7/29/2019 Pump Motor Thermal Transnt
1/14
Robert Fritz EngineeringGlendale, CA 91206
Document: RJ F-001
Revision NC
THERMAL ANALYSIS REPORT
for a
PUMP MOTOR, TWO POLE
Date: XXXX
Prepared for:
XXXXX
XXXXX
Approvals
Originator ______________________ _____________
Robert Fritz Date
Customer _______________________ _____________XXXX XXXX Date
7/29/2019 Pump Motor Thermal Transnt
2/14
Doc No: RJF-001 PAGE 2
TABLE OF CONTENTSSECTION TITLE PAGE
1. INTRODUCTION 31.1 Purpose of Analysis 3
1.2 Summary 32. DESCRIPTION OF ANALYSIS 33. SOFTWARE AND REFERENCES 64. DETAIL THEORETICAL ANALYSIS 64.1 Heat Generated by the Pump Motor 64.2 Rough Order of Magnitude Motor Temp. after 300 Seconds Operating -
No Cooling6
4.3 Heating Values used in the FEA 64.4 Material Properties used in the FEA 74.5 Average Temperature Rise of Coolant 74.6 Thermal Gradient Across the Coolant Convection-Film 8
LIST OF FIGURESFIGURE TITLE PAGE
1. Coolant Temperature vs. Coolant Flow Rate 42. Maximum Temperature of Pump Motor Coil vs. Coolant Rate 43. Transient Solution FEA Thermal Gradient Output of the Pump
Motor at 300 Seconds of Operation5
5. Steady-State Results of the FEA Model 7
LIST OF TABLESTABLE TITLE PAGE
I Material Properties Used in the FEA 7II Temperature Rise of the Coolant at Various Flow Rates 8III Temperature Rise Across the Coolant Convection-Film at Various
Flow Rates8
LIST OF APPENDICIESAPPENDIX TITLE PAGE
A Transient Solution FEA Thermal Gradients of Previous Designs A1-A5
7/29/2019 Pump Motor Thermal Transnt
3/14
Doc No: RJF-001 PAGE 3
1. INTRODUCTION
1.1 Purpose of Analysis
This report presents the thermal design analysis for a Two-Pole Pump Motor. The
primary task of the Pump Motor is to pump coolant. The Pump Motor is a 198 horsepowerpump motor designed to perform in continuous operation for a period of 300 seconds from start-up. It has an efficiency of 97.1% and an operating speed of 27,487 rpm. It is desirable to keep
the maximum temperature of the areas of the motor in contact with coolant to less than 59. Thecoolant was assumed to be at 29 initially.
The results of the thermal analysis include maximum heat generated, maximum predictedthermal gradients and graphs of critical hot areas of the motor vs. flow rate of the coolantthrough the pump motor.
1.2 Summary
The results of the thermal analysis show the operation of the Pump Motor as a viable designsolution per the requirements of its function. The optimum design depends on a certain amountof coolant to cool the pump motor. Figure 1 shows a graph of the flow rate of the coolant vs. thetemperature of the coolant. Figure 2 shows a graph of the flow rate of the coolant vs. themaximum coil temperature of the Pump Motor. Figure 3 is a transient solution FEA thermalgradient output of the Pump Motor at 300 seconds of operation. The coolant is assumed to bean infinite heat sink for this solution. The coolant temperature is adjusted in figure 1 to accountfor the heat transfer from the Pump Motor itself. The maximum coil temperature was adjusted
in figure 2 to account for both the rise in the coolant temperature and the temperature rise acrossthe forced-convection film of the coolant flow. Figure 4 shows the design layout of the PumpMotor.
Appendix A shows prior designs as analyzed and the transient solution FEA at the end of 300seconds of operation. Again, these solutions assumed an infinite heat sink in place of the liquidhydrogen cooling passages.
2. DESCRIPTION OF THE ANALYSIS
The detail theoretical analysis describes the fundamentals and procedure by which the final
results were obtained. As previously mentioned, the coolant in the cooling passages of thePump Motor housing was initially assumed to be an infinite heat sink in order to simplify theFEA model. The theoretical analysis was used to derive two other thermal gradients which werecombined with the values in the FEA. The two other thermal gradients are the temperature risein the coolant and the thermal gradient across the forced-convection film of the coolant.
7/29/2019 Pump Motor Thermal Transnt
4/14
Doc No: RJF-001 PAGE 4
Figure 2. Maximum Temperature of Pump Motor Coil vs. Coolant Flow
225
230
235
240
245
250
255
260
265
270
275
0 5 10 15 20 25 30 35 40 45
Coolant Flow in GPM
MaxTemperatureofCoil
Figure 1. Coolant Temperature vs. Coolant Flow Rate
29
31
33
35
37
39
41
43
45
47
49
51
0 5 10 15 20 25 30 35 40 45
Coolant Flow in GPM
CoolantTemperature
7/29/2019 Pump Motor Thermal Transnt
5/14
Doc No: RJF-001 PAGE 5
Figure 3. Transient Solution FEA Thermal Gradient Output of the Pump Motor at300 Seconds of Operation
2. DESCRIPTION OF ANALYSIS (Cont.)
It was assumed that the entire system starts at 29 prior to the operation of the pump. As soon asthe pump is started and it begins pumping coolant, the pump motor coils begin to heat up.Initially, the entire heat generated by the coils is absorbed by the thermal capacitance of thepump motor housing material. As the material begins heating up, a proportionally increasingamount of heat reaches the outer part of the housing where the coolant passages are located. Acontrolled amount of coolant is used to provide the pump motor with a means of extracting someof the heat away from its coils. The results were derived in order to provide the end user withenough information to perform a reasonable trade-off study and arrive at an appropriate coolant
flow rate.
The resultingT of the analysis varies from 203 to 241, which is very much in the ballpark of239 which was calculated in section 5.2. This validates the FEA results.
7/29/2019 Pump Motor Thermal Transnt
6/14
Doc No: RJF-001 PAGE 6
3. SOFTWARE AND REFERENCES
Finite Element Analysis Software: Algor MECH/E Integrator; 9/23/96Algor Heat Transfer Analysis Extender; 9/23/96
Algor Inc.Pittsburgh, PA
Graphing Software: Excel, version 7.0Microsoft Corp.
Theoretical Analysis References: Marks Standard Handbook for Mechanical Engineers,Eighth Edition, Baumeister; 1978
Cooling Techniques for Electronic EquipmentDave S. Steinberg; 1980
4. DETAIL THEORETICAL ANALYSIS
4.1. Heat Generated by the Pump Motor
Q =(power)(efficiency) =(198 hp)(745.7 watts/hp)(3.413 Btu/hr/watt)(.029) =14614 Btu/hr
4.2. Rough Order of Magnitude Motor Temp. after 300 Seconds Operating - No Cooling
E =wCPTE is heat energy input
w is weight of mass being heatedCP is specific heat of the mass being heated
T is the change in temperature
E =Qt =(14614 Btu/hr)(300 seconds)/(3600 sec/hr) =1218 Btuw =51 lb
CP .1 Btu/lb-F
T 239 temperature rise oraverage temperature =268 after 300 seconds with no cooling.This value is important, as it is a check to validate the FEA results with a ballpark value.
4.3. Heating Values used in the FEA
Volume of Coils =32.4 in3; Volume of Lamination =150 in3It was assumed that 25% of the heat generated came from the coil in the axisymmetric model ofthe FEA and 75% came from the laminations. Therefore,(q/vol)laminations =(10961 Btu/hr)/(150 in
3) =73.1 Btu/hr- in3(q/vol)coils =(3654 Btu/hr)/(32.4 in
3) =113 Btu/hr- in3
7/29/2019 Pump Motor Thermal Transnt
7/14
7/29/2019 Pump Motor Thermal Transnt
8/14
Doc No: RJF-001 PAGE 8
Qtransient =Qsteady-state(T transient/ T steady-state)T transient =228 - 29 =199T steady-state=909 - 29 =880
Qtransient =14614 Btu/hr(199/880) =3305 Btu/hr
Now, from the initial equation, WT =Q/CP =(3305 Btu/hr)/(2.4 Btu/lbm-F) =1377 lbm-F/hrH2 =(4.42 lbm/ft
3)/(7.481 gal/ft3) =.591 lbm/gal
WT =(1377 lbm-R/hr)/( .591 lbm/gal)/(60 min/hr) =38.8 gpm-F
Table II. Temperature Rise of the Coolant at Various Flow RatesFlow rate (gpm) 2.5 5 10 20 40
T 16 7.8 3.9 1.9 1.0
4.6. Thermal Gradient Across the Liquid Hydrogen Convection-Film
T =Q/hcA, which is the change in temperature across a forced-convection film
hc is the liquid forced-convection coefficient =J C GC
KP
P
2 3/
J is the Colburn factor =.
( ) .025
02NRfor turbulent flow conditions, or NR >7000.
G =W/AXC where W is the weight flow of the liquid and AXC is the cross section area of theflow
The following are constant values used throughout:
AXC =.0152 ft2
D is the hydraulic diameter =2ad
a d=.0565 ft
is the viscocity of coolant =.024 lbm/ft-hr
K is the thermal conductivity of coolant =.0726 Btu/hr-ft-R
A is the surface area of the coolant passage =1.97 ft2
Q is the heat leaving =3305 Btu/hr
Table I II. Temperature Rise Across the Coolant Convection-Film at Various Flow Rates
Flow rate (gpm) 2.5 5 10 20 40Weight flow rate, W (lbm/hr) 89 178 355 710 1420
Weight flow velocity, G (lb/hr-ft2) 5839 11678 23355 46711 93421
Reynolds Number, NR (dimensionless) 13745 27491 54981 109963 219926
Colburn factor, J (dimensionless) .00372 .00324 .00282 .00245 .00214
Forced-convection coeff., hc (Btu/hr-ft2-F) 73.7 128 224 389 679
T (R) 23 13 7.5 4.3 2.5
7/29/2019 Pump Motor Thermal Transnt
9/14
APPENDIX A
Transient Solution FEA Thermal Gradients of
Previous Designs
7/29/2019 Pump Motor Thermal Transnt
10/14
Report #RJF-001 Page A1
Initial Design No Forced Cooling
Design #1 Thermal Gradient without Coils
7/29/2019 Pump Motor Thermal Transnt
11/14
Report #RJF-001 Page A2
Design #2 Thermal Potting Around Coils
7/29/2019 Pump Motor Thermal Transnt
12/14
Report #RJF-001 Page A3
Design #3 L iquid Cooling In J acket, No Heat Sink Around Coils
Design #3 Thermal Gradient without Coils
7/29/2019 Pump Motor Thermal Transnt
13/14
Report #RJF-001 Page A4
Design #4 L iquid Cooling In J acket With Heat Sink Around Coils
7/29/2019 Pump Motor Thermal Transnt
14/14
Report #RJF-001 Page A5
Design #6 No Heat Sink or J acket Complete Immersion in Coolant