CN107782014B - Solar adsorption type refrigerating device and method for permafrost region roadbed engineering - Google Patents
Solar adsorption type refrigerating device and method for permafrost region roadbed engineering Download PDFInfo
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- CN107782014B CN107782014B CN201711215214.0A CN201711215214A CN107782014B CN 107782014 B CN107782014 B CN 107782014B CN 201711215214 A CN201711215214 A CN 201711215214A CN 107782014 B CN107782014 B CN 107782014B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B27/00—Machines, plants or systems, using particular sources of energy
- F25B27/002—Machines, plants or systems, using particular sources of energy using solar energy
- F25B27/007—Machines, plants or systems, using particular sources of energy using solar energy in sorption type systems
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
- F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- F25B15/00—Sorption machines, plants or systems, operating continuously, e.g. absorption type
- F25B15/02—Sorption machines, plants or systems, operating continuously, e.g. absorption type without inert gas
- F25B15/025—Liquid transfer means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A30/00—Adapting or protecting infrastructure or their operation
- Y02A30/27—Relating to heating, ventilation or air conditioning [HVAC] technologies
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/62—Absorption based systems
Abstract
The embodiment of the invention provides a solar adsorption refrigeration device and a method for permafrost region roadbed engineering. The device mainly comprises: stainless steel pipe, glass pipe, mechanical seal structure, and connection member; the stainless steel pipe and the glass pipe are nested inside and outside to form a vacuum sleeve structure, the mechanical sealing structure is arranged at the top of the vacuum sleeve structure, the part of the vacuum sleeve structure buried in the frozen soil foundation is an evaporation refrigeration section, the part above the ground surface is divided into a heat collection/adsorption section and a condensation section, and the heat collection/adsorption section and the evaporation refrigeration section are respectively filled with an adsorbent and a refrigerant; the heat collection/adsorption section automatically converts solar energy into heat energy to drive adsorption refrigeration cycle, and the refrigerant desorption process and the adsorption process are performed repeatedly by utilizing the difference of day and night solar intensity. The invention can utilize solar energy to perform automatic adsorption refrigeration, realize real-time and efficient protection of frozen soil, and effectively prevent permafrost degradation and roadbed engineering heat injury.
Description
Technical Field
The invention relates to the technical field of frozen soil engineering, in particular to a solar adsorption refrigeration device and method for roadbed engineering in a permafrost region.
Background
The permafrost in China is mainly distributed in Qinghai-Tibet plateau, north of great and great Khingan of northeast, tianshan of west and Altaishan, and occupies about 22.4% of the territorial area. When road engineering construction is carried out in the area, the hydrothermal balance state of the original permafrost is broken due to the change of the conditions of heat exchange between the original natural earth surface and the atmosphere, the hydrothermal transport of the seasonal melting layer and the like, so that the depth of the natural seasonal melting layer under the roadbed is changed, and various bad permafrost phenomena are caused. When solid ice in permafrost is liquefied, the permafrost is solidified, softened and changed, the bearing capacity and stability of the foundation are weakened, and the long-term service performance of the road is affected. Therefore, when constructing roads and railways in permafrost areas, the thermal stability of the roadbed is considered first, and the thermal stability of the roadbed is directly related to the temperature field of the underlying stratum of the roadbed. Under certain engineering conditions, the temperature is a key factor causing roadbed diseases and is the only controllable factor under the condition that all control measures are effective but diseases still exist. Therefore, for roadbed engineering in permafrost areas, it is extremely necessary to maintain and restore the original temperature state of permafrost along the line by adopting active cooling measures.
In the prior art, a method of actively cooling a roadbed is generally adopted to pass through a permafrost region, and the permafrost region comprises a block/broken stone air cooling structure, a ventilation pipe, a heat pipe and the like. Wherein, the block/broken stone structure and the ventilation pipe are based on the principle of air convection heat exchange, and the formation cold reserves are increased through the low-temperature atmosphere in the cold season. The heat pipe is based on the gas-liquid two-phase circulation heat exchange principle, is the measure with the highest cooling efficiency at present, and has obvious cooling effect on frozen soil.
The limitation of the above measures is that the block/macadam structure, ventilation tube, regulate the heat transfer effect mainly by geometric parameters, optimizing is relatively difficult. Even the heat pipe with highest cooling efficiency still belongs to a passive heat transfer element, and the phase change heat exchange circulation is driven by means of the ground air temperature difference. Because of the reversibility of the heat flow direction, the heat pipe can only protect frozen soil by pre-storing or supplementing cold energy in cold seasons, and the heat pipe must stop working after entering warm seasons, so that the season matching property is poor. With the influence of global warming on the climate environment of the permafrost region, the conventional roadbed cooling measures cannot completely meet the requirement of roadbed thermal stability protection of the permafrost region. Therefore, it is necessary to develop a novel active refrigeration device for a permafrost region roadbed so as to improve the current situations of low cooling efficiency and poor season matching of the permafrost region roadbed thermal stability protection measures.
Compared with the indirect passive heat transfer working mechanism that the conventional permafrost region roadbed cooling measures are used for counteracting summer heat erosion through cold accumulation in winter, the most direct measure for achieving permafrost protection is to increase a heat output process in warm seasons, namely, heat is extracted from a permafrost layer and transferred to the atmosphere. In this additional process, heat needs to be transferred from the low temperature medium (roadbed) to the high temperature medium (atmosphere), which falls into the refrigeration category. In the field of refrigeration technology, refrigerants and refrigerant cycles are critical to refrigeration devices. For long-term refrigeration requirements of long-distance roadbed engineering, the device development direction should be defined as: a small-sized free-standing refrigeration device with a refrigerant circulation system. The refrigerating device requires: (1) the refrigerant can independently run, and the refrigerant circulation process does not need to consume electricity or has smaller electricity consumption; (2) the layout mode is flexible, the shape is preferably a column shape, and the foundation is convenient to install; (3) the volume is small, the occupied foundation space is limited, and the influence on the bearing capacity and other performances of the foundation is avoided; (4) the number of moving parts is small, the operation is stable and reliable, and the service life is long; (5) the refrigerant can run below 0 ℃ to effectively freeze the underground water.
At present, the vapor mechanical compression refrigeration is the most mature refrigeration technology, the refrigeration cycle is driven by high-grade electric energy, the technology is mature, the equipment is compact, and the vapor mechanical compression refrigeration device can be manufactured into large, medium and small sizes so as to adapt to the needs of different occasions, has wide refrigeration temperature range, has higher circulation efficiency in the common refrigeration temperature range, and is most widely applied to the fields of building environment adjustment and industrial application. However, since the distance of line engineering is long, the infrastructure along the line is relatively backward, and particularly, the power supply is difficult, and a compression refrigeration system using grid-connected power supply cannot be adopted in a limited area field like building environment adjustment, industrial application, and manual freezing construction methods of projects such as mines, tunnels, subways, and the like.
Fortunately, there is a well developed class of refrigeration technologies in addition to vapor compression refrigeration technologies, namely thermally driven refrigeration technologies. The heat driven refrigeration is a refrigeration cycle process taking heat energy as driving force, and the cycle modes comprise a steam jet type, a liquid absorption type and a solid adsorption type, so that low-grade heat energy such as solar energy, geothermal energy, waste heat and the like can be directly utilized as driving sources. Among them, solar energy is the most advantageous renewable energy source. Permafrost in China is mainly distributed on northeast, western mountain and Qinghai-Tibet plateau, and the regions have abundant solar energy resources. In particular, the Qinghai-Tibet plateau has clean and thin atmosphere and the number of sunshine hours per year 2800-3200 h/a, and the solar radiation intensity is up to 2558kWh/m 2 A, the solar energy utilization condition is superior after the solar energy utilization device is inferior to the saharan desert, the second place in the world. Meanwhile, for a permafrost foundation, the urgent refrigeration requirement in summer is exactly matched with strong solar radiation, and with the increase of solar radiation energy, a heat-driven refrigeration system driven by a solar light heat source can generate more cold energy.
Therefore, the refrigerating technology based on solar photo-thermal driving has wide application prospect aiming at the thermal stability maintenance requirement of the frozen soil covered foundation under the roadbed engineering of the permafrost region.
Disclosure of Invention
The embodiment of the invention provides a solar adsorption refrigeration device and a method for permafrost region roadbed engineering, which are used for manufacturing low temperature below 0 ℃ without power consumption and realizing maintenance of thermal stability of permafrost region roadbed engineering.
In order to achieve the above purpose, the present invention adopts the following technical scheme.
The invention provides a solar adsorption refrigeration device for permafrost roadbed engineering, which is characterized by mainly comprising: the stainless steel tube and the glass tube are internally and externally nested to form a vacuum sleeve structure, and the stainless steel tube and the glass tube are hermetically sleeved by the glass-metal sealing joint; the spring bracket is arranged between the glass tube and the stainless steel tube for position fixing, the stainless steel tube is fixed on the central axis of the device, and the mechanical sealing structure is arranged at the top of the vacuum sleeve structure;
The vacuum sleeve structure is characterized in that the part buried in the frozen soil foundation is an evaporation refrigeration section, the part above the ground surface is divided into a heat collection/adsorption section and a condensation section, the heat collection/adsorption section and the evaporation refrigeration section are respectively filled with an adsorbent and a refrigerant, the heat collection/adsorption section automatically converts solar energy into heat energy to drive adsorption refrigeration circulation, and the refrigerant desorption process and the adsorption process are performed repeatedly by utilizing the difference of day and night solar intensity.
Preferably, the apparatus further comprises: solar selective absorbing coating, refrigerant vapor channel, stainless steel mesh, filler, and connection member;
the connecting part of the device comprises: screw flange, bolt, flange gasket and flange blind plate.
Preferably, the apparatus further comprises:
the bottom end of the evaporation refrigeration section, the top end of the heat collection/adsorption section and the bottom end of the mechanical sealing structure are respectively welded with the threaded flange;
the threaded flange at the bottom end of the evaporation cooling section is connected with the flange blind plate through the bolt and the flange gasket;
the threaded flange at the bottom end of the mechanical sealing structure is connected with the threaded flange at the top end of the heat collection/adsorption section through the flange gasket and the bolts.
Preferably, the heat collection/adsorption section is a stainless steel pipe with the vacuum sleeve structure arranged above the ground surface and the inside thereof, and the heat collection/adsorption section has heat collection and adsorption functions;
the pipe wall of the stainless steel pipe is drilled with a round hole type refrigerant vapor channel;
sputtering a layer of solar energy selective absorption coating on the outer pipe wall of the stainless steel pipe, and directly heating the adsorbent on the adsorption bed in the stainless steel pipe after solar energy photo-thermal conversion is carried out by the solar energy selective absorption coating in the daytime under good sunlight conditions;
the part of the stainless steel pipe above the ground surface is an adsorption bed, the adsorption bed is filled with the adsorbent, and the stainless steel wire mesh is used for sealing the adsorbent so as to prevent the adsorbent from leaking.
Preferably, the condensing section is an interlayer space between the stainless steel pipe and the glass pipe, wherein the vacuum sleeve structure is arranged on the part above the ground surface;
the glass-metal sealing joint is used for relieving the longitudinal expansion deformation difference of the stainless steel pipe and the glass pipe due to different temperatures;
and a spring bracket is arranged between the glass tube and the stainless steel tube and used for fixing the relative positions of the stainless steel tube and the glass tube, fixing the stainless steel tube on a central axis and preventing the high-temperature solar selective absorption coating on the outer wall of the stainless steel tube from being damaged due to touching the glass tube.
Preferably, the mechanical seal structure comprises: the device comprises a threaded flange, a stainless steel pipe joint, a pressure relief valve and a one-way valve; welding a threaded flange on one side of the stainless steel pipe joint, connecting a pressure release valve on the other side of the stainless steel pipe joint, and welding a one-way valve on the middle part of the stainless steel pipe joint to form the mechanical sealing structure;
the check valve can be opened only in one direction and can not be opened under the action of reverse pressure, and is used for vacuumizing, refrigerant filling and sealing of the system;
the pressure in the device is controlled in a safe magnitude range by the pressure release valve, so that the glass tube is prevented from being damaged by too high methanol vapor pressure during desorption.
Preferably, the adsorbent and the refrigerant are used as an adsorption type refrigeration working medium pair of the device, the adsorbent adopts active carbon, and the refrigerant adopts methanol;
the methanol belongs to a low saturated vapor pressure refrigerant, a higher vacuum degree is set in a vacuum sleeve structure before the activated carbon initially adsorbs the methanol, and the refrigeration temperature of the methanol reaches below 0 ℃ and is used for protecting permafrost;
the activated carbon is columnar particles with the diameter of 3-6 mm, the particle gaps of the activated carbon are migration channels of the methanol vapor, and the activated carbon is enabled to adsorb the gaseous methanol through the one-way valve by utilizing the vacuum degree in the vacuum sleeve structure under the low-temperature environment of the adsorption bed until reaching an adsorption equilibrium state; the adsorption capacity of the activated carbon to the methanol is weakened after the activated carbon is heated in the daytime, the gaseous methanol is desorbed, the gaseous methanol is liquefied into liquid methanol after releasing heat through the glass tube of the condensation section, and the liquid methanol flows to the evaporation refrigeration section for storage under the action of dead weight; the adsorption capacity of the activated carbon to the gaseous methanol is enhanced after the activated carbon is cooled at night, and the liquid methanol in the evaporation refrigeration section is gasified after continuously absorbing heat and is adsorbed to the activated carbon to generate a refrigeration effect, so that a refrigeration cycle is completed.
Preferably, the glass tube adopts a single-layer high-boron silicon 3.3 glass tube body, the solar light transmittance of the glass tube is more than or equal to 95.5%, the vacuum degree is less than or equal to 10 < -3 > mbar, and the glass tube is used for improving the photo-thermal conversion efficiency of the heat collection/adsorption section and preventing the oxidation of the solar selective absorption coating;
and the glass tube is used as the outer wall of the condensing section, and in the desorption stage, the gaseous methanol is condensed into the liquid methanol after directly carrying out heat exchange with the external atmosphere through the glass tube.
Another aspect of the present invention provides a solar adsorption refrigeration method for roadbed engineering in permafrost areas, applied to the device of any one of claims 1 to 8, comprising:
step 1: in the low-temperature environment of the adsorption bed, utilizing the vacuum degree in the vacuum sleeve structure to enable the adsorbent to adsorb the gaseous refrigerant through the one-way valve until reaching an adsorption equilibrium state;
step 2: after the temperature is raised in the daytime, the solar selective absorption coating collects solar energy and performs photo-thermal conversion to obtain heat energy, the adsorption bed is heated by using the heat energy, the adsorbent desorbs the gaseous refrigerant, the gaseous refrigerant is liquefied after releasing heat through the glass tube of the condensation section, and the liquid refrigerant flows to the evaporation refrigeration section for storage under the action of dead weight;
Step 3: after the temperature is reduced at night, the adsorption capacity of the adsorbent to the refrigerant is enhanced, and the liquid refrigerant in the evaporation refrigeration section continuously absorbs heat and is gasified and adsorbed to the adsorbent to generate refrigeration effect;
and (3) circulating the steps 2 and 3 to realize an adsorption refrigeration cycle process driven by solar light and heat and actively refrigerating permafrost.
Preferably, the method further comprises:
the solar adsorption type refrigerating device for permafrost region roadbed engineering is applied, the device is arranged in the roadbed engineering with permafrost heat damage after being subjected to non-excavation type mechanical pore forming, and the installation and application steps comprise:
(a) Determining the degradation depth range of a frozen soil layer covered under the roadbed for many years;
(b) Measuring thermophysical parameters and a target temperature range of the permafrost stratum, and calculating summer cooling load;
(c) Designing parameters such as drilling depth, diameter, hole spacing and the like;
(d) Drilling construction, and installing an adsorption type refrigeration pipe;
(e) And debugging and starting operation of the device.
According to the technical scheme provided by the embodiment of the invention, the embodiment of the invention integrally adopts an inner nested double-tube structure and an outer nested double-tube structure of a stainless steel tube and a glass tube, and combines a solar vacuum heat collection technology, a solid adsorption refrigeration technology and a heat and mass transfer strengthening technology to autonomously provide a photo-thermal heat source, drive and complete a desorption process of refrigeration, and the whole device does not need external power supply and forms an independent refrigeration unit; the alcohol refrigerant can be used for running below 0 ℃, refrigerating by evaporating the refrigerant, freezing unfrozen water in the permafrost stratum within a certain range around the evaporating refrigerating section, preventing the permafrost from thawing and sinking, and inhibiting the segregation and frost heaving of the permafrost. The invention has no consumption of electric energy and mechanical energy, and the operation is stable and reliable; the device has compact structure, small volume, convenient integrated and integrated installation, does not need a matched power supply circuit, and can be used for preventing permafrost degradation and hot thawing diseases of a covered foundation under long-distance line engineering in a permafrost region.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the description of the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a schematic structural diagram of a solar adsorption refrigeration device facing to roadbed engineering in permafrost regions according to an embodiment of the present invention;
FIG. 2 is a schematic view of section A-A of FIG. 1;
FIG. 3 is a schematic view of section B-B of FIG. 1;
FIG. 4 is a schematic view of section C-C of FIG. 1;
fig. 5 is a schematic diagram of a mechanical seal structure of a solar adsorption refrigeration device facing to roadbed engineering in permafrost regions according to an embodiment of the present invention;
fig. 6 is a schematic cross-sectional view of a solar adsorption refrigeration device facing permafrost region roadbed engineering according to an embodiment of the present invention;
Fig. 7 is a step flowchart of a solar adsorption refrigeration method for permafrost region roadbed engineering provided by an embodiment of the present invention;
the device comprises a 1-mechanical sealing structure, a 2-heat collecting/adsorbing section, a 3-condensing section, a 4-evaporating refrigerating section, a 5-pressure relief valve, a 6-stainless steel pipe joint, a 7-one-way valve, an 8-threaded flange, a 9-bolt, a 10-flange gasket, an 11-glass-metal sealing joint, a 12-glass pipe, a 13-solar selective absorption coating, a 14-spring bracket, a 15-refrigerant vapor passage, 16-methanol, a 17-flange blind plate, 18-bolt pore passages, 19-stainless steel wire mesh, 20-stainless steel pipes, a 21-adsorption bed, 22-active carbon and 23-filling.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless expressly stated otherwise, as understood by those skilled in the art. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the purpose of facilitating an understanding of the embodiments of the invention, reference will now be made to the drawings of several specific embodiments illustrated in the drawings and in no way should be taken to limit the embodiments of the invention.
Example 1
The embodiment of the invention provides a solar adsorption refrigeration device and a method for permafrost region roadbed engineering, which are characterized in that a stainless steel pipe and a vacuum sleeve structure nested inside and outside a glass pipe are designed, solar heat energy is collected to drive a refrigerant to circulate, and activated carbon-methanol is used as a refrigeration working medium pair for adsorption refrigeration, so that maintenance of thermal stability of permafrost region roadbed engineering is realized.
1. An aspect of the embodiment of the invention provides a solar adsorption refrigeration device for permafrost region roadbed engineering.
The structural schematic diagram of a solar adsorption refrigeration device facing roadbed engineering in permafrost areas is shown in fig. 1-6, and the device mainly comprises: stainless steel tube 20, glass tube 12, mechanical seal structure 1, glass-metal seal joint 11, spring bracket 14, and threaded flange 8 and bolt 9; the stainless steel pipe 20 and the glass pipe 12 are nested and sealed inside and outside to form a vacuum sleeve structure, the vacuum sleeve structure is buried in the frozen soil foundation and extends upwards to the ground surface, the part of the vacuum sleeve structure buried in the frozen soil foundation is an evaporation refrigeration section 4, and the part of the vacuum sleeve structure above the ground surface is divided into a heat collection/adsorption section 2 and a condensation section 3.
The specific structure and working principle of each component of the device are as follows:
(1) Heat collection/adsorption section
The heat collection/adsorption section is a stainless steel pipe with a vacuum sleeve structure arranged above the ground surface and the inside of the stainless steel pipe.
Round-hole refrigerant vapor channels 15 are drilled on the wall of the stainless steel pipe at certain intervals, and a layer of solar selective absorption coating 13 is sputtered on the outer pipe wall of the stainless steel pipe by adopting a magnetron sputtering method; the portion of the stainless steel pipe above the ground surface serves as an adsorption bed 21 of the adsorption refrigeration cycle, and the adsorption bed 13 is filled with activated carbon 22 and sealed with a stainless steel wire mesh 19 to prevent leakage of the activated carbon 22. The top end of the heat collection/adsorption section is welded with a threaded flange 8 for fixing, and the threaded flange 8 at the top end of the heat collection/adsorption section is in sealing butt joint with a mechanical sealing structure through bolts 9 and flange gaskets 10.
The heat collection/adsorption section has the functions of solar heat collection and refrigerant adsorption and desorption, the adsorption bed is formed by filling a stainless steel tube with cylindrical activated carbon, the adsorption and desorption performance is excellent, the outer wall of the stainless steel tube is sputtered with a solar selective absorption coating for absorbing solar radiation and performing photo-thermal conversion, and the circular hole type refrigerant vapor channel 15 attached to the wall of the heat collection/adsorption section has good heat and mass transfer performance.
The activated carbon 22 is columnar particles with the diameter of 3-6 mm, and the particle gaps of the activated carbon 22 are migration channels of the methanol 16 vapor.
(2) Condensation section
The condensing section is an interlayer space between the stainless steel pipe and the glass pipe, the vacuum sleeve structure of which is arranged above the ground surface.
The stainless steel pipe and the glass pipe are in sealing sleeve joint by the glass-metal sealing joint 11, the thermal expansion coefficients of the stainless steel pipe and the glass pipe are different, and the longitudinal expansion deformation difference of the stainless steel pipe and the glass pipe caused by different temperatures can be relieved by adopting the glass-metal sealing joint 11. A spring bracket 14 is arranged between the glass tube and the stainless steel tube and used for fixing the relative positions of the stainless steel tube and the glass tube, and the stainless steel tube is fixed on the central axis to prevent the high-temperature solar selective absorption coating 13 on the outer wall of the stainless steel tube from touching the glass tube to damage.
The glass tube is the outer wall of the condensing section, adopts a single-layer high-boron silicon 3.3 glass tube body, has solar light transmittance of more than or equal to 95.5 percent (AR), and can keep higher vacuum degree (vacuum degree is less than or equal to 10) -3 mbar), in the desorption phase, the gaseous methanol 16 can be condensed and liquefied after heat exchange with the external atmosphere directly through a glass tube, and the glass tube is beneficial to improving the photo-thermal conversion efficiency of the heat collection/adsorption section and preventing the oxidation of the solar selective absorption coating 13.
(3) Evaporation refrigeration section
The evaporation cooling section is a part of the vacuum sleeve junction buried in the permafrost foundation, and the inside of the stainless steel pipe of the evaporation cooling section is filled with a columnar filler 23.
Respectively welding a threaded flange 8 at the tail end of the evaporation cooling section and the tail end of the stainless steel pipe, wherein the centers of the stainless steel pipe and the threaded flange 8 are on the same straight line; and the flange blind plate 17 is in sealing butt joint with the threaded flange 8 at the tail end of the evaporation and refrigeration section through the bolts 9 and the flange gaskets 10.
The device takes active carbon-methanol as a refrigeration working medium pair, wherein the active carbon is taken as an adsorbent, the methanol is taken as a refrigerant, the refrigeration temperature of the methanol can reach below 0 ℃, the methanol belongs to a low saturated vapor pressure refrigerant, and the vacuum degree in a maintaining system is the key of refrigeration performance. The evaporation refrigeration section is used as a liquid storage section of the refrigerant methanol, and refrigeration of frozen soil is realized by utilizing the evaporation heat absorption effect of the refrigerant.
(4) Mechanical seal structure
The mechanical seal structure includes: the device comprises a threaded flange 8, a stainless steel pipe joint 6, a pressure relief valve 5 and a one-way valve 7; one side of the stainless steel pipe joint 6 is welded with a threaded flange 8, the other side is connected with a pressure relief valve 5, and the middle part of the stainless steel pipe joint is welded with a one-way valve 7, so that a mechanical sealing structure is formed. The mechanical sealing structure is in sealing butt joint with a threaded flange 8 at the top end of the heat collection/adsorption section 2 through bolts 9 and flange gaskets 10.
The check valve 7 in the mechanical sealing structure can be opened only in one direction, and can not be opened due to the action of reverse pressure, so that the vacuum degree and the tightness of the inner space of the refrigeration pipe are ensured, and the check valve is used for vacuumizing, refrigerant filling and sealing of a system.
The pressure in the system can be controlled within an allowable pressure range by the pressure release valve 5 in the mechanical sealing structure, so that the damage to the glass tube caused by the too high pressure of methanol vapor in desorption is prevented.
It will be appreciated by those skilled in the art that the shape of the vacuum sleeve structure formed by nested sealing of the stainless steel tube and the glass tube is merely exemplary, and that other shapes of the vacuum sleeve structure may be used in the present invention, and are intended to be within the scope of the present invention, and are incorporated herein by reference.
The components of the device form two working systems: solar photo-thermal collection system and adsorption refrigeration system. The solar photo-thermal collecting system consists of a glass tube and a stainless steel tube, wherein the outer wall of the stainless steel tube is coated with a solar selective coating for absorbing solar radiation, and the absorptivity is more than or equal to 95%. In daytime, the converted solar heat energy can directly heat the activated carbon on the adsorption bed in the stainless steel pipe through the stainless steel pipe, so that heat loss is reduced, and the solar energy utilization rate of the refrigerating system is improved. The adsorption refrigeration system consists of a heat collection/adsorption section, an evaporation refrigeration section and an active carbon-methanol working medium pair. The absorption refrigeration principle is as follows: the adsorption capacity of the activated carbon to the methanol changes along with the different temperatures and pressures, and the higher the temperature is, the weaker the adsorption capacity of the activated carbon to the methanol is, so that the intermittent gas-liquid two-phase circulation refrigeration process of the thermal desorption and the cold adsorption of the methanol is realized through the periodical change of the day-night temperature of the adsorption bed.
According to the specific content and connection relation of the components of the device, the steps for manufacturing the device comprise: the device processes and fills the active carbon-methanol working medium pair.
The device processing steps comprise:
(a) Round hole type refrigerant vapor passages are drilled at certain intervals in the stainless steel pipe with the determined design length.
(b) And sputtering a solar selective absorption coating on the outer pipe wall of the stainless steel pipe above the ground surface by adopting a magnetron sputtering method.
(c) And a spring bracket is arranged between the glass tube and the stainless steel tube, and meanwhile, a glass-metal sealing joint is adopted to carry out sealing and sleeving on the glass tube and the stainless steel tube.
(d) And the tail end of the evaporation cooling section and the tail end of the stainless steel pipe are respectively welded with a threaded flange, and the centers of the stainless steel pipe and the threaded flange are ensured to be on the same straight line.
(e) And sealing and butting the flange blind plate with a threaded flange at the tail end of the evaporation refrigeration section through bolts and flange gaskets.
(f) And a threaded flange is welded on one side of the stainless steel pipe joint, the other side of the stainless steel pipe joint is connected with a pressure release valve, and a one-way valve is welded in the middle of the stainless steel pipe joint to form a mechanical sealing structure.
The step of filling the active carbon-methanol working medium comprises the following steps:
(a) And filling columnar activated carbon, wherein the part below the surface of the inner part of the stainless steel pipe is filled with a filler, the part above the surface of the inner part of the stainless steel pipe is an adsorption bed, and the adsorption bed is filled with the activated carbon and then is packaged by a stainless steel wire net so as to prevent the poured activated carbon from being scattered.
(b) The mechanical sealing structure is in sealing butt joint with a threaded flange at the top end of the heat collection/adsorption section through bolts and flange gaskets;
(c) Evacuating the interior of the vacuum sleeve structure, and vacuumizing the interior of the vacuum sleeve structure to be in a vacuum state through a one-way valve in a high-temperature environment, wherein the vacuum degree is less than or equal to 10 -3 Pa；
(d) The adsorption of the methanol, the vapor generated by the adsorption of the methanol by the active carbon is realized by utilizing the vacuum degree of the heat collection/adsorption section through a one-way valve under the low-temperature environment;
(e) And after the activated carbon-methanol working pair reaches an equilibrium adsorption state, sealing the vacuum sleeve structure through the one-way valve.
Wherein: the glass tube adopts an air cooling mode in the desorption process.
2. Another aspect of the embodiments of the present invention provides a solar adsorption refrigeration method for permafrost roadbed engineering, where the steps of the method are as shown in fig. 7, and the method specifically includes the following steps:
step S710: and in the low-temperature environment of the adsorption bed, the adsorbent adsorbs the gaseous refrigerant through the one-way valve by utilizing the vacuum degree in the vacuum sleeve structure until the adsorption equilibrium state is reached.
Step S720: after the temperature rises in the daytime, the solar selective absorption coating collects solar energy to carry out photo-thermal conversion to obtain heat energy, the adsorption bed is heated by the heat energy, the adsorbent desorbs gaseous refrigerant, the gaseous refrigerant is liquefied after releasing heat through the condensation section, and the liquid refrigerant flows to the evaporation refrigeration section for storage under the action of dead weight.
During the daytime, the solar selective absorption coating collects solar energy to perform photo-thermal conversion to obtain heat energy.
Starting from the morning sun rise, the solar selective absorption coating on the stainless steel tube surface absorbs solar radiation and converts solar energy into thermal energy by photothermal conversion.
The heat energy obtained by converting the solar selective absorption coating is utilized to heat the adsorption bed, the temperature of the activated carbon in the adsorption bed is increased, and when the temperature of the activated carbon is increased to the desorption temperature of the methanol, the methanol is desorbed from the activated carbon to be methanol vapor. And when the pressure of the methanol in the vacuum sleeve structure gradually rises and reaches the saturation pressure corresponding to the condensation temperature, the methanol releases condensation heat on the inner wall of the glass tube and condenses into a liquid state, and the liquid state is stored in the evaporation refrigeration section under the action of gravity. When the pressure of the methanol vapor is too high and the glass tube can be damaged, the pressure release valve is opened to release the pressure, so that the pressure in the vacuum sleeve structure is controlled within a safe range. During the day, the process of desorbing methanol from activated carbon to methanol vapor continues until the evening solar radiation fails to provide the heat required for methanol desorption.
Step S730: after the temperature is lowered at night, the adsorption capacity of the adsorbent to the refrigerant is enhanced, and the liquid refrigerant in the evaporation refrigeration section continuously absorbs heat and is gasified and adsorbed to the adsorbent to generate refrigeration effect.
After the sunlight disappears from night, the temperature of the adsorption bed starts to decrease, and when the temperature of the activated carbon decreases to the adsorption temperature, the activated carbon starts to adsorb the methanol vapor.
The pressure of the methanol in the vacuum sleeve structure gradually decreases, and when the pressure reaches the saturated vapor pressure corresponding to the liquid methanol in the evaporation refrigeration section, the liquid methanol starts to gasify and absorb the latent heat of gasification so as to supplement the absorbed methanol vapor.
At night, the activated carbon continuously adsorbs the methanol vapor so that the pressure of the methanol vapor is always lower than the corresponding saturated vapor pressure of the evaporation section, so that the methanol is continuously gasified and absorbs the heat of the frozen soil layer around the evaporation refrigeration section until the activated carbon is saturated in adsorption.
Step S740: and (3) circulating the steps S720-S730 to realize an adsorption refrigeration cycle process driven by solar light and heat and actively refrigerating permafrost.
The device is applied to roadbed engineering in permafrost regions, and is arranged on roadbed engineering with permafrost heat damage after non-excavation mechanical pore forming, and the specific application steps are as follows:
(a) Determining the degradation depth range of a permafrost layer covering a plurality of years of frozen soil layers under a roadbed in a permafrost region;
(b) Measuring thermophysical parameters and a target temperature range of the permafrost stratum, and calculating summer cooling load;
(c) Designing parameters such as drilling depth, diameter, hole spacing and the like of the non-excavation mechanical hole forming;
(d) Drilling construction of non-excavation type mechanical pore forming is carried out, and the solar adsorption type refrigeration pipe is installed;
(e) And debugging and starting the device.
Example two
The embodiment provides a solar adsorption refrigeration device for roadbed engineering in permafrost areas, which has a specific implementation structure shown in figures 1-6 and comprises the following specific components:
the device mainly comprises an evaporation refrigeration section 4 buried in a permafrost foundation, a mechanical sealing structure 1 arranged above the ground surface, a heat collection/adsorption section 2 and a condensation section 3. The heat collection/adsorption section 2 is composed of stainless steel tubes 20, refrigerant vapor channels 15, and solar selective absorption coating 13. The condensing section 3 is formed by sleeving a glass tube 12 and a stainless steel tube 20 through a glass-metal sealing joint 11. The mechanical seal structure 1 is composed of a pressure relief valve 5 and a one-way valve 7.
The manufacturing of the solar adsorption type refrigeration tube comprises device processing and filling of active carbon-methanol working medium pairs. The device processing steps comprise:
(a) Round hole type methanol refrigerant vapor channels 15 are drilled on the stainless steel tube 20 with the designed length at certain intervals;
(b) Sputtering a solar selective absorbing coating 13 on the outer surface of the stainless steel pipe 20 above the ground surface by adopting a magnetron sputtering method;
(c) A spring bracket 14 is arranged between the glass tube 12 and the stainless steel tube 20, and meanwhile, a glass-metal sealing joint 11 is adopted to carry out sealing sleeve joint on the glass tube 12 and the stainless steel tube 20;
(d) Respectively welding a threaded flange 8 at the tail end of the evaporation cooling section 1 and the tail end of the stainless steel pipe 20, wherein the centers of the stainless steel pipe 20 and the threaded flange 8 are on the same straight line;
(e) The flange blind plate 17 is in sealing butt joint with the threaded flange 8 at the tail end of the evaporation cooling section 1 through the bolts 9 and the flange gaskets 10;
(f) And a threaded flange 8 is welded on one side of the stainless steel pipe joint 6, one side is connected with a pressure relief valve 5, and a one-way valve 7 is welded in the middle, so that the mechanical sealing structure 1 is obtained.
The step of filling the active carbon-methanol working medium comprises the following steps:
(a) Filling columnar activated carbon 22, filling the part below the surface of the inner part of the stainless steel pipe 20 with a filler 23, forming an adsorption bed 21 above the surface of the inner part of the stainless steel pipe 20, and packaging the adsorption bed 21 with a stainless steel wire net 19 after the adsorption bed 21 is filled with the activated carbon 22 to prevent the injected activated carbon 22 from being scattered;
(b) The mechanical sealing structure 1 is in sealing butt joint with a threaded flange 8 at the tail end of the heat collection/adsorption section 2 through bolts 9 and flange gaskets 10;
(c) Evacuating the adsorption type refrigeration tube, and vacuumizing the inside of the adsorption type refrigeration tube through the one-way valve 7 in a high-temperature environment, wherein the vacuum degree is less than or equal to 10 -3 Pa；
(d) Adsorption of methanol 16, wherein the activated carbon 22 adsorbs vapor generated by the methanol 16 by utilizing the vacuum degree of a refrigerating pipe through the one-way valve 7 in a low-temperature environment;
(e) After the active carbon-methanol working pair reaches an equilibrium adsorption state, the sealing of the refrigeration pipe is completed through the one-way valve 7.
Wherein: the glass tube 12 adopts an air cooling mode in the desorption process.
The working principle of the solar adsorption type refrigeration tube is as follows:
the adsorbent activated carbon 22 is sensitive to the change of the adsorption capacity of the refrigerant methanol 16 according to the temperature and the pressure, and the higher the temperature is, the weaker the adsorption capacity of the activated carbon 22 is, so intermittent refrigeration is realized by utilizing the cyclic adsorption and desorption processes of the diurnal temperature difference conversion.
During the daytime, when the solar radiation is sufficient, the temperature of the heat collection/adsorption section 2 is increased, so that the refrigerant methanol 16 adsorbed by the activated carbon 22 is desorbed and gasified. The pressure in the stainless steel tube 20 rises, the desorbed methanol 16 vapor enters the condensing section 3, and when the saturated pressure corresponding to the condensing temperature is reached, the methanol 16 vapor releases heat into the air through the glass tube 12 and condenses into a liquid state. The liquid methanol 16 flows back to the evaporation refrigeration section 4 under the action of dead weight, and the process is continued until the evening, namely the desorption process. At night or when solar radiation is insufficient, the environment temperature is reduced, the temperature is reduced after the heat collection/adsorption section 2 is naturally cooled, the activated carbon 22 starts to adsorb the vapor of the methanol 16, the pressure in the refrigerating tube is reduced, the liquid methanol 16 is continuously gasified, the heat of the frozen soil stratum is absorbed to generate a refrigerating effect, and the process is continued until the morning of the next day, namely the adsorption process. Thus, the refrigeration cycle is completed through round-the-clock cycle reciprocation, and a continuous refrigeration effect is generated.
The solar adsorption type refrigerating pipe is arranged in roadbed engineering with permafrost heat injury after being formed by non-excavation type mechanical pore-forming, and the application steps comprise:
(a) Determining the degradation depth range of a frozen soil layer covered under the roadbed for many years;
(b) Measuring thermophysical parameters and a target temperature range of the permafrost stratum, and calculating summer cooling load;
(c) Designing parameters such as drilling depth, diameter, hole spacing and the like;
(d) Drilling construction, and installing an adsorption type refrigeration pipe;
(e) And debugging and starting operation of the device.
Compared with the prior art, the invention has the following advantages:
(1) The invention adopts low-grade solar heat energy to drive the refrigerant to circulate, and has good season matching property. The stronger the solar radiation, the larger the photo-thermal heat collection amount, and the higher the refrigerating efficiency of the device. Meanwhile, the more serious the permafrost heat injury is, namely the urgent refrigeration requirement of the roadbed is exactly matched with the solar radiation required by solar refrigeration, and the sunshine peak period is consistent with the roadbed refrigeration load.
(2) The invention is integrally of an inner nested double-tube structure and an outer nested double-tube structure of a stainless steel tube and a glass tube, combines a solar vacuum heat collection technology, a solid adsorption refrigeration technology and a heat and mass transfer strengthening technology, and autonomously provides a photo-thermal heat source to drive and complete the desorption process of refrigeration. In the desorption stage, the liquid refrigerant formed by condensation returns to the evaporation refrigeration section under the action of dead weight, the refrigerant circulation can be completed without a circulating pump, and the whole device does not need external power supply and forms an independent refrigeration unit.
(3) The invention has novel layout, the stainless steel pipe has the functions of heat collection and adsorption bed, the heat collection temperature of the stainless steel heat collection pipe is high, the structural strength is high, and the invention is suitable for roadbed vibration environment. The metal heat collecting pipe and the glass pipe are nested inside and outside to manufacture a closed vacuum environment. The glass tube is also beneficial to increasing the transmittance of sunlight, and meanwhile, the contact area with air is large, and the condensation heat exchange efficiency is high.
(4) The invention adopts alcohol refrigerant, namely methanol, and can operate below 0 ℃. By utilizing the physical property that the refrigerant changes along with the change of pressure and temperature, the refrigerant is refrigerated by evaporating, and unfrozen water in the permafrost stratum in a certain range around the evaporating refrigeration section is frozen. On one hand, the method can prevent permafrost from thawing and sinking, and increase the mechanical strength of stratum; on the other hand, the continuous negative temperature freezing reduces the driving force of moisture migration to the freezing zone, thereby inhibiting the segregation and frost heaving of the frozen soil.
(5) The invention has no mechanical moving parts, thus no electric energy and mechanical energy are consumed, and the operation is more stable and reliable. The device has compact structure, small volume, small occupied area, convenient integrated and integrated installation, no need of matched power supply lines, unattended operation and capability of preventing and treating permafrost degradation and hot thawing diseases of a foundation covered under long-distance line engineering in permafrost areas.
In summary, in the embodiment of the invention, by adopting the vacuum double-tube structure with the stainless steel tube and the glass tube nested inside and outside, solar energy is automatically collected in the heat collection/adsorption section and converted into heat energy to drive the adsorption refrigeration cycle, and the difference of day and night solar radiation intensity is utilized to realize the reciprocating operation of the desorption process and the adsorption process of the methanol refrigerant; the opening and sealing of the system are controlled by a one-way valve of a mechanical sealing structure, and the working pressure of the system is controlled by a pressure relief valve; active carbon and methanol are adopted as a refrigerating working medium pair, and the refrigerating temperature can reach below 0 ℃; in summer, the greater the solar radiation intensity is, the higher the working efficiency of the device is, and the device is consistent with the roadbed cold load in a permafrost region and has good season matching performance. The invention can fully utilize the abundant solar energy resources in the permafrost region of China, and is combined with the solar photo-thermal technology and the heat-driven adsorption refrigeration technology to form an independent refrigeration unit; the device has compact structure, small volume, convenient integrated and integrated installation, no need of matched power supply lines, unattended operation, capability of fully meeting the requirement of thermal stability maintenance of the covered soil foundation under the roadbed engineering in the permafrost region and preventing permafrost degradation and thermal thawing diseases of the covered soil foundation under the long-distance line engineering in the permafrost region.
Those of ordinary skill in the art will appreciate that: the drawing is a schematic diagram of one embodiment and the modules or flows in the drawing are not necessarily required to practice the invention.
In this specification, each embodiment is described in a progressive manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for apparatus or system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, with reference to the description of method embodiments in part. The apparatus and system embodiments described above are merely illustrative, wherein the elements illustrated as separate elements may or may not be physically separate, and the elements shown as elements may or may not be physical elements, may be located in one place, or may be distributed over a plurality of network elements. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art will understand and implement the present invention without undue burden.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (4)
1. Solar adsorption type refrigerating device for permafrost region roadbed engineering, which is characterized by mainly comprising: the stainless steel tube and the glass tube are internally and externally nested to form a vacuum sleeve structure, and the stainless steel tube and the glass tube are hermetically sleeved by the glass-metal sealing joint; the spring bracket is arranged between the glass tube and the stainless steel tube for position fixing, the stainless steel tube is fixed on the central axis of the device, and the mechanical sealing structure is arranged at the top of the vacuum sleeve structure;
the vacuum sleeve structure is embedded in the frozen soil foundation and comprises an evaporation refrigeration section, the part above the ground surface is divided into a heat collection/adsorption section and a condensation section, the heat collection/adsorption section and the evaporation refrigeration section are respectively filled with an adsorbent and a refrigerant, the heat collection/adsorption section automatically converts solar energy into heat energy to drive adsorption refrigeration circulation, and the refrigerant desorption process and the adsorption process are performed repeatedly by utilizing the difference of day and night solar intensity;
The apparatus further comprises:
the bottom end of the evaporation refrigeration section, the top end of the heat collection/adsorption section and the bottom end of the mechanical sealing structure are respectively welded with a threaded flange;
the threaded flange at the bottom end of the evaporation refrigeration section is connected with the flange blind plate through bolts and flange gaskets;
the threaded flange at the bottom end of the mechanical sealing structure is connected with the threaded flange at the top end of the heat collection/adsorption section through the flange gasket and the bolt;
the heat collection/adsorption section is a stainless steel pipe with the vacuum sleeve structure arranged at the part above the ground surface and the inside of the stainless steel pipe, and has heat collection and adsorption functions;
round-hole refrigerant vapor channels are drilled on the pipe wall of the stainless steel pipe at certain intervals;
sputtering a layer of solar selective absorption coating on the outer pipe wall of the stainless steel pipe, and directly heating the adsorbent on the adsorbent bed inside the stainless steel pipe after solar photo-thermal conversion is carried out on the solar selective absorption coating in the daytime under good sunlight conditions;
the part of the stainless steel pipe above the ground surface is an adsorption bed, the adsorption bed is filled with the adsorbent, and the adsorbent is sealed by a stainless steel wire mesh for preventing leakage of the adsorbent;
The condensing section is an interlayer space between the stainless steel pipe and the glass pipe, wherein the vacuum sleeve structure is arranged at the part above the ground surface;
the glass-metal sealing joint is used for relieving the longitudinal expansion deformation difference of the stainless steel pipe and the glass pipe due to different temperatures;
a spring bracket is arranged between the glass tube and the stainless steel tube and used for fixing the relative positions of the stainless steel tube and the glass tube, fixing the stainless steel tube on a central axis and preventing the high-temperature solar selective absorption coating on the outer wall of the stainless steel tube from being damaged due to touching the glass tube;
the mechanical seal structure includes: the device comprises a threaded flange, a stainless steel pipe joint, a pressure relief valve and a one-way valve; welding a threaded flange on one side of the stainless steel pipe joint, connecting a pressure release valve on the other side of the stainless steel pipe joint, and welding a one-way valve on the middle part of the stainless steel pipe joint to form the mechanical sealing structure;
the check valve can be opened only in one direction and can not be opened under the action of reverse pressure, and is used for vacuumizing, refrigerant filling and sealing of the system;
the pressure release valve is used for controlling the pressure in the device within a safe magnitude range and preventing the glass tube from being damaged due to the fact that the methanol vapor pressure is too high during desorption;
The adsorbent and the refrigerant are used as an adsorption type refrigeration working medium pair of the device, the adsorbent adopts active carbon, and the refrigerant adopts methanol;
the methanol belongs to a low saturated vapor pressure refrigerant, a higher vacuum degree is set in a vacuum sleeve structure before the active carbon initially adsorbs the methanol, and the evaporation refrigeration temperature of the methanol reaches below 0 ℃ and is used for protecting permafrost;
the activated carbon is columnar particles with the diameter of 3-6 mm, particle gaps of the activated carbon are migration channels of the methanol vapor, and the activated carbon adsorbs the gaseous methanol through the one-way valve under the low-temperature environment of the adsorption bed by utilizing the vacuum degree in the vacuum sleeve structure until the adsorption equilibrium state is reached; the adsorption capacity of the activated carbon to the methanol is weakened after the activated carbon is heated in the daytime, the gaseous methanol is desorbed, the gaseous methanol is liquefied into liquid methanol after releasing heat through the glass tube of the condensation section, and the liquid methanol flows to the evaporation refrigeration section for storage under the action of dead weight; the adsorption capacity of the activated carbon to the gaseous methanol is enhanced after the activated carbon is cooled at night, and the liquid methanol in the evaporation refrigeration section is gasified after continuously absorbing heat and is adsorbed to the activated carbon to generate a refrigeration effect, so that a refrigeration cycle is completed between an adsorption refrigeration working substance pair consisting of the activated carbon and the methanol;
The glass tube adopts a single-layer high-boron silicon 3.3 glass tube body, the solar light transmittance of the glass tube is more than or equal to 95.5 percent, and the vacuum degree is less than or equal to 10 -3 mbar, the glass tube is used for improving the photo-thermal conversion efficiency of the heat collection/adsorption section and preventing the oxidation of the solar selective absorption coating;
and the glass tube is used as the outer wall of the condensing section, and in the desorption stage, the gaseous methanol is condensed into the liquid methanol after directly carrying out heat exchange with the external atmosphere through the glass tube.
2. The solar adsorption refrigeration device for permafrost region roadbed engineering according to claim 1, wherein the device further comprises: solar selective absorbing coating, refrigerant vapor channel, stainless steel mesh, filler, and connection member;
the connecting part of the device comprises: screw flange, bolt, flange gasket and flange blind plate.
3. A solar adsorption refrigeration method for roadbed engineering in permafrost areas, which is applied to the device of claim 1 or 2, and is characterized by comprising the following steps:
step 1: in the low-temperature environment of the adsorption bed, utilizing the vacuum degree in the vacuum sleeve structure to enable the adsorbent to adsorb the gaseous refrigerant through the one-way valve until reaching an adsorption equilibrium state;
Step 2: after the temperature is raised in the daytime, the solar selective absorption coating collects solar energy and performs photo-thermal conversion to obtain heat energy, the adsorption bed is heated by using the heat energy, the adsorbent desorbs the gaseous refrigerant, the gaseous refrigerant is liquefied after releasing heat through the glass tube of the condensation section, and the liquid refrigerant flows to the evaporation refrigeration section for storage under the action of dead weight;
step 3: after the temperature is reduced at night, the adsorption capacity of the adsorbent to the refrigerant is enhanced, and the liquid refrigerant in the evaporation refrigeration section continuously absorbs heat and is gasified and adsorbed to the adsorbent to generate refrigeration effect;
and (3) circulating the steps 2 and 3 to realize an adsorption refrigeration cycle process driven by solar light and heat and actively refrigerating permafrost.
4. The solar adsorption refrigeration method for permafrost region roadbed engineering according to claim 3, wherein the method further comprises:
the solar adsorption type refrigerating device for permafrost region roadbed engineering is applied, the device is arranged in the roadbed engineering with permafrost heat damage after being subjected to non-excavation type mechanical pore forming, and the installation and application steps comprise:
(a) Determining the degradation depth range of a frozen soil layer covered under the roadbed for many years;
(b) Measuring thermophysical parameters and a target temperature range of the permafrost stratum, and calculating summer cooling load;
(c) Designing drilling depth, diameter and hole spacing parameters;
(d) Drilling construction, and installing an adsorption type refrigeration pipe;
(e) And debugging and starting operation of the device.
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| CN108487227A (en) * | 2018-05-17 | 2018-09-04 | 俞祁浩 | A kind of displacement of center of gravity formula air door automatic control system |
| CN109506379A (en) * | 2018-12-29 | 2019-03-22 | 北方工业大学 | Adsorption type solar energy light-gathering automatic temperature-adjusting radiation system for hot areas, roof and wall |
| CN109853518B (en) * | 2019-01-22 | 2023-12-15 | 石家庄铁道大学 | Solar jet type refrigerating device suitable for frozen soil area and frozen soil protection method |
| CN109577126B (en) * | 2019-01-22 | 2023-10-20 | 石家庄铁道大学 | Heat pipe type solar thermal device for frost heaving of roadbed and frost heaving prevention method of roadbed |
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