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DEVELOPMENT, IMPLEMENTATION AND VALIDATIONOF A NON-DIMENSIONAL
PUMP MODEL IN ENERGYPLUS
Kaustubh Phalak
Advisor: Dr. Daniel FisherCommittee members
Dr. Jeffery SpitlerDr. Lorenzo Cremaschi
Mechanical and Aerospace Engineering DepartmentOklahoma State University, Stillwater, 74078
2
PRESENTATION ORGANIZATION
Theoretical Study Performance prediction models Non-dimensional model
Experimental Validation Implementation in EnergyPlus
3
PERFORMANCE PREDICTION MODELS Study effect of pump parameters on
pump performance Effective pump head = Hth - hlosses
Hth= f(D2, N, W, Q, β2)
hlosses= g(D1, D2, N, W, Q, Z, β2 , β2)
H
4
RESULTS OF PERFORMANCE PREDICTION MODELS
Results of Tuzson and Spannhake model match with manufacturers data
Friction losses are minor losses (max 10% of theoretical head)
5
RESULTS OF PERFORMANCE PREDICTION MODELS
Calibration of models
Effect of Impeller diameter
Effect of Impeller inlet diameter
Limitations
6
RESULTS OF PERFORMANCE PREDICTION MODELS: SIZING
Observation: shutoff head is 30% of the calculated theoretical head
Observation: design flow rate is proportional to square of impeller inlet diameter
0.3
p
2
1×
1.524d2 n
2
BEP1 dn
qk 0.002 = d
7
ND
m=
31
NON-DIMENSIONAL Π-PRODUCTS
HVAC Toolkit Simplified model, fewer
inputs Inconsistent with the
affinity laws Effect of rotational
speed on π-products Effect of impeller
diameter on π-products Geometrical similarity
8
MODIFIED NON-DIMENSIONAL MODEL
NDA
m=
ND
m31
D3 factor replaced by AD, to be consistent with the affinity laws
Effect of diameter is not completely eliminated
Maximum deviation up to -30% is observed
Better results obtained with modified model
9
EXPERIMENTAL VALIDATION
Validation of pump model and the affinity laws
Validation with respect to rotational speed
Verification of power savings: 50% reduction in rotational speed →88% reduction in power
10
EXPERIMENTAL RESULTS
Non-dimensional pump curve
Flow rate and ф vs. rotational speed
Pressure rise and ψ vs. rotational speed
Output power vs. rotational speed
11
EXPERIMENTAL RESULTS: POWER SAVINGS
Power savings: dependent on pump input power
Large deviation in actual and estimated input power
Applicability of affinity laws: i/p power directly proportional to o/p power
Component efficiencies not constant
E. motor efficiency curves highly steep w.r.t. rotational speeds
hp Motor η Threshold% Allowable speed
reduction
0-1 65 13.4
1.5-5 45 23.4
5.5-15 30 33.1
15-25 25 37.0
30-60 18 43.5
75-100 10 53.6
12
ENERGYPLUS: EARLIER PUMP MODELS
Constant speed pumps: nominal flow rate and rated power for all the systems irrespective of pumping load
Variable speed pumps: flow between the min-max flow range and power from PLR curve
Plant Pressure Systems
13
ENERGYPLUS: FLOW RESOLUTION Newton-Raphson or a successive
substitution method investigated Newton-Raphson: presence of maxima or
minima of the equation leads to divergence
Successive substitution: calculating sequence and information flow decides convergence
Reversing the sequence is not simple if divergence is detected
14
ENERGYPLUS: MODIFIED SUCCESSIVE SUBSTITUTION
Slopes at operating point decides converging flow sequence
Inclusion of damping factor
Iterations are reduced
Divergence is avoided
15
VFD CONTROL
Manual control: Pump curve is scaled according to RPM schedule
Pressure set-point control
0
7 0
1 4 0
2 1 0
0 7 5 1 5 0
Head
Flow
VFD pressure control range
max RPMSystem Curve
A
B
C
Dmin RPM
E F
16
ENERGYPLUS: RESULTS & FUTURE WORK Flow resolution:
convergence is achieved for various systems
Power consumed dependent on resolved flow rate
VFD controls tested Efficiency curves
Mode
no.
Type of
operationMass flow rate
Energy
(kWhr)
1No pressure
simulation
6.28 (Rated flow
rate )192
2
Pressure
simulation
constant speed
pump
4.63 133.5
3VFD (RPM
schedule)0.51 - 4.22 22.7
4VFD (Pressure set-
point control)0.33 - 3.98 18.9
17
THANK YOU
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