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