Fluid displacement system

In a fluid displacement system having a pressure vessel, an expansion vessel, first and second tubes in fluid communication with the two vessels, and an energy source, fluid contained within the system is transferred from one vessel to the other by activating the energy source, which in turn generates pressure in the pressure vessel. The generated pressure in the pressure vessel, in turn, displaces the fluid in the expansion vessel, and the system advantageously has no moving parts.

FIELD OF THE INVENTION 
The present invention is in the field of fluid displacement systems and 
more specifically it is concerned with a system useful as a cyclic fluid 
pulse generator. By another aspect of the invention, the system is useful 
also as a fluid flow rectifier. 
BACKGROUND OF THE INVENTION AND PRIOR ART 
Fluid displacement systems with which the present invention is concerned 
are at times referred to as "passive" or "self-pumping pump system", 
"geyser-type pump systems", "heat" or "thermal actuated pump systems" etc. 
However, heretofore prior art systems in the related field typically 
comprise mechanical or electromechanical components such as pumping means, 
valves etc, which require control means and an energy source and which in 
many cases are suitable only for liquids and are not suitable for handling 
gas or vapor or a combination of gas or vapor and liquid. Furthermore, 
such mechanical components require periodical maintenance and replacing 
due to wear. 
The following is a brief description of some prior art references which are 
in the related field and from which the present invention is clearly 
distinguishable: 
U.S. Pat. No. 4,573,525 discloses a heat actuated heat exchange system 
comprising a conduit in a primary heating zone, a boiler in a second 
heating zone and an accumulator in a third heating zone, connected by 
another conduit zone to a condenser two check valves and a heat rejector, 
forming together a sealed device containing a condensable coolant. 
The drawbacks of this patent are that it requires heat as an energy source 
which heat must be effected to three different stages of the device. 
Furthermore, the system requires two check valves for ensuring fluid flow 
in desired direction only. It is also apparent that the system will not 
function unless it is sealed. 
U.S. Pat. No. 4,552,208 discloses an apparatus for circulating a heat 
transfer liquid from a heat collector such as a solar collector panel, to 
a heat exchanger such as heat storage means. However, this device is 
level-dependant and will operate only if the heat exchanger is located at 
a level below that of the heat collector. 
U.S. Pat. No. 4,478,211 is a "geyser-type" heat exchanger which depends on 
the production of differences in liquid levels so as to create sufficient 
hydrostatic pressure imbalance for promoting flow of a heated liquid. 
The liquid displacing forces in the '208 and '211 are limited by the 
elevation differences between the inlet and the outlet of the heated 
liquid connecting tube. 
The heat exchange system disclosed in U.S. Pat. No. 3,929,305 comprises a 
reservoir for a coolant liquid conveyed via a conduit through a heating 
zone and a check valve for preventing a reverse flow in the conduit. Apart 
from the fact that this system requires a check valve, it is also 
sensitive to the heat applied to the system, and the cycle under which the 
device operates resembles the generative cycles of Sterling or Ericson 
engines. 
U.S. Pat. No. 2,738,928 discloses a sealed heat exchange system having an 
internal pumping mechanism consisting of a heat separator in which 
dimensions of the associated components are critical in order to keep the 
system in balance. Moreover, the system relies on a connecting tube 
extending between a heating vessel and a distribution, said connecting 
tube being of a capillary caliber in order to ensure liquid level rise 
within the tube, regardless of any other factors. This arrangement ensures 
that the opening of the connecting tube is sealed within the heating 
vessel is always sealed by the capillary rise of liquid within the tube, 
owing to the surface tension force acting between the tube's lowermost 
edge and the liquid within the heating vessel. For that reason, the 
opening of the connecting tube is typically flared i.e, bell-like shaped. 
It thus appears that the system according to that patent is operable only 
with liquids as a working fluid, and not with gases. 
Other references which are in the field of the invention are U.S. Pat. Nos. 
3,484,045; 4,177,019; 4,197,060; 4,246,890; 4,270,521; 4,366,853; 
4,467,862; 4,611,654; and 4,676,225 each of which shares one or more of 
the drawbacks disclosed in the above disclosed patents and are thus 
considered to be distinguishable. 
It is an object of the present invention to provide a new and improved, 
self activated fluid displacement system, devoid of any mechanical or 
electromechanical components and in which the above-referred to drawbacks 
are substantially reduced or overcome. 
SUMMARY OF THE INVENTION 
According to the present invention there is provided a fluid displacement 
system comprising a pressure vessel, an expansion vessel, first and second 
tubes being each in flow communication with the two vessels, fluid 
contained within the system, and an energy source for generating pressure 
in said pressure vessel; said first tube having a first opening within 
said pressure vessel, a second opening within said expansion vessel, and 
tube sections extending between said first and said second openings 
connected to one another by a first intermediate section; said second tube 
having a third opening at a bottom portion of said pressure vessel and a 
fourth opening within said expansion vessel; said first opening being 
above said third opening; wherein at a rest stage of the system, prior to 
activating the energy source, the fluid level within the vessels exceeds 
at least one of the first and second opening and at least one of the third 
and fourth opening. In most embodiments of the invention the fluid is a 
liquid and the energy source is a pressure source applying direct pressure 
to the pressure vessel or a heat source which by heating the fluid causes 
a pressure raise within the pressure vessel. 
Pressure rise in the pressure vessel expels the liquid from it until liquid 
level drops below the lowermost portion of the first tube whereby gas or 
vapor escape through the first tube, thus creating bubbles in the vertical 
portions thereof and eventually evacuating the first tube. The specific 
gravity difference of liquid columns in tube portions within the vessels, 
induces spontaneous liquid flow in the second tube in a reversed 
direction, whereby bubble flow via the first tube is increased and the 
system returns to its initial stage. 
By a first application of the present invention, the system is useful as a 
cyclic fluid pulse generator, wherein a second intermediate section 
extends between said third and said fourth openings, said second 
intermediate section being below said first intermediate section. 
When the system is used as a cyclic fluid pulse generator, there exists a 
working stage of the system wherein the fluid level in the expansion 
vessel is higher than fluid level in the pressure vessel; the difference 
in height being such that once liquid is cleared from said first tube to 
an extent to allow gas communication between the two vessels, there is a 
pressure head sufficient to overcome flow losses in said second tube so as 
to allow reverse flow of liquid therethrough up to a level equal to or 
above said first opening. 
By a second application of the invention, the system is used as a liquid 
flow rectifier, wherein the tube sections of the first tube extend 
downwards from the first and second openings and said first intermediate 
section is a lowermost section, said second opening is at the bottom of 
the expansion vessel and said fourth opening is positioned above said 
second opening. In a specific embodiment of a flow rectifier according to 
the present invention the fourth opening is essentially at the same level 
as the first opening. 
By a modification of the first application, where the system is used as a 
cyclic fluid pulse generator, the expansion vessel is sealed and it 
comprises a fluid outlet connected to a cylinder with a piston 
reciprocally retained therein, whereby linear reciprocal motion is 
obtained. Optionally, the piston is linked to a crank shaft for converting 
linear reciprocating motion of the piston into circular motion. Because 
the expansion vessel is sealed in this embodiment, the energy source in 
this embodiment cannot be a pressure source that introduces gas into the 
system. 
Preferably, the expansion vessel further comprises a pressure reducing 
system such as a condenser, for improving condensation of a vapor retained 
therein. 
By still a further modification of the first application, the system is 
used as a compressor or a pump, wherein the piston sealingly divides the 
cylinder into a first and a second chamber, said first chamber being in 
flow communication with the expansion vessel and said second chamber 
comprising a first check valve for fluid inlet and a second check valve 
for pressurized fluid outlet. However, instead of a piston, an immiscible 
liquid may be used. 
According to another embodiment of the present invention, the system is 
used as an energy meter, for measuring heat exchange between a heat source 
extending through the pressure vessel thus constituting the energy source, 
and a cold source extending through the expansion vessel for facilitating 
vapor condensation; the system vessel further comprises a counting unit 
activated by an activator displaceable upon change in fluid level; the 
tube sections of the first tube extend downwards from the first and second 
openings and said first intermediate section is a lowermost section. In a 
specific embodiment the counting unit is placed within the expansion 
vessel. 
By specific embodiments of the energy meter according to the invention the 
actuator is a float member having a conductive portion for closing an 
electric circuit of the counting unit. Alternatively, the actuator is a 
float member having an inductive portion for magnetically activating the 
counting unit or, a float member adapted for mechanically activating said 
counting unit e.g, by a toggle switch. 
The system according to the present invention may also be used as a liquid 
pump, wherein a cyclic fluid pulse generator is used in conjunction with a 
flow rectifying arrangement, wherein the flow rectifying arrangement is a 
flow rectifier in accordance with the second embodiment of the present 
invention. 
In accordance with one embodiment of a liquid pump according to the 
invention, the expansion vessel of a cyclic fluid pulse generator is in 
flow communication with the pressure vessel of the flow rectifier, 
allowing gas transfer only. Preferably, there is provided a siphon-like 
arrangement connecting the expansion vessel of the cyclic fluid pulse 
generator and the pressure vessel of the flow rectifier for assuring gas 
transfer only. 
According to another embodiment of a liquid pump according to the 
invention, the second tube of the cyclic fluid pulse generator is in flow 
communication with a bottom portion of the pressure vessel of the flow 
rectifier. Optionally, the expansion vessel of the cyclic fluid pulse 
generator comprises an airing port, or a chamber useful as an accumulator 
for a closed system. 
Still another application of the invention is a self priming boiler wherein 
steam is provided to a steam operated system (e.g. a steam engine, etc.) 
from the pressure vessel of a fluid pulse generator, there being a cold 
liquid source connected to the expansion vessel via a check valve, 
allowing flow only into the expansion vessel. By a specific application 
the steam flows from the steam operated system, via condenser into the 
cold liquid source. 
A liquid pump may be obtained by using a flow rectifying arrangement 
consisting of two check valves positioned in series with the cyclic fluid 
pulse generator. 
A liquid pump with which the invention is concerned may be useful for 
circulating liquid between a liquid heating device and a heat consumer, 
wherein the energy source is a temperature difference between an inlet and 
an outlet of the pump. 
By another application of the invention there is provided a low pressure 
circulating pump with an integral accumulator, wherein the second tube of 
the system is parallely connected to a cooling unit, the arrangement being 
such that fluid flows from the pressure vessel via a flow rectifier to the 
cooling unit and then cool liquid flows into the expansion vessel and via 
a second flow rectifier back to the pressure vessel. 
The liquid pump may also be applicable for circulating a liquid coolant 
agent of an engine, wherein heat emitted from the engine is used as the 
energy source. 
The system according to the present invention may also be useful as a gas 
flow rectifier wherein the vessels and the tubes are inverted and whereby 
the first and second tubes each comprise tube sections extending upwardly 
from the first, second, third and fourth openings respectively, the 
respective tube sections being connected by uppermost intermediate 
sections; wherein at the rest stage of the system, the fluid level within 
the vessels at least exceeds the second and the third openings but does 
not reach the first and fourth openings. 
By still another application of the invention, there is provided a liquid 
displacing system comprising a cyclic fluid pulse generator operable with 
a first liquid having a low boiling temperature; and a flow rectifier 
operable with a second liquid having a high boiling temperature; the fluid 
pulse generator being in flow communication with the flow rectifier via a 
first pipe connecting the expansion vessel of the fluid pulse generator 
with the pressure vessel of the flow rectifier; and a second tube 
extending from a bottom portion at the pressure vessel of the flow 
rectifier into a heating unit, via a first heat exchanger within the 
pressure vessel of the fluid pulse generator, then via a second heat 
exchanger within the expansion vessel of the fluid pulse generator and 
returning into the expansion vessel of the flow rectifier, at a top 
portion thereof.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
Attention is first directed to FIGS. 1(a) to 1(d) of the drawings for 
understanding the basic principles of the present invention, which as will 
be hereinafter explained, are applicable for all the applications and 
embodiments of the invention. 
The system consists of a pressure vessel 2 and an expansion vessel 4, the 
vessels being connected to one another by a first tube 6 and a second tube 
8, both tubes having an essentially U-like shape. 
The first tube 6 has a first opening 10 within the pressure vessel 2 and a 
second opening 12 within the expansion vessel 4, with a lowermost portion 
14 therebetween. The second tube 8 has a third opening 16 within the 
pressure vessel 2 and a fourth opening 18 within the expansion vessel 4, 
with a lowermost portion 20 therebetween. As can further be seen in the 
drawings, the first opening 10 is somewhat lower than the second opening 
12 but extends at a noticeable height above the third and fourth openings 
16 and 18 which extend adjacent the bottom portions of the vessels 2 and 
4, respectively. 
The system further comprises a pressure increasing means which in the 
present example is a heating element 26 connected to a power source 28. 
Additionally, or instead, there is provided a gas pressure generator 
(compressor) 30 for increasing the pressure in the pressure vessel, via 
tube 32. In various embodiment of the invention used as example herein, 
the pressure generator can be, for example, a fluid heating element or a 
compressor, which ever is appropriate for use with a particular 
embodiment. 
The system is filled with a liquid 36, and as seen in FIG. 1(a), at an 
initial stage both vessels 2 and 4 are filled with liquid at pressure P0, 
which owing to rule of connected vessels extends at the same level L0 in 
both vessels 2 and 4. The first, third and fourth openings 10, 16 and 18, 
respectively, are immersed in the liquid, whereas the second opening 12 
extends above the liquid level L0 at a height .DELTA.h which is smaller 
than the height difference .DELTA.X measured between the highest point 40 
of the first lowermost portion 14 (first tube 6) and the highest portion 
42 of the second lowermost portion 20 (second tube 8). 
Further reference is made to FIG. 1(b) wherein a cycle of operation of the 
system above described begins with increasing the pressure in the pressure 
vessel 2 by either or both raising the temperature of the liquid 36 by the 
heat element 26 and/or by applying pressure by the pressure generator 30. 
As the pressure in the pressure vessel 2 reaches pressure PI, liquid flows 
via tubes 6 and 8 in direction of arrows 44 and 46 respectively (small 
arrow resembling small amounts, large arrow resembling large amounts), 
raising the liquid level in the expansion vessel 4 to level LI. 
It is obvious that owing to area difference between the pressure vessel 2 
and the first tube 6, once liquid level in the pressure vessel 2 has 
dropped beneath height HI of the first opening 10, the amount of liquid 
flowing via the second tube 8 is essentially larger than that flowing via 
the first tube 6. 
At a further stage of the cycle, as illustrated in FIG. 1(c), when pressure 
in the pressure vessel 2 increases to PII, fluid level in the pressure 
vessel continues to decrease until it reaches the critical height 40 
(highest point at the first lowermost portion 14 of the first tube 6), at 
which vapor enters the first tube 6 and vapor bubbles 50, flowing in 
direction of arrow 52 (dashed arrow resembling vapor flow), evacuate 
liquid from the first tube 6. The presence of vapor or gas bubbles in the 
liquid contained within the first tube 6, lowers the specific gravity of 
the liquid-bubble mixture in the first tube below that of the pure liquid 
contained within the second tube 8. When liquid level LII in the expansion 
vessel 4, being higher than the liquid level in the pressure vessel 2, the 
difference of specific gravity in the liquid columns, having equal length 
D.sub.1 =D.sub.2 (as illustrated in FIGS. 1b and 1c), induces spontaneous 
liquid flow in the second tube 8 in a reversed direction i.e, in direction 
of arrow 56, whereby gas or bubble flow via the first tube is increased, 
the system returns to its initial stage. The term "flip" as used in the 
description designates the spontaneous, gravity induced change of liquid 
flow direction within the second tube 8. 
The final stage of the cycle, illustrated in FIG. 1(d) takes place when 
fluid level in the pressure vessel 2 reaches level LIII which is the 
height HI of the first opening 10, where once again liquid fills the first 
tube 6, returning the system to its initial stage. A new cycle will occur 
upon raising the pressure in the pressure vessel 4, as explained 
hereinabove. 
Attention is now directed to FIGS. 2(a) to 2(d), schematically illustrating 
a different embodiment of a cyclic fluid pulse generator system. For the 
sake of clearance and understanding, those elements which are principally 
similar to those described with reference to FIGS. 1(a) to 1(d) are 
designated by the same reference number with the additional offset of one 
hundred. 
A pressure vessel 102 is connected to an open expansion vessel 104 via a 
first tube 106 and a second tube 108 below the first tube. The first tube 
has a lowermost portion 114 and comprises a first opening 110 within the 
pressure vessel 102 and a second opening 112 within the expansion vessel 
104. The second tube 108 has a third opening 116 within the pressure 
vessel and a fourth opening 118 within the expansion vessel. Pressure 
vessel 102 further comprises pressure raising means 130, which in the 
present embodiment is a pressure generator (a compressor), but as can be 
understood, may also be suitable liquid heating means, as explained in 
connection with the first embodiment. 
As can further be seen in FIG. 2(a), the expansion vessel 104 is positioned 
above the pressure vessel 102 and the difference in fluid level H between 
liquid level Lp0 in the pressure vessel 102 and liquid level Le0 in the 
expansion vessel 104, may be determined according to minimal pressure head 
sufficient to overcome flow losses in the second tube 108, so as to allow 
liquid flow up to a level at least equal to the level of the first opening 
110, as will hereinafter be explained. 
As seen in FIG. 2(b), Upon applying pressure PI in the pressure vessel 102 
by the pressure generator 130, liquid flows via the first and second tubes 
106 and 108 in directions of arrows 144 and 146, respectively. As soon as 
liquid level within the pressure vessel 102 reaches the critical level lc 
(the uppermost point 140 at the lowermost portion 114 of the first tube 
106), vapor will enter the first tube 106 (see FIG. 2(c)) and vapor 
bubbles 150 flowing in the direction of dashed arrow 152 will expel liquid 
from the first tube to the expansion vessel 104, entailing occurrence of 
the "flip ", whereby liquid under influence of different static pressure 
heads begins to flow in reverse direction in the second tube 108, as 
illustrated by arrow 156. As soon as liquid level in the pressure vessel 
102 reaches level IpIII (at the height of the first opening 110) it fills 
up the first tube 106, preventing further gas or vapor flow from the 
pressure vessel to the expansion vessel, thus ending the cycle (see FIG. 
2d). The system is again ready for a new cycle to take place upon pressure 
increase in the pressure vessel 102. 
FIGS. 3 to 8 schematically illustrate different practical applications of 
the system according to the present invention. 
FIG. 3(a) illustrates how the system may be used for obtaining mechanical 
work i.e, as an engine. The system comprises among others, the basic 
components as illustrated in the embodiment illustrated in FIGS. 1(a) to 
1(d) and thus, for the sake of clearance and understanding, those elements 
which are principally similar are designated by the same reference 
numerals with additional offset of two hundred. 
As seen, the system consists of a pressure vessel 202 and a sealed 
expansion vessel 204 connected to one another by a first and a second tube 
206 and 208, respectively, the first tube having first and second openings 
210 and 212 in the pressure vessel and expansion vessel, respectively and 
the second tube 208 has third and fourth openings 216 and 218, in the 
pressure vessel and expansion vessel, respectively. The tubes are 
configured as hereinabove explained with respect to the embodiment 
discussed with reference to FIGS. 2(a) to 2(d). The system also comprises 
a pressure generating member 230. When the expansion vessel 204 is sealed 
and not vented, the pressure generating member 230 is a heat source. 
As can further be seen, the expansion vessel 204 is connected via tube 274 
to a cylinder 276 accommodating a piston 278 adapted for linear reciprocal 
displacement as known per se. The system also comprises a pressure 
reducing unit 280, e.g, a heat exchanger coil or a vent, wherein in the 
case of a heat exchanger, chilled fluid flows through the coils as known 
in the art. 
The arrangement is such that a pressure pulse within the expansion vessel 
204 (see explanation relating to FIG. 2(b), above) entails a pressure 
pulse also in the cylinder 276 whereby, the piston 278 is propelled in the 
direction of arrow 284. However, as the "flip" occurs in the system, 
pressure decreases within the expansion vessel 204 (see explanation 
regarding FIG. 2(c), above), and vacuum builds up therein, entailing 
displacing the piston 278 in direction of arrow 286, and so on, whereby a 
motor with a pulsating piston is obtained, useful in a variety of 
mechanical applications. 
The purpose of the cooling system 280 is to increase the condensation rate 
of the vapor within the expansion vessel 204 for reducing vapor volume in 
order to ensure sufficient pressure drop therein, so as to facilitate 
displacement of the piston in the direction of arrow 286. 
FIG. 3(b) is a simple example illustrating how the embodiment of FIG. 3(a) 
may be used for transferring linear reciprocal motion into cyclic output 
by pivotably connecting one end of a crank shaft 290 to the piston 278 and 
an opposed end to a fly wheel 292, as known per se. 
FIG. 4 illustrates how the embodiment of FIG. 3(a) may be used as a 
compressor or a pump, whereby a front chamber 294 of the cylinder 276 
comprises a first check valve 296 allowing flow only in direction of arrow 
297, and a second check valve 298 allowing flow only in direction of arrow 
299. The arrangement is such that displacement of the piston 278 in the 
direction of arrow 286 brings about filling of the chamber 294 with a 
fluid, via check valve 298, where displacement of the piston in the 
direction of arrow 284 compresses the fluid via check valve 296. 
FIG. 5 of the drawings illustrates a heat actuated pulsating liquid pump, 
the pumped liquid serving both as a driving and as a cooling media. The 
system consists of a basic cyclic fluid pulse generator system according 
to the present invention and as described, for example with reference to 
FIGS. 2(a) to 2(d) above. The system comprises a pressure vessel 302 with 
a heating element 326 and an expansion vessel 304 connected via a first 
tube 305 and a second tube 306 to the pressure vessel 302. The expansion 
vessel 304 further comprises an inlet pipe 307 provided with a first check 
valve 308 allowing flow only in the direction of arrow 310, and an outlet 
pipe 312 provided with a second check valve 314, allow flow only in the 
direction of arrow 316. 
The system operates as explained with reference to FIGS. 2(a) to 2(d), 
whereby upon pressure increase within the expansion vessel (as a result of 
increasing the pressure in the pressure vessel 302), the liquid is 
expelled via pipe 312 and when the "flip" occurs, vacuum builds up in the 
expansion vessel 304 entailing suction of liquid via pipe 307 from a 
reservoir (not shown). 
The vacuum in the expansion vessel 304 is caused owing to condensation of 
vapor in the expansion vessel, thus decreasing the volume of the vapor and 
building up vacuum. Since the pumped liquid constitutes the sole cooling 
media of the system, it is essential that its temperature is below that of 
the vapor's condensation temperature, at suction pressure. 
By the arrangement of FIG. 5, the amount of liquid egressing via pipe 312 
is equal to that ingressing via pipe 307. The outlet pressure of the 
liquid (emitted from pipe 312) mainly depends on the temperature of the 
liquid within the pressure vessel 302, whereas the output rate of the 
liquid via pipe 312, depends on the heat flow of the heating element 326. 
Attention is now directed to FIGS. 6(a) and 6(b) illustrating how the fluid 
displacement system of the invention may be used as an energy meter, for 
measuring heat consumption. 
The meter consists of an insulated housing 400 comprising a thermally 
insulated pressure vessel 402 and an thermally insulated expansion vessel 
404 above the pressure vessel. The vessels are in flow communication with 
one another via a first tube 406 and a second tube 408, the first tube 
having a U-like shape with a first opening 410 adjacent the top of the 
pressure vessel 402 and a second opening 412 adjacent the top of the 
expansion vessel 404 (see FIG. 6(a)). The second tube 408 is essentially 
vertical and has third and fourth openings 416 and 418 adjacent bottom 
portions of the pressure vessel and expansion vessel, respectively. 
The energy meter further comprises a heat source 430 extending through the 
pressure vessel, which for example, may be a pipe supplying hot water to a 
consumer, whereby heat from the pipe is exchanged to the pressure vessel 
402. A second pipe 431 extends through the expansion vessel 404 and 
carries cold water (for example water returning from the consumer), thus 
serving as a condenser. 
A magnetic float member 450 is accommodated within the expansion vessel 
404, being displaceable between a lowermost position (as illustrated by 
solid lines in FIG. 6(a)) and an upper position (as illustrated by dashed 
lines. A pick-up unit 460 consists of an electric inductive coil 462 
coiled over a core member 464 and is connected to a meter 466 for 
registering and reading the number of occurrences in which the float 
member 450 reaches its uppermost position in which it inducts electric 
current in the coil 462. 
The arrangement is such that at an initial stage, the pressure vessel 402 
is filled with liquid to a level at least above the first opening 410. 
When hot water flows via tube 430, heat is transferred to the liquid until 
it reaches a boiling stage. Vapor displaces the liquid which then flows 
via the first and second tubes 406 and 408 to the expansion vessel sel 
404, as a result of which the magnetic float member 450 reaches the top 
portion of the expansion vessel (illustrated by dashed lines) inducting an 
electric current in coil 462 which is then registered by the meter 466. 
When the liquid level in the pressure vessel 402 drops below the top 
portion of bend 470 of the first tube 406, vapor enters the top, expansion 
vessel 404, as a result of which a "flip" occurs and the liquid returns to 
the pressure vessel via the second tube 408. 
Since the heat transferred by the hot and cold tubes 430 and 431 
respectively, is directly proportional to the temperature and quantity of 
fluid flowing via the tubes, the device measures the energy content 
difference between the ingressing and egressing fluid. It should be 
realized that such a system is useful in a variety of applications where 
it is required to measure heat consumption, e.g. for measuring the amount 
of hot water energy consumed by different consumers (domestic or 
industrial), etc. It should further be understood that instead of the 
electric inductance pick-up unit as described above, there may be used 
other means such as, for example, a mechanical counter or switch which is 
activated each time the float member reaches a predetermined level within 
the expansion vessel, or an electric circuit which is activated each time 
the float member closes a circuit between two conducting members 
positioned at the top portion of the expansion vessel, etc. 
Attention is now directed to FIGS. 7(a) to 7(d) which illustrate a fluid 
flow rectifier which is devoid of mechanical components, i.e. check 
valves, pumps, etc. 
Similar to the basic configuration of the cyclic fluid pulse generator 
disclosed with reference to FIGS. 1(a) to 1(d), the flow rectifier 
consists of a pressure vessel 502 connected to an expansion vessel 504 via 
a first tube 506 and a second tube 508, both having a U-like shape with a 
lowermost portion 510 and 512, respectively, thus behaving as syphontubes. 
The first tube 506 has a first opening 514 within the pressure vessel 502 
and a second opening 516 within the expansion vessel 504. The second tube 
508 has a third opening 518 within the pressure vessel and a fourth 
opening 520 within the expansion vessel. 
The construction is such that the first opening 514 and the fourth opening 
520 are adjacent top portions of the respective vessels, whereby the third 
opening 518 and the second opening 516 are adjacent bottom portions of the 
respective vessels. 
The pressure vessel 502 further comprises a pressure generator 528 which as 
explained hereinabove may be a fluid heating element or a compressor, etc. 
At an initial stage, as illustrated in FIG. 7(a), the pressure vessel 502 
is filled with liquid up to level lI, which owing to the rule of connected 
vessels, extends at the same level also within the vertical portion 532 of 
the second tube 508 (within the expansion vessel 504). Liquid level in the 
expansion vessel 504 is at level lII, which again, owing to rule of 
connective vessels extend at the same level lII also within the vertical 
portion 534 of the first tube 506 within the pressure vessel 502. As can 
be seen, this arrangement actually constructs two systems of connected 
vessels being in flow communication with one another. 
At a first stage of operation (see FIG. 7(b)), pressure is raised in the 
pressure vessel 502 by the pressure generator 528, whereby liquid flows 
from a pressure vessel 502 to the expansion vessel 504, in essentially 
small quantities via the first tube 506 (in the direction of arrow 536) 
and in essentially large quantities via the second tube 508 (in the 
direction of arrow 538), for the reasons hereinabove explained. 
As seen in FIG. 7(c), the liquid continues to flow from the pressure vessel 
502 to the expansion vessel 504 via both tubes 506 and 508 until 
equilibrium is obtained wherein the height difference .DELTA.H1 (between 
the level lIII of the fourth opening 520 and liquid level lIV at the 
vertical portion 542 of the second tube 508 adjacent the present vessel 
502) is identical with the height difference .DELTA.H2 between the liquid 
level lV at the expansion vessel 504 and the liquid level lVI at the 
vertical portion 544 of the first tube 506 adjacent the pressure vessel 
502. That is .DELTA.H1.tbd..DELTA.H2, where an outcome of this relation is 
that (lIII-lV).tbd.(lIV-lVI). Care should be taken to assure that the 
liquid level lV is lower than lIII, for ensuring that the liquid will 
under no circumstances flow in reverse direction, i.e. from the expansion 
vessel 504 to the pressure vessel 502, unless the pressure generator 
applies negative pressure (i.e. vacuum) or in case a second pressure 
generator 550 connected to the expansion vessel 504 is activated (shown in 
dashed lines in FIG. 7d), whereby the vessel and tube exchange tasks and 
liquid will flow only from the expansion vessel 504 to the pressure vessel 
502, in large quantities in the first tube 506 (in the direction of arrow 
554) and in small quantities in the second tube 508 (in the direction of 
arrow 556), whereby a flow rectifier is obtained. 
FIG. 8 of the drawings illustrates how the system according to the present 
invention may be used as a gas flow rectifier, devoid of any mechanical 
components (such as check valves, pumps, etc.). The system comprises a 
pressure vessel 602 and an expansion vessel 604 connected to one another 
by a first tube 606 and a second tube 608, both having an inverted U-like 
shape and behaving as syphon tubes. 
The first tube 606 has a first opening 610 within the pressure vessel and a 
second opening 612 within the expansion vessel 604 and the second tube 608 
has a third opening 614 within the pressure vessel and a fourth opening 
616 within the expansion vessel, the first and fourth openings 610 and 616 
being at top portions of the respective vessels, and the second and third 
openings 612 and 614 being adjacent the bottom of the respective vessels. 
The pressure vessel 602 further comprises a gas ingress pipe 620, a gas 
egress pipe 622 and a pressure generator 624 as hereinabove explained. As 
can further be seen in FIG. 8, at an initial stage the vessels are filled 
with liquid at a level li, over the second and third openings 612 and 614 
respectively, but below the first and fourth openings 610 and 616 
respectively. 
The arrangement is such that upon introducing gas into the pressure vessel 
602 via pipe 620 and increasing pressure by the pressure generator 624 
(e.g. by heating), liquid level in the pressure vessel will slightly 
decrease, entailing a rise of a fluid column in the vertical portion 630 
of the second tube 608 to level l1, serving as a block, whereby gas will 
be forced to flow through the first opening 610, via the first tube 606 to 
the expansion vessel 604 (in the direction of arrow 632), exiting at the 
expansion vessel via the second opening 612 and then, via the fourth 
opening 616 flows through the second tube 608 back to the pressure vessel 
602 (in the direction of arrow 634), and out of the system via pipe 622. 
It should be realized that gas cannot flow in reverse directions, unless 
pressure is raised in the expansion vessel 604, whereby the vessels and 
tubes exchange roles. 
Further reference is made to FIG. 9 illustrating a low pressure liquid 
circulating pump consisting of a liquid displacing system generally 
designated 700 and constructed of a pressure vessel 702, an expansion 
vessel 704, a first tube 706 connecting between the vessels and having a 
U-like shape, and a second tube generally designated 708 and consisting of 
a first and a second tube portion 710 and 714, respectively. The first 
tube portion 710 extends from a bottom portion of the pressure vessel 702 
and connected via a first check valve 720 , allowing flow only in 
direction of arrow 722, to a cooling unit 724 such as radiator with a fan 
726, as known per se. The second tube portion 714 extends from the cooling 
unit 724 via a connecting tube 730 into a bottom portion of the expansion 
vessel 704 and back into the pressure vessel 702 via a second check valve 
738, allowing flow only in the direction of arrow 742. A heat source 746 
is provided within the pressure vessel 702 as explained in connection with 
the previous applications. 
The arrangement is such that pressure increase by vaporization within the 
pressure vessel 702 entails liquid flow to the expansion vessel 704 via 
the first tube 706 and via tube 710, in direction of arrow 722. Then, the 
liquid passes through the cooling unit 724 and continues via tube 714 into 
the expansion vessel 704. The cooled liquid entering the expansion vessel 
causes condensation of vapor accumulating within the expansion vessel, at 
the time the "flip" occurs, and thus reduces the pressure of the system to 
the initial pressure of the system. 
The above described construction ensures that liquid always flows in 
direction of arrows 722 and 742, whereby a liquid pump is obtained. 
The pressure head of the pump is set by pressure vessel and expansion 
vessel temperatures of the liquid and maximum head of the liquid within 
the tube 706. 
It should, however be obvious that one or both of the check valves 720 and 
738 may be replaced by a flow rectifier of the type described, for 
example, with reference to FIGS. 7a-7d. 
The application schematically illustrated in FIG. 10 of the drawings 
illustrated a self pumping boiler applicable, for example, in steam 
operated systems. The system consists of a pressure vessel 750 connected 
to an expansion vessel 752 via a first tube 754, having an essentially 
U-like shape, and a second tube 756, extending from bottom portions of the 
vessels. The pressure vessel 750 is also provided with a heating element 
760, as explained in connection with the previous embodiments. 
A steam operated restriction member such as an engine or a restriction 
valve, generally designated 764, is connected via tube 766 at a top 
portion of the expansion vessel 750. By one application, illustrated in 
FIG. 10 by solid lines, the expansion vessel 752 is connected via a tube 
771 and through a check valve 778 to a cold liquid source 779. By a second 
application, illustrated in FIG. 10 by dashed lines, the restriction 
member 764 is connected via a return tube 770 to a condenser 772 for 
converting the return vapor into liquid, which liquid is returned to the 
expansion vessel 752 via check valve 778. During the "flip" occurrence, 
cool liquid flows via check valve 778 back into the expansion vessel 752. 
The above described system provides a self priming boiler which is suitable 
for connecting to a steam consuming device (engine, vapor heated 
container, etc.), whereby the thermal efficiency of the pumping system is 
ultimate since the steam used for inducing the "flip" is fully utilized 
for pre-heating the cool liquid feed. 
Attention is now directed to FIGS. 11(a) and 11(b) illustrating two 
variations of a liquid pump with an integral flow rectifier, wherein the 
flow rectifier does not comprise an independent pressure source but is 
rather activated by the liquid displacing system. 
Referring first to FIG. 11(a), there is a liquid displacing system 
generally designated 860 and having a configuration similar to that 
described with reference to FIGS. 1(a) to 1(d) with a pressure source 862 
connected to the pressure vessel 864 which in turn is connected via a 
first tube 866 and a second tube 868 to an expansion vessel 870. 
A flow rectifier unit generally designated 872 has a configuration similar 
to that described above with respect to FIGS. 7(a) and 7(d), and comprises 
a pressure vessel 874, an expansion vessel 876 and first and second tubes 
connecting therebetween, 878 and 880 respectively. Preferably, an 
accumulator 881 is connected to the flow rectifier unit 872, for reducing 
the overall dimensions of the pressure and expansion vessels. 
However, instead of an independent pressure source (such as pressure 
generator 528 in FIG. 7(a)), the pressure vessel 874 of the rectifier unit 
872 is connected to the expansion vessel 870 of the liquid displacing 
system 860 via a pipe 882 extending at top portions of the vessels, 
whereby the rectifier is initialized by pressure received from the liquid 
displacing system, and a uni-directional liquid circulating pump is 
obtained. 
Similar to the arrangement illustrated in FIG. 11a, the arrangement of FIG. 
11(b) also comprises a liquid displacing system generally designated 884 
comprising the same principal components as in FIG. 11(a), including a 
pressure source 886. 
The system further comprises a flow rectifier generally designated 888 
which also comprises the same principal components as in FIG. 11(a) 
described above). However, in this case too, the flow rectifier 888 is 
devoid of a separate pressure source and is rather connected via a tube 
890 extending from a bottom portion of the pressure vessel 892 of the flow 
rectifier 888 to a lowermost portion of the second tube 894 of the liquid 
displacing system 884. However, according to this configuration, the flow 
rectifying unit 888 should preferably comprise an accumulator 896 for 
reducing the size of the system's vessels. 
In this case too, the flow rectifier is initialized by the pressure 
received from the liquid displacing system and a uni-directional liquid 
pump is obtained. 
FIG. 12 is a schematic illustration of still another practical application 
of the system according to the invention useful for circulating a liquid 
in a heating or cooling system, having a low temperature difference 
between ingressing and egressing liquid, for example, in a domestic solar 
heating system, whereby a thermo-syphon system is obviated, thus hot water 
may be circulated also downward without the need of mechanical pumps, etc. 
(In conventional solar heating systems the solar panels must always be 
below the hot water reservoir, otherwise, pumps are required). The problem 
with existing non-thermo-syphon systems is that they rely on propelling 
the water by steam bubbles which are formed within the system when the 
water reaches its boiling point. However, it is obvious that standard 
flat-panel solar collectors are unable to reach temperatures exceeding 
about 60-80.degree. C. (depending on geographic location, period of the 
year and time of the day). 
The system illustrated in FIG. 12 consists of a liquid displacement system 
generally designated 900 being operable with a first liquid having a low 
boiling temperature point, and a flow rectifying unit generally designated 
901 being operable with a second liquid having an essentially high boiling 
temperature point, such as water. The liquid displacing system 900 
comprises a pressure vessel 902 connected to an expansion vessel 904 via a 
first, syphon-like tube 908 and a second tube 910 extending between bottom 
portions of the vessels. The flow rectifying unit 901 comprises a pressure 
vessel 920 and an expansion vessel 922 connected to one another by a first 
tube 924. The second tube of the flow rectifying unit extends via the 
solar panel and heat exchanging system of the device, as explained 
hereinafter. 
As explained with reference to FIG. 11a, the expansion vessel 920 of the 
flow rectifying unit 901 is connected to the expansion vessel 904 of the 
liquid displacement system 900 by a tube 930, whereby the rectifier will 
be initialized by pressure received from the liquid displacing system, and 
a uni-directional liquid circulating pump is obtained as already explained 
with respect to FIG. 11(a). 
The second tube of the flow rectifying unit 901 is constituted by a tube 
portion 936 extending from a bottom portion of the pressure vessel 920 
which is connected to a solar panel 940. The solar panel is connected in 
turn to a first heat exchanging portion 942 extending within the pressure 
vessel 902 of the liquid displacing system 900 and then continues to a 
container 944 with an associated accumulator 946. A tube 948 extends from 
the accumulator to a second heat exchanging portion 950 within the 
expansion vessel 904 of the liquid displacing system and a return tube 952 
is connected to the expansion vessel 922 of the flow rectifying unit 901, 
whereby the loop of the second tube of the rectifying unit is completed. 
The arrangement is such that liquid heated in the solar panel 940 flows to 
the heat exchanging portion 942 within the pressure vessel 902 of the 
liquid displacement system, thus constituting a heat source for raising 
pressure within the pressure vessel. Then, the liquid flows via the 
container and accumulator 944 and 946, respectively, expelling the cold 
liquid therefrom. The expelled cool liquid then passes through the second 
heat exchanging portion 950 within the expansion vessel 904 condensing the 
vapor of the second liquid, as explained hereinabove with respect to 
previous embodiments. The liquid then returns via tube 952 to the 
expansion vessel 922 of the rectifying unit 901, flows via the first tube 
924 into the expansion vessel 920 and then via tube 936 closes the loop 
where it enters the solar panel 940 for re-heating and beginning a new 
cycle. 
However, it should be obvious that the liquid is displaced within the 
system by the liquid displacing system 900 with the rectifying unit 901 
ensuring liquid flow in the desired direction only, with the displacement 
system constituting the initiating source of the rectifying unit (as 
explained with respect to FIG. 11(a)). The entire system is energized by 
the solar heat collected by the solar panel 940 and transferred to the 
pressure vessel 902. 
The system described hereinabove with reference to FIG. 12 is devoid of 
membranes which are typically required in existing systems for separating 
between the first, so-called propelling liquid, and the second, so-called 
propelled liquid. Furthermore, it is not necessary to bring the propelled 
liquid to its boiling point, whereby a larger variety of liquids may be 
used. 
It should be obvious to a person versed in the art that the system above 
described may be utilized in a variety of other applications such as, for 
example, industrial or domestic heating or cooling systems and various 
elements may be replaced e.g. the solar panel may be replaced by a boiler 
and the container may be replaced by a heating radiator. It should also be 
noted that the liquid flow rectifying unit may be replaced by suitable 
check valved with the required changes mutatis mutandis. 
FIG. 13 schematically illustrates how the invention may be utilized in a 
cooling system for a motor, e.g. in a vehicle's engine. 
The system consists of four principal components, namely, an engine 
generally designated 1000 which is actually a heat source requiring 
cooling, a liquid cooling unit generally designated 1002 such as a 
vehicle's radiator and fan as known per se, a liquid displacing system 
generally designated 1004 for cycling the coolant liquid, and a flow 
rectifying unit designated 1006 serving as a check valve for controlling 
flow direction. All the components are in flow communication for conjoined 
operation as will hereinafter be explained. 
The liquid displacing system 1004 consists of a pressure vessel 1012 
mounted on the engine's block 1013 for receiving heat, and an expansion 
vessel 1014 connected to the pressure vessel via a first U-like tube 1016 
and a second, vertical tube 1018. The expansion vessel 1014 is provided 
also with an inlet pipe 1019. 
The liquid flow rectifying system 1006 is principally similar to that 
described in connection with FIGS. 7(a) to 7(d) having a pressure vessel 
1022 and an expansion vessel 1024 connected to one another via a first 
tube 1026 and a second tube which in the present embodiment exits the 
expansion vessel by tube portion 1028, passes through the liquid 
displacing system 1004, the engine 1000 and the cooling unit 1002 and 
returns back to the pressure vessel 1022 by pipe 1030. As can readily be 
understood, the purpose of the flow rectifier 1006 is to ensure coolant 
liquid flow only in the direction of the arrows appearing in the diagram. 
Also, the flow rectifier described above may be replaced by suitable check 
valves as schematically illustrated by dashed lines and designated 1040 
and 1041. 
The system further comprises an accumulator 1044 mounted in flow 
communication with tube 1026, which accumulator is required for 
transferring essentially large quantities of coolant liquid. However, the 
accumulator 1044 which does not constitute a part of the flow rectifier 
1006 may be omitted provided that the pressure and expansion vessels 1022, 
1012, 1024 and 1014, respectively, are sufficiently large for receiving 
large liquid volumes. 
The cooling system 1002 consists of a radiator 1052 comprising a plurality 
of fins (not shown) and a fan 1054 activated by an electric motor 1056 for 
exciting air through the radiator 1052 for exchanging heat with the hot 
liquid as known per se. As an option, the electric motor 1056 driving the 
fan 1054 may be replaced by a liquid displacing system having a mechanical 
output, e.g. of the type described in FIGS. 3(a) and 3(b). 
In operation, only when the engine reaches a minimal predetermined 
temperature and the coolant liquid reaches its boiling temperature, the 
liquid displacing system 1004 will be activated as explained hereinabove 
with respect to some of the previous embodiments, whereby liquid begins to 
flow from the engine 1000 via the cooling system 1002, where its 
temperature is reduced, and then via the flow rectifier 1006 and via the 
liquid displacing system 1004, to complete a cycle. 
Obviously, various components may be positioned at different locations, and 
may also be replaced by mechanical components as known per se. 
It should be understood by a skilled person that a large combination of 
different embodiments may be made for various applications, mutatis 
mutandis.