Dual cycle cooling system for vacuum tube transport system

Abstract

The present invention relates to a cooling apparatus (100) for efficiently cooling heat-generating components (202) of a vacuum tube transportation system The cooling apparatus (100) includes an immersion container (204) filled with a coolant (206) in which the heat-generating components (202) are fully immersed. Heat radiated from the components (202) results in boiling of the coolant (206). Vapours of the coolant (206) pass to a condenser (216), where the vapours are converted into liquid form, and re-supplied and maybe sprayed on the components (202) in the immersion container (204). The cooling apparatus (100) reduces temperature of vapours flowing into the condenser coil (208) using a cooling fluid (214), which is pumped into a condenser (216) housing the condenser coil (208) from a fluid container (218). The cooling fluid (214) is maintained at a reduced pressure environment with help of pressure regulating valve (222), to control boiling temperature.

Description

DUAL CYCLE COOLING SYSTEM FOR VACUUM TUBE TRANSPORT SYSTEMFIELD OF INVENTION[1] The present invention relates to vacuum tube transport systems and more particularly, to a cooling apparatus for a vacuum tube transport system for efficiently dissipating heat from various components of the vacuum tube transport system.BACKGROUND OF THE INVENTION[2] The subject matter discussed in the background section should not be assumed to be prior art merely because of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognised in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may correspond to implementations of the claimed technology.[3] A vacuum tube transport system, such as Hyperloop, is a high-speed mode of transportation where a pod carrying passengers or cargo travels inside a tube at high speeds. The tube is typically a large, sealed low-pressure tube, usually in the form of a long tunnel. The pod is generally selected as a coach pressurised at atmospheric pressure, running substantially free of air resistance or friction inside the tube using magnetic propulsion and levitation. A conventional vacuum tube transport system also includes terminals that handle pod arrivals and departures.[4] The Hyperloop operates similarly to Maglev (also known as “magnetic levitation trains”), where propulsion of the pod is performed by employing Linear Induction Motors (LIMs) while simultaneously levitating the pod using electromagnetism. The difference between the Hyperloop and the Maglev is that the former runs inside a partial vacuum condition maintained inside the tube. The pod inside the partially vacuum tube encounters reduced resistance, such as frictional forces and aerodynamic drag, thereby reducing the energy consumption required for the propulsion of the pod.[5] The Hyperloop generally operates under a partial vacuum and is similar to an electric train. During the operation of the Hyperloop, a lot of heat is generated, which isdifficult to liberate. Examples of components that contribute to this generation of heat are LIMs, which are used to propel the pod in a forward direction; Electromagnetic Suspension (EMS), which levitates the pod; batteries that power components installed in the pod; and other electrical components ranging from inverters, control boards, regulator, and others. The Maglevs are also prone to the generation of excessive heat. However, such challenges in the case of Maglevs may be easily resolved since atmospheric air may be used to assist dissipation of heat from Maglev’s components. Contrary to this, heat cannot be easily dispersed in an enclosed transportation system such as Hyperloop. Since the Hyperloop operates in near-vacuum conditions, the availability of atmospheric air to dissipate the heat is extremely restricted.[6] Efforts have been made to develop techniques for dissipating heat generated during the operation of enclosed transportation systems. For instance, the air-cooling method uses fans to blow air over heat exchangers or radiators and is currently being used to cool motors and compressors. However, air-cooling is not an efficient means to be employed in the case of the Hyperloop since such a transportation system operates at near vacuum pressure (1 kPa Absolute, lOlkPa is atmospheric pressure). In other words, the direct heat carrying capacity of an air coolant is 17100thas compared to an air coolant operating in atmospheric conditions. The liquid-cooling method is generally employed for dissipating heat in automobile engines and electronic components. However, liquid cooling poses many challenges when employed in a high-speed transportation system. Since a typical liquid cooling system has to operate in a closed loop and to be vacuum compatible a radiator or a similar arrangement is necessary for liberating heat from a circulating liquid coolant. Further, the cryogenic cooling method is a process involving the cooling of components of a conventional magnetic levitation transportation system using liquid nitrogen or other cryogenic liquids. This technique is suitable for cooling superconducting components in these transportation systems and is generally employed in Maglevs. However, such a cooling technique is not viable for a vacuum tube transportation systems, since the same operates in an enclosed environment. Using any of the above cooling techniques, it is extremely difficult to liberate the excessive heat from the train and transfer it to the environment due to the absence of any heat transfer medium or heat sink.[7] Phase change materials (PCMs) are materials that can absorb and release large amounts of heat during the process of melting and solidification. PCMs suffer less from the challenges of heat dissipation to a sink, as they are capable of storing heat for an extendedperiod. However, the PCMs are required to be cooled after a certain time of operation. The use of PCMs for cooling heat-contributing components of the vacuum tube transportation systems is not feasible since the replacement of the PCMs at regular intervals is necessary to achieve an optimum cooling effect. Moreover, low thermal conductivities associated with the PCMs pose a challenge while implementing the same in high heat transfer rate applications. Other techniques, such as water and steam storage systems, and steam injection systems face similar challenges when employed in enclosed transportation systems. The vacuum environment of the vacuum tube transport system essentially rules out any cooling technique that relies on the dissipation of heat into the atmosphere or surrounding environment.[8] There is, therefore a need in the art to provide techniques for uniformly dissipating heat generated during the operation of enclosed transportation systems, such as vacuum tube transport systems, while addressing the aforementioned shortcomings of conventional high-pressure pumping devices.OBJECT OF THE INVENTION[9] The object of the present invention is to provide a cooling apparatus capable of efficiently dissipating heat from components of a vacuum tube transport system.

[0010] Another object of the present invention is to provide a simple and low -cost cooling apparatus for cooling the components of the vacuum tube transport system, during its operation.

[0011] Another object of the present invention is to provide a cooling apparatus which employs the principle of immersion cooling to dissipate heat from components of the vacuum tube transport system.

[0012] Still, another object of the present invention is to provide a dual- cycle cooling apparatus for dissipating heat from components of the vacuum tube transport system, capable of being easily retrofitted into existing vacuum tube transport systems.SUMMARY OF THE INVENTION

[0013] The summary is provided to introduce aspects related to a cooling apparatus for a vacuum tube transportation system, and the aspects are further described below in thedetailed description. This summary is not intended to identify essential features of the claimed subject matter, nor is it intended for use in determining or limiting the scope of the claimed subject matter.

[0014] The vacuum tube transportation system, such as Hyperloop, includes a pod or casing located inside a low-pressure vacuum environment of a tube. The tube may be a large, sealed low-pressure conduit, usually in the form of a long tunnel. The pod may be a coach pressurised at atmospheric pressure that runs substantially free of air resistance or friction inside the tube using magnetic propulsion. The cooling apparatus is capable of uniformly cooling heat-generating components of the vacuum tube transportation system by efficiently dissipating heat away from the heat-generating components, such as, Linear Induction Motors (LIMs), Electromagnetic Suspension (EMS), batteries and other electrical components installed in the vacuum tube transportation system.

[0015] In an embodiment, the cooling apparatus for the vacuum tube transportation system comprises an immersion container filled with a coolant and enclosing heatgenerating components of the vacuum tube transportation system. The cooling apparatus further comprises a condenser coil for cooling vapours of the coolant generated by absorbing heat from the heat-generating components. The vapours of the coolant are cooled using a coiled condenser installed in the system. The cooling apparatus further comprises a coolant pump for pumping cooled liquid back into the immersion container. The cooling apparatus further comprises a plurality of spray nozzles provided in the immersion container for uniformly spreading the coolant on the heat-generating components.

[0016] In an aspect, the cooling apparatus operates using immersion cooling to disperse heat away from the heat-generating components.

[0017] In an aspect, the cooling apparatus is located within the pod or in a vacuum environment inside the tube.

[0018] In an aspect, the condenser coil includes a plurality of coiled sections made of a material having high thermal conductivity.

[0019] In an aspect, the cooling apparatus further comprises a pressure-regulating valve for maintaining an optimal pressure inside the condenser to ensure that a phase of the cooling fluid transforms at the required temperature.

[0020] In an aspect, the immersion container and the condenser are present as different sections connected together using pipes.

[0021] In an aspect, a liquefied form of the coolant is sprayed at high pressures into the coolant directed at a corners and teeth of the heat-generating component, for preventing film formation in hot spots regions and dry-outs.

[0022] In an aspect, the immersion container includes one or more outlet ports for releasing vapours of the coolant and an inlet port through which the plurality of spray nozzles supply the coolant back into the immersion container from the condenser.

[0023] The cooling apparatus is cost-effective and utilizes the principle of immersion cooling to disperse heat away from the heat-generating components. The cooling apparatus may also be appropriately positioned in the pod to reduce operating temperature of the heatgenerating components located in the pod.BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0024] The accompanying drawings constitute a part of the description and are used to provide a further understanding of the present invention. Such accompanying drawings illustrate the embodiments of the present invention used to describe the principles of the present invention. The embodiments are illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this invention are not necessarily to the same embodiment, and they mean at least one. In the drawings:

[0025] Fig. 1 illustrates a conventional vacuum tube transportation system;

[0026] Fig. 2 illustrates a schematic representation of a cooling apparatus for uniformly cooling components of a vacuum tube transportation system, in accordance with an embodiment of the present invention;

[0027] Fig. 3 illustrates a perspective view of an immersion container of the cooling apparatus, in accordance with an embodiment of the present invention;

[0028] Fig. 4 illustrates an exemplary representation of a test setup of the cooling apparatus, in accordance with an embodiment of the present invention; and

[0029] Figs. 5A and 5B illustrate plots depicting variation of temperature (°C) with respect to time (seconds) for immersion cooling of a component of the vacuum tube transportation system, in accordance with an embodiment of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0030] The detailed description set forth below in connection with the appended drawings is intended as a description of various embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced. Each embodiment described in this disclosure is provided merely as an example or illustration of the present invention and should not necessarily be construed as preferred or advantageous over other embodiments. The detailed description includes specific details for the purpose of providing a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

[0031] The present invention relates to a cooling apparatus for efficiently cooling components of a vacuum tube transportation system (also referred to as “transportation system” hereinafter), such as Hyperloop, by uniformly dissipating heat away from the components. The cooling apparatus is capable of cooling the components, such as, Linear Induction Motors (LIMs), Electromagnetic Suspension (EMS), batteries and other electrical components ranging from inverters, control boards, regulators and the like, installed in the vacuum tube transportation system.

[0032] As shown in Fig. 1, a vacuum tube transportation system typically includes a pod 102 located inside a vacuum environment 104 of a tube 106. The tube 106 is a large, sealed low-pressure conduit, usually in the form of a long tunnel. The pod 102 is generally a coach pressurized at atmospheric pressure that runs substantially free of air resistance or friction inside the tube 106 using magnetic propulsion. The pod 102 is generally configured to transport passengers or cargo from one place to another.

[0033] Fig. 2 illustrates a schematic representation of the cooling apparatus 100 for uniformly cooling one or more heat-generating components 202 of the transportation system 100. The cooling apparatus 200 is cost-effective, and utilizes the principle of immersion cooling to disperse heat away from the heat-generating components 202 of the transportation system 100. The cooling apparatus 200 is located in the vacuum environment 104 inside the tube 106. The cooling apparatus 200 may also be appropriately positioned within the pod 102. The heat-generating components 202 may be enclosed in an immersion container 204 of the cooling apparatus 200 filled with a dielectric material or coolant 206. The heat radiated from the heat-generating components 202, for instance, an LIM, increasestemperature of the coolant 206 and results in boiling of the coolant 206 at an operational temperature in the form of vapours. These vapours of the coolant 206 pass to a condenser coil 208 of the cooling apparatus 200, where the vapours are cooled back into liquid form. The condenser coil 208 contains a plurality of coiled sections made of a material having high thermal conductivity. This cooled liquid form of the coolant 206 is pumped, by a coolant pump 210, back into the immersion container 204. A plurality of spray nozzles 212 maybe present which ensure a uniform spread of the resupplied coolant 206 on the heatgenerating components 202 disposed in the immersion container 204.

[0034] The cooling apparatus 200 reduces temperature of vapours of the coolant 206 flowing into the condenser coil 208 using a cooling fluid 214, which is pumped into a condenser 216 from a fluid container 218 with the help of a pump 220. The condenser 216 houses the condenser coil 208, one end 208-1 of which is connected to the immersion container 204 either directly or indirectly through some additional arrangement, to receive the vapours of the coolant 206 with the other end 208-2 connected to the coolant pump 210 adapted to pump the cooled coolant 206 in liquid form to the spray nozzles 212. As the cooling fluid 214, such as water, passes through the condenser 216, it takes away heat from the condenser coil 208. The condenser 216 may be maintained at a reduced pressure with the help of a pressure-regulating valve 222. The pressure-regulating valve 222 facilitate an optimal pressure environment inside the condenser 216 to ensure that a phase of the cooling fluid 214 transforms at a lower temperature, thereby allowing latent heat capacity of the cooling fluid 214 to play a more prominent role.

[0035] The immersion container 204 filled with the coolant 206, which has a boiling point close to a threshold temperature that the heat-generating component 202 of the transportation system 100 needs to maintained, for optimal performance thereof. The coolant 206 boils in the form of vapour and passes through the condenser coil 208, which liquefies the coolant 206 and returns it to the immersion container 204. This return maybe assisted by a coolant pump 210. Thus, the coolant 206 flows in a closed loop. While entering the immersion container 204, the liquefied coolant 206 may pass through the spray nozzles 212 which increases heat transfer rate thereof, to ensure uniform spraying of the liquefied dielectric coolant 206 on the heat-generating component 202 so as to efficiently reduce the operating temperature thereof.

[0036] The fluid container 218 stores the cooling fluid 214 which maybe water or refrigerant for cooling of the coolant 206 present in the condenser 216. The cooling fluid214 passes to the condenser 216 via the pump 220. Once in the condenser 216, the cooling fluid 214 evaporates at a lower pressure maintained inside the condenser 216 via the pressure regulating valve 222. Boiling of the cooling fluid 214 takes heat away from the condenser coil 208. Once the cooling fluid 214 is converted into steam, it is released into the vacuum environment 104 of the tube. Thus, the cooling fluid 214 flows in an open loop. The heat-generating component 202 is a component of the transportation system, which gets heated when it is in operation. The heat-generating component 202 may include, but not limited to, LIM, EMS, batteries or any other electrical component, air-conditioning unit, electrical boards, etc. installed in the transportation system.

[0037] In the cooling apparatus 200, immersion cooling works on the principle of phase change, wherein the heat-generating component 202 to be cooled is wholly immersed in a fluid (coolant 206). The coolant 206 is formed of a material having low electrical conductivity to ensure that electrical insulation is sufficiently maintained, and prevents or rapidly quenches electric discharges to prevent short circuits, in case the heat-generating component 202 is an electric or electronic component of the transportation system. The cooling apparatus 200 includes a dual cycle arrangement with the coolant 206 flowing in the closed loop, i.e., by recirculation in the immersion container 204, and the cooling fluid 214 flowing in the open loop, i.e., by release or discharge in the vacuum environment 104 of the tube.

[0038] Heat is generated by the component 202 while performing its regular operation. This heat is dissipated into the coolant 206 surrounding the component 202, whose temperature increases until it reaches the saturation temperature. After that, the coolant 206 starts to undergo a phase transformation, which maintains its temperature at a near-constant value while the phase transformation is completed. The saturation temperature of the coolant 206 is carefully selected such that the temperature at saturation of the same maybe roughly 10 degrees less than an optimal operating temperature of the component 202. Due to the high heat capacity and constant temperature associated with the boiling of the coolant 206, it is ideally suited for high heat transfer rates and high heat flux applications. Once the phase change of the coolant 206 starts, the vapours generated due to their lower density start moving upward through the coolant 206. The vapours generated as a result of phase change of the coolant 206 are not condensed within the immersion container 204.

[0039] The cooling apparatus 200 uses a modular design, in which the vapours are removed from the immersion container 204, acting as an evaporator, and condensed outsidein a coiled vertical condenser 216. The evaporator (immersion container 204) and the condenser 216 are connected using pipes / tubes, such as but not limited to flexible pipes, which makes for placing the evaporator 204 and the condenser 216 in separate sections, and not taking up a single unit of space. Moreover, having the vapours of the coolant 206 flow through a coiled pathway of the condenser coil 208, or any other pathways which increase contact time thereof, instead of condensing against a flat surface like in conventional cooling devices, provides higher cooling rates because of principles of flow boiling and centrifugal effects associated with the condenser coil 208.

[0040] Also, a secondary fluid (cooling fluid 214) flows through the condenser 216 that takes up heat from the vapours of the coolant 206. The secondary fluid 214 may be water or any other refrigerant fluid, maintained at a low pressure such that it boils-off by accepting heat from the vapours of the dielectric coolant 206. The secondary fluid can be stored inside the pod of the transportation system, and once evaporated, is dispersed into the vacuum environment 104 of the tube. Thereafter, the fluid container 218 may be refilled with the fluid, whenever required. The cooling apparatus 200 is suited for low-pressure environments since the primary coolant (coolant 206) is completely inside a closed-loop unit without any physical interaction with the outside low-pressure environment 104 encountered in the tube of the transportation system. The secondary coolant (cooling fluid 214) works as evaporative cooling, where it is liberated into the vacuum environment 104 of the tube after phase transformation. For maximum efficiency of immersion cooling, a Heat Flux dissipated by the heat-generating component 202, such as LIM, maybe maintained within the Nucleate Boiling region, i.e., less than the Critical Heat Flux (CHF) of the coolant 206. The CHF of the coolant 206 of the 3M Novec™ category typically ranges between 15-20 W / cm2. The coolants 206 for which a value of the CHF (qCrit) is not available may be roughly approximated using Zuber’s correlation. The coolant 206 may be composed of Novec, EthylGlycol, ethanol, n-hexane, R12, or any coolant with high dielectric constant or boiling point in range of 20-100°C.

[0041] The observed heat fluxes from an LIM are expected to be in the range of 10-15 W / cm2, which is close to the CHF for most 3M Novec™ coolants. This poses a risk of dryout and cross-over to the film boiling regime. To compensate for this problem, the liquefied coolant 206 may be injected and sprayed at high pressures into the coolant 206 directed at a comer and teeth of the LIM (heat-generating component 202), where hot spots and dryouts have more probability of occurring. The sprays of the liquefied coolant 206 may beused to break any film formation in the hot spot regions, and efficiently prevent dry-outs. Thus, the cooling apparatus 200 may combine the principle of immersion cooling and evaporative cooling with spray cooling to make high heat transfer rates possible, in the case of passenger vehicle transport systems.

[0042] Referring now to Fig. 3, where a perspective view of the immersion container 204 is shown. The immersion container 204 acts as an evaporator of the cooling apparatus 200. The immersion container 204 may have a circular cross-section, rectangular crosssection, or any enclosure to match cooling requirement, and may be made of a metal, composites, plastics or glass. The diameter and length of the immersion container may be adjusted to be slightly more than the component 202, providing enough space for the heatgenerating component 202 to be fully immersed in the coolant 206 present in the immersion container 204. The immersion container 204 ensures integrity and prevents fluid leakages under high temperatures.

[0043] The immersion container 204 may include several outlet ports 302 located at a top portion through which vapours of the coolant 206 exits, and an inlet port 304 positioned on a side portion through which the spray nozzles 212 may supply the recirculated / condensed coolant 206 back into the immersion container 204 from the condenser 216. The input port 304 and the outlet ports 302 allow for efficient circulation of the coolant 206. The outlet ports 302 maybe strategically positioned to ensure the vapours of the dielectric coolant 206 to exit the immersion container 204, to efficiently reduce pressure build-up inside the immersion container 204.

[0044] Fig. 4 illustrates a test setup 400 of the cooling apparatus 200. To simulate the generation of heat by the heat-generating component 202 in the transportation system, a heating element 402 was placed inside the immersion container 204 filled with the coolant 206. The heating element 402 in the container was an electric heater of dimensions such that at its rated voltage, it generates a heat flux in the range of approximately 10 W / cm2, thereby simulating thermal loads from an LIM (component 202) in the case of a real- world source of heat in the transportation system. The heating element 402 was affixed to the immersion container 204 using metal flanges and silicon gaskets. Since the principles of pool boiling are only dependent on heat flux as long as the coolant 206 used is the same, the test setup 400 of the cooling apparatus 200 mimic thermal conditions in the real-world scenario.

[0045] The test setup 400 was provided with multiple outlet pipes 404 from the outlet ports 302 of the immersion container 204. The outlet pipes 404 were connected to the coiled condenser 216, using a set of valves. The primary fluid outlet end 208-2 of the coil condenser 208 was connected to the spray nozzles 212 via the dielectric coolant pump 210. This forms a closed loop, in which the dielectric coolant 206 operates. Initially, the evaporator (immersion container 204) is filled with sufficient dielectric coolant 206. The heating element 402 is connected to a power supply unit 306. When the heating element 402 is turned on, evaporation of the dielectric coolant 206 starts, and phase transformation of the coolant 206 in the form of vapours occurs. The vapours of the coolant 206 move up through the immersion container 204 and into the outlet pipes 404 through the ports 302 and further into the condenser 216, in which a secondary coolant (cooling fluid 214) having a lower temperature is flowing through annular space of the coiled condenser 216, that serves as a heat sink for the primary coolant (dielectric coolant 206) to dissipate its heat, and condense it into liquid form. The outlet pipes 404 may be joined using T-joints 308 to form a single inlet port at the primary fluid inlet end 208-1 of the condenser coil 208.

[0046] The coiled condenser 216 may have a coiled height of around 0.3m and an uncoiled length of approximately 2m. This design of the condenser 216 provides a longer path length and a larger surface area for the vapours of the coolant 206 flowing through the condenser 216 under a compact size arrangement. Also, centrifugal forces acting on the vapours as it moves down the spiral tubings of the condenser coil 208 cause liquid to stick to walls of the condenser 216 and the vapours comes to a core region thereof. This enhances heat transfer between the primary coolant 206 and the secondary coolant 214. The heat transfer between the primary coolant 206 and the secondary coolant 214 through the walls of the condenser 216 results in condensation of the vapours completely by the time it reaches bottom coils of the condenser coil 208.

[0047] The calculations for the path length of the coiled condenser 216, flow rate of secondary coolant 214, etc., were done using empirical correlations of Me Adams (modified for coiled condensers) for the case of single -phase flow of the secondary coolant 214. These calculations were verified in experiments to ensure the path length and flow rates were sufficient for complete condensing of the vapours of the primary coolant 206. The case of the coiled condenser 216 differs from the evaporator (immersion container 204) as the boiling occurring in the condenser 216 is convective flow boiling as opposed to pool boiling in the evaporator 204. It was observed that mass flow rate of the vapours coming into thecondenser 216 differs in the test setup 400 compared to the real-world scenario. Due to this, the flow rate of the secondary coolant 214 and the path of the condenser's length required also changes. It was also observed that the length of the coiled condenser 216 was higher for the actual case of 15kW heat transfer rate. To accommodate such an abnormally long condenser 216 is difficult. Moreover, the fluid container 218 required to store the secondary coolant 214 in the actual case was large. To compensate such abnormality, calculations were done to check feasibility of using two-phase secondary coolant flow (water at 30kPa). The results concluded usage of a small fluid container 218 and lesser path length for the vapours. It was observed that the test setup 400 was a reliable and effective technique for maintaining the thermal performance of devices and components under extremely high thermal load conditions. The design of the immersive container 204 featuring a continuous glass container eliminates risk of leakage, ensuring accurate and repeatable results. Also, the closed-loop unit of the secondary coolant 214 supports its use case in low-pressure environments of vacuum tube transportation systems, such as Hyperloop.

[0048] During experimentation of the test setup 400, 3M Novac™ was used as the primary coolant 206 and water was used as the secondary coolant 214. However, any suitable coolant with good dielectric properties and low electrical conductivity may be employed as the primary coolant 206. The primary coolant 206 is also required to be stable and non-corrosive in nature, and have a boiling point at latm pressure to be between 40- 90°C. Accordingly, the primary coolant 206 may be selected from the any of Novec 7100, Novec 649, ethylene glycol and ethanol, etc. Moreover, the requirement of the secondary coolant 214 is that it should have high latent heat of transformation between the pressures of 0.1-latm absolute pressure with saturation temperature lying between 30-100°C. The secondary coolant 214 is also required to be non-toxic when released into the environment, should be cost-effective as it is consumed over time.

[0049] The condenser 216 may be selected as a helical condenser made of glass. However, other types of condensers capable of releasing or collecting heat energy may also be used. The condenser 216 may be made from any thermally conductive material, and is required to be rigid to handle pressure differences. The condenser 216 should also be ductile to be produced with thin walls. The condenser 216 may be formed with a material having high corrosion resistance, such as metals like copper, aluminium and steel, plastics, composites, and the like, as it faces the primary and secondary coolants. Further, though helical coils 208 of the condenser 216 provides a counter-flow system capable of improvinglogarithmic mean temperature difference during the release or collection of heat energy, other types of heat exchangers working on different configuration and arrangements, such as cross-flow configuration, parallel flow configuration, fin type configuration, shell and tube configuration, concentric tubes, plate type configuration, and the likes, may be employed to form the condenser 216.

[0050] Spraying the liquefied primary coolant 206 on the heat-generating component 202 is an essential part of improving heat transfer efficiency thereof. The number of spray nozzles 212 used to spray the liquefied primary coolant 206 may be based on the size and shape of the heat-generating component 202 to allow uniform cooling of the same. The spray nozzles 212 may be arranged in rectangular patterns, circular patterns, polygonal patterns, hexagonal patterns or similar arrangements on the surface of the immersion container 204. Other forms of fluid delivery mean, such as sprinklers, dispensers, and the like, may be employed instead of the spray nozzles 212 to ensure uniform cooling of the heat-generating component 202 of the transportation system.

[0051] Figs. 5A and 5B illustrate plots depicting variation of temperature (°C) with respect to time (seconds) for immersion cooling of the heat-generating component 220. Computational fluid dynamics (CFD) simulations were carried out for the evaporator 204 using the Eulerian Two-Phase model in ANSYS FLUENT™, with appropriate turbulent models. The simulation was carried out using different coolants, namely, Novec 7100, Novec 649, water, ethylene glycol, and ethanol as the primary coolant 206. For condenser 216, experimental correlations were made. Results of the simulations show that the surface temperature of the heating element 402 mimicking the heat-generating component 202 of the transportation system 100 remains constant as long as there is sufficient primary coolant 206 inside the immersion container 204 to fully immerse the heating element 402. The results also indicate that the operating temperature of heating element 402 was around 5- 8°C higher than the saturation temperature of the primary coolant 206. The simulation plot of temperature versus time curve for immersion cooling of the heating element 402 with heat flux of 10W / cm2in the evaporator 204 with the primary coolant 206 selected as water is shown in Fig. 5A. The evaporator 204 used in the test setup 402 has a length of 220mm and a diameter of 70mm. In an implementation, the primary coolant 206 used was water whose saturation temperature is around 100°C at room temperature. It was observed that the surface temperature of the heating element 402 was maintained at 100- 105 °C for more than 2 minutes as compared to the surface temperature of the heating element 402 of 150-170°Cwithout any cooling. Variation of the surface temperature of the heating element 402 with respect to time is shown in Fig. 5B.

[0052] In another implementation, the primary coolant 206 used was Novec 7100, whose saturation temperature is 61 °C at room temperature. It was observed that a surface temperature of the heating element 402 was maintained close to the saturation temperature of the primary coolant 206, i.e., at 66-67°C for more than 2 minutes as compared to the surface temperature of the heating element 402 of 150-170°C without any cooling.

[0053] In view of the present disclosure, which describes the present invention, all changes, modifications, and, variations within the meaning and range of equivalency are considered within the scope of the invention. It is to be understood that the aspects and embodiment of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiment may be combined together to form a further embodiment of the disclosure.

Claims

CLAIMS:

1. A cooling apparatus (100) for a vacuum tube transportation system, comprising: an immersion container (204) filled with a coolant (206) and enclosing heatgenerating components (202) of the vacuum tube transportation system; a condenser coil (208) for cooling vapours of the coolant (206) generated by absorbing heat from the heat-generating components (202), wherein the vapours of the coolant (206) are cooled using a cooling fluid (214) pumped into a condenser (216) from a fluid container (218) by a pump (220); a coolant pump (210) for pumping cooled liquid back into the immersion container (204); and a plurality of spray nozzles (212) provided in the immersion container (204) for uniformly spreading the coolant (206) on the heat-generating components (202).

2. The cooling apparatus (100) as claimed in claim 1, wherein the cooling apparatus (200) operates using immersion cooling to disperse heat away from the heat-generating components (202).

3. The cooling apparatus (100) as claimed in claim 1, wherein the cooling apparatus (100) is located within the pod (102) or in a vacuum environment (104) inside the tube (106).

4. The cooling apparatus (100) as claimed in claim 1, wherein the condenser coil (208) includes a plurality of coiled sections made of a material having high thermal conductivity.

5. The cooling apparatus (100) as claimed in claim 1, further comprises a pressureregulating valve (222) for maintaining an optimal pressure inside the condenser (216) to ensure that a phase of the cooling fluid (214) transforms at a lower temperature.

6. The cooling apparatus (100) as claimed in claim 1, wherein the immersion container (204) and the condenser (216) are present as different sections connected together using pipes.

7. The cooling apparatus (100) as claimed in claim 1, wherein a liquefied form of the coolant (206) is sprayed at high pressures into the coolant (206) directed at a corners and teeth of the heat- generating component (202), for preventing film formation in hot spots regions and dry-outs.

8. The cooling apparatus (100) as claimed in claim 1, wherein the immersion container (204) includes one or more outlet ports (302) for releasing vapours of the coolant (206) and an inlet port (304) through which the plurality of spray nozzles (212) supply the coolant (206) back into the immersion container (204) from the condenser (216).

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