convective co-efficient of plastic tube

Replies

• 

  Ramani Aswath

  Almost all iv tubes are made using biocompatible plasticised PVC. It does not have any convective heat transfer coefficient. It is the fluid flowing through it that has this. In what way is this relevant?
• 

  MURTUZA ZAVERI

  A.V.Ramani

  Almost all iv tubes are made using biocompatible plasticised PVC. It does not have any convective heat transfer coefficient. It is the fluid flowing through it that has this. In what way is this relevant?

  a friend of mine is working on a project, in which a case like this has arose.
  
  cool water at 10 degree C is made to flow through such a tube of total length of 5 meters.
  
  now he wants to determine, how much of heat the water gains, by the time the water exits from the tube (flows out from the other end of the tube).
  
  does the velocity of the flow of water also help in heat gain ?
• 

  Ramani Aswath

  The limiting factor here is probably the diameter and thickness of the tube. PVC is a poor conductor. The flow rate and ambient temperature are also required.
  If these are available it is a simple equation to calculate the heat gain from published data.
• 

  Ritesh Patil

  Pawl supiran

  HI all
  
  what is the convective co-efficient of the material, with which those plastic tubes meant for administering Intravenous is made of ?
  
  can anyone tell me ?

  Hey Paul!
  Convective heat transfer coefficient is a property of fluids and no solid has this. If you are looking for conductive heat transfer coefficient and if what Mr. Ramani points out is correct, then according to www.engineeringtoolbox.com, thermal conductivity of PVC is 0.19 W/(m.K). Feel free to browse through the link if in case you come to know the right material of the tube.
  As for your next question, yes, fluids moving through a tube, tend to heat up proportional to their viscosity, velocity, diameter and length of tube due to shearing action. This is a subject of fluid mechanics how fluids tend to lose pressure per unit length of tube. And that energy lost in pressure, is gained in heat i.e. they heat up.
  This is in no way a straight forward calculation and you should consult someone experienced in Heat Transfer as well as Fluid Mechanics.
• 

  Ramani Aswath

  There are three heat transfer coefficients involved here. The airside one, the conductive one through the wall of PVC and the fluid side one all in series. In this case all are poor. The overall coefficient has to be calculated. After that the heat gain can be calculated easily.
• 

  Ritesh Patil

  No arguments there. But doing an experimental study will be much easier and more validated than doing an analytical study.
• 

  Ramani Aswath

  Not really. Enough data is available to get a good approximation. In real life use, iv fluids are given in AC rooms at about 20 C temperature. If critical, the fluid is warmed to body temperature before delivery.
  
  Reverting to the problem, the overall coefficient can be calculated from taking the reciprocal of the sum of the reciprocals of all the coefficients in series.
  www.engineeringtoolbox.com
• 

  Ramani Aswath

  Not really. Enough data is available to get a good approximation. In real life use, iv fluids are given in AC rooms at about 20 C temperature. If critical, the fluid is warmed to body temperature before delivery.
  
  Reverting to the problem, the overall coefficient can be calculated from taking the reciprocal of the sum of the reciprocals of all the coefficients in series.