KGCOE MSD Technical Review Agenda
Meeting Purpose: To review the detailed design proposal to ensure design adequacy.
Materials to be Reviewed:
Customer Specifications rev.5
Engineering Analysis rev.2
Risk Analysis rev.2
BOM and Budget rev.1
Meeting Date: February 13, 2009
Meeting Location: 09-4435
Meeting time: 10 a.m. - 12 a.m.
Timeline:
Meeting Timeline
Start Time
Topic of Review
Required Attendees
10:00
Introductions, Review Agenda
Day, Phillips, Wellin
10:02
Design Review 1 Action Items
Day, Phillips, Wellin
10:03
System Design and BOM
Day, Phillips, Wellin
10:15
Fluids Analysis – Electrical Simulation, Results
Day, Phillips, Wellin
10:35
Blood Tank – Bubble Rise Time, Fluid Extraction
Day, Phillips, Wellin
10:40
Water Bath – Heat Transfer
Day, Phillips, Wellin
10:45
Tubing – Heat Transfer
Day, Phillips, Wellin
10:50
Automated Resistance - Linear motor’s force approximation
Day, Phillips, Wellin
11:00
Compliance Tank – Arterial Tank Dimensioning, Electrical
Equivalent Model
Day, Phillips, Wellin
11:15
Custom LVAD Connection
Day, Phillips, Wellin
11:20
System Drain – Saline Flush
Day, Phillips, Wellin
11:25
Pressure, Flow, and Temperature Sensors and DAQ
Day, Phillips, Wellin
11:50
LabView Front Panel Concept
Day, Phillips, Wellin
11:55
Wrap-up
Day, Phillips, Wellin
P09021 Hydraulic VAD Test Loop
System Level Design Review
Project #
Project Name
Project Track
Project Family
P09021
Hydraulic VAD Test
Loop
Assistive Devices and
Bioengineering
Artificial Organ
Engineering
Start Term
Team Guide
Project Sponsor
Doc. Revision
2008-2
Dr. Day
Dr. Day
3.0
Expected Project Benefits:
Project Description
Project Background:
The left ventricle is responsible for pumping blood out
to the body and for a person with heart disease might
not be strong enough. A left ventricular assist device
(LVAD) can be surgically implanted to give the heart
the boost it needs. RIT is developing a magnetically
levitated axial flow LVAD.
Past senior design projects have worked on creating
a durability tester for the LVAD, and a centering
magnet device.
Additionally two projects have
focused on developing hemodynamic flow simulation
systems.
Problem Statement:
The main goal of this project is to create and
construct a flexible system that can be run and
operated from a user interface on LabView and allow
the creation of flow and pressure curves generated
from LVAD devices. The system will be able to test
LVAD device both with and without Pulsatile
Ventricular Simulator (PVS) with fluids and blood.
Objectives/Scope:
1. Collect and process data to generate pressure and flow
curves for static system which is automatically adjusted.
3. Capable of extracting fluids while running in order to
determine damage to blood caused by LVAD.
3. Collect and process data to generate pressure and flow
curve for dynamic system which is a scaled model of the
physiological circulatory system working with a PVS.
Deliverables:


Functional,
partially
biocompatible
Left
Ventricular Assist Device test loop.
Pressure, Temperature, and Flow characteristic
curves for static and dynamic systems.
January 16, 2009


Aide in development of magnetically levitated
axial flow LVAD by helping to characterize the
amount of assistance which is generated, finding
the optimal pressure assist, and determining
pumps impact on blood.
Reinforcing the bioengineering program at RIT.
Core Team Members:







Jonathan Klein – Project Manager
Kyle Menges – Technical Lead
Nguyen Dinh Vu – Technical Lead
Christine Lowry – Design Engineer (ME)
Chris Stein – Design Engineer (ME)
Priyadarshini Narasimhan – EE
Julie Coggshall – ISE
Strategy & Approach
Assumptions & Constraints:
1.
2.
3.
4.
Understand the pressure, volume, flow rate, and
temperature of the physiological circulatory
system.
Working with an existing steady state VAD closed
loop, the team will be able to begin their analysis
before designing a loop with the LV Simulator.
Proposed Budget: $2,000 - $3,000
Minimize test loop volume and simplistic design
due to blood expenses and risk of damage/
clotting.
Issues & Risks:
o
o
o
Available Resources

Functional Pulsatile Ventricular
Simulator
Blood Issues

Certification

Purchasing and storage

Locations and use
Project Understanding by team

Bio compatibility

Physiological Simulation

Electrical Needs
2
P09021 Hydraulic VAD Test Loop
System Level Design Review
P09021: VAD Test Loop – Customer Needs
Importance
Need
#
Needs to
(Scale: High,
Medium, Low)
1
Able to incorporate LVAD R2 pump into Test Loop
High
2
Able to run with and without Pulsatile Ventricular Simulator
High
3
Simulate phyiological properties of the human body (i.e., temperature, resistance, compliance)
High
4
Consist of Biocompatible components to minimize blood damage
High
5
Closed loop system that cannot leak
High
6
Generate Pressure and Flow curves at associated temperatures
High
7
Operate using multiple fluids (water, water/glycerin mixture, blood)
High
8
Extraction of fluid samples cannot interrupt test while running
High
9
Within budget
High
10
Safe for operators, observers and surrounding environment
High
11
Correlate existing pump functionality test with collected data
Medium
12
Easy to fill and drain fluids
Medium
13
Volume cannot exceed that of blood bag
Medium
14
Test device needs to be self contained and portable
Medium
15
Easy to maintain and calibrate device
Medium
16
Minimal comprehension of the system's functionality is needed to operate (friendly user
interface, preferably LabVIEW)
Medium
January 16, 2009
3
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
4
P09021 Hydraulic VAD Test Loop
KGCOE MSD
System Level Design Review
DR1 Action Items
Meeting Purpose: To review the following material in order to gain input based off of attendees’
experience.
Materials Reviewed: 26 Page packet included: 1 page summary, needs and specifications, Pugh
charts, and sub-system descriptions. PowerPoint Visual Aide.
Attendees: Julie Coggshall –IE, Priya- EE, Chris- ME, Kyle- ME, Nguyen- ME, Christine- ME, Jon- IE,
Dr. Day- Customer and faculty guide, David Gomez and members of LVAD team- work for Dr. Day,
Dr. Doolittle- Professor Head for the School of Life Sciences, Dr. Phillips- EE Professor, Prof. WellinME.
Meeting Date: 16 Jan 09
Item #
Description
Responsible
Comments
Valve and non-valve
connections
Calculated bubble
rise time
A001
Create Quick Connect Design
IE-Jon
A002
Reservoir Calculations – Air Bubbles
ME-Nguyen
A003
Temperature Control – Heating Tank, find out what
changes are in the human body with regards to
temperature?
ME-Chris
Heating element,
water bath
A004
Should we use the flow sensors Dr. Day has?
EE-Priya
Yes
EE-Priya
Use Bleed port
ME - Kyle
Automate clamp
A005
A006
Pressure Sensor Selection – are resolution, output
format and frequency response appropriate? Will
sensor trap blood?
Select Resistance Generation Method – research
automated clamp valve
A007
Compliance Tank Analysis – Do we need two tanks? EE-Priya
Do not need
A008
Compliance Tanks – What are the clinical
comparisons for the compliance values, what about
different disease states.
ME-Christine,
Nguyen
A009
Blood removal - Look into self healing membrane.
ME - Chris
Ideal value ~2
mL/mm Hg, range
varies for different
diseases
Disposable syringe,
extended connection
January 16, 2009
5
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
6
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
7
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
8
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
9
P09021 Hydraulic VAD Test Loop
System Level Design Review
Electrical Equivalent Simulation
Purpose: Analyze the effect of the venous compliance tank (is it really necessary?)
Figure 1. – Complete system including both capacitors (compliance tanks)
If a resistor represents the resistance in the system, pressure is represented by the voltage in a circuit
and the current is the flow rate, a model using electric components can be used to represent the test
loop. R1 , R2 , R3 and R4 are the resistors representing the resistance of tubing while R5 is the
variable resistor used to vary the resistance in the system so as to achieve desired flow and pressure
curves. The 2mF capacitor is the arterial compliance and since it has the units of ml/mmHg the capacitor
is in micro farads to follow the units of compliance as opposed to l/mmHg in which case the capacitor
value would be 2F. The 50mF capacitor also follows the units of the venous compliance which has the
value of 50ml/mmHg. A square wave representing the LVAD and PVS, LVAD is indicated the 1V base
voltage and the 100V is the PVS mimicing the left ventricle's pumping. The pulse width is 360ms as it
because it best models the duration of a single heart beat and the period was set for 60 beats per
minute.
Calculation of the total resistance in Figure 1=>
1
1
Frequency of the circuit
=T=1
The impedance of capacitor
=
1
2𝜋𝑓𝐶
Therefore the total resistance of the above circuit=>
0.51Ω//50mF
=
1
1
+
0.51
1
1
𝑗2𝜋50𝑒−3
= (0.4972 - j0.07966) Ω
(0.4972 - j0.07966)Ω in series with 0.51Ω, 13 Ω, 0.51 Ω = 0.4972 - j0.07966 + 0.51+0.51+13
= (14.5173 – j0.07966) Ω
January 16, 2009
10
P09021 Hydraulic VAD Test Loop
(14.5173 – j0.07966) Ω // 2mF=
System Level Design Review
1
1
+
0.51
=
1
1
𝑗2𝜋50𝑒−3
(14.5172 - j0.067101) Ω
(14.5172-j0.067101) Ω in series with 0.51 Ω = 14.5172-j0.067101 + 0.51 = (15.0272 – j0.067101) Ω
100
(286.957m,96.610)
50
(49.351m,87.605)
(286.957m,6.6473)
(93.507m,3.0701)
0
(286.957m,3.4120)
(9.0909m,9.853)
(20.779m,320.801m)
-50
0s
0.5s
V(R1:2)
-I(R2)
1.0s
V(C1:1)
1.5s
V(V1:+)
Time
Figure 2.: Figure shows the simulation of figure 1
Figure 3. – System without venous capacitor (compliance tank).
The total resistance of Figure 3=>
Total impedance in figure 1 – 0.51 Ω //50mF
= (15.0272 – j0.06710) Ω - (0.4972 - j0.07966) Ω
= (14.53 – j0.01256) Ω
January 16, 2009
11
P09021 Hydraulic VAD Test Loop
System Level Design Review
100
(256.522m,96.363)
(49.351m,87.435)
50
(9.0909m,9.844)
0
(243.478m,7.1310)
-50
0s
0.5s
V(R1:2)
-I(R2)
1.0s
1.5s
V(V1:+)
Time
Figure 4.: Figure shows the simulation of figure 3
Voltage
(pres s ure) at
the arterial
capacitor.
(V)
With
venous
capacitor
Without
venous
capacitor
Voltage
(pres s ure ) at Current(flow
the venous rate) in the
capacitor (V) loop(A)
Ris e time of
the arterial
capacitor
(s )
Ris e time of
the venous
capacitor
(s )
96.61
3.41
6.64
0.0403
0.0727
96.36
0
7.13
0.0403
0.0000
Table 1: Results to the simulation of figure 1 and 3 showing the voltage at the nodes near each capacitor, the total
current and rise times for both arterial and venous.
Figure 1 was the schematic used to simulate the test loop with an arterial capacitor and venous
capacitor while figure 3 was the schematic used to simulate the test loop without a venous tank. Figure
2 shows the results of the simulation of figure 1 and figure 4 shows the results of the simulation of figure
3. Table 1 shows the results of both simulations in a table form with the voltages at the nodes near the
arterial and venous capacitance. It also shows the total current in the loop and also the rise time of both
the arterial and venous capacitance. Besides this, the table compares the results obtained with and
without the venous capacitor. It shows that by removing the venous capacitor, the voltage at the node
near the arterial capacitor decreases slightly since the total current in the loop has increased. The rise
time is going to be the same since the capacitor value is not changed. So since there is no drastic change
in the voltage at the arterial tank, it will not be required to have the venous. To keep the current, or the
rate of flow of the liquid, the variable resistor should be varied.
January 16, 2009
12
P09021 Hydraulic VAD Test Loop
System Level Design Review
Fluids Analysis
**Refer to Introduction to Fluid Mechanics by Fox et. Al for all equations, tables and figures referenced
for the fluids analysis.
Properties:
𝐵𝑙𝑜𝑜𝑑 𝑣𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦 = 0.0027 𝑁𝑠⁄𝑚2
𝐵𝑙𝑜𝑜𝑑 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 = 1060 𝑘𝑔⁄𝑚3
𝑅𝑒 =
(
𝜌𝑣̅ 𝐷
𝜇
𝑃1
𝑣̅1 2
𝑃2
𝑣̅2 2
+ 𝛼1
+ 𝑔𝑧1 ) − ( + 𝛼2
+ 𝑔𝑧2 ) = ℎ𝑙𝑇
𝜌
2
𝜌
2
𝑒𝑞 8.29
Assumptions:
The assumptions that were chosen for the fluids analysis include:



Laminar Flow
Incompressible Flow
Steady State
The fact that blood is a non-Newtonian fluid and that our calculated Reynolds number was 3,936
indicates that there will be some variability between theoretical calculations and the actual pressures
and flow measured within the system. Introducing the PVS into the system creates a non-steady
condition, and therefore we decided to analyze the system at the maximum desired flow rate for
physiological simulation (6 Liters/minute). Under the assumed conditions, the PVS and LVAD both
contribute a negative head loss to the system using eq. 8.29, and therefore will benefit the system in
terms of pressure loss.
Minor Losses:
To find friction factor f a VBA code (written by Mr. John Wellin) was used. The code requires an input of
the Reynolds number and roughness of the pipe/tubing to perform several iterations in order to
determine the friction factor based on the Moody Diagram.
January 16, 2009
13
P09021 Hydraulic VAD Test Loop
System Level Design Review
ℎ𝑙𝑚
𝐿 𝑣̅ 2
=𝑓
𝑒𝑞 8.34
𝐷 2
ℎ𝑙𝑚 = 𝐾
𝑣̅ 2
𝑒𝑞 8.40𝑎
2
For Bend in tube at bottom of loop Table 8.4 was used for 90o elbows (worse case)
For all changes in diameter, including the LVAD Reducer, Fig. 8.14 was used to find the appropriate loss
coefficients (Kc, Ke).
For Quick Connects a loss coefficient of K=0 was used as provided in the data sheet from the
manufacturer.
The Blood loop and Glycerin water solution loop were analyzed for head losses due to the tubing,
connections, tanks and other affects of the system. From our calculations both systems will be able to
run and have enough pressure to complete the circuit even with the associated head losses. For the
fluids analysis of the Glycerin loop steady state was assumed any variations from this assumption while
using the PVS can be accounted for in testing.
January 16, 2009
14
P09021 Hydraulic VAD Test Loop
System Level Design Review
Blood Loop
January 16, 2009
15
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
16
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
17
P09021 Hydraulic VAD Test Loop
System Level Design Review
Physiological
Loop
January 16, 2009
18
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
19
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
20
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
21
P09021 Hydraulic VAD Test Loop
System Level Design Review
Bubble Rise Time
Abstract: this is an analysis to figure out how much time needed for a bubble to reach the surface of
liquid. It can be applied for dimensioning the blood tank.
Scheme / given information:
Fb
2R
mg
-
blood viscosity µ=0.0027 at 100°F
blood density ρblood=1060 kg/m3
air density ρair=1.177 kg/m3 at 100°F
-
bubble volume 𝑉𝑜𝑙 = 3 𝜋𝑅 3
-
buoyancy force 𝐹𝑏 = 𝜌𝑏𝑙𝑜𝑜𝑑 𝑔𝑉𝑜𝑙
drag force 𝐹𝑑 = 6𝜋𝜇𝑏𝑙𝑜𝑜𝑑 𝑅𝑉
gravity force mg
velocity of fluid inside the tubing Vfluid=0.79 m/s
4
Fd
Assumption: bubbles is sphere-shape, temperature is constant at 100˚F, the bubble rises vertically.
Analysis:
𝑚𝑎 = 𝐹𝑏 − 𝐹𝑑 − 𝑚𝑔
4
𝑑𝑉
4
4
⇒ 𝜌𝑎𝑖𝑟 𝜋𝑅 3
= 𝜌𝑏𝑙𝑜𝑜𝑑 𝑔 𝜋𝑅 3 − 6𝜋𝜇𝑏𝑙𝑜𝑜𝑑 𝑅𝑉 − 𝜌𝑎𝑖𝑟 𝜋𝑅 3 g
3
𝑑𝑡
3
3
𝑑𝑉
𝜌𝑏𝑙𝑜𝑜𝑑 − 𝜌𝑎𝑖𝑟 9𝜇𝑏𝑙𝑜𝑜𝑑
⇒
=𝑔
−
𝑉
𝑑𝑡
𝜌𝑎𝑖𝑟
2𝜌𝑎𝑖𝑟 𝑅 2
The bubble will reach its maximum velocity when the acceleration is zero:
2
𝜌𝑏𝑙𝑜𝑜𝑑 − 𝜌𝑎𝑖𝑟
𝑉𝑚𝑎𝑥 = 𝜋𝑔𝑅2
9
𝜋𝜇𝑏𝑙𝑜𝑜𝑑
We calculated for a bubble of 0.5mm in radius. All the bubble with smaller size will take more time
to rise.
After calculation in Maple, we found that the time and distance for that the bubble reach its
maximum velocity are negligible. So we can assume that the velocity of the bubble is constant with
the value V=Vmax=0.213m/s. As a result, the traveled distance is represented as below:
January 16, 2009
22
P09021 Hydraulic VAD Test Loop
System Level Design Review
Figure 1. Distance traveled by the bubbled in function of time
If we assume that the velocity of liquid inside the tank is two times less than the velocity in the tubing.
So the time needed for a fluid element pass through the tank is:
𝑡=
𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒 𝑖𝑛𝑝𝑢𝑡/𝑜𝑢𝑡𝑝𝑢𝑡
0.5 × 𝑉𝑓𝑙𝑢𝑖𝑑
With this time, the distance that a bubble raises is:
𝐻 = 𝑉𝑚𝑎𝑥 × 𝑡 =
𝑉𝑚𝑎𝑥 × 𝐷𝑖𝑠𝑡𝑎𝑛𝑐𝑒
0.5 × 𝑉𝑓𝑙𝑢𝑖𝑑
So, in the case of the blood tank, the distance between input and output is ID=4.75 in, so H=2.5 in. In the
case of the arterial tank, the distance is IDxcos45o, so H=3.0 in. In the two cases, the bubble gets far
enough.
Maple code:
> restart;
> mju_blood:=0.0027:
rho_blood:=1060:
rho_air:=1.177:
g:=9.81:
> R:=0.5e-3:
> eqn:=diff(V(t),t) = g*(rho_blood-rho_air)/rho_air (6*mju_blood)/(rho_air*(4/3*R^2))*V(t);
eqn :=
d
V ( t ) = 8825.024325 K 41291.41887 V ( t )
dt
> V:=rhs(dsolve({eqn,V(0)=0},V(t)));
January 16, 2009
23
P09021 Hydraulic VAD Test Loop
System Level Design Review
45256535
45256535 0K
V :=
K
e
211750866
211750866
1
4129141887
t
100000
> V_max:=4/3*Pi*R^3*g*(rho_blood-rho_air)/(6*Pi*mju_blood*R);
V_max := 0.2137253834
> t_max:=Re(solve(V=V_max,t));
t_max := 0.0005203217489
The distance made from 0 to t_max
> int(V,t=0..t_max);
0
.0001060299410
The distance made from t_max
> Distance:=int(V,t=0..t_max)+V_max*(t-t_max);
Distance := K 0.0000051760243 C 0.2137253834 t
> plot(Distance,t=t_max..1,x=0..0.25, labels=["time(s)", "distance(m)"]);
If we change the size of the bubble, we obtain:
-
R=0.1mm
January 16, 2009
24
P09021 Hydraulic VAD Test Loop
-
System Level Design Review
R=1mm
January 16, 2009
25
P09021 Hydraulic VAD Test Loop
System Level Design Review
Heat Transfer of Tanks
Tank Dimensions: Ø = 4.875” x 5.5”
Tw = 98oF = 310.15K
Tw
Tb = 70oF (room temperature) = 294.26K
Tb
Attempt w/ LCM (Lumped Capacitance Method)
∙ 𝑢𝑠𝑒 𝑖𝑓 𝐵𝑖 # 𝑖𝑠 < 0.1
𝐵𝑖 = ℎ𝐿𝑐 ⁄𝐾
𝐿𝑐 = 𝑉⁄𝐴 = 𝑟⁄2 = 2.4375⁄2 = 1.21875
𝐾302 𝑆𝑡𝑎𝑖𝑛𝑙𝑒𝑠𝑠 = 15.1 𝑤⁄𝑚𝑘 𝑡𝑎𝑏𝑙𝑒 𝐴. 1
𝑉𝑜𝑙𝑢𝑚𝑒 𝑏𝑙𝑜𝑜𝑑 = 1.9𝐿 = .0019𝑚3
ℎ=
𝜌𝑣𝐶𝑝
𝜏𝐴𝑠
𝑇∞ = 98.2℉
r2
r1
Ti
𝑇∞
Ti
q”
ln(𝑟2 ⁄𝑟1 )
2𝜋𝐾𝑇 𝐿
1
2𝜋𝑟2 ℎ𝐿
𝐿 = 6.756" = .1714𝑚
𝐾𝑔𝑙𝑦𝑐𝑒𝑟𝑖𝑛 = .286 𝑊⁄𝑚𝐾
ℎ = .1714𝑚 = 6.75 𝑖𝑛
𝐾𝑠𝑡𝑎𝑖𝑛𝑙𝑒𝑠𝑠 = 15.1 𝑊⁄𝑚𝐾
𝑟1 = .062 𝑚 = 2.4375 𝑖𝑛
𝑟1 = .060 𝑚 = 2.375 𝑖𝑛
January 16, 2009
26
P09021 Hydraulic VAD Test Loop
System Level Design Review
𝑅𝑇𝑜𝑡 =
𝑅𝑇𝑜𝑡 =
ln(𝑟2 ⁄𝑟1 )
1
+
2𝜋𝐾𝑇 𝐿
2𝜋𝑟2 ℎ𝐿
ln(. 062𝑚⁄. 060𝑚)
1
+
𝑊
𝑊
2𝜋(15.1 ⁄𝑚𝐾 )(.1714𝑚) 2𝜋(. 062𝑚)( ⁄𝑚𝐾 )(.1714𝑚)
𝑅𝑇𝑜𝑡 = .002 𝐾⁄𝑤 + 52.37 𝐾⁄𝑤 = 52.37 𝐾⁄𝑤
𝑅𝑇𝑜𝑡 = 52.37 𝐾⁄𝑤
𝑞=
𝑇∞ − 𝑇𝑖 310.05𝐾 − 294.26𝐾
=
= .02 𝑤
𝑅𝑇𝑜𝑡
52.37 𝐾⁄𝑤
𝑤=
𝐵𝑖 =
ℎ𝐿𝑐 ℎℎ2 𝑜 𝐿𝑐 ℎℎ2 𝑜 (𝑟⁄2)
=
=
𝑘
𝑘𝑏𝑙𝑜𝑜𝑑
𝑘𝑏𝑙𝑜𝑜𝑑
ℎ=
ℎℎ2 𝑜 =
𝐽
𝑆
𝜌𝑣𝑐𝑝
𝜏𝐴𝑠
15.1 𝑊⁄𝑚𝐾
2𝜋𝐾𝑇 𝐿
𝐾𝑇
=
=
= 7427.6 𝑊⁄ 2
𝑚 𝐾
2𝜋𝑟2 𝐿 ln(𝑟2 ⁄𝑟1 ) 𝑟2 ln(𝑟2 ⁄𝑟1 ) . 062𝑚 (ln(. 062 ))
. 060
𝐵𝑖 =
𝜉 = 2.3455
7427.6 𝑊⁄ 2 (3114𝑚⁄2)
𝑚 𝐾
= 42.16
15.1 𝑊⁄𝑚𝐾
𝐶1 = 1.5993
𝛼𝑠𝑡𝑎𝑖𝑛𝑙𝑒𝑠𝑠 = 3.91 × 10−6 𝑚2 ⁄𝑠
In order to find the approximate time for the blood in the tank to heat as well as the time it took for the
water bath tank to heat to temperature the Lumped Capacitance method was used. We inputted these
equations and values into excel and found that the time for the blood loop to heat would be less than 2
hours. These numbers indicate a show temperature rise that will be less likely to damage the blood.
January 16, 2009
27
P09021 Hydraulic VAD Test Loop
System Level Design Review
Heat Loss in Tubes
𝑻∞= 𝟕𝟎℉
Ti=98oF
Tm=?
y
x
|<-------------------L=50in------------->|
Blood Properties
70℉ @ µ = .00345 𝑁𝑠/𝑚2
98℉ @ µ = .0027 𝑁𝑠/𝑚2
𝛲 = 1060 𝑘𝑔/𝑚3
𝑣̅ = .789 𝑚⁄𝑠
𝐷 = .5𝑖𝑛 = 1.27 × 10−2 𝑚
𝐴𝑐𝑟𝑜𝑠𝑠 = 1.267 × 10−4 𝑚2
𝐶𝑝 𝑔𝑙𝑦𝑐𝑒𝑟𝑖𝑛 = 2.49 × 103 𝐽⁄𝑘𝑔𝐾
310𝐾 @ 𝐾𝑔𝑙𝑦𝑐𝑒𝑟𝑖𝑛 = 286 × 10−2 𝑊 ⁄𝑚𝐾
𝑁𝑢𝐷 = 0.027𝑅𝑒𝑑 4⁄5 𝑃𝑟 1⁄3 (𝜇⁄𝜇𝑠 )0.14
Equations
𝑅𝑒𝑑 = 𝑒𝑣̅ 𝐷⁄𝜇
ℎ = 𝑁𝑈𝐷 𝐾 ⁄𝐷
𝑑𝑇𝑚
𝑑𝑥
=
𝑃
ℎ(𝑇𝑠
𝑚̇𝐶𝑝
− 𝑇𝑚 ) Pg. 498 equation 8.37
Properties and Equation from Fundamentals of Heat and Mass Transfer 6th editions
Solution
𝑑𝑇𝑚
𝑃ℎ
𝑃ℎ
=
𝑇𝑠 −
𝑇
𝑑𝑥
𝑚̇𝐶𝑝
𝑚̇𝐶𝑝 𝑚
January 16, 2009
28
P09021 Hydraulic VAD Test Loop
System Level Design Review
𝑑𝑇𝑚
𝑃ℎ
𝑃ℎ
+
𝑇𝑠 =
𝑇
𝑑𝑥
𝑚̇𝐶𝑝
𝑚̇𝐶𝑝 𝑚
𝐶=
𝑃ℎ
𝑚̇𝐶𝑝
Homogenous
𝑇𝑚 1 +
Assume solution:
𝑃ℎ
𝑇 =0
𝑚̇𝐶𝑝 𝑚
𝑇𝑚 1 = 𝑟𝑒 𝑟𝑥
𝑇𝑚 = 𝑒 𝑟𝑥
𝑟+
𝑃ℎ
=0
𝑚̇𝐶𝑝
𝑟=
−𝑃ℎ
𝑚̇𝐶𝑝
Particular Solution
Assume Solution:
𝑇𝑚 = 𝐴𝑥 + 𝑏 , 𝑇𝑚 1 = 𝐴
𝐴+
𝑃ℎ
𝑃ℎ
𝐴𝑥 +
𝑏 = 𝐶𝑇𝑠
𝑚̇𝐶𝑝
𝑚̇𝐶𝑝
𝑃ℎ
𝐴𝑥 = 0 → 𝐴 = 0
𝑚̇𝐶𝑝
𝑃ℎ
𝑏 = 𝐶𝑇𝑠 → 𝑏 = 𝑇𝑠
𝑚̇𝐶𝑝
𝑃ℎ
Now:
𝑇𝑚 = 𝑒
( ̇ )𝑥
𝑚𝐶𝑝
+ 𝑇𝑠
These calculations required the solution of a first order ordinary differential equation. The solution to
this ODE led us to a find the final temperature of the tubes after a certain distance. The solution to this
final equation was graphed in excel. The data shows that there is less than 1 degree change in
temperature over 50 in of tubing. From this calculation it is clear that the heating system that we have
chosen will heat and maintain the blood at the appropriate temperature to model the human circulatory
system.
January 16, 2009
29
P09021 Hydraulic VAD Test Loop
System Level Design Review
Linear motor’s force approximation
Abstract: this is an analysis to approximate the force needed by the linear motor.
Scheme / given information:
Fmotor
Pfluid
Constants:
- Fluid maximum pressure: Pfluid=2 psi
- Outer diameter of the tubing: OD=11/16 in
- Width of clamp: W=1 in
Assumption: The resistance of the tubing has been neglected
Analysis:
OD
Fmotor
When the tubing is totally clamped, the length of clamp area is:
Circumference 𝜋𝑂𝐷 𝜋 11⁄16
𝐿=
=
=
= 1.1 𝑖𝑛
2
2
2
So the force can be approximated as:
𝐹𝑚𝑜𝑡𝑜𝑟 = 𝑃𝑓𝑙𝑢𝑖𝑑 × 𝐿 × 𝑊 = 2𝑝𝑠𝑖 × 1.1𝑖𝑛 × 1𝑖𝑛 = 2.2 𝑝𝑜𝑢𝑛𝑑𝑠
So if we neglect the resistance of the tubing, the force needed is 2.2 pounds.
January 16, 2009
30
P09021 Hydraulic VAD Test Loop
System Level Design Review
Arterial tank dimensioning
Abstract: this is an analysis to dimension the arterial tank, and calculate its properties.
Scheme / given information:
Constants from the physiological mocking system:
- Compliance Cv=2.2 mL/mmHg=1.65e-8 m3/Pa
- Fluid pressure at the output (absolute) Pf=860 mmHg =1.147e5 Pa
- Density of glycerin ρ=1060km/m3
ID
Pair
h
Constants from material constraints:
hf
- Inner diameter of the tank ID=7.75 in=0.197 m
- Height of the tank h=0.6 ft=0.183 m
Other constant: gravity g=9.81 m/s2
Assumption: ideal gas, small change in fluid height
Analysis:
From the equation:
𝐶𝑣 =
𝑉𝑎𝑖𝑟 𝑉𝑡𝑎𝑛𝑘 − 𝐴𝑡𝑎𝑛𝑘 ℎ𝑓
=
𝑃𝑎𝑖𝑟
𝑃𝑓 − 𝜌𝑔ℎ𝑓
We come up to the expression:
ℎ𝑓 =
𝐶𝑣 𝑃𝑓 − 𝐴𝑡𝑎𝑛𝑘 ℎ
= 0.121𝑚 = 4.78 𝑖𝑛
𝐶𝑣 𝜌𝑔 − 𝐴𝑡𝑎𝑛𝑘
And:
𝑃𝑎𝑖𝑟 =
𝑉𝑎𝑖𝑟
= 1.13𝑒5 (𝑎𝑏𝑠𝑜𝑙𝑢𝑡𝑒)
𝐶𝑣
So we find that we need to fill in 4.78 inch-height liquid, and the pressure of the air in the tank must
be 1.75psi to have a pressure of 100mmHg at the output of the tank.
Reference:
Yingjie Liu, Paul Allaire, Yi Wu, Houston Wood, Don Olsen. Construction of an artificial heart pump
performance test system. Springer Science + Business Media. 11/30/2006
January 16, 2009
31
P09021 Hydraulic VAD Test Loop
January 16, 2009
System Level Design Review
32
P09021 Hydraulic VAD Test Loop
System Level Design Review
Saline Flush
In search for a solution to flush out LVAD test loop post- blood testing, Drugs.com (a Drug
Information Online source) suggested the use of Sodium Chloride Irrigation, which is commonly
used in Clinical Pharmacology. 0.9% Sodium Chloride Irrigation USP is used for a variety of clinical
indications such as sterile irrigation of body cavities, tissues or wounds, indwelling urethral
catheters, surgical drainage tubes, and for washing, rinsing or soaking surgical dressings,
instruments and laboratory specimens. It also serves as a diluent or vehicle for drugs used for
irrigation or other pharmaceutical preparations. 0.9% Sodium Chloride Irrigation USP provides an
isotonic saline irrigation identical in composition with 0.9% Sodium Chloride Injection USP (normal
saline).1
Many vendors of biocompatible tubing or valves, which we will likely purchase materials,
such as Cole-Parmer.com, suggest sterilization by autoclave, radiation, or ethylene oxide. An
autoclave is a pressurized machine that heats aqueous solutions above their boiling point at normal
atmospheric pressure to make objects sterilized.2 Autoclaves can cost anywhere between $1,756
and $3,958, and are out of the price range of this project. 3 Radiation is also an option not suited for
this project, and would divert too much focus away from the scope. Ethylene oxide is the organic
compound with the formula C2H4O. This colorless flammable gas with a faintly sweet odor is the
simplest epoxide, a three-member ring consisting of two carbons and one oxygen atom, and is also
used for medical sterilization.4 This chemical is used in a chamber sterilization method, which a
chamber is flooded with a mixture of ethylene oxide and other gases that are later aerated. Because
of this, and the fact that it is toxic to inhale, we are choosing not to use ethylene oxide (nor radiation
or autoclave) to sterilize the LVAD test loop, but rather normal saline.
1Drugs.com.
Sodium Chloride Irrigation. http://www.drugs.com/pro/sodium-chlorideirrigation.html
2Wikipedia- Autoclave. http://en.wikipedia.org/wiki/Autoclave
3 MedSupplier.com. http://www.medsupplier.com/autoclaves-andsterilizers.aspx?gclid=CMiLl92otZgCFROgnAod4hT5bA
4 Wikipedia- Ethylene Oxide. http://en.wikipedia.org/wiki/Ethylene_oxide
January 16, 2009
33
P09021 Hydraulic VAD Test Loop
System Level Design Review
Sensor and DAQ analysis
This report looks at the resolution and sensitivity of the sensors and also the resolution of the DAQ. Besides is also looks
at output voltage of then sensors so it is possible to compare DAQ and a sensor to figure out if they will be compatible
with each other.
Sensitivity =
50𝑚
5
= 10mV/psi
If using accuracy of measurement for pressure is 0.1 in H20
Resolution = 10mV/psi × (0.1inches of water × 0.0361) psi = 36.1µV
Pressure Sensor (Omega PX26-005DV )
Specs
Model's specs
Output format
(@10V) 50mV
Price
$36.00
Sensitivity=
10
=
64
0.156V/liter
Resolution= 0.156V/liter × 0.05liter =7.8mV
Flow sensor (Transducer+board digiflow-ext1 )
Specs
Model's specs
Resolution
1ml/min
Output format
-5V to 5V
Max measurement
±32 𝑙/𝑚𝑖𝑛
Frequency
15kHz to 18MHz
(transmitter
frequency)
Price
Don’t need to
purchase
January 16, 2009
34
P09021 Hydraulic VAD Test Loop
System Level Design Review
Thermocouple. (Omega - KMQSS-020G-12)
Specs
Model's specs
Type
Ungrounded
Price
$28.65
Resolution in volts =
𝑓𝑢𝑙𝑙 𝑠𝑐𝑎𝑙𝑒 𝑟𝑎𝑛𝑔𝑒
2𝑀
=
160𝑚
224
= 9.54nV/code
Thermocouple DAQ (NI 9211A)
Specs
Model's specs
Resolution
24bit
Number input pins
4
Voltage range
-80mV to 80mV
Sampling rate
15 S/s (samples per
secs)
Price
$521
January 16, 2009
35
P09021 Hydraulic VAD Test Loop
System Level Design Review
Resolution in volts =
5−(−5) 10
=222
2𝑀
Resolution in volts =
62𝑚−(−62𝑚) 124𝑚
= 222
2𝑀
= 2.384µV/code
= .2956nV/code
DAQ (OMB-DAQ-54)
Specs
Model's specs
Resolution
22 bits
Number input pins
10 single ended
Voltage range
31mV to 20V
Sampling rate
80 S/sec
Price
$649
Looking at the results for what was obtained from the calculations to figure out the sensitivity of the
sensor and resolution of both the DAQ and sensor, it was found that if the PX2300 was purchased it can
be coupled with the flow sensor and the USB 6009 DAQ. If instead the PX26 was purchased it is possible
to couple it with the NI9211A DAQ and thermocouple. But if the OMB-DAQ-54 was bought it is possible
to incorporate all the sensors including the flow sensor as it has a total of 10 single ended analog inputs.
Since the NI9211 has the a range of ±80𝑚𝑉 along with the thermocouple, this makes it possible to use
the PX26 pressure sensor, besides this it has a resolution of about 10nV/bit showing that it will be able
to resolve the minute fluctuation of the sensors. The sensor is shown to output 10mV per psi of change.
Assuming that required accuracy of the pressure reading is 0.1inches of water, it was found that the
resolution of the sensor to be 36.1µV, meaning that the when the sensor detects 36.1µV then it
indicates a change in pressure.
For the flow sensor, it has a sensitivity of about 0.156V/liter and a resolution of 7.8mV if it is assumed
that the accuracy of the reading needs to be a 0.05 liter change. The output voltage range also
corresponds of the OMB-DAQ-54 so they can be used together.
January 16, 2009
36
P09021 Hydraulic VAD Test Loop
System Level Design Review
LabVIEW Front Panel Prototype
Controls:
Indicators:








LVAD Speed (rpm)
Desired Flow ( L/m)
Desired Pressure Decrease (mm Hg)
PVS Speed (rpm)
PVS upper/ lower (bpm)
Resistance Valve control (in)




January 16, 2009
Real time/ Summary of pressure/ flow graphs
PVS Change in Pressure and Flow with max/ min
indicators
Temperatures in tank and at LVAD
Boolean Warning lights if temperature is out of
range
2 Pressure Sensors
2 Flow Sensors
37