEA
Parker Hannifin Manufacturing Finland Oy

Outline
•Background
•Methodology
oExperimental setup
oUncertainties
•Results
oEffect of temperature
oEffect of flow rate
oEffect of contamination load
•Conclusions
Effect of temperature, flow rate and contamination on hydraulic filtration
2

Background
- Background
0
5
10
15
20
25
30
1E-02
1E-01
1E+00
1E+01
1E+02
1E+03
1E+04
1E+05
1E+06
1E+07
110 100
Number of particles / mL
Particle sze (µm)
ISO 4406
0
2
4
6
8
10
Fe Cr Cu Pb Sn Na SiO2 B
PPM
Wear elements Additives SEM images of
particles in oil
Hydraulic filtration process is highly uncertain
oFiltration efficiency is a function of flow / fluid variables, ambient temperature, operation and
calibration of feed systems
oUnpredictable characteristics of contamination including the particle size and shape, specific weight
and concentration of solids, chemical composition of impurities and diverse intermolecular and
adhesive forces highly influence the filtration.
Contamination levels of Hydraunycoil FH6 used for the lubrication of a hydraulic power pack
Effect of temperature, flow rate and contamination on hydraulic filtration
3

Background
ΔP (bar) across element
Filtering time
Maintenance costs
Resource availability
System
failure
System
failure
Reactive maintenance
Predictive maintenance
Planned maintenance
Reactive maintenance
Predictive maintenance
Planned maintenance
Objective: To predict filter clogging and failure at actual operating conditions
Conventional practice of preventive maintenance of hydraulic and fuel filters is purely
time-based
oUnnecessary maintenance costs
oUnanticipated downtime
Effect of temperature, flow rate and contamination on hydraulic filtration
4
Sensor Hub
Oil condition
Element condition
Pressure drop
Gateway to Cloud
Multi protocol
Data security
Parker Cloud
Data storage
Data security
Analytics
Human Machine Interface
Alarm
Plots
Reports

Methodology
C
1, C2
Coolers
F
1, F2
Cleaning and testing filters
H
1, H2, H5
Three
-way ball valves
H
3, H4
Two
-way ball valves
H
6, H7
Flow regulators
M
1
Gear motor (SEW EURODRIVE R32DT71D4, 0.55 kW)
M
2
AC MOTOR (ABB M2AA90L, 2.5 kW)
M
3
Gear motor (Magnetek Speed+, 3VZ132S4, 5.5 kW)
N
1, N2
Pressure indicators
P
1
Allweiler
A6 Pump (ADP 153 B21 P01, Q = 0.4-0.7 L/min)
P
2
Allweiler
A6 Pump (NB 25-200/ϕ185, Q = 30 L/min)
P
3
Pump (Aktiebolaget D4F052K1)
T
1, T2
Temperature sensors in tanks t
1and t2, respectively.
t
1, t2, t3
Tanks for particle
-supply, particle-oil mixing and overflow
V
1, V2
Check valves
VM
1, VM2
Flow meters (SCFT
-300-32-07 of Parker and VLA-ZF03 of
Kytola
with 10-300 L/min and 0.1-1 L/min range
VG 32 oil
ISO medium test duct
Media: Glass fiber
Filtration grade: 5 μm
Effective surface area of 0.154 m2
Dirt holding capacity = 140 g/m2
Bubble point tests were conducted to
confirm the membrane integrity
Effect of temperature, flow rate and contamination on hydraulic filtration
5

Methodology
Devices
1. Filter
2. Control unit
Sensors
3. Upstream pressure sensor
4. Downstream pressure sensor
5. Particle counter
6. Flow meter
7. Temperature sensor reading
Output
8. Data logger
Effect of temperature, flow rate and contamination on hydraulic filtration
6

Variable
Value*
Temperature
(oC)
30, 40, 50, 60
Flow rate (L/min)
40, 120
Contamination gravimetric level (mg/L of oil)
2, 5, 8, 10
*Uncertainty: + 1.7% in the flow rate, and + 2.5% in temperature
0
1
2
3
4
5
6
010 20 30 40
Pressure drop (bar)
Filtration time (min)
Aleatoric uncertainty
0
1
2
3
4
5
6
010 20 30 40
Pressure drop (bar)
Filtration time (min)
Statistical uncertainty due to the stochasticity in the test bench equipment is irreducible.
Tests were repeated to increase the confidence.
Methodology
Study matrix
40 L/min, 40oC 40 L/min, 50oC
Effect of temperature, flow rate and contamination on hydraulic filtration
7

Results
Effect of temperature
oAs the temperature increases, the oil viscosity decreases due to weakened cohesive forces
oFiltration rate is inversely proportional to fluid viscosity
oEffect of temperature for different flow rates on the pressure drop across the element is not linear
Effect of temperature, flow rate and contamination on hydraulic filtration
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Results
Effect of oil flow rate
oAt higher flow rates, particles accumulate faster and therefore pressure builds up in lesser time
oThree times higher flow rate causes three times faster pressure rise (Darcy–Forchheimer law)
oHigh flow rates produce a gradual shift in ΔP curves from low-slope regime to high-slope, which is
abrupt at low flow rate
Effect of temperature, flow rate and contamination on hydraulic filtration
9

Results
Effect of contaminant gravimetric level in the oil
oHigher concentration of solid particles, which results in faster clogging of the element
oTime to reach 5 bar ΔP for 2 mg/L concentration at 60oC is approx. 5 times of the case of 10 mg/L
Flow rate = 120 L/min
Effect of temperature, flow rate and contamination on hydraulic filtration
10

Outlook
•Recall ΔP = f (flow variables, oil condition parameters)
•Development of data driven correlation model that considers the ΔP, flow rate,
viscosity and contamination loading
•Adaptive learning from time-series data and trend estimation for filter condition
prediction
Effect of temperature, flow rate and contamination on hydraulic filtration
11

Acknowledgements
Effect of temperature, flow rate and contamination on hydraulic filtration
12