GB2440290A

GB2440290A - Cooling an underground tube carriage with a roof heat exchanger containing soft ice

Info

Publication number: GB2440290A
Application number: GB0720521A
Authority: GB
Inventors: Denis Clodic; Youssef Riachi
Original assignee: Association pour la Recherche et le Developpement des Methodes et Processus Industriels
Current assignee: Association pour la Recherche et le Developpement des Methodes et Processus Industriels
Priority date: 2004-09-10
Filing date: 2007-10-19
Publication date: 2008-01-23
Anticipated expiration: 2024-09-10
Also published as: GB0720521D0; GB2440290B

Abstract

Air in an underground tube railway carriage is cooling with a soft ice slurry of water and glycol which was pumped from a fixed storage tank (8, fig 2) into a heat exchanger 17 that occupies substantially the whole length and width of the carriage roof. Alternatively if the carriage runs in the open air, it may have an on-board cooling system for replenishing the soft ice. The heat exchanger 17 has pipes 50-100mm in diameter that store cold; allow circulation; and transfer heat to the air with fans and fins. The slurry is circulated inside the heat exchanger 17 by pump 19. Controls mix the cooled air with recirculated air; counter passengers in zones of the carriage; and optically measure the refractive index of the soft ice.

Description

1 2440290

METHOD FOR COOLING OF TUBE CARRIAGES WHICH DOES NOT

DISCHARGE HEAT INTO THE UNDERGROUND, AND CAN EVEN

CONTRIBUTE TOWARDS COOLING THE STATIONS

It is known that cooling of any volume (a carriage, a building, the underground, etc) to a temperature level which is lower than the ambient temperature of the atmosphere makes it necessary to discharge this heat to the exterior of the said volume, and at a level slightly higher than the ambient temperature, in order for the heat exchange to be able to take place. Thus, according to the teaching of thermodynamics, a given volume is cooled only by removing heat. The consequence of this principle is that cooling a train as it travels in the open air does not cause any problems, since the heat is discharged into the atmosphere. On the other hand, underground, such as in a tube circuit, cooling of the carriages and the passengers in them involves discharge of the heat extracted into the tunnels and stations, which heat is further increased by the energy supplied to the cooling system, which is expressed simply for compression cooling systems by the ratio: Q_rejetée = Q_frig + P_élec where: S. ** :** Qfrig is the cooling power supplied in order to * maintain the temperature at the required level in Watts P-élec is the electrical power consumed by the compressor(s) and fans in Watts Q_rejetée is the calorific power discharged to the exterior of the carriage in Watts.

For an efficient system and for a temperature difference between the cooled volume and the exterior of approximately 20 C, P_élec typically represents between 30 and 40% of the cooling power. For production of 1 unit, at least 1.3 is discharged to the exterior. This involves a very substantial increase in temperature in all of the underground network, and in particular in the stations, as can be found in the New York subway, where the sets of carriages are air-conditioned, but the stations and tunnels are not.

Characteristics of the invention The object of the method according to the invention is to cool all the carriages without discharging the heat into the underground network. In addition, the coolant production on board the carriages can contribute towards cooling the stations and the network of tunnels.

The invention relates to a method of cooling a tube carriage, the method comprising the steps of: Providing soft ice comprising a mixture of water and :..::: glycol; Pumping said soft ice from a storage means to a heat exchange means, said heat exchange means located in or on said tube carriage, such that heat energy is transferred from said carriage to said soft ice; wherein the heat :** exchange means occupies substantially the width and length * of the roof of the carriage.

The basis of the cooling method uses cold which is stored in soft ice which coexists with a liquid phase. This soft ice is obtained typically when water and glycol are made to coexist in a mixture. The temperature of melting of this soft ice can also be controlled according to the composition of the water-glycol mixture. This soft ice is known as slurry in English, which can be translated into French as "sorbet liquide". This state of the soft ice material makes it possible to pump the liquid -solid mixture, and it can thus be transferred from a storage volume to a volume of use, and can also circulate in exchangers.

According to one embodiment, the soft ice includes a mixture of water and glycol, the temperature of which can be controlled according to the composition of the mixture.

According to one embodiment, the soft ice is produced on board a tube carriage when the carriage is travelling in the open air.

According to one embodiment, the soft ice is produced outside a tube carriage, and is pumped on board the tube carriage. *... * S S...

According to one embodiment, the volume of soft ice pumped *..S on board said tube carriage represents half of the volume ***...

* . of the heat exchange means. * S *

According to one embodiment, the volume of use comprises * pipes with fins.

According to one embodiment, air recirculation is implemented in order to make it possible to mix the air which is recirculated and the air being cooled in contact with the volume of use, in order to regulate the temperature inside the carriage.

According to one embodiment, zone fans permit regulation according to zones.

According to one embodiment, a passenger counter is disposed on each door of the carriage in order to ascertain the number of passengers present in the zones of the carriage and to regulate the zones accordingly.

According to one embodiment, modulated blowing to the exterior of the carriage makes it possible to cool a tunnel or a station through which the carriage is travelling, at the same time as cooling the interior of the carriage.

According to one embodiment, the residual quantity of soft is ice is determined by means of an optical method which is based on the variation of the index of refraction of the liquid relative to the soft ice.

The invention also relates to an air conditioning system for cooling tube carriages comprising a storage means for storing soft ice therein, said soft ice comprising a S..

mixture of water and glycol, and comprises a heat exchange I..

means located in or on said tube carriage, said system further comprising a pump arranged to pump said soft ice from said storage means to said heat exchange means, S.'. wherein the heat exchange means occupies the width and * length of the roof of the carriage.

According to one embodiment, at least one tube carriage includes an on-board cooling system in order to produce soft ice on board the said tube carriage when the carriage is travelling in the open air, the storage tank and the heat exchange means being on board said carriage.

According to one embodiment, with the soft ice being produced outside a tube carriage and stored in a storage means.

According to one embodiment, the volume of soft ice pumped on board said tube carriage represents half of the volume of the heat exchange means.

According to one embodiment, the heat exchange means comprises pipes with fins.

According to one embodiment, a system for regulation by air recirculation is implemented in order to mix the air which is recirculated and the air being cooled in contact with the volume of use, in order to regulate the temperature inside the carriage. I. * * S...

According to one embodiment, the regulation system includes zone fans which permit regulation according to zones.

S..... * S

According to one embodiment, a passenger counter is : disposed on each door of the carriage in order to ascertain * the number of passengers present in the zones of the carriage and to regulate the zones accordingly.

According to one embodiment, means for modulated blowing to the exterior of the carriage make it possible to cool a tunnel or a station through which the carriage is travelling, at the same time as cooling the interior of the carriage.

According to one embodiment, the residual quantity of soft ice is determined by means of an optical method which is based on the variation of the index of refraction of the liquid relative to the soft ice.

Other characteristics and advantages of the invention will become apparent by means of the following description, the latter being provided by way of non-limiting description, with reference to the attached drawings, in which: Figure 1 represents a system according to the invention; and Figure 2 represents a view of the cooling exchanger of a carriage.

The system as a whole is shown in figure 1. The elements represented in figure 1 are as follows: 1. condenser 2. compressor S. * . * .** 3. piping (with its pressure reducing valve) for supply of *...

cooling agent to the evaporator *5** 4. cooling agent intake piping 5. evaporator which produces a mixture of liquid -ice which can be pumped 6. pump to supply the mixture of soft ice -liquid from the tank 7. pump for recirculation of liquid -soft ice 8. tank for storage of the soft ice -liquid mixture 9. three-way valve making it possible to regulate the quantity of ice in the liquid -soft ice mixture 10. pump for recharging the on-board exchanger 11. pump 10 liquid supply piping 12. pump 10 soft ice supply piping 13. fixed liquid -soft ice supply piping of the onboard system 14. fixed piping for return of liquid from the on-board system to the tank 8 15. carriage 16. on-board cooling system The melting of the ice is used during underground travel in tunnels and in stations. The method makes it possible to cool the carriages and even to blow cold air into the tunnels and stations according to a ratio to be defined, in order to contribute to the overall cooling of the underground network.

The liquid -ice mixture is produced either at the termini of the lines, or "on board" for tube lines which have a significant portion of travel in the open air. A detailed

description of the method and the system based on

illustrations provided hereinafter will make it possible to understand the invention better. * *.S **** * *

Figure 2 shows a view of the cooling exchanger of a carriage, provided with the technical characteristics which are essential in order to use a method of this type. The elements represented in figure 2 are as follows: * * * 17. carriage cooling exchanger * 18. fins which make it possible to improve the exchange 19. pump for circulation of the liquid -soft ice mixture 20. zone fan 21. recirculation fan 22. box for mixture of renewed air/cooled air 23. air renewal 24. on-board cooling system condenser (optional) 25. on-board cooling system compressor (optional) 26. cooling agent -soft ice evaporator for on-board cooling system (optional) 27. on-board piping for filling of the exchanger 17 with liquid -soft ice 28. on-board piping for emptying the liquid from the exchanger 17 29. lower part of the plenum chamber The condenser 24, the compressor 25 and the evaporator 26 are installed in each carriage only for tube lines which have a path partially in the open air. These components are therefore not installed for tube lines which are entirely underground, the exchanger 17 is then reloaded with a mixture of liquid -soft ice by the piping 27 and the liquid is emptied from it by the piping 28.

It is known that space is extremely limited inside carriages and sometimes even in tunnels, and therefore the exchanger must have a low height, but can advantageously occupy the substantial part of the available width and length of the roof of the carriage. In addition, it is essential to be able to distribute the coolness throughout the entire volume, which is why the system for circulation of the liquid -soft ice mixture must use pipes with a 0..: 25 sufficient diameters, typically of between 50 and 100 mm, these pipes having a dual role of transfer of cold to the air circulating on the exterior, by means of fans, and a role of energy storage. In order to give an idea of the sizes, power and energy levels stored by a system of this type, for a carriage containing 170 passengers lit with electrical power of approximately 1 kW, and therefore producing thermal power of 20 kW for a one-hour journey, it is therefore necessary to extract energy of 20 kwh, which represents heating of a quantity of approximately 410 kg of soft ice and liquid at from 0 to + 10 C which completes the melting of the ice. For a mixture of soft ice -liquid of 40% by weight of soft ice, the cold energy stored Q in kJ or kwh is calculated according to the formula: Q=0.4xmtxlf+mtxcpegxAt wherein, with Q in kJ me: total mass (water + soft ice) in kg 1f: latent heat of melting of the soft ice in kJ/kg CPeg: calorific capacity of the mixture of water + glycol in kJ/kg C Lit: difference between the initial and final temperatures in C.

For tubes with lines which are entirely underground, the system is reloaded at the termini by an extremely rapid loading system, typically with a flow rate of 20 us, which makes it possible to reload the quantity of ice required via the fixed 14 and on-board 27 piping, which is typically ,,* 20 approximately 50% by volume, whereas the corresponding *...

liquid volume is discharged via the on-board 28 and fixed 14 piping. The operation lasts for less than a minute, and involves a system of automatic male/female stowage of the * piping 13 and 27 on the one hand and 14 and 28 on the other hand. The accuracy of loading is provided by a volumetric *:*. device which makes it possible to extract the volume of liquid which corresponds exactly to the volume of ice loaded. This volumetric control is continuous and is typically carried out by filling and emptying the controllable external volumes.

For underground lines where travel in the open air represents 1/4 to 1/3 of the total travel time, it is then possible to produce the liquid -soft ice mixture by means of an on-board cooling system comprising a condenser 21, one or more compressors 22, and a cooling agent -soft ice evaporator 23, and the said cooling system produces the liquid -soft ice mixture which makes it possible to S reconstitute the quantity of ice used in the underground part.

In addition, the method can contribute to a certain extent to the overall cooling of the tunnels and stations, by means of modulated blowing to the exterior of the carriage, together with the cooling which takes place in the interior of the carriage.

In order to create conditions of comfort for the passengers inside the carriage, the air must be blown at the coldest level at a temperature of 8 C and up to a typical temperature of 14 C. Taking into account the fact that the surface temperature of the exchanger pipes can be regulated to less than 0 C or to 0 C, it is advantageous to have an air recirculation system which makes it possible to mix the air recuperated with the air which has been cooled on the surface of the pipes, in order to control the blowing temperature in the carriage, thus guaranteeing the conditions of comfort for the passengers.

In addition, this air-conditioning system must be provided * with a passenger counter which is disposed on each door, thus making it possible to determine sufficiently accurately the number of passengers entering and leaving, and therefore, by means of the difference, the number of passengers present in the set of carriages for each of the zones of the carriage, consequently permitting regulation according to zones. This regulation according to zones is carried out by the zone fans 20, the speed of which is variable.

Below the pipes there are positioned collectors which make it possible to recuperate the condensation water from the atmosphere, which prevents this water from running onto the lower part of the plenum chamber 29. The system for transfer of the coolness thus comprises: Pipes with fins with a wide diameter, which constitute the cooling exchanger of the carriage 17. These pipes are used both for storage and exchange between the air and the soft ice mixture.

A pump 19 which permits circulation of the liquid -soft ice mixture.

A tank B which permits rapid loading and unloading transfers for the cold production systems located at the terminus. * .1*

The ventilation system comprises recirculation fans 21 which assure renewal of the interior air and slight excess * * pressure of the plenum chamber, the plenum chamber being the volume of the carriage which is delimited by the roof and the inner lining which may be perforated in order to *:*. assure distribution of the air throughout the volume. This perforation is also adapted according to the presence of passengers seated or standing, corresponding to the interior arrangement of the carriage (seats and passageways).

In addition, the circulation of the air from the top downwards, which permits both cooling of the air on the pipes with fins and diffusion of the air through the diffusing ceiling, is assured by the zone fans 20.

In addition, if it is chosen to cool not only the carriage, but also the underground and the stations, flaps are provided on the upper part, as well as internal ducts which make it possible to diffuse part of the flow to the exterior of the carriage. It will be appreciated that in this case, but also according to the thermal load level, the temperature of the liquid -soft ice mixture may be reduced significantly, to -10 to -15 C, in order to store a larger quantity of cooling energy.

The regulation system takes into account the number of passengers and the air temperature in the underground, and thus establishes according to the proportion of new air / renewed air, the flow of air to be blown onto the exchanger and towards the carriage, and optionally to the exterior of the carriage. :. 20 * ***

The quantity of residual ice can be controlled in two ways.

The first of these, which is basic, consists of monitoring S...

the initial temperature of the liquid -soft ice mixture.

When this initial temperature (after the pump at the intake of the exchanger) goes clearly above 0 , and typically to 1 to 2 , the ice is then completely melted and there remains a reserve of cold which is still approximately 5 kW and permits limited cooling until the next reloading at a station takes place, or until the next time the carriage passes into the open ar, so that the cooling system can be operated.

It is possible to use an optical system which is based on the variation of the index of refraction of the liquid relative to the soft ice, thus making it possible to determine the residual quantity of ice before the latter is used up. This level of reserve can thus be ascertained and therefore transferred to the overall regulation system. S. S. * I.. S... * S *.I. S... * a I... *

SSSSS * . S. S. S. S * S

SS S * . . S *S

Claims

CLAIMS

1. Method of cooling a tube carriage, the method comprising the steps of: -providing soft ice comprising a mixture of water and glycol; -pumping said soft ice from a storage means to a heat exchange means, said heat exchange means located in or on said tube carriage, such that heat energy is transferred from said carriage to said soft ice, wherein the heat exchange means occupies substantially the width and length of the roof of the carriage.

2. Method according to claim 1, wherein the soft ice includes a mixture of water and glycol, the temperature of which can be controlled according to the composition of the mixture.

3. Method according to claim lor claim 2, wherein the soft ice is produced on board a tube carriage when the carriage is travelling in the open air.

4. Method according to claim 1 or claim 2, wherein the soft ice is produced outside a tube carriage, and is pumped on board the tube carriage.

5. Method according to claim 4, wherein the volume of soft ice pumped on board said tube carriage represents half of the volume of the heat exchange means.

6. Method according to any one of the preceding claims, wherein the heat exchange means comprises pipes with fins.

7. Method according to any one of the preceding claims, wherein air recirculation is implemented in order to make it possible to mix the air which is recirculated and the air being cooled in contact with the heat exchange means, in order to regulate the temperature inside the carriage.

8. Method according to any one of the preceding claims wherein zone fans permit regulation according to zones.

9. Method according to claim 9, wherein a passenger counter is disposed on each door of the carriage in order to ascertain the number of passengers present in the zones of the carriage and to regulate the zones accordingly. * * a...

10. Method according to any one of the preceding claims, wherein modulated blowing to the exterior of the carriage makes it possible to cool a tunnel or a station through which the carriage is travelling, at the same time as cooling the interior of the carriage.

11. Method according to any one of the preceding claims, wherein the residual quantity of soft ice is determined by means of an optical method which is based on the variation of the index of refraction of the liquid relative to the soft ice.

12. An air conditioning system for cooling tube carriages comprising a storage means for storing soft ice therein, said soft ice comprising a mixture of water and glycol, and comprising a heat exchange means located in or on said tube carriage, said system further comprising a pump arranged to pump said soft ice from said storage means to said heat exchange means, wherein the heat exchange means occupies substantially the width and length of the roof of the carriage.

13. System according to claim 12, wherein the soft ice includes a mixture of water and glycol, the temperature of which can be controlled according to the composition of the mixture.

14. System according to claim 12 or claim 13, wherein at least one tube carriage includes an on-board cooling system in order to produce soft ice on board the said ... 20 tube carriage when the carriage is travelling in the open air, the storage tank and the heat exchange means being on board said carriage. *S..

* S...

* S 15. System according to claim 12 or claim 13, wherein the soft ice is produced outside a tube carriage and stored in a storage means.

16. System according to claim 15, wherein the volume of soft ice pumped on board said tube carriage represents half of the volume of the heat exchange means.

17. System according to any one of claims 12 to 16, wherein the heat exchange means comprises pipes with fins.

18. System according to any one of claims 12 to 17, wherein a system for regulation by air recirculation is implemented in order to mix the air which is recirculated and the air being cooled in contact with the heat exchange means, in order to regulate the temperature inside the carriage.

19. System according to any one of claims 12 to 18, wherein the regulation system includes zone fans which permit regulation according to zones.

20. System according to claim 19, wherein a passenger counter is disposed on each door of the carriage in order to ascertain the number of passengers present in the zones of the carriage and to regulate the zones accordingly.

21. System according to any one of claims 12 to 20, wherein means for modulated blowing to the exterior of ".. the carriage make it possible to cool a tunnel or a I...

station through which the carriage is travelling, at "S.

the same time as cooling the interior of the carriage. * .

22. System according to anyone of claims 12 to 21, wherein S.. the residual quantity of soft ice is determined by means of an optical method which is based on the variation of the index of refraction of the liquid relative to the soft ice.

23. A system as hereinbefore described with reference to any of claims 12-22