Project by karan pradeep


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THERMAL AND STRUCTURAL MODELING OF ARTERIES SUBJECTED TO SUB ZERO TEMPERATURE CONDITIONS

  • PROJECT BY

  • KARAN PRADEEP

  • ARVIND C.J

  • KARTHIK KUMAR B

  • NAJUMUDEEN A


INTRODUCTION



ARTHEROCLEROSIS

  • Deposition of fat - Plaque

  • Clogging of arteries

  • Reduces blood flow to the legs and feet

  • Increases risk of

    • Infection
    • Leg ulcers
    • Gangrene
    • Amputation.


METHODS FOR THE TREATMENT OF ARTHEROCLEROSIS

  • Lifestyle changes & medication

  • Bypass surgery

  • Angioplasty

      • Insertion of balloon into the artery.
      • Passing of saline water.
  • Stents

    • Placement of alien body as support
  • Cryoplasty therapy



CRYOPLASTY

  • Catheter balloon material

    • expanded PolyTetraFluoroEthylene
    • Diene polymer
  • Usage of nitrous oxide

  • Temperature -10 to -200C

  • Inside pressure 6 bar

  • Time for treatment is 50 seconds



APOPTOSIS

  • Programmed cell death - induced within a precisely defined temperature zone.

  • Too low temperatures may result in necrosis

  • Injury - cellular inflammation, cell proliferation, and restenosis.

  • Temperatures that are not cold enough have little or no effect



LITERATURE SURVEY & SCOPE OF THE PROJECT



LITERATURE SURVEY

  • IN VITRO STUDIES OF ARTERIAL FREEZING INJURY by James D. Joye, DO, FACC and Kristine Tatsutani, Ph.D

  • FEASIBILITY AND SAFETY OF A NOVEL CRYOPLASTYTM SYSTEM by Mitsuyasu Terashima, Yasuhiro Honda1, Frederick St. Goar, Margaret Yoklavich, Paul G. Yock, Peter J. Fitzgerald

  • CRYOPLASTY PROCEDURE PROPOSED MECHANISMS OF ACTION by Kristine Tatsutani, PhDPrinciple Scientist, Cryobiologist CryoVascularSystems, Inc.

  • Current research topic in

    • Texas A & M University
    • University of Minnesota, Twin cities


SCOPE OF PROJECT

  • Lack of clear understanding of the mechanism restricts its usage to peripheral arteries

  • Most of the present research in this field is concentrated on 1-D analysis

  • No particular focus on the thermal effects of cryoplasty on the artery walls.

  • A 2-D analysis would serve to identify any high stress level due to the sub-zero temperature



PHASE I SIMPLIFIED MODEL



ASSUMPTIONS

    • Properties of artery walls are same as that of water.
    • Length of the artery in contact with the catheter balloon alone is considered.
    • The effects of the following are ignored
    • Temperatures considered
      • Initial temperature 37o C
      • Outer surface temperature 37o C
      • Inner surface temperature -20o C


MATERIAL PROPERTIES - CONDUCTIVITY



MATERIAL PROPERTIES - ENTHALPY

  • Formulation of enthalpy values for phase change material, water.

  • Arbitrary datum, enthalpy h = 0, at T1=-20o C

  • At T2 =0o C ,

  • h2 = h1 + ρ( Cp ice)(T2 – T1) = 41602000 J/m3

  • At T3 = 0.5o C ,

  • h3 = h2 + ρ( Cp ice,water)(T3 – T2) + ρhsl = 45478000 J/m3

  • At T4 = 20o C ,

  • h4 = h3 + ρ( Cp water)(T4 – T3) = 127690000 J/m3

  • Where

  • Cp ice = 2261 J/kg K

  • Cp water = 4216 J/kg K



MATERIAL PROPERTIES - ENTHALPY

  • Enthalpy values used to simulate the effects of phase change



DESIGN – 2D MODEL



DESIGN – AXISYMMETRIC MODEL



RESULTS

























CONCLUSIONS

  • Temperature distribution along any radius is the same.

  • Temperature distribution along the radial direction are the same for both the models.

  • Temperature distribution does not vary along the axial direction.



FUTURE PLAN

  • Phase 2: Plaque layer and its effects on temperature distribution.

  • Phase 3: Inclusion of the balloon layer.

  • Phase 4: Effects of flow of nitrous oxide on temperature distribution.

  • Phase 5: Temperature distribution along axial direction

  • Phase 6: Determination of the stress distribution.



REFERENCES

  • BOOKS

    • Annual review of heat transfer, volume 9
    • By Chang L Tien
    • Heat conduction
    • By Latif M Jiji
    • The CRC handbook of thermal engineering
    • By Frank Keith
    • Heat and mass transfer data book
    • By C P Kothandaraman and S Subramanyan
  • WEB SITES

    • www.cryoplasty.com
    • www.umn.edu
    • www.wikipedia.org
    • www.tamu.edu



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