Docstoc

HEAT PIPES FOR CONTROL

Document Sample
HEAT PIPES FOR CONTROL Powered By Docstoc
					HEAT PIPES FOR CONTROL

    CAN THEY BE USED IN
    CHEMICAL REACTORS?
             David Reay


        16TH PIN MEETING, RUNCORN,   1
             9 SEPTEMBER 2008
A Sodium Heat Pipe I Made Some
Time Ago Introduces the Concept




          16TH PIN MEETING, RUNCORN,   2
               9 SEPTEMBER 2008
And this is Developed into an ‘Active
    Feedback Controlled VCHP’




Which controls the source (reactor) temperature to
+-1Deg.C

                  16TH PIN MEETING, RUNCORN,         3
                       9 SEPTEMBER 2008
Back to Basics - Thermosyphons & Heat
         Pipes: What are they?




                                  Conventional heat pipe schematic. (1) HP
                                  case, (2) porous wick, (3) vapour channel,
                                  (4) vapour, and (5) liquid.

       Thermosyphon
 (Gravity-assisted liquid
 transport)

                        16TH PIN MEETING, RUNCORN,                         4
                             9 SEPTEMBER 2008
A Little Bit of History


                                Perkins Tubes used
                                to transfer heat from a
                                hot air stream to a
                                cold one – gas-gas
                                heat recovery.



                        The Perkins tube is a
                        thermosyphon – relies on
                        gravity for liquid return




   16TH PIN MEETING, RUNCORN,                             5
        9 SEPTEMBER 2008
  The Perkins Oven – use coal to bake
bread without getting soot on the dough!




             16TH PIN MEETING, RUNCORN,   6
                  9 SEPTEMBER 2008
Closer to Chemical Engineering – safety
                first!




            16TH PIN MEETING, RUNCORN,    7
                 9 SEPTEMBER 2008
The current version of the Perkins Heat
              Exchanger




            16TH PIN MEETING, RUNCORN,    8
                 9 SEPTEMBER 2008
Heat Pipe Working Fluids


                              Fluids can cover
                              temperature ranges
                              appropriate to most
                              reactors.
                              Liquid metals used – eg
                              sodium.




     16TH PIN MEETING, RUNCORN,                         9
          9 SEPTEMBER 2008
Comparison of fluid performance


                                Merit number compares
                                relative heat transport
                                capability of different
                                working fluids.


                                Strong function of latent
                                heat, surface tension,
                                viscosity




        16TH PIN MEETING, RUNCORN,                          10
             9 SEPTEMBER 2008
Limitation to heat transport are several

                                  Capillary limit affected by
                                  orientation of heat pipe &
                                  wick design.
                                  The wick is a passive
                                  pump.


                                  Sonic limit occurs when
                                  fluid density high (eg at low
                                  T)




            16TH PIN MEETING, RUNCORN,                            11
                 9 SEPTEMBER 2008
Types of Heat Pipe




  16TH PIN MEETING, RUNCORN,   12
       9 SEPTEMBER 2008
Applications as a Function of Heat Pipe
               Features




            16TH PIN MEETING, RUNCORN,    13
                 9 SEPTEMBER 2008
                    Isothermalisation


Isothermalisation – or
evening out of
temperatures, is an
inherent feature that
may benefit reactors




                         16TH PIN MEETING, RUNCORN,   14
                              9 SEPTEMBER 2008
Variable Conductance HP in a Reactor
             (Nuclear)




           16TH PIN MEETING, RUNCORN,   15
                9 SEPTEMBER 2008
  Benefits in Chemical Reactors
Catalysts have been put on heat pipes, with surface reactions.
The heat pipe is in ideal way of heat removal/input to the
catalyst thereon.




                 16TH PIN MEETING, RUNCORN,                      16
                      9 SEPTEMBER 2008
More possible benefits in Reactors




          16TH PIN MEETING, RUNCORN,   17
               9 SEPTEMBER 2008
Chinese Chemical Heat Pipe Reactor




          16TH PIN MEETING, RUNCORN,   18
               9 SEPTEMBER 2008
VCHP Concepts – Passive Control




         16TH PIN MEETING, RUNCORN,   19
              9 SEPTEMBER 2008
VCHP – Passive Feedback Control




         16TH PIN MEETING, RUNCORN,   20
              9 SEPTEMBER 2008
VCHP – Active Feedback Control – as
           shown earlier




          16TH PIN MEETING, RUNCORN,   21
               9 SEPTEMBER 2008
As with the SDR, rotation aids heat
   transfer and fluid transport


                                       Used for cooling
                                       rotating
                                       machinery




          16TH PIN MEETING, RUNCORN,                      22
               9 SEPTEMBER 2008
Other rotating variants




    16TH PIN MEETING, RUNCORN,   23
         9 SEPTEMBER 2008
                    In Conclusion
• The heat pipe, in its several variants, has many
  interesting heat transfer features.
• The heat pipe/thermosyphon could act to isothermalise
  reactor vessels, minimising uneven reaction rates.
• The ability to passively control temperatures at its
  evaporator could contribute to minimise excursions in
  endo- or exothermic reactions.
• The application of active feedback control can lead to
  precise temperature control.

• Newcastle University is able to collaborate with potential
  partners in bringing the technology into the marketplace.

                    16TH PIN MEETING, RUNCORN,             24
                         9 SEPTEMBER 2008
Common wastewater treatment




       16TH PIN MEETING, RUNCORN,   25
            9 SEPTEMBER 2008

				
DOCUMENT INFO
Shared By:
Categories:
Tags: HEAT, PIPES, CONTROL
Stats:
views:42
posted:3/16/2010
language:English
pages:25
Description: HEAT PIPES FOR CONTROL