FR2460456A1 - SOLAR COLLECTOR AND HEAT PUMP SUITABLE IN PARTICULAR FOR A SOLAR COLLECTOR - Google Patents

Abstract

SOLAR COLLECTOR PRESENTING AN ABSORBER IN THE FORM OF A PLATE1 SERVING TO CAPTURE SOLAR RADIATION AND CONNECTED IN A WAY TO ENSURE THE THERMAL CONDUCTION TO A VAPORIZER2 OF THE CALODUC3, WHICH CAN BE THERMAL EXCHANGED BY A CONDENSER4 TO ANOTHER TRANSPORT SYSTEM5 HEAT PIPE CONTAINING ISOBUTANE AS ACTIVE FLUID. THE HEAT PIPE IS SUITABLE FOR THE SOLAR COLLECTOR AUDIT. APPLICATION: SOLAR COLLECTOR.

Description

-1- "solar collector and heat pipe suitable in particular for

a solar collector.

  The invention relates to a solar collector

  an absorber designed to capture the solar radiation

  connected, so as to ensure the conduction

  to a vaporizer component (called

  hereinafter vaporizer) of a transport system of

  as a heat pipe and which can be

  heat generated by a condenser component (

  peeled hereinafter condenser) with another transmission system

  port of heat, an active fluid in the Io heat pipe and having a critical temperature, which is below the maximum allowable temperature in

  the other heat transport system.

  A solar collector of the kind mentioned above

  is known from U.S. Patent No. 3,390.

672.

  In solar collectors of this kind, the flui-

  condensed asset accumulates in the cold state in the

  porator of the heat pipe. The active fluid is evaporated in

  the case of a heat input from the absorber.

  2o The steam flows to the condenser where it gives up its

  heat to the fluid contained in the other system of trans-

  heat port. Then the condensate is refluxed

Sprayer.

  The heat transport from the vaporizer to the condensation

  It continues as long as a phase transition of the active fluid can occur. So if

  the temperature of the heat pipe exceeds the critical temperature

  active fluid, the transmission power of each

  their disappearance practically disappears, which makes it possible to determine, by the choice of the active fluid, the maximum temperature at which the heat transfer stops, which is of primary importance because the other heat transport system to which is brought heat

  must not exceed a certain temperature in general.

  From the above patent of the United States of America

24.6O456

-2-

  No. 3,390,672, it is known for several temperature ranges.

  of active fluids such as ethyl alcohol, ethyl ether, freon 11, freon 13. In addition, there is

  literature mentioning active fluids for

  duke, like ammonia, propane, and several other freons. It should be noted that freon is a registered trademark. All these known active fluids have the disadvantage of disintegrating after some time, so that residual gases are formed, which no longer contribute

  I0 to the process of evaporation and condensation and which

  accumulate in the highest part of the condenser. This results in the inactivity of a part and, after some time, of all the condenseuxi and, therefore, of the heat pipe. The invention aims to provide a solar collector of the kind mentioned above o the active fluid of the heat pipe is constituted by a fluid, which does not disintegrate after some time and which has a heat transmission capacity varying quite rapidly with the temperature , so that at normal operating temperature,

  there is still a great power of transmission of

  which then declines very rapidly until

  their zero at the critical temperature. In addition, the trans-

  heat is only effected by thermal conduction.

and convection.

  The collector according to the invention is characterized

  in that the active fluid is constituted by i-

sobutane.

  Isobutane offers the great advantage of being a com-

  very stable even at higher temperatures and

  not be subject to disintegration.

  In addition, isobutane has a critical temperature

  tick of 135-, which constitutes an acceptable temperature

  maximum for the other transport system of

their.

  The heat transfer power of the isobutane

  does not vary rapidly with temperature, which

  It can be seen that the heat transfer power at the critical temperature is zero, whereas at the required operating temperature of about 90.degree.

  already a notable value. A great power of transmission

  under operating conditions is important because the surface of the condenser

  may be smaller as the power of trans-

Heat mission is bigger.

  In addition, the invention relates to a heat pipe con-

  I0 coming in particular to a solar collector and character-

  in that as active fluid, it contains isobutane

tane.

  The description below, with reference to the drawing

  annexed, all given as a non-limitative example

  make it clear how the invention can be

  Lisée. The single figure schematically represents a

  solar collector according to the invention.

  The solar collector shown in the drawing

  takes a plate-shaped absorber 1, which is connected

  in order to ensure thermal conduction by vaporisation

  2 of a tubular heat pipe 3. The absorber 1 is provided with

  at its upper part, a layer absorbing the

their solar.

  In addition, the heat pipe 2 is provided with a capacitor 4, which is in heat exchange with a liquid contained in another heat transport system 5, which is only partially shown in the drawing. The absorber plate 1 and the vaporizer 3 of the heat pipe are housed in a glass envelope 6 of a section

  circular. This envelope 6 is closed down at 7.

  At the top, the envelope is closed by a part 8,

  made of glass, which is sealed to a thin-walled tube 9 of a suitable metal, for example chromium-iron, which

  is welded or hermetically sealed to the heat pipe 2.

  This construction avoids, at least for the most part, thermal stresses between the heat pipe and the glass envelope. In the glass envelope reign

depression.

  At the ends of the plate-shaped absorber 1

  plates 11 and 12 are arranged.

  12 serves simultaneously centering the heat pipe.

  The application of the absorber 1 and the vaporizer

  3 in a vacuum envelope reduces

  heat. Another improvement on this subject can be obtained by a whole or partial coating of the inner wall of the glass envelope of a layer

  selective heat reflector, for example oxy-

  of indium doped with zinc.

  In heat pipe 2 isobutane is

  active fluid, which evaporates as a result of the heat

  secured by the absorber plate 1 to the vaporizer part

  3. The steam flows to the condenser and

  dense, while yielding its heat of evaporation to liquid

  of content in the system 5 via the

condenser wall.

  The operating temperature of the collector

  is preferably limited to about 90.degree.

  tane still having a transmission power of

suitable heat.

  When, for one cause or another, the temperature of the collector rises, for example because the system draws too little heat, it is possible that the temperature rises in particular, or even above 300- C, and it has been found that in this case, isobutane

  is not subject to disintegration. The power of trans-

  heat mission decreases rapidly as a result of the evaporationcondensation cycle until, at about C, the critical temperature of isobutane has become

  zero. In this case, the heat is not transported to the system.

  5 only by conduction and convection, so that the

  system temperature does not rise too much.

  Compared to other known active fluids,

  in systems operating at an acceptable temperature

  Since isobutane offers the advantage of being a very stable compound from the thermal point of view, which means that no gas is allowed to disrupt the operation of the

heat pipe.

  In addition to this high stability, isobutane

  a great power of heat transmission at the time

  normal operating temperature, which implies

  that the surface of the condenser part 4 can be

latively small.

Claims (2)

  l. Solar collector with an absorber (1) designed   to capture the solar radiation and connected, so as to ensure   thermal conduction, to a vapor component   (2), (hereinafter referred to as vaporizer) of a heat transport system as a heat pipe (3) and   heat exchange by a constituent part   denser (4) (hereinafter referred to as a condenser) with another heat transport system (5), an active fluid being   the heat pipe and having a critical temperature, which is   below the maximum admissible temperature in the other heat transport system, characterized in that the   active fluid consists of isobutane.   2. Heat pipe particularly suitable for solar collector according to claim 1, characterized in that as active fluid, it contains isobutane. g1