WO2018067025A1

WO2018067025A1 - Moisture separator and air cycle refrigeration system containing such moisture separator

Info

Publication number: WO2018067025A1
Application number: PCT/RU2016/000661
Authority: WO
Inventors: Vladislav Ruslanovich TSIPLAKOV
Original assignee: Deta Engineering Llc; Mirai Intex Sagl
Priority date: 2016-10-04
Filing date: 2016-10-04
Publication date: 2018-04-12

Abstract

This invention relates to the area of refrigeration and serves the purpose of air dehumidification in closed air cycle refrigeration systems. The character of the claimed moisture separator comprises the separation of moisture in a closed casing wherein air moves from the bottom upwards. Air goes through a labyrinth formed by metal plates with area less than the area of the casing base. The plates are fastened to the opposing casing walls in an alternating pattern and are disposed at an angle to the perpendicular line of the casing. Thus, the plates form gaps in a fishbone pattern, and air passing through this labyrinth undergoes compression and expansion multiple times. The plates are interlaid with metal mesh that serves multiple purposes: moisture separator filter and means of snow/ice build-up aiding. The key feature of the claimed moisture separator is the mesh size changing from higher values (at the inlet, at the bottom of the casing) to lower values (at the outlet, at the top of the casing). The mesh is disposed between the plates in such a way that air cannot move beyond it in any way. A combination of various principles of moisture separation ensures a reliable and non-stop operation of the air cycle refrigeration unit within a wide temperature range (from +5 to -80°C) without excessive design complexities and with streamlined maintenance.

Description

Moisture Separator and Air Cycle Refrigeration System Containing Such

Moisture Separator

This invention relates to refrigeration devices and may be used to build refrigerators, f eezers, rapid chilling systems, A/C and/or indoor temperature control systems and other systems based on air cycle refrigeration.

An air cycle refrigeration system (ACRS) is a type of refrigeration system where air is used as a working medium. Such systems belong to closed cycle systems. Air enters a compressor and undergoes adiabatic compression with a rise in temperature. Then, compressed air is cooled by coolers (mostly heat exchangers using ambient air and/or cold return flow) and sent to an expander where it undergoes adiabatic expansion with a drop in temperature. Cold air is sent to the object to be cooled, interacts with it and goes back to the compressor.

ACRS's have the following distinctive features:

1) . Reduced energy usage. The energy of compressed air is used to rotate the expander; if the expander and the compressor use the same shaft, the energy used to rotate the compressor is partially compensated.

2) . Safety for the environment, ease of maintenance. Unlike toxic refrigerants currently in use (e. g. widely-used aliphatic saturated fluorine-containing hydrocarbons), air used as a refrigerant is not toxic. It means ACRS's are environmentally clean refrigeration systems.

3) . Safety. The refrigerant used in the system is not explosive or inflammable, unlike other refrigerants in use (e. g. ammonia, propane, butanes and other hydrocarbons). The operating pressure does not exceed 1 bar (g) making ACRS's safe for use in refrigeration systems.

Similar ACRS's are well described in prior art.

Thus, prior art describes a space vehicle freezer system that uses outer space (patent US 5943877 A, IPC B64G1/22, B64G1/66, F25B 11/02 published on 31/08/1999). Said patent describes a freezer system that can operate as a closed cycle ACRS, with a compressor and an expander mounted on a single shaft and compressed air cooled using a radiating device disposed in outer space. Another prior art product is a counter- flow plate fin type heat exchanger and ACRS for containers (patent application JP 2010025438 A, IPC F28D9/02, F25B9/00 published on 04/02/2010). Said document discloses, among other things, an ACRS where a compressor and an expander are mounted on a single shaft and compressed air is cooled in a heat exchanger using a flow of return air from a cold room. The above arrangement may be seen as optimal and has been used as a prototype of the declared ACRS.

However, using air as refrigerant also results in certain difficulties due to the build-up of ice in the area of contact with the cooled object, in the ACRS components and air ducts. It is caused by the presence of water in the air and its precipitation at the drop of temperature. Ice build-up impairs ACRS's efficiency right down to the system's breakdown and leads to frequent maintenance. It should be noted that, firstly, removal of ice from air ducts and components of a closed cycle ACRS is a sophisticated problem and, secondly, it requires system shutdown. Therefore, ACRS's turn out to have limited maximum running time.

One of the solutions may be using special moisture removal devices — moisture separators (MS)— within the ACRS cycle. Currently, the following MS types are widely used:

1) . Absorbers (e. g. see patent RU 2200283 CI, IPC F25B37/00, B01D53/04 published on 10/03/2003) that use a special sorbent.

2) . Dehumidifiers (e. g. see patent RU 2360186 CI, IPC F243/14 published on 27/06/2009) that dehumidify air via cooling.

However, MS of these types have multiple drawbacks, and their operation presents a number of difficulties.

Thus, in absorbers, a low temperature of the air flow (-60/-80°C) results in a low level of sorbent absorptiveness leading to a frequent replacement of columns/absorbers for regeneration purposes, right down to the loss of sorbent function. Moreover, presence of water in its liquid and solid phases in the air creates a snow/ice crust at the inlet of the dehumidifier's working volume; this crust builds up fast and reduces the clear opening of the device, right down to the shutoff of the entire opening. Furthermore, the level of absorptiveness in absorbers ^ is much lower for air at atmospheric pressure than the compressed air.

However, designing a dehumidifier operating in this temperature range

(temperature of the air flow 60/-80 °C) is a challenging engineering task (it would require a cascade refrigerator with multiple refrigerants) that goes against the principles of the air refrigeration cycle, i. e. the exclusive use of air as refrigerant at a relatively low operating pressure (max 1 bar (g) in the power section of the cycle). Moreover, atmospheric-pressure refrigerant dehumidifier requires an extended surface of heat transfer.

Prior art includes continuously regenerating disk absorbers; however, using these absorbers is related to a significant rise in temperature during operation and a high level of energy consumption for the regeneration system

Known prior art includes an oil mist removing apparatus (patent application JP 2004066162 A, IPC B01D45/06 published on 04/03/2004). Said apparatus represents a labyrinth-form MS wherein moisture is separated by repeated constriction expansion of the passage. Water (or oil) accumulates on the plates that form the labyrinth and runs down. However, this apparatus will not operate if a change of phase takes place (if water or another substance freezes) as this change will shut off the entire clear opening.

Known prior art includes a method of moisture removal from refrigerant (patent GB 2380246 A, IPC B01D53/26, F25B43/00 published on 02/04/2003). In this solution, air passes through a housing filled with a metal mesh. Moisture is deposited on the mesh and runs down into the housing. In this case a drop in temperature below 0°C creates the same problem as with absorption dehumidifiers, i. e. build-up of ice crust at the inlet of the mesh unit resulting in the rise of flow resistance of the mesh unit, right down to the shutoff of the entire clear opening.

Known prior art includes a gas- liquid separation device for an engine (patent application US 064642 Al, IPC B01D46/00 published on 12/03/2009). Said device represents a number of plates forming a labyrinth wherein liquid precipitates. It should be noted that this device cannot be used for the removal of moisture from cold air and is only mentioned here due to its design similarity to the scope of the present invention. The design of the device does not provide for the separation of the vapor phase - it only ensures separation of fine and dripping liquid and gas. The design is not intended for the transition of a substance into another physical phase (ice).

The purpose of the present invention is the development and construction of a fundamentally new, universal MS that would allow for a cyclical process of water (liquid, fine moisture and steam) separation in a temperature range from +5 °C (moisture drop coalescence and separation) to -80 °C (moisture freeze-out on the device surfaces and filtration of solid-phase moisture). Important requirements included simple design, low energy consumption for device regeneration, no need for additional refrigerants.

It was complemented by the task of developing an ACRS that employs said MS.

The technical result of the invention provides for design simplification relative to dehumidifiers, increased efficiency and running time relative to absorbers. It also ensures high flexibility of the invention for any operating mode and reduces energy consumption. The technical result of the invented ACRS provides for design simplification and ensuring non-stop operation in wide range of operating temperatures.

The claimed invention includes a moisture separator comprising a vertically oriented casing with an air inlet at the bottom and an air outlet at the top that contains the following:

Multiple plates with at least two butt ends, with one end fastened to a vertical wall of the casing in such a way that even-numbered plates are fastened to one of the vertically oriented walls of the casing while uneven-numbered plates are fastened to the opposing vertically oriented wall of the casing; additionally, there is some clearance between each plate and the vertically oriented casing wall opposing the wall which the plate is fastened to; the plates have no contact with one another,

Mesh dragged through from the bottom plate to the top plate in such a way that it goes round the free butt ends of the plates;

The plates are placed at an angle to the vertically oriented casing walls so that <- the free butt end of each plate is lower than the butt end fastened to the wall.

The distinction of the claimed moisture separator is also the rectangular parallelepiped form of the casing.

The distinction of the claimed moisture separator is also the mesh size changing from higher values at the bottom of the moisture separator to lower values at the top.

The distinction of the claimed moisture separator is also the variable mesh width.

The distinction of the claimed moisture separator is also the opening for moisture removal at the bottom of the casing.

The distinction of the claimed moisture separator is also the funnel-like opening for moisture removal.

The claimed invention also includes an air cycle refrigeration system (ACRS) comprising a compressor and an expander mounted on motor shaft, a heat exchanger and a freezer connected via air ducts wherein the above moisture separator is used.

The distinction of said ACRS is also the mounting of the moisture separator at the output of the cold room.

The character of the claimed MS comprises the separation of moisture in a closed casing wherein air moves from the bottom upwards. Air goes through a labyrinth formed by metal plates with area less than the area of the casing base. The plates are fastened to the opposing casing walls in an alternating pattern and are disposed at an angle to the perpendicular line of the casing. Thus, the plates form gaps in a fishbone pattern, and air passing through this labyrinth undergoes compression and expansion multiple times. The plates are interlaid with metal mesh that serves multiple purposes: moisture separator filter and means of snow/ice build-up intensification. The key feature of the claimed MS is the mesh size changing from higher values (at the inlet, at the bottom of the casing) to lower values (at the outlet, at the top of the casing). The mesh is disposed between the ribs in such a way that air cannot move beyond it in any way. Therefore, the claimed MS applies multiple principles of moisture separation:

1) . Use of gravity effect in a vertically oriented labyrinth.

2) . Repeated constriction/expansion of the passage.

3) . Use of moisture separator filter made of mesh with variable width.

4) . Extended surface of ice build-up along the passage of the air flow.

This combination of multiple principles leads to an effect that is unique for this type of device: capability of operation within a huge temperature range, from +5 °C to -80°C. Thus, at relatively high temperature condensation on the lower surface of the ribs is the most efficient while at low temperature moisture is mostly separated by freeze -out on the rib surface and filtration of solid particles by the mesh. The vertical orientation of MS provides for an easy moisture removal: condensed moisture runs down the ribs due to their angular position and is removed via an opening at the bottom of the casing. The vertical orientation of the design also makes heat-up and dehumidification of MS easy and non-energy intense. Thus, when heat-up originates at the top, provided that ice build-up mostly occurs at the bottom, it ensures a higher rate of melt water drainage not requiring extra heat-up of other surfaces and removal of moisture from the discharge of the moisture separator. In this case energy consumption is significantly lower than in MS with other designs. Maintenance of MS is also streamlined. The design of the moisture separator helps arrange heat-up from the bottom to melt water without impairing the key properties of the device. The claimed design is also simple to manufacture and reliable in operation.

The character of the claimed ACRS comprises the addition of the claimed MS to the known ACRS design (see the prototype) between the cold room (cooled object) and the heat exchanger, at a section of return air reverse movement air duct It ensures non-stop operation of ACRS in a wide range of operating temperatures without excessive complexities and increased energy consumption.

The above attributes, features and advantages of the present invention as well as tiie used methods will be further clarified in the following description of the methods and forms of invention embodiments with references to drawing views wherein: Fig. 1 shows the preferable design of the claimed ACRS; Fig. 2 shows a layout view of the claimed MS; Fig. 3 shows a 3D layout view of the claimed MS.

The claimed ACRS comprises (Fig. 1) cold room 101 , compressor and expander 102, the first heat exchanger 103, MS 104 and the second heat exchanger 105. Cold room 101 is not necessarily a chamber. Item 101 may represent a cooled object. Thus, the cold room may be replaced by a heat exchanger with an external system for cooling a an external object. Cold room (or cooled object) 101 is cooled via duct 106 coming from the expander. The return air leaves room 101 via duct 107. Compressor and expander 102 comprises a motor 108 that has compressor 109 and expander 110 mounted on its shaft. The first heat exchanger 103 is a heat exchanger using countercurrent gas flows (e. g. as described in the ACRS prototype). It ensures heat exchange between a flow of hot air coming from the compressor and a flow of return air from the cold room moving via duct 107. The second heat exchanger 105 is an extra and is used for heat exchange between compressed hot air coming from compressor 109 and the ambient environment. To improve heat exchange with ambient environment, heat exchanger 105 may be equipped with fan 111. MS 104 to be described below in more detail is mounted on duct 107 between room 101 and the first heat exchanger 103. Arrows on Fig. 1 denote direction of air flow in the air duct.

The claimed MS (Fig. 2) represents a vertically oriented casing 201. In the preferred embodiment, the casing is rectangular, however, as an expert would understand from the description below, other casing shapes are also possible (e. g. cylinder). The shape of the casing is not a fundamental concern relative to the achievement of the claimed technical result. The casing comprises an inlet opening for moist air 202 and an outlet opening for dehumidified air 203. The openings provide for an air -tight connections of the inlet and the outlet air ducts. The inside of the casing comprises multiple plates 204. The plates form am air duct with constrained and expanded sections. In the preferred embodiment, if casing 201 is rectangular, plates 204 are disposed on two opposing walls of casing 201 in an alternating pattern. The area of plates 204 is a little less than the area of the casing base. Therefore, the opening of the formed air duct expands at the ends of the plates and contracts abruptly close to the opposing wall of casing 201. Plates 204 are disposed at a downward angle to allow condensed water to run down by the action of gravitation. Mesh 205 is disposed between Ihe plates acting as a filter and contributing to moisture freeze-out. The design of the mesh provides for its size to change from higher values at the MS inlet to lower values at the MS outlet. Parameters of the mesh may vary depending on the specific purposes and tasks at hand and the expected scope of MS application. In the preferred embodiment, the separated water drains through funnel-like opening 206. Opening 206 is disposed at the bottom of casing 201. Item 207 outlines the direction of the heat flow during MS heat-up. A heater may be used for MS heat-up (omitted for clarity).

In the preferred embodiment, all MS components are made of metal. MS must preferably be air-tight. Both various seals/pastes and rubber gaskets may be used for sealing purposes at the manufacturing stage. The number of plates inside MS and its dimensions depend on the purposes and tasks at hand and must be calculated with due regard to the expected scope of application for a specific MS.

Fig. 3 represents a 3D image of MS wherein the components are labeled with the relevant numbers. This 3D image contributes to a better understanding of the character of the present invention.

Even though the present invention is illustrated and described in detail by means of its preferred methods and embodiments, it is not limited to the cited sample uses. Experts who possess the required qualification and experience in this area may come up with alternative designs without breaching the scope of protection of the claimed invention.

Claims

1. Moisture separator comprising a vertically oriented casing with an air inlet at the bottom and an air outlet at the top that contains the following:

The plates are placed at an angle to the vertically oriented casing walls so that the free butt end of each plate is lower than the butt end fastened to the wall.

2. Moisture separator according to claim 1 wherein the casing is a rectangular parallelepiped.

3. Moisture separator according to claim 1 wherein the mesh size changes from higher values at the bottom of the moisture separator to lower values at the top.

4. Moisture separator according to claim 1 wherein the opening for moisture removal is disposed at the bottom of the casing.

5. Moisture separator according to claim 5 wherein the opening for moisture removal has a form of a funnel.

6. Air cycle refrigeration system comprising a compressor and an expander mounted on motor shaft, a heat exchangers and a cold room connected via air ducts wherein the above moisture separator according to claims 1-5 is used.

7. Air cycle refrigeration system according to claim 6 wherein the moisture separator is installed at the outlet of the cold room.