CA1283549C - Heat pipe having a turbine built therein and apparatus using same - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A heat pipe having a turbine built therein includes a vertically oriented, closed tube containing working fluid therein, a hollow taper tube rotatably disposed within the closed tube and having an increasing diameter toward the upper end, and turbine blades attached to the outer periphery of the hollow tube at its intermediate wherein the upper and lower end of the closed tube are heated and cooled, respectively, to create a flow of vapor-phase working fluid through the closed tube to thereby rotate the turbine blades and the hollow tube, and liquid-phase working fluid is fed upward through the hollow tube by the resultant centrifugal force. An apparatus using such a turbine-equipped heat pipe can perform heat transport and electric power generation at the same time by attaching turbine blades to a rotary shaft rotatably supported in the closed tube such that the blades are driven by a flow of vapor-phase working fluid and coupling the rotary shaft with a generator disposed outside the closed tube.

Description

Thls Inventlon re~ates to a heat plpe havlng a turbine bullt t~1ereln whereln worklng fluld In vapor phase rotates the turblne to transdllce thermal energy Into mechanlcal energy, as well as an apparatus uslng the heat plpe.

The present Inventlon will be Illustrated by way of the accompanylng drawlngs, In whlch:~-Flg. 1 Is a schematlc cross-sectlonal vlew of a heat plpe havlng a turblne bullt thereln accordlng to one em~odlment of the present 7nventlon;

Flg. 2 Is a schematlc cross-sectlonal vlew of a flrst embodIment of the apparatus uslng a heat plpe havlng a turblne bullt thereln accordlng to the present Inventlon;

Flg. 3 Is a schematlc cross-sectlonal vlew of a second embodlment of the apparatus uslng a heat plpe havlng a turblne bullt thereln accordlng to the present Inventlon;
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Flg. ~ Is a schematlc cross-sectlonal vlew of a thlrd embodlment of the apparatus usln~ a heat plpe havlng a turblne bullt thereln accordln~ to the present Inventlon;

2~ Flg.s 5A and ~B dlagramatlcally Illustrate thermal cycles, Flg. 5A showlng a T-s curve for water and Flg. 5B showlng a P-l curve for Fron R-114;

Flg.s ~A and 6B Illustrate dlfferent examples of non-return means, Flg. 6A showlng a check valve and Flg. 6B showlng atrap;

Flg. 7 Is a schematlc cross-sectlonal vlew of a fourth embodlment of the apparatus uslng a heat plpe havlng a turblne bUllt thereln accordlng to the present Inventlon;

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Flg~ 8 1s a schematlc cross-sectlonal vlew of a flfth embodlment of the apparatus uslng a heat plpe havlng a turblne bullt thereln accordlng -to the present Inventlon;

Flg. 9 Is a T-s curve dlagram showln~ the thermal cycle In the apparatus shown In Flg. 8;

Flg. 10 Is a partlal cross-sectlon of the turblne blades havlng a cone on the upstream slde;

Flg. 11 Is a schematlc vlew showlng an apparatus for performlng geothermal power generatlon uslng a heat plpe havlng a turbine bullt thereln;

1~ Flg. 12 Is a cross-sectlonal vlew of the turblne-equIpped heat plpe used In the apparatus of Flg. 11;

Flg. 13 Is a schematlc vlew showlng an apparatus for performlng recovery of waste heat and power generatlon at the same tlme uslng a heat plpe havlng a turblne bullt thereln;

Flg. 14 Is a cross-sectlonal vl0w of the turblne-equlpped heat plpe used In the apparatus of Flg. 13;
, Flg. 11; Is a schematlc perspectlve, partlally cut-away, vlew showlng an apparatus for performlng solar power generatlon uslng a heat plpe havlng a turblne bullt thereln;

Flg. 16 Is a cross-sectlonal vlew of the turblne-equlpped heat plpe used In the apparatus of Flg. 15;

Flg. 17 Is a schematic perspectlve, partially cut-away, vlew showlng an apparatus for meltIng the snow on a roof uslng a heat plpe havlng a turblne bullt thereln;

Flg. 18 Is a cross-sectlonal vlew of ~he turblne-- 1a -' ~ ' ' ' ~ '-. . : ' , ~3,~
equlpped heat plpe used In the apparatus of Flg. 17;

Flg. 19 Is a cross-sectlonal vlew showlng a prlor art structure whereln he~t plpes are serlally Jolned; and Flg~ 20 Is a cross-sectlonal vlew showlng another prlor art structure.

Heat plPes are ~ell known In the art. ~n general, the heat plpe comprises a closed contalner usually In the form of an elongated tube havlng a wlck dlsposed and worklng fluld charged thereln. One end of the closed contalner serves as a heatlng zone and the other end as a coollng zone. The worklng fluld Is heated In the ~leatlng zone to evaporate Into vapor and then flows toward the coollng zone at a low vapoUr pressUre where it releases heat and condenses, to thereby transport heat In the form of latent heat of the worklng fluld whlle the ll~uld-phase worklng fluld Is returned by the caplllary pressure created by the wlck. The heat plpe thus has a coefflclent of heat trans~er several ten to one hundred and several ten tImes grater than those of metals llke copper.

The prlor art heat plpe Is generally deslgned such that llquld-phase workln~ fluld Is clrculated under the caplllary pressure. In a speclal applIcatlon where a heat plpe Is vertl-cally placed wlth Its upper and lower ends servlng as heatlng and coollng zones, respectlvely, that Is, top heat mode, If the ver-tlcal dlstance between the heatlng and coolln~ zones exceeds sev-eral ten centImeters, the head of liquld-phase worklng fiuld between the heatlng and coollng zones becomes greater than the caplllary pressure of the wlck to prevent the llquld-phase work-lng fluld from returnlng to the heatlng zone, undeslrably falllng to perform heat transport.

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~33~i~9 Such a problem may be o~ercome, for example, as shown in FIG.
19, by serially alignlng and joining a plurality of heat pipes 150, 151 on a common axis, and providing a structured portion 152 at the joint to provide an increased heat transfer area to the~eby shorten the clistance over which the liquid-phase working fluid is circulated. With this construction, circulation of liquid-phase worki.ng fluid is not necessarily smooth around the structured portions~ Since each of heat pipes 150, 151 has a substantial length of ~ as shown in FIG. 19, circulation of liquid-phase working fluid becomes insufficient in the top heat mode. Differently stated, there result a poor heat transport capacity and a substantial d:if~erence in temperature between the opposite ends.

~nother arrangement is proposed wherein a first heat pipe 153 is formed as a hollow cylindrical column as shown in FIG. 20.
Second heat pipes 154 and 155 are inserted into the bore of first heat pipe 153 from the opposite sides to thereby integrally jo.in these heat pipes 153, 154, 155. In such a connection, however, the close contact between hollow cylindrical heat pipe 153 and second heat pipes 154, 155 can be deteriorated to leave an air gap therebetween. In addition, between the working fluid within first heat pipe 153 and that wit.hin second heat pipes 154, 155 there intervene two of wic.ks 156, 157, 158 and walls of containers 159, 160, 161. The thermal resistance (overall thermal resistance) between first heat pipe 153 and second heat pipes 154, 155 becomes high, resulting in poor heat transfer between second heat pipes 154 and 155 via first heat pipe 153. In the case of top heat mode, heat transfer cannot be performed to a sufficient extent even if sufficient circulation of liquid-phase working fluid takes place.

, ~835~9 In the prior art, several methods were proposed in order to effectively ci.rcula-te liqu.id-phase workiny fluid, including external impar-ting of centrifugal, elec-trostatic, or electromagnetic ~orce or utilization of osmotic pressure - 2a -.

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besides the capillary action. These methods might enable liquid-phase working fluid to be circulated to a relatively high level even in the top heat mode. However, the utilization of centrifugal, electrostatic, or electromagnetic force is the consumption of an externally supplied energy, which means that the feature of a heat pipe that heat transport is performed without supplying any external energy is lost. When electrostatic or electromagnetic force or osmotic pressure is utilized, only a limited type of wor~ing fluid can be used.
Further, heat pipes are generally used only as heat transport mean~. Typically, a heat pipe is located between a high-temperature heat source and a low-temperature medium to be heated whereby heat transfer is carried out between the high-temperature heat source and the low-temperature medium to be heated. When it is desired to utilize the recovered heat as another form of energy, the heat the medium has received is used to drive a certain equipment, or heat exchange is performed between the heated medium and another medium from which a desired form o energy is derived through the necessary energy conversion.
When the thus recovered thermal energy is used to carry out electric power generation, prior art systems require heat exchange with waste gas for heat recovery and an additional heat exhange as mentioned above, resulting in a very low efficiency and complicated construction and control of the system.
To transduce a thermal energy into an electric energy, one may use an element capable of generating an electromotive force in accordance with a temperature difference. The use of such an element appears effective because electricity is directly produced. However, although such power generation is possible theoretically or in a laboratory, there is not available any element which is practically acceptable in efficiency and durability. Power generation utilizing the heat recovered from exhaust gases is thus impossible unless 3~9 tlle ~leat is transcluced into a mechanical energy to rotate a -turbine and a generator. This power generation process is a usual process wherein heat is used to produce a high--temperature, high-pressure gas and a turbine and generator is driven by the pressure di~ference occurring upon condensation of the gas by eooliny.

We have carefully studied the behavior of working fluid within a heat pipe to ~ind that the working fluid, after evaporated into vapor UpOIl receipt of external heat, flows to a site where a lower pressure prevails, condenses there into liquid, and is then returned under the capillary pressure across the wiclc or gravity. This behavior cE the workiny fluid is similar to that of water between a steam boiler and turbine and a condenser, for example. This indicates that vapor-phase working fluid within the heat pipe can actuate any mechanical means such as a turbine to perform electric power generation. Since the heat pipe is designed such that vapor and li~ui.d streams are produced in a single closed tube and is only heat transport means in itself, there remain many problems to be solved in order to accomplish efficient power generation in pxactice. Even the problems have not been fully recognized or Glarif.ied in the prior art. No further investigation has bee.n made on this power generation process particularly with respect to its application.

The present invention provides an improved heat pipe having a turbine built therein wherein a closed tube having a condensable working fluid charged therein is vertically disposed, a hollow taper tube is rotatably provided in the closed tube such that the diameter of the hollow tube increases toward the top, and the hollow tube on its intermediate outer periphery is provided with turbine blades whereby the flow of working fluid in vapour phase moving from the top to the bottom of the closed tube drives the turbine blades to rotate the hollow tube and the : ' :
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33~9 resultant centri.fugal ~orce causes workiny .Eluid in liquid phase to c.irculate to the -top of the closed tube through the duct in the holl.ow tu~e. T~e heat pipe of the present inventi.on thus permits the liquid-phase working fluid to be circu]ated against gravity, ensuring effective heat transport from a hi~her level to a lower level.

Th.e present invention also provides an improve~ appara-tus including a heat pipe having a turbine built therein wherein a closed tube having a condensable working fluid charged therein is vertically disposed, a hollow tube is axially provided for rotati.on in the closed tube each that the working fluid having condensed into liquid may enter the hollow tube from its top, the hollow tube on its intermediate outer periphery is provided with turbine blades whereby the flow of working fluid in vapor phase drives the turbine blade~, and a generator is disposed outside the closed tube and coupled to the hollow tube. The apparatus of the present invention performs heat transport and electric power yeneration at the same time. Since the liquid-phase working fluid passes through the duct in the hollow tu~e and the vapor-phase work.ing fluid passes outside the hollow tube, the li~ui~-and vapor-phase working fluids do not form a counterflow, eliminating one of the factors interfering with cixculation of liquid~phase working Eluid~

The present invention again provides an improved apparatus including a heat pipe having a turbine built therein which can perform recovery of waste heat and electric power generation at the same time.

The present invention further provides an improved apparatus including a heat pipe having a turbine-built therein.which can perform recovery of geothermal heat and ele~tric power generation at the same time.

~ ~35~9 The present inven-tion again provides an improved apparatus including a heat pipe having a turbine built therein which can perform collection of solar heat and elec-tric power generation at the same time.

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S~9 Accordlng ~o the prcsent Inventlon there Is provlded a heat plpe havlng a turblne bulit thereln, comprlslng a closed -tube contalnlng worklng fluld thereln and havlng one end to be heated and the other end to be cooled whereby the workIng fluld Is evaporated a~ the one end wlthln sald closed tube and then passed to the other end where It Is condensed Into llquld thereby conductlng ~e~t transport, characterlzed In that sald closed tube Is vertlcally placed such that the upper end of the closed tube constltutes an evaporatlon zone whlch Is externally heated to evaporate the worklng $1uld, and the lower end constltutes a con-densatlon ~one whlch re~eases heat to the exterlor to condense the worklng fluld, sald closed tube Includes a reservolr sect70n dlsposed at the lower end for collectlng the worklng fluld In llquld phase, a hollow taper tube havlng a duct therethrough Is dlsposed for rotatlon about Its axls wlthln sald closed tube and Is tapered frvm the upper end to the lower end of the closed tube, the lower end of sald hollow tube Is Inserted Into sald reservolr sectlon so as to be Immersed In the llquld-phase work-lng fluld thereln, and turblne blades are attached to the outer perIphery of s~ld hollow tube at Its Intermedla~e such that the blades are drlven by the worklng fluld In vapor phase passlng through sald closed tube. Sultably the Inner wall of the lower open end portlon of sald hollow taper tube Is provlded wlth axlal pump blades for drawlng the llquld-phase worklng fluld Into the duct of sald hollow taper tube. Deslrably the upper open end of sald hollow taper tube Is provlded wlth a dlsc for guldlng the llquld-phase worklng fluld toward the Inner wall of sald closed tube whlle It Is belng splashed by the centrlfugal force.

The present Inventlon also provldes an apparatus com-prlslng a heat plpe havlng a turblne bullt thereln, sald heat plpe comprlslng a closed tube contalning worklng fluld therein and havlng one end to be heated and the other end ~o be cooled whereby the worklng fluld Is evaporate~ at ~he one end wlthln sald closed tube and then passed to the other end where It Is condensed Into llquld thereby conductIng heat transport, charac-3~9 terlzed In that sald heat plpe Is vertlcally placed such that thelower end portlon o~ the heat plpe constltutes an evaporatlon zone whlch Is exte~nally heated to evaporate the worklng fluld, a hollow tube havlng a ~uct theret~rough Is axlally dlsposed for rotatlon wlthln sald closed tube, means Is provlded for Introduc-lng the llquid-phase worklng fluld generated In the upper end portlon of sald closed tube Into the duct of sald hollow tube, turblne blades are attached to the outer perlphery of sald hollow tube such that ~he blades are drlven by the worklng fluld In vapor phase passlng through sald closed tube, and a generator Is dlsposed outslde sald closed tube and coupled to sald hollow tube. Sultably the upper end portlon of sald closed tube constl-tutes a condensatlon zone where the worklng fluld Is condensed Into llquld, and sald Fluld Introduclng means Includes a funnel-llke member connected to the upper end of sald hollow tube andopenlng upward In sald condensatlon zone for collectlng the llquld-phase worklng fluld. Deslrably sald fluld Introcluclng means Includes a radlator tube havlng one end connected to the upper end portlon of sald closed tube for externally releaslng heat, sald radlator tUb0 constltutlng a condensatlon zone, the other end of sald radlator tube belng connected to sald hollow tube.

The present Inventlon agaln provldes an aPParatUs com-prlslng a heat plpe havlng a turblne bUllt thereln, sald heat plpe comprlslng a closed ~ube contalnlng worklng fluld thereln and havlng one end to be heated and the other end to be cooled whereby the worklng fluld Is evaporated at the one end wlthln sald closed tube and then passed to the other end where It Is condensed Into llquld thereby conductlng heat transport, charac-terlzed In that sald heat plpe Is vertlcally placed such that the lower end portlon of the heat plpe constltutes an evaporatlon zone whlch Is externally heated to evaporate the worklng fluld, a rotary shaft Is axlally dlsposed for rotatlon wlthln sald closed tube, turblne blades are attached to sald rotary shaft such that the blades are drIven by the worklng fluld In vapor phase passlng 3~8~3~

through sald closed tube, a bypass condult Is added to sald closed tu~e, sald bypass condul-t communlcatlng a predetermlned slte wlthln sald closed tube and above sald turblne blades to sald evaporatlon zone, and sald bypass condult Is provlded at an Intermedlate wlth a condensatlon zone for removlng heat from the vapor-phase worklng fluid to condense the worklng fluld Into 11~-uld. Sultably non-return means Is provlded In sald bypass con-dult between the condensatlon and evaPoratlon zones for prevent-lng the vapor-phase worklng ~luld from enterlng the bypass con-dult. Deslrably heatln~ means Is attached to sald closed $ubebelow sald turblne blades for further heatlng the YapOr - phase worklng fluld. Alternatlvely sald non-return Means 15 a chec~
valve. Deslrably sald closed tube Is confl~ured such that that portlon of sald closed tube where sald turblne blades are located has a smaller Inner dlameter than the lower end portlon constl-tutlng the evaporatlon zone. Sultably sald non-return means Is a trap In the form of a U-tube capable of reservlng the llquld-phase workln~ fluld. Preferably sald heatlng means conslsts of a coll of small dlameter tublng around the closed tube, a hlgh-tem-perature fluld belng passed through sald colled tublng.

In another aspect o~ the present Inventlon there Isprovlded an appara~us comprlslng a hea~ plpe havlng a turblne bullt thereln, sald heat plpe comprlslng a closed tube contalnlng workIng f luld thereln and havlng one end ~o be heated and the other end to be cooled whereby the worklng fluld Is evaporated at the one end wlthln sald closed tube and then passed to the other end where lt Is condensed Into llquld thereby conductlng heat transport, a rotary shaft axlally dlsposed for rotatlon wlthln sald closed tube, turblne blades attached to sald rotary shaft such that the blades are drlven by the worklng fluld In vapor phase passlng through sald closed tube~ and a generator dlsposed outslde sald closed tube and coupled to sald rotary shaft, whereln the lower end of sald heat plpe Is embedded In a hlgh-temperature reglon In the earth and the upper end portlon of saldheat plpe Is provlded wlth coollng means for removln~ heat from ~ 7a -~ ~33~9 sald heat plpe.

In a stlll ~urther aspect of the present Inventlon there Is provlded an ~PParatUs comprlsln~ a heat plpe havlng a turblne bullt thereln, sald heat plpe comprlslng a closed tube contalnlng worklng fluld thereln and havlng one end to be heated and the other end to be cooled whereby the worklng fluld Is evap-orated at the one end wlthln sald closed tube and then passed to the other end where It Is condensed Into llquld thereby conduct-Ing hea-t transport, a rotary shaft axlally dlsposed for rotatlon wlthln sald closed tube, turblne blades attached to sald rotary sha~t such ~hat the blades are drlven by the worklng fluld In vapor phase passlng through sald closed tube, and a generator dlsposed outslde sald closed tube and coupled to sald rotary shaFt, whereln an axlal approxlmately hal~ sectlon of sald heat plpe Is located wlthIn a flowpath through whlch a hlgh-tempera-ture fluld Is Passed, and the remalnlng half sectlon Is located wlthln another flowpath through whlch a medlum to be heated hav-lng a lower temperature than sald hlgh-temperature fluld Is passed.

In another aspect thereo~ the present Inventlon pro-vldes an apparatus comprlslng a heat plpe havlng a turblne bullt thereln, sald heat plpe comprlslng a closed tube contalnlng wor~-In~ fluld thereln and havlng one end to be heated and the otherend to be cooled whereby the wor~lng ~luld 1 5 evaporated at the one end wlt711n sald closed tube and then passed to the other end where It Is condensed Into llquld thereby conductlng heat trans-port, a rotary shaft axlal~y dlsposed for rotatlon wlthln sald closed tube, turblne blades attached to sald rotary shaft such that the blades are drIven by the worklng fluld In vapor phase passlng through sald closed tube, and a generator dlsposed out-slde sald closed tube and coupled to sald rotary shaft, whereln one end portlon of sald heat plpe Is located In a solar heat col-lectlng sectlon and the other end portlon Is located In a flow-path through whlch a low-temperature medlum to be heated Is _ 7b -.
, , ' passed.

In a stlll other aspect thereof the present Inventlon provldes an apparatus comprlslng a heat plpe havlng a turblne bullt thereln, sald heat plpe comprlslng a closed tube contalnlng working fluld thereln and havlng one end to be heated and the other end to be cooled whereby the worklng flu!d Is evaporated at the one end wlthln sald G losed tube and then passed to the other end ~here It Is condensed into llquId thereby conductlng heat transport, a rotary shaft axlally dlsposed for rotatlon wlthln sald closed tube, turblne blades attached to sald rotary shaft such that the blades are drIven by the worklng fluld In vapor phase passlng through sald closed tube, and a generator dlsposed outslde sald closed tube and coupled to sald rotary shaft, whereln sald heat plpe is located adJacent a roof shingle and one end of sald heat plpe Is located In a flowpath through whlch a hlgh-temperature fluld Is passed.

- 7~ -~2~3~g Referring to ~lG. 1, -there is illustrated one embodiment of -the heat pipe of the present invention as comprising a closed -tube 1 standiny vertically upright. The closed tube 1 has an upper end closed wi-th a plug 2. The plug 2 is provided with an infusion por-t 3 which is sealed after any incondensable gas in closed -tube 1 is purged and working fluid is infused in-to tube 1 there-through. The closed tube 1 llas a lower closed end which constitutes a reservoir section ~or collecting liquid working fluid. A hollow taper tube 4 (to be simply referred to as taper tube, hereinafter) is inserted within closed tube 1 along its central axis. The tube 4 is tapered to provide one open end 5 with a larger diameter and an opposite open end 6 with a smaller diameter. The taper tube 4 is rotatably supported by a pair of upper and lower bearings 7 and ~ which are in turn held by retainers 9 and 10, respec-tively, such that larger and smaller diameter ends 5 and 6 are positioned at the top and the bottom, respectively. The thus constructed taper tube. 4 on the outer periphery at its intermediate is integrally provided with turbine blades 11 such that taper tube 4 is driven and rotated by turbine blades 11.

The taper tube ~ on its inner wall at its lower end is provided with axially extending blades 12 for an axial flow pump. The blades 12 are immersed in liquid-phase working fluid 13 in the bottom or reservoir secti~n of closed tube 1.
The lower end portion of taper tube 4 having blades 12 secured is received within a casing 14 which is suspended from lower retainer 10~ The blades 12 form an axial flow pump with casing 14 so that rotation of blades 12 with taper tube 4 pumps liquid-phase working fluid 13 upward into taper tube 4. The casing 14 at its lower end is provided with a check valve 16 wherein a ball 15 automatically closes an opening in the casing bottom wall.

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~2~335~9 The taper tube 4 at its top is provided with a disc 17 for guiding liquid-phase working fluid 13 coming up along the inner wall of taper tube 4 toward the inner wall of the top end of closed tube 1. The closed tube 1 at the inner wall of its top end is provided with a reservoir section 18 opening upward for collecting liquid-phase working fluid 13 delivered from disc 17. A wick 19 is closely secured to the top inner wall of closed tube 1 and extended into reservoir section 18.
The retainers 9 and 10 are perforated with passage ports 21 and 22 for allowing vapor-phase working fluid 20 to pass therethrough. One of these passage ports 21 and 22 that is located above turbine blades 11, that is, passage ports 21 in retainer 9 are formed as a throttle for accelerating vapor phase working fluid 20 to increase its flow velocity relative to turbine blades 11. Of course, vapor-phase working fluid 20 need not be necessarily accelerated at the forward stage when turbine blades 11 are of the displacement turbine type.
The thus constructed heat pipe operates as follows. The heat pipe is usually placed vertically as shown in FIG. 1.
The upper end constitutes an evaporation zone H and the lower end constitutes a condensation zone C. Since liquid-phase working fluid 13 is in direct contact with the upper inner surface of closed tube 1 through wick 19 partially extending into reservoir section 18, liquid-phase working fluid 13 is evaporated there by the heat that is externally imparted to evaporation zone H. On the other hand, condensation zone C is deprived of heat so that working fluid is condensed there into liquid~ The pressure within closed tube 1 is then higher on the side of evaporation zone H than on the side of condensation zone C. A flow o vapor-phase working fluid 20 is created by this pressure distribution to drive and rotate turbine blades 11. As a result, taper tube 4 is rotated with turbine blades 11. When turbine blades 11 are of the expansion turbine type, vapor-phase working fluid 20 flow may be accelerated through passage ports 21 in upper retainer 9 to more positively drive and rotate turbine blades 11.

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As taper tube 4 rotates as mentioned above, liquid-phase working fluid 13 in the bottom pool of closed tube 1 is pumped into taper tube 4 by means of blades 12 on the lower inner wall of taper tube 4. Since liquid-phase working fluid 13 within taper tube 4 is rotated with tapsr tube 4, a centrifugal force is applied to the fluid. Due to tapering of tube 4 or enlargement of taper tube inner diameter toward the upper end, liquid-phase working fluid 13 is progressively urged upward and eventually returned to reservoir section 18 through delivèry disc 17. Thereafter, liquid-phase working fluid 13 is again distributed over the upper end inner surface of closed tube 1 and heated for evaporation.
The above-mentiGned heat pipe is designed such that liquid-phase working fluid 13 is f~d back to evaporation zone H by a centrifuga] force resulting from rotation of taper tube 4 by turbine blades 11.
When it is desired to increase the amount of liquid-phase working fluid fed back in order to provide an increased heat transport quantity, a plurality of fins for reheating are preferably provided around closed tube 1 on the inlet side of turbine blades 11, that is, an upstream side in the flow direction of vapor-phase working fluid 20 and evaporation zone H is extended up to the finned area, thereby increasing the enthalpy of vapor-phase working fluid 20 on the inlet side of turbine blades 11.
FIG. 2 is a cross-sec~ional view illustrating one embodiment of an apparatus using a heat pipe having a turbine built therein. The apparatus includes a heat pipe 30 of the same structure as conventional ones wherein a closPd tube 31 made of a metal such as copper and aluminum is purged of incondensable gases such as air from the interior until vacuum and then charged with a working fluid 32 in the form of a condensable fluid such as water and Fron. In contact with the inner wall of closed tube 31 is placed a wick 33 comprised of extremely fine filaments like carbon fibers, metal mesh or narrow grooves. The heat pipe 30 is placed vertically upright ~335~

such that a region of a certain length from its lower end constitutes an evaporation zone H adapted to be externally heated to evaporate working fluid 32. Within heat pipe 30 is disposed a liquid delivery tube 35 which is supported by a bearing 34 so as to rotate about the axis of heat pipe 30.
The lower end of liquid delivery tube 35 is immersed in working fluid 32 in evaporation zone H while the upper end is positioned a certain distance below the upper end of closed tube 31. A rotating shaft 36 is coaxially connected to the upper end of iiquid delivery tube 35, rotatably supported by a bearing/sealing means 37 at the upper end of closed tube 31, and extended upward through the upper end of closed tube 31 in an air-tight manner. The extension of sha~t 36 is connected to a generator 38. Axial turbine blades 39 are fixedly secured to liquid delivery tube 35.
A radiator tube 41 equipped with fins 40 is provided outside heat pipe 30. One end of radiator tube 41 is communicated to the upper end portion of closed tube 31 while the other end is extended into the interior of closed tube 31 through its wall and communicated to liquid delivery tube 35 through a rotary joint 42 interposed between liquid delivery tube 35 and rotating sha~t 36. That is, the provision is made such that wor~ing fluid vapor is guided into radiator tube 41 where it is condensed into liquid. Tha radiator tube 41 constitutes a condensation zone C.
In order to generate electric power with the above-mentioned apparatus, heat is supplied to evaporation zone H by utilizing any desired heat source including factory waste heat, solar heat or geothermal heat, whereas condensation zone C is brought into contact with cooling medium such as cold water and cool air to remove heat. As a result, working fluid 32 is evaporated into vapor to provide an increased pressure in evaporation zone ~ whereas working fluid 32 is cooled into liquid to provide a reduced pressure in condensation zone C.
The working fluid vapor thus flows as an upward stream through closed tube 31 at a high velocity as shown by arrows V. Since ~L~83~i~9 turbine blades 39 are located where the working fluid vapor flows, the working fluid vapor undergoes adiabatic expansion during passage across turbine blades 39, causing turbine blades 39 to rotate and consequently, driving generator 38 through liquid delivery tube 35 and rotary shaft 36 to generate electric power. The working fluid vapor having experienced adiabatic expansion enters radiator tube 41 or condensation zone C through the upper end portion of closed tube 31. It is deprived of heat and thus condensed into liquid in the interior of radiator tube 41. As a result, the back pressure of turbine blades 39 is kept at a low level.
The liquefied working fluid passes from radiator tube 41 to liquid delivery tube 35 through rotary joint 42 and finally flows downward to evaporation æone H under gravity. Since the return path of liquid-phase working fluid and the flowpath of vapor-phase working ~luid are isolated by liquid delivery tube 35, splashing of liquid-phase working fluid by a vapor flow is prevented even when the vapor flow exceeds the sound velocity because of an increased quantity of heat supplied. The apparatus is compact in that liquid delivery tube 35 serving as a return flowpath for working fluid is incorporated within heat pipe 30.
Next, another embodiment of the apparatus of the present invention is described by referring to FIG. 3. The apparatus illustrated herein includes a heat pipe 30 whose upper end portion constitutes a condensation zone C and a generator 38 is provided below heat pipe 30. The lower end wall of a liquid delivery tub~ 35 is formed with a plurality of ports 43 opening in a radial direction for liquid passage. A rotary shaft 36 is extended through the lower end of heat pipe 30, s~pported by a bearing/sealing means 37 in an air and water-tight manner, and connected to the lower end of liquid delivery tube 35. The lower end of rotary shaft 36 is connec~ed to generator 38. On the upper end of liquid delivery tube 35 is located an upward funnel 44 having an increasing opening diameter in an upward direction for ~2~3~

collecting liquid. The lower end of collecting funnel 44 i5 connected for rotation to the upper end of liquid delivery tube 3S through a rotary joint 45. A cooling heat pipe 46 provided with fins 47 at its upper and lower portions i5 extended through the upper end of closed tube 31. More specifically, the lower end of cooling heat pipe 46 is inserted up to approximately the level of the uppermost opening of liquid collecting funnel 44. Provision i5 made such that heat is removed from the upper end portion of closed tube 31 by keeping the upper portion of cooling heat pipe 46 in contact with cooling medium. Thus the upper portion of closed tube 31 constitutes condensation zone C.
With the apparatus shown in FIG. 3, working fluid is evaporated into vapor by a supply of heat from the exterior, flows through closed tube 31 as an upward stream, and undergoes adiabatic expansion at the site of turbine blades 39 to rotate them~ As a result, generator 38 is driven for rotation through liquid delivery tube 35 and rotary shaft 36 to generate power. The working fluid vapor having experienced adiabatic expansion is deprived of heat in the upper portion of closed tube 31 by cooling heat pipe 46 where it is condensed into liquid to impart a sufficiently low back pressure to turbine blades 39. The resulting liquid-phase working fluid is returned to evaporation zone H from liquid collecting funnel 44 through liquid delivery tube 35. Since the return path of liquid-phase working fluid and the flowpath of vapor-phase working fluid are isolated by liquid delivery tube 35, splashing of liquid-phase working fluid by a high velocity vapor flow is prevented. The apparatus is compact in that liquid delivery tube 35 serving as a rotating shaft for turbine blades 39 is incorporated within heat pipe 30.
A further embodiment of the apparatus of the present invention will be described. Referring to FIG. 4, a heat pipe is illustrated as comprising a closed tube 50 made of a metal such as copper and aluminum, which is purged of incondensable gases such as air from the interior until vacuum and then ' ~ '.

~l2~33S~

charged with a working fluid 51 in the form of a condensable fluid. In contact with the inner wall of closed tube 50 is placed a wick 52 comprised of extremely fine filaments like carbon fibers or metal mesh. The working fluid may be any desired fluid depending on the temperature at which the heat pipe is to be operated, for example, water and Fron. The closed tube 50 i5 placed vertically upright such that a region of a certain length from its lower end constitutes an evaporation zone H adapted to be externally heated to evaporate working fluid 51. More specifically, the lower end portion of closed tube 50 is surround~d by a jacket 53 through which a high temperature fluid 54 such as exhaust gas is passed to supply heat to working fluid 51 in closed tube 50 to evaporate it into vapor. Preferably, the lower end portion of closed tube 50 surrounded by jacket 53 may be provided with fins (not shown) in order to provide an increased heating sur~ace area.
An axial turbine having blades 55 is located within closed tube 50 and above evaporation zone H with its axis in substantial alignment with closed tube 50. The turbine has a rotary shaft 56 supported for rotation by bearings 57 at the upper end of closed tube 50. ~he rotary shaft 56 is air-tightly held by a suitable sealing member, for example, a mechanical seal 58 and extended out of closed tube 50. The extension of rotary shaft 56 is coupled to a generator 59.
A bypass conduit 60 provides a fluid communication between that portion of closed tube 50 which is located above turbine blades 55 and that portion of closed tube 50 which is ; below the level of working fluid 51 in evaporation zone H.
Bypass conduit 60 is provided at its intermediate with a cooling jacket 61 through which cooling medium such as water is passed, thereby forming a condensation zone C where heat is removed from the working fluid in the bypass conduit 60 to condense the working fluid into liquid. Of course, an increased heating surface are~ is obtained by prsviding the ~3~9 outer surface of bypass conduit 60 in codensation zone C with fins 63.
In order to generate electric power with the above-mentioned apparatus, a hot fluid 54 is passed through jacket 53 in evaporation zone H while cooling medium 62 is passed through jacket 61 in condensation zone C. Then in evaporation zone H, liquid-phase working fluid 51 being compressed by a water head due to gravity is evaporated into vapor upon receipt of heat from hot fluid 54, thereby increasing the pressure beLow turbine blades 55. On the contrary, the pressure above turbine blades 55 is low due to direct communication with condensation zone C at a low temperature.
Then the vapor-phase working fluid flows upward through closed tube 50 at a high velocity and undergoes adiabatic expansion at the site of turbine blades 55 to drive them for rotationO
The turbine blades 55 then rotate generator 59 to produce electricity.
The working fluid having experienced adiabatic expansion is changed into wet steam in the case of water or superheated vapor in the case of Fron R-113 and passes to condensation zone C through bypass conduit 60 in that form. In condensation zone C, the working fluid is deprived of heat by cooling medium 62 fed to jacket 61 so that all the vapor-phase working fluid is condensed into liquid. As a result, the back pressure of ~urbine blades 55 is sufficiently reduced The thus liquefied working fluid flows down through bypass conduit 60 and eventually returns to evaporation zone H.
In the above-mentioned generator apparatus, a vapor flow V of working fluid rises through closed tube 50 and a liquid flow L of working fluid returns to evaporation zone H through bypass conduit 60. The isolation of these flows prevents splashing of liquid-phase working fluid by vapor flow V even when vapor flow V reaches a maximum velocity approximate to the sound velocity. Dif~erently stated, liquid-phase working fluid is positively and sufficiently returned to evaporation zone H without interfering with the flow of vapor-phase .
:

~8~9 working fluid, thereby ensuring efficient and continuous power generation~
The thermal cycle the above-mentioned apparatus undergoes is illustrated in FIGS. 5A and 5B. FIG. SA
illustrates a thermal cycle occurring with a working fluid in the form of water. Liquid phase working fluid increases its pressure along the saturation liquidus line, evaporates into dry saturated steam at a predetermined pressure, then turns into wet saturated steam through adiabatic expansion to rotate ~0 turbine blades 55, and thereafter condenses into liquid while releasing heat to the exterior. FIG. SB illustrates a thermal cycle occurring with a working fluid in the form of Fron R-113. In this case, the working fluid turns into superheated vapor through adiabatic expansion and then condenses into liquid while releasing heat to the exterior. In either case, the heat efficiency n is given by n = (i3 - i4)/ti3 - il).
It should be noted that the pressure in condensation 20ne C is substantially lower than that in evaporation zone H.
If for a certain design reason, the lower end of bypass conduit 60 is opened at the lower end portion Oe closed tube 50, but above the level of working fluid 51, part of the vapor-phase working fluid could inconveniently pass to condensation zone C diractly through bypass conduit 60 and thus not be utilized in power generation. In such a case, non-return means is preferably inserted in bypass conduit 60 below condensation zone C. Some illustrative examples of the non-return means are shown in FIGS. 6A and 6B. FIG. 6A shows a check valve 64 adapted to close when the pressure in evaporation zone H exceeds the head of liquid-phase working fluid created in condensation zone C. FIG. 6B shows a trap 65 of U-tube form wherein liquid-phase working fluid 51 collected in the U-portion prevents vapor-phase working fluid from directly entering condensation zone C~
FIG. 7 is a schematic illustration of a further - 35 modification of the above-mentioned apparatus for the purposes of compactness and increased power generation capacity. A

3S~9 closed tube 50~ is designed for a heat pipe structure and configured to taper from its lower end serving as an evaporation zone H toward its neck portion where turbine blades 55 are positioned. The remaining components are substantially the same as those of the arrangement shown in FIG. 4. In the arrangement shown in FIG. 7, closed tube 50A
itself functions as a diffuser so that a great volume of working fluid concentratedly acts on turbine blades 55 at a high velocity. Despite compactness, this arrangement offers an increased power generation capacity.
It will be understood that the heat pipe is designed such that working fluid is returned to the evaporation zone to continuously carry out heat transport. When the above-mentioned apparatus receive a great amount of heat in excess of the heat transport capacity of closed tubes 50 and 50A
serviny as a heat pipe, there does not occur continuous circulation of working fluid involving both evaporation and condensation cycles, resulting in no power generation. In such a case, if the heat supply cannot be controlled, the number o the above-mentioned apparatus should be increased to reduce the supply of heat per unit or a modification should be made so as to increase the heat efficiency of a single apparatus. Such a modified organization is shown in the schematic cross section of FIG. 8. The apparatus of FIG. 8 is substantially the same as that of FIG. 4 except that a heating zone 66 is provided below that portion of closed tube 50 having turbine blades 55 disposed therein. The heating zone 66 is provided for the purpose of converting the dry saturated steam of working fluid generated in evaporation zone H into superheated steam and constructed, for example, by coiling around closed tube 50 a small diameter tubing for allowing passage of the same hot fluid 54 as supplied to evaporation zone H as a heat source. With this arrangement of the apparatus shown in FIG. 8, the working fluid is changed into superheated steam in heating zone 66 and then subject to - adiabatic expansion in the region of axial turbine blades 55 ~ Z~33S~9 to rotate them, thereby effecting power generation. Such a thermal cycle is illustrated in FIG, 9 wherein the heat efficiency ~ given by ~ = (i4 - i5)/ti4 - il) is higher than those of the apparatus shown in FIGS~ 4 and 7.
It should be noted that the heat source to heating zone 66 is not limited to the same hot fluid 54 as used in evaporation zone H. For instance, when the primary purpose is power generation rather than waste heat recovery, an auxiliary heat source m~y be previously prepared and used.
The apparatus of the present invention have turbine blades 55 built therein as shown in FIGSo 4, 7, and 8. The provision of such turbine blades is not limited to one stage and more than one stage of turbine blades may be provided if - desired. Further, more efficient rotation of turbine blades 55 may be accomplished by aligning a sub~tantially conical center body 67 on the upstream side of turbine blades 55 as shown in FIG. 10 because the gap between the inner wall of closed tube 50 and cone 67 functions like a diffuser.
Another system for geothermal power generation using a heat pipe having a turbine built therein is shown in FIGS. 11 and 12. A length of heat pipe 70 is inserted into the earth so as to reach a region 71 which i5 at a high temperature due to the presence of magma. The upper end portion of heat pipe 70 extends beyond the ground surface and is disposed in a cooling zone 72. The cooling zone 72 serves to remove heat from heat pipe 70 and, for example, includes a vessel 73 through which the upper end portion of heat pipe 70 is inserted and cooling medium in the form o~ water 74 is passed.
The heat pipe 70 is designed so as to conduct power generation as well as transport of heat from high-temperature region 71.
One exemplary arrangement of such heat pipe is shown in FIG.
12.
The heat pipe 70 is of the same structure as conventional ones wherein a closed tube 75 made of a metal ; 35 such as copper and aluminum is purged of incondensable gases such as air from the interior until vacuum and then charged ~283~ 9 with a working fluid 76 in the form of a condensable fluid such as water and Fron. In contact with the inner wall of closed tube 75 is placed a wick 77 comprised of extremely fine filaments like carbon fibers, metal mesh or narrow grooves.
In the illustrated embodlment, an axial turbine with blades 78 is disposed in a middle section of the duct of heat pipe 70 where working fluid vapor flows, with its axis in alignment with the heat pipe axis. The rotary shaft 79 of the axial turbine is rotatably supported by bearings 80 arranged within heat pipe 70 and a bearing/sealing means 81 in the upper end of heat pipe 70. The rotary shaft 79 is extended out of heat pipe 70 through bearing/sealing means 81 and the extension is coupled to a generator 82.
In the apparatus of the abové-mentioned arrangement, the lower end portion of heat pipe 70 positioned in hot region 71 in the earth is heated by geothermal energy so that working fluid 76 in the pipe is evaporated into steam. On the other hand, a suitable cooling medium such as cold water 74 is passed to cooling zone 72 to cool the upper portion of heat pipe 70 so that the internal pressure in the upper duct portion of heat pipe 70 is lowO As a result, the working fluid vapor flows upward at a high velocity and is subject to adiabatic expansion at the site of axial turbine blades 78 to rotate the turbine which in turn drives generator 82 to produce electricity~ The working fluid having experienced adiabatic expansion further flows to the upper duct portion or cooling zone 72 of heat pipe 70 where it is deprived of heat and condensed into liquid. A sufficiently low back pressure is thus created with respect to axial turbine blades 78. When the cPoling medium used is water, there results hot water which may be cooled in a cooling tower for reuse as the cooling medium or fed to any suitable installation for hot water supply or air conditioning purposes. On the other hand, the working fluid having condensed into liquid is returned to the lower portion of heat pipe 70 under gravity combined with , ~83~9 the capillary pressure due to wick 77 and then heated again to evaporate into vapor.
In the system shown in FIGS. 11 and 12, all processes including generation of steam, rotation of a turbine by steam, condensation o~ steam to impart a back pressure to the turbine, and return of liquid take place within a single heat pipe. This leads to many advantages including a single well to be sunk, utilization of geothsrmal energy without the need for sand removing equipment which is otherwise required to remove sand which can enter in piped fluid in usual geothermal utilization, and elimination of a pump required to pump liquid to the hot region in the earth. The present invention thus allows for simple construction of the entire system and efficient and economic power generation due to little thermal loss and no special operating cost.
FIGSo 13 and 14 illustrates an arrangement of a plurality o~ turbine-equipped heat pipes for producing electricity by using waste heat. More illustratively, the interior space of a casing 90 having a rectangular box configuration is divided into upper and lower compartments by a partition 91. The lower compartment defines a hot fluid flowpath 9~ through which a hot waste gas to be disposed of is passed whereas the upper compartment defines a flowpath 93 through which a low-temperature medium to be heated, for example, air is passed. A plurality of heat pipes 94 are vertically extended through partition 91 in a fixed manner and provided on their outer surface in both the upper and lower portions with fins 95 for imparting an increased heating surface area~
FIG. 14 is a cross section of one of heat pipes 94 used in the foregoing arrangement. The heat pipe 94 is of the conventional structure wherein a closed metal tube 96 serving as a container is purged of incondensable gases such as air from the interior until vacuum and then charged with a working fluid 97 in the form of a condensable fluid such as water and Fron. In contact with the inner wall of closed tube 96 is ~Z~33~i4~1 placed a wick 98 comprised of extremely fine filaments, metal mesh or narrow grooves. In the illustrated embodiment, an axial turbine with blades 99 is disposed in an axial middle section of the duct of heat pipe 94 where working fluid vapor flows, with its axis in alignment with the heat pipe axis.
The rotary shaft 100 of the axial turbine is rotatably supported by a bearing/sealing means 101 in the upper end o~
heat pipe 94. The rotary shaft 100 is extended out of heat pipe 94 through bearing/~ealing means 101 and the extension is connected to a generator 102.
With this arrangement, th~ lower hal~ of heat pipe 94 immersed in hot fluid flowpath g2 becomes a heating zone which receives heat from the hot fluid whereas the upper half in flowpath 93 for the mediu~ to be heated becomes a cooling zone where heat is removed by the medium. Thus, working fluid 97 within heat pipe 94 recei~s heat from waste gas passing through hot fluid flowpath 92 and is evaporated into steam which flows at a high vel~ocity toward the upper portion where a low pressure is prevalent due to cooling. Since turbine blades 99 are located in the passage of working fluid vapor, the upward ~low of working fluid vapor causes turbine blades 99 to rotate which in tur~, drives generator 102 to generate electric power. The working fluid continues to flow upward after driving turbine blades 99 and is deprived of heat by the medium to be heated passing outside the heat pipe 94, resulting in a su~ficiently low back pressure with respect to turbine blades 93. It will be understood that the medium which has received heat from heat pipe 94 and raised its temperature may be effec~ively used as a heat source in any desired equipment for air-conditioning or similar purposes.
The working fluid having condensed into liquid is returned to the lower end portion of heat pipe 94 under gravity combined with the capillary press~re due to wick 98 and heated again to evaporate into vapor.
The apparatus shown in FIGS. 13 and 14 has great advantages in practical ~plication including efficient ~2~33~

electric power generation and size reduction of the entire system because no heat exchange occurs between heat recovery and electric power generation.
~ still further embodiment is shown in FIGS. 15 and 16 wherein heat pipes having a turbine built therein are arranged so as to constitute a solar power generating system. More specifically, the solar power generating system illustrated is placed on the roof or outdoor in a slant manner such that it is substantiàlly perpendicular to solar rays. A solar heat collecting section 110 is configured as a rectangular box.
Along the upper end of heat collecting section 110 is generally horizontally extended a flowpath-defining member 112 through which a medium to be heated in the form of water 111 is passed. A plurality of heat pipes 113 are arrayed such that one end portion is exposed in solar heat collecting section 110 and the other end portion is inserted through heat-receiving medium flowpath 112 in a water-tight manner.
The solar heat collecting section 110 on the face side is closed with a glass cover 114 to avoid heat loss due to air convection. On the back side of glass cover 114 is attached a selective transmission film 115 which transmits solar rays, but reflects thermal radiation (infrared rays of 2 to 20 ~um) from below. On the outer surface of the one end portion of heat pipe 113 exposed in solar heat collecting section 110 is formed a selective absorption film of a material capable of -more absorption of infrared rays of 2 to 20 /um useful in temperature rise, but less radiation at the wavelength range.
The bottom surface of box-like solar heat collecting section 110 is preferably a reflective surface capable of reflection of solar rays toward heat pipes 113.
The heat pipe 113 is of the conventional structure wherein a closed tube 116 formed of a metal such as copper and aluminum is purged of incondensable gases such as air from the interior until vacuum and then charged with a working fluid 117 in the form of a condensable fluid such as water and Fron.
In contact with the inner wall of closed tube 116 is placed a ~33~i~9 wick 118 comprised of extremely fine filaments, metal mesh or narrow grooves. In the embodiment illustrated in FIG. 16, an axial turbine with blades 119 is disposed in that portion of the interior of heat pipe 113 intervening between solar heat collecting section 110 and heat-receiving medium flowpath 112, with its axis in alignment with the heat pipe axis. The rotary shaft 120 of the axial turbine is rotatably supported by a bearing/sealing means 121 disposed in the upper end of heat pipe 113 adjacent heat-receiving medium flowpath 112.
The rotary shaft 120 is extended out of heat pipe 113 through bearing/sealing means 121 and the extension is connected to a generator 122~
When the above-constructed unit is exposed to the sun, heat pipes 113 are heated by therm~l radiation to evaporate working fluid 117 in heat pipes ~113 into vapor. The heat-receiving medium in the form of low-temperature water 111 is passed through the flowpath 112 to cool the corresponding end portion of heat pipes 113 where a low pressure is prevalent.
Consequently, working fluid ~apor flows at a high velocity in a direction shown by an arrow in FIG. 16 and is subject to adiabatic expansion at the site of axial turbine blades 119 to rotate them which in turn, drives generators 122 to produce electricity. The working fluid having experienced adiabatic expansion reaches the other end portion of heat pipes 113 where it imparts heat to water 111 in flowpath 112 while being condensed into liquid. Then water 111 supplied to ~lowpath 112 at a relatively low temperature can be taken out as hot water which may be supplied to any desired equipment for hot water supply and air-conditioning purposes. The liquefied working fluid is returned to the one end portion of heat pipes 113 on the side of solar heat collec~ing zone 110 under gravity combined with the capillary pressure due to wick 118.
The system shown in FIGS. 15 and 16 enables efficient power generation by the use of solar heat and provides hot water at the same time while affording the additional advantage of compactness.

.
.

354~

FIGS. 17 and 18 schematically show an embodiment wherein heat pipes each having a turbine built therein are used to melt the snow on a roof. An ordinary slant roof has a shingle 130. Heat pipes 131 are slantwise disposed below and in contact with the lower surface of shingle 130. Each heat pipe 131 has a lower end portion inserted in a warm fluid pipe 132 which is horizontally extended below the lower edge of shingle 130. The heat pipe 131 itself is of the same structure as conventional ones wherein a closed tube 133 made of a metal such as copper and aluminum is purged of incondensable gases such as air ~rom the interior until vacuum and then ~harged with a working fluid 134 in the form of a condensable fluid such as water and Fron. In contact with the inner wall of closed tube 133 is placed a wick 135 comprised of metal mesh, extremely fine filaments or narrow grooves. In the embodiment illustrated in FIG. 18, an axial turbine with blades 136 is disposed in an intermediate section of the duct of heat pipe 131 where working fluid vapor flows, that is, a site remote from the lower end inserted in the warm fluid pipe 132 toward the upper end, with its axis in align~ent with the heat pipe axis. Tile rotary shaft 137 of the axial turbine is rotatably supported by a bearing~138 arranged within heat pipe 131 and a bearing/sealing means 139 in the upper end of heat pipe 131.
The rotary shaft 137 is extended out of heat pipe 131 through bearing/sealing means 139 and the extension is connected to a generator 140.
A warm fluid 141 useful as a heat source for snow melting is passed through warm fluid pipe 132 which thus transfers heat to heat pipe 131. The warm fluid 141 is only required to have a temperature above 0C and preferably has as high a temperature as possible. Use may be made of warm waste water from hot spring or well and warm waste gas from cookroom.
The above-illustrated system is operated during the snow falling season as follows. Any suitable warm fluid 141 is passed through warm fluid pipe 132 such that the lower end 33S~

portion of heat pipes 131 inserted in warm fluid pipe 132 becomes a heating zone and the remaining major portion of heat pipes 131 in contact with shingle 130 becomes a cooling zone.
The working fluid 134 in liquid phase receives heat from warm fluid 141 in the lower portion of heat pipe 131 and is thus evaporated into vapor which flows at a high velocity toward the upper portion which is at a low pressure due to cooling with snow. The working fluid vapor is subject to adiabatic expansion at the site of axial turbine blades 136 to rotate them which in turn drives generator 140 to produce electricity. The working fluid vapor further delivers heat to the snow deposited on the roof to melt it while the fluid vapor itself is condensed into liquid, providing a sufficiently low back pressure with respect to axial turbine blades 136. The liquefied working fluid is returned to the lower end portion or heating zone of heat pipe 131 under gravity combined with the capillary pressure due to wick 135.
The system illustrated in FIGS~ 17 and 18 can melt the snow on a roof and produce electricity at the same time. A
wide variety of heat sources may be used in the illustrated apparatus. Only the heat of warm fluid used as such a heat source is utilized without directly contacting the fluid with snow. When warm water or well water is used as the warm fluid, it may be recycled so that the operating cost is reduced and the amount of water discharged is prevented from lncreasing .

Claims (3)

1. An apparatus comprising a heat pipe having a turbine built therein, said heat pipe comprising a closed tube containing working fluid therein and having one end to be heated and the other end to be cooled whereby the working fluid is evaporated at the one end within said closed tube and then passed to the other end where it is condensed into liquid thereby conducting heat transport, characterized in that said heat pipe is vertically placed such that the lower end portion of the heat pipe constitutes an evaporation zone which is externally heated to evaporate the working fluid, a hollow tube having a duct therethrough is axially disposed for rotation within said closed tube, means is provided for introducing the liquid-phase working fluid generated in the upper end portion of said closed tube into the duct of said hollow tube, turbine blades are attached to the outer periphery of said hollow tube such that the blades are driven by the working fluid in vapor phase passing through said closed tube, and a generator is disposed outside said closed tube and coupled to said hollow tube.

2. An apparatus comprising a heat pipe having a turbine built therein according to claim 1 wherein the upper end portion of said closed tube constitutes a condensation zone where the working fluid is condensed into liquid, and said fluid introducing means includes a funnel-like member connected to the upper end of said hollow tube and opening upward in said condensation zone for collecting the liquid-phase working fluid.

3. A heat pipe having a turbine built there in according to claim 1 wherein introducing means includes a radiator tube having one end connected to the upper end portion of said closed tube for externally releasing heat, said radiator tube constituting a condensation zone, the other end of said radiator tube being connected to said hollow tube.