WO2009112700A2

WO2009112700A2 - Method and device for cooling using water from subsea depths as a cold source

Info

Publication number: WO2009112700A2
Application number: PCT/FR2009/000101
Authority: WO
Inventors: Bruno Garnier
Original assignee: Bruno Garnier
Priority date: 2008-01-31
Filing date: 2009-01-29
Publication date: 2009-09-17
Also published as: WO2009112700A3; FR2927160A1; FR2927160B1; FR2927158A1; FR2927158B3

Abstract

The present invention relates to a cooling method, characterized in that it comprises setting up a closed-loop circuit of heat-transfer fluid by carrying out the following steps: installing at least one heat device (1) at the site that it is desired to cool; immersing at least one heat exchanger (2) at a subsea depth at which the water temperature is at a first level; and connecting the heat device (1) and the exchanger (2) by means of two ducts, a supply duct (3) and a return duct (4), at least one of said ducts (3, 4) being equipped with at least one device (5) for circulating a heat-transfer fluid.

Description

METHOD AND APPARATUS FOR COOLING USING UNDERWATER DEPTH WATER AS COLD SOURCE

The present invention relates to a method and a cooling device using water from the depths of oceans, seas or lakes as a cold source. It applies in particular, but not exclusively, to the production of a stream of cooled water that can be used to cool rooms.

In general, it is known that there are already cooling installations using heat exchangers connected to a device for pumping seawater to a submarine depth corresponding to a desired temperature, by means of a pump connected to a partially submerged pipe.

The seawater thus sucked passes into the primary circuit of an exchanger and is then discharged into the sea. When passing through this primary circuit, the seawater exchanges heat with the secondary circuit of the exchanger, which can for example connected to an air conditioning system.

It is also known that the implementation of this solution requires the use of pipes having a minimum diameter, namely generally pipes having at least 60 centimeters in internal diameter. Indeed, the pumping by suction of a liquid in a pipe causes, due to pressure losses, a decrease in the pressure and therefore the vaporization temperature of this liquid, the vaporization temperature of a liquid flowing in a pipe being proportional to the pressure of this liquid. However, the vaporization of the liquid is undesirable, particularly because of the induced cavitation phenomenon which alters the structure of the equipment. Thus, in order to avoid the undesirable vaporization of a liquid circulating in a pipe, pipes having a minimum diameter are used so as to reduce the pressure drops which depend in particular on the friction surface of the liquid with the inner wall of the pipe. .

However, the use of "big" pipes for this type of application has the following drawbacks:

• heavy and expensive infrastructure is required for transportation and / or installation;

• They are in the form of bars, generally 12 meters long, which must be welded on site;

• their high manufacturing and / or transport and / or installation costs increase the break-even point of the device.

The invention therefore more particularly aims to overcome these drawbacks by proposing a method and a device that allow a heat exchange between a coolant circulating in closed circuit and the water located at a depth corresponding to a desired temperature, for example to a depth of 1000 meters at which the temperature of the oceans oscillates on average between 3 and 5 ⁰ C. The use of a forced circulation in closed circuit makes it possible to push back the "limit of aspiration" which one can define as the threshold of maximum suction power before which the liquid vaporizes, and thus to use piping with a small inside diameter. For this purpose, the invention proposes a cooling method, characterized in that it comprises producing a closed-loop coolant circuit by implementing the following steps:

The installation of at least one thermal device at the site that it is desired to cool, this thermal device possibly comprising at least one fan coil;

• immersing at least one heat exchanger at a depth at which the water temperature is at a first level which corresponds to the desired temperature; Connecting the thermal device and the heat exchanger by means of two conduits respectively for supplying and returning a heat-transfer fluid, at least one of said ducts being equipped with at least one circulation device of said coolant.

In this way and advantageously, in the closed-loop circuit, a hydrodynamic equilibrium is obtained which makes it possible to push back the "suction limit" and thus to use more "small" supply and return ducts.

Thus, these conduits may have an internal diameter of less than 60 centimeters and preferably between 10 and 25 centimeters.

The use of "small" conduits of the aforementioned type has the following advantages:

• they can be presented in rolls of 100 meters in length, which simplifies their transport and more generally their displacement;

• they are easier to manipulate by the operators;

• they require for their installation nautical means (such as cargo barges, fishing boats) often present on the installation site and therefore cheap; • the necessary device for the implementation of the process can be installed at a reasonable price, which makes this technology accessible to "average" consumers (such as hotels).

Preferably, the circulating device of said heat transfer fluid is included on or in the descending pipe, namely the duct in which the coolant flows to the immersed heat exchanger.

In addition, advantageously, the implementation of the method according to the invention makes it possible in particular to benefit from the following advantages:

• the maintenance of this exchanger is extremely reduced or non-existent;

• the exploitation of the invention does not degrade the environment indeed, the solutions of the state of the art require periodically "clean" the ducts by injecting a chlorine solution which will inevitably be found in the marine environment gold, a closed loop avoids this pollution;

The installation, operation and maintenance of the invention are simplified.

Embodiments of the invention will be described below, by way of non-limiting examples, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of the device for implementing the method according to the invention.

FIG. 2 is a schematic representation of the thermal device of the device for implementing the method according to the invention. Figure 3 is a schematic representation of a tank of frigories being bypassed through a bypass duct comprising two nonreturn valves.

Figures 4.a and 4.b are a schematic representation of a submerged heat exchanger respectively comprising a tubular element and a tubular element associated with a pump.

In the example shown in FIG. 1, the device for implementing the method according to the invention comprises a closed-loop heat transfer fluid circuit comprising in particular:

A thermal device 1 located on the site that it is desired to cool;

A heat exchanger 2 which may be in particular but not exclusively of the tube and calender type. In this case, this heat exchanger 2 comprises many metal tubes in which circulates the heat transfer fluid to be cooled, the tubes bathed in the water in which the exchanger 2 is immersed, which allows to create a thermal contact over a large area between the heat transfer fluid to be cooled and the water. This heat exchanger 2 in this case is immersed to a depth at which the temperature of the water is at a first level, this temperature being sufficiently low to cause a cooling of the heat transfer fluid to a desired temperature, in order to allow operation effective thermal device 1;

• A supply duct 3 and a return duct 4 partially immersed, these ducts 3, 4 having in this case a "small" internal diameter, preferably an internal diameter of less than 30 centimeters. The respective lower end of each of these ducts 3, 4 is connected to said heat exchanger 2 while their respective upper end is connected to the thermal device 1; At least one circulation device 5 for the coolant, such as a pump, this circulator 5 being included on or in one of said conduits; feed 3 or return 4; more specifically, this circulation device 5 of the heat transfer fluid is preferably included on or in the descending pipe so that the heat transfer fluid is pulsed and not sucked.

Thus, in the case of a cooling of a site, for example in summer, under the effect of the action of the circulation device 5, the coolant present in the circuit circulates successively:

• in the thermal device 1 where it absorbs calories from the environment and therefore it heats up (high temperature);

• in the return duct 4 in which it is drawn and where it cools progressively by yielding a fraction of the calories that it has absorbed in the thermal device 1;

• in the immersed exchanger 2 where it gives up the remaining fraction of the calories that it has absorbed by cooling to reach the desired low temperature (which is very close to the water temperature at the depth at which the exchanger 2 is immersed);

• in the supply duct 3 which can be surrounded by an insulating sheath in order to maintain its internal temperature constant and thus prevent its warming on contact with layers of shallower and therefore warmer seawater.

As shown in FIG. 2, the thermal device 1 may comprise at least one fan coil connected to an ice-water plant 1 "so as to constitute an ice-water loop connected to said supply pipes and 3, 4 (not shown) More specifically, this thermal device 1 comprises in this case four fan coils arranged in parallel, each fan coil being connected respectively at the input and at the output by a branch of an "upstream" duct 21 and a "downstream" duct 22 of the chilled water loop 20. These "upstream" and "downstream" ducts 22 are connected to the inlet and the outlet of said central unit. 'water 1 "ice that allows to maintain or lower the temperature of the water flowing in the loop 20, the latter thus allowing for example to transfer frigories of ice water in the air of a room to be air-conditioned.

In addition, it is known that the demands of heat and cold production vary according to the seasons, the climatic conditions, but also the hours of the day. Thus, there are peaks and troughs of consumption.

In order to respond satisfactorily to these variations in demand, it is possible to use:

A cooling device according to the invention, shaped and dimensioned so as to be able to respond to consumption peaks, and which operates in degraded mode the rest of the time; or

A cooling device according to the invention, shaped and dimensioned so as to be able to respond to an average consumption, this cooling device comprising a frigory storage system making it possible to cope with the peaks of demand.

According to an alternative embodiment of the invention, this storage device may consist of a reservoir of a fluid such as water, the temperature of which is lowered by using the "excess night cold", the chilled water of this tank being used in order to satisfy the peaks of diurnal demands of cold production.

According to this alternative embodiment of the invention, this reservoir is preferably divided into horizontal strata by means of semi-permeable plates in order to allow the water contained in this reservoir to be distributed in stratified layers, each layer having a level of temperature and the coldest layers remaining in the lower part of the tank, the latter being connectable to said thermal device 1. The The coldest layers of this reservoir may for example be fed with chilled water, preferably at night, in the depths.

According to another alternative embodiment of the invention, this storage device may consist of a tank disposed on the surface and comprising a fluid whose solidification temperature is within a determined range, for example between 8 ° and 10 ° C. In this way, the passage of a stream of chilled water in this tank, the temperature of which is below this solidification temperature (for example, a temperature close to 0 ° C.), makes it possible to cause solidification of said fluid; phase change resulting in a return of heat that is substantially proportional to the mass and the latent heat of solidification of the fluid. Thus, the flow of water at the outlet of the reservoir will be warmed by this return of heat resulting from the solidification of said fluid.

Conversely, the passage of a stream of heated water in this tank, whose temperature is greater than said solidification temperature (for example, a temperature of 10 ° C.), makes it possible to cause a melting of said fluid; phase change resulting in heat absorption which is substantially proportional to the mass and the latent heat of fusion of the fluid. Thus, the flow of water out of the reservoir will be cooled by this absorption of heat resulting from the melting of said fluid.

In this way, by way of non-limiting example, in the case where it is desired to cause solidification of said fluid included in the tank, it is possible to connect the supply duct 3 and the return duct 4 of the coolant circuit. respectively at the inlet and the outlet of said tank, the coolant present in the circuit then circulates successively:

• in the return duct 4 in which it is drawn and where it cools gradually; • in the submerged heat exchanger 2 where it gives up the remaining fraction of the calories it has absorbed by cooling to reach the desired low temperature;

In the supply duct 3 which can be surrounded by an insulating sheath in order to keep its internal temperature constant;

• in said tank where its low temperature makes it possible to cause at least partial solidification of the fluid in the tank, the heat transfer fluid thus being heated;

• in the return duct 4 or in the thermal device 1 of the aforementioned type.

Thus, this operation is particularly conducive at night indeed, the heat transfer fluid flowing in the supply duct 3 is colder, which thus allows to cause the solidification of the fluid included in the reservoir.

Obviously, the heat transfer fluid circuit may comprise at least one branch circuit that may comprise valves or valves, which allows the coolant to bypass the passage in said tank when it is not considered necessary to have a reserve of frigories. In the latter case, by way of example, as shown in FIG. 3, the reservoir 40 is bypassed by means of a bypass duct 11 comprising two nonreturn valves and at the outlet of said bypass duct 11, these valves 12 which are oriented in an opposite direction may be of the spring type.

By way of non-limiting example, said fluid may be included in the reservoir, may be a fatty acid of general formula CH 3 - (CH 2) n - COOH (where n is from 2 to 16), such as in particular lauric acid , myristic acid, stearic acid, or a mixture of fatty acids for fixing the melting temperature at a determined value (s). Furthermore, preferably, each exchanger 2 is made of cupronickel (CuNiIO) and is of tubular type, this exchanger 2 then comprising an array of substantially parallel tubes shaped and arranged to allow the coolant to circulate more slowly than in the supply duct 3 and return 4, which results in an increase in the heat exchange time between the coolant and the seawater in which the exchanger 2 is immersed.

Advantageously, according to an alternative embodiment of the invention, as shown in Figure 4.a, the exchanger 2 may be "controlled convection". Thus, this exchanger 2 may comprise a tubular element 30, in this case vertically oriented, in the interior space of which coaxially extend the metal tubes or the coil of said exchanger 2.

In this way, natural convection is favored by creating a movement (in the ascending species) of the fluid in which the metal tubes or the coil are immersed, namely in this case seawater, which allows optimize the energy efficiency of said exchangers 2.

Advantageously, as shown in FIG. 4.b, the immersed exchanger 2 can be "forced convection" and then additionally comprises a means such as a circulation pump 31 which makes it possible to optimize even more the energy efficiency of said exchangers 2.

Each exchanger 2 can thus be of the "natural convection" type, or "controlled convection", or "forced convection" type. In addition, each exchanger 2 may be hybrid and consist of the combination of several of said types of exchanger 2.

Claims

claims

1. Cooling method, characterized in that it comprises the realization of a closed loop heat transfer fluid circuit by the implementation of the following steps:

Installing at least one thermal device (1) at the site that it is desired to cool;

• immersing at least one heat exchanger (2) at a depth at which the water temperature is at a first level; Connecting the thermal device (1) and the exchanger (2) via two supply ducts (3) and return ducts (4), at least one of said ducts (3, 4) being equipped with at least one circulation device (5) for a heat transfer fluid.

2. Cooling device for implementing the method according to claim 1, characterized in that it comprises a closed loop heat transfer fluid circuit comprising a thermal device (1) located on the site that it is desired to cool, this thermal device (1) being connected to at least one heat exchanger (2) immersed at an underwater depth at which the temperature of the water is at a first level, via two supply ducts respectively (3) and return (4), at least one of said conduits (3, 4) being equipped with a circulation device (5) of the coolant.

3. Device according to claim 2, characterized in that the heat exchanger (2) is of the tube and calender type.

4. Device according to one of claims 2 and 3, characterized in that the supply duct (3) and / or the return duct (4) is at least partially covered by a thermally insulating sheath.

5. Device according to one of claims 2 to 4, characterized in that in the case of a cooling of a site, under the effect of the circulation device (5), the coolant present in the circuit circulates successively :

• in the thermal device (1) where it absorbs calories from the environment and consequently it heats up; • in the return duct (4) where it cools progressively by yielding a fraction of the calories that it has absorbed in the thermal device (1);

In the exchanger (2) where it gives up the remaining fraction of the calories which it has absorbed while cooling to reach the desired low temperature which corresponds substantially to the temperature of the seawater at the depth at which the heat exchanger (2) is immersed;

• In the supply duct (3) which can be surrounded by an insulating sheath in order to keep its internal temperature constant and thus prevent its heating in contact with layers of shallower and therefore warmer seawater.

6. Device according to one of claims 2 to 5, characterized in that the thermal device (1) comprises at least one fan coil (V) connected to an ice water plant (1 ") to form a loop of water. chilled water (20) connected to said supply and return ducts (3, 4), said thermal device (1) comprises fan coils (V) arranged in parallel, each fan coil (V) being respectively connected to inlet and outlet by a branch of an "upstream" duct (21) and a "downstream" duct (22) of the chilled water loop (20), these "upstream" (21) and "downstream" ducts (22) are connected to the input and output of the ice water plant (1 ") which allows to maintain or even lower the temperature of the water circulating in the loop (20).

7. Device according to one of claims 2 to 6, characterized in that the supply ducts (3) and return (4) have an internal diameter of less than 60 centimeters.

8. Device according to one of claims 2 to 7, characterized in that it comprises a frigory storage system.

9. Device according to claim 8, characterized in that the storage device consists of a reservoir of a fluid such as water, whose temperature is lowered by using "excess cold night", the ice water of this tank being used in order to satisfy peaks of diurnal demands for cold production; this tank is divided into horizontal strata by means of semi-permeable plates in order to allow the water contained in this reservoir to be distributed in stratified layers, each layer having a determined temperature level and the coldest layers remaining in the part tank bottom, the latter being connectable to said thermal device (1).

10. Device according to claim 8, characterized in that said storage device consists of a reservoir (40) disposed on the surface and comprising a fluid whose solidification temperature is within a determined range; in this way, the passage of a stream of ice water in the tank (40), the temperature of which is below this solidification temperature makes it possible to cause solidification of said fluid, this phase change resulting in a return of heat which is substantially proportional to the mass and the latent heat of solidification of the fluid; thus, the flow of water at the outlet of the tank (40) will be heated thanks to this heat return resulting from the solidifying said fluid; conversely, the passage of a flow of heated water in this tank (40), the temperature of which is higher than said solidification temperature makes it possible to cause a melting of said fluid, this phase change resulting in a heat absorption which is substantially proportional to the mass and the latent heat of fusion of the fluid; thus, the flow of water at the outlet of the reservoir (40) will be cooled by this absorption of heat resulting from the melting of said fluid.

11. Device according to claim 10, characterized in that in the case where it is desired to cause solidification of said fluid included in the reservoir (40), the supply duct (3) and the return duct (4) of heat transfer fluid circuit are respectively connected to the inlet and outlet of said tank (40), the coolant present in the circuit then circulates successively: o in the return duct (4) in which it is drawn and where it is cool gradually; o in the immersed heat exchanger (2) where it gives up the remaining fraction of the calories that it has absorbed while cooling to reach the desired low temperature; o in the supply duct (3) which can be surrounded by an insulating sheath in order to keep its internal temperature constant; o in said reservoir (40) where its low temperature makes it possible to cause at least partial solidification of the fluid included in this reservoir (40), the heat transfer fluid thus being heated; o in the return duct (4) or in the thermal device (1) of the aforementioned type.

12. Device according to one of claims 10 and 11, characterized in that the coolant circuit comprises a bypass circuit which allows the coolant to bypass the passage in said tank when it is not considered necessary to have a reserve of f .gories.

13. Device according to claim 12, characterized in that the closed loop heat transfer fluid circuit comprises at least one bypass duct (11) comprising two nonreturn valves (12) disposed respectively at the inlet and the outlet of said bypass duct (11), these valves (12) which are oriented in an opposite direction may be of the spring type.

14. Device according to one of claims 10 to 13, characterized in that the fluid can be included in the reservoir, is a fatty acid of general formula CH3 - (CH2) n - COOH (where n is from 2 to 16) , such as in particular lauric acid, myristic acid, stearic acid, or a mixture of fatty acids for setting the melting temperature at a determined value (s).

15. Device according to one of claims 2 to 14, characterized in that each exchanger (2) is made of cupronickel (CuNiIO) and is of tubular type, this exchanger (2) then comprising a network of substantially parallel tubes shaped and arranged so as to allow the coolant to circulate more slowly than in the feed (3) and return (4), which results in an increase in the heat exchange time between the coolant and the water in which the exchanger (2) is immersed.

16. Device according to one of claims 3 to 15, characterized in that the exchanger (2) comprises a tubular element (30) in the inner space of which extend the metal tubes of said exchanger (2).

17. Device according to claim 16, characterized in that the exchanger (2) comprises a means such as a circulation pump (31).