CN116918602A - Greenhouse adopting phase-change material - Google Patents
Greenhouse adopting phase-change material Download PDFInfo
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- CN116918602A CN116918602A CN202210380765.7A CN202210380765A CN116918602A CN 116918602 A CN116918602 A CN 116918602A CN 202210380765 A CN202210380765 A CN 202210380765A CN 116918602 A CN116918602 A CN 116918602A
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- polyethylene glycol
- change material
- phase change
- greenhouse
- heat
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- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
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- 150000007513 acids Chemical class 0.000 claims description 4
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Classifications
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
- A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
- A01G9/14—Greenhouses
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
- A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
- A01G9/24—Devices or systems for heating, ventilating, regulating temperature, illuminating, or watering, in greenhouses, forcing-frames, or the like
-
- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01G—HORTICULTURE; CULTIVATION OF VEGETABLES, FLOWERS, RICE, FRUIT, VINES, HOPS OR SEAWEED; FORESTRY; WATERING
- A01G9/00—Cultivation in receptacles, forcing-frames or greenhouses; Edging for beds, lawn or the like
- A01G9/24—Devices or systems for heating, ventilating, regulating temperature, illuminating, or watering, in greenhouses, forcing-frames, or the like
- A01G9/246—Air-conditioning systems
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
- C09K5/02—Materials undergoing a change of physical state when used
- C09K5/06—Materials undergoing a change of physical state when used the change of state being from liquid to solid or vice versa
- C09K5/063—Materials absorbing or liberating heat during crystallisation; Heat storage materials
-
- 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
- Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
- Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture
- Y02A40/25—Greenhouse technology, e.g. cooling systems therefor
Abstract
The invention discloses a greenhouse adopting a phase-change material. The greenhouse provided by the invention comprises: the inner cavity of the heat preservation wall is filled with composite phase change materials, wherein the composite phase change materials comprise phase change materials and heat conduction reinforcing materials, and the phase change temperature of the composite phase change materials is between 5 and 35 ℃. The greenhouse disclosed by the invention is simple in structure, reasonable in arrangement, low in manufacturing cost, energy-saving, environment-friendly and wide in application range.
Description
Technical Field
The invention relates to the technical field of greenhouses, in particular to a greenhouse adopting phase-change materials.
Background
The planting greenhouse industry makes historic contributions for solving the problems of low-season vegetable supply, increasing income of farmers, saving energy sources, promoting adjustment of agricultural industry structures, driving development of related industries, setting employment, avoiding environmental pollution caused by greenhouse effect, improving living standard of urban and rural residents, stabilizing society and the like which are puzzled in northern China in winter for a long time.
At present, the planting greenhouse mainly comprises a surrounding wall body, a rear roof and a front roof, wherein the front roof is all lighting surfaces of the planting greenhouse, the front roof only covers plastic films for lighting in day lighting period, and when outdoor illumination is weakened, the plastic films are covered by movable heat preservation covers in time so as to strengthen heat preservation of the planting greenhouse. However, in the north in winter, the temperature difference between day and night is large, the temperature at night is low, plant growth is not facilitated, and freezing is likely to occur, so that some planting greenhouses are heated by adopting a stove, the temperature of the planting greenhouses is ensured, but the environment is polluted, and energy is wasted.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a greenhouse adopting phase-change materials.
In order to achieve the above object, in a first aspect, the present invention provides a greenhouse using a phase change material, comprising:
the inner cavity of the heat preservation wall is filled with composite phase change materials, wherein the composite phase change materials comprise phase change materials and heat conduction reinforcing materials, and the phase change temperature of the composite phase change materials is between 5 and 35 ℃.
Preferably, the thermal conductivity enhancing material comprises ceramic particles and/or graphite, preferably at least one selected from the group consisting of expanded graphite, thermally exfoliated graphene, mechanically exfoliated graphene, liquid phase exfoliated graphene, high temperature carbonized graphene, oxidized graphene, reduced oxidized graphene and graphite powder, more preferably from the group consisting of graphite powder,
preferably, the heat conductive reinforcing material further comprises steel wool.
In a second aspect, the present invention provides a method for manufacturing a greenhouse using a phase change material according to the first aspect, wherein the steps for manufacturing a heat-insulating wall include:
step 1, constructing the side surface and the bottom surface of a heat-insulating wall by utilizing at least one metal plate and a corresponding wall main body;
step 2, injecting a composite phase change material;
and 3, packaging the top surface of the heat preservation wall.
The greenhouse adopting the phase-change material has the beneficial effects that:
(1) The composite phase change material is injected into the inner cavity of the heat preservation wall, and when the temperature of the heat preservation wall is higher than the phase change temperature of the composite phase change material, the composite phase change material stores heat. When the temperature of the heat preservation wall is lower than the phase change temperature of the composite phase change material, the composite phase change material releases heat, so that the temperature in the shed can be effectively maintained;
(2) According to the invention, graphite and steel wool are further added into the composite phase-change material, so that the thermal stability and the heat conduction capacity of the composite phase-change material can be improved, and the greenhouse can be suitable for different regional environments;
(3) The greenhouse disclosed by the invention is simple in structure, reasonable in arrangement, low in manufacturing cost, energy-saving, environment-friendly and wide in application range.
Drawings
FIG. 1 is a graph showing the change in crystallization temperature of polyethylene glycol 600 in examples 1, 3, examples 5 to 7 and comparative example 1 according to the present invention;
FIG. 2 is a graph showing the temperature change of the composite phase change materials of examples 3 to 4 and examples 8 to 9 according to the present invention under irradiation of sunlight at different times;
fig. 3 is a graph showing the temperature change at the same time of the different mass steel wool of the composite phase change materials according to examples 1, 4 and 10 of the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present invention.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.
In a first aspect, the present invention provides a greenhouse employing a phase change material, comprising: the inner cavity of the heat preservation wall is filled with composite phase change materials, wherein the composite phase change materials comprise phase change materials and heat conduction reinforcing materials, and the phase change temperature of the composite phase change materials is between 5 and 35 ℃.
It should be noted that the greenhouse of the present invention further includes materials required for the conventional greenhouse such as a shed frame, a shed film, a shed cover, etc., and the present invention is not limited thereto.
Wherein the phase change material is used as a medium for latent heat storage, and a solid phase and a liquid phase are transformed in a certain temperature range, and in this process, the phase change material absorbs a large amount of heat, has a high latent heat storage capacity, is capable of storing more energy than a sensible heat material (water, oil, etc.) having the same volume, and can maintain a temperature almost constant when the solid phase and the liquid phase are transformed, i.e., absorbing or releasing heat energy. The high heat storage capacity and the constant temperature performance have great application space in energy conservation and emission reduction.
In China, especially in northern areas, the day and night temperature difference is large, the day and night temperature difference can reach 15 ℃ or even more than 20 ℃, the day temperature reaches the highest at 10-14 points, and can reach more than 30 ℃, so that in the invention, the phase transition temperature of the composite phase change material is between 5 and 35 ℃, and more preferably, the phase transition temperature is between 10 and 25 ℃.
According to the present invention, the phase change material may comprise an organic-based phase change material and/or an inorganic hydrated salt-based phase change material, preferably an organic-based phase change material, more preferably an organic-based phase change material comprising an alkane, carboxylic acid, ester or alcohol.
Preferably, the alkane is selected from the group consisting of medium-long alkanes, preferably C 5 H 12 、C 9 H 20 、C 14 H 30 、C 16 H 34 、C 17 H 36 And C 18 H 38 At least one of (a) and (b);
preferably, the carboxylic acid is selected from the group consisting of medium-long chain acids, preferably C 8 -C 11 Acids, more preferably octanoic acid and/or nonanoic acid;
preferably, the alcohol is selected from medium-long chain mono-alcohols and/or polyols, preferably C 10 -C 13 Alcohols, more preferably undecanol and/or dodecanol, and/or
The polyhydric alcohol is selected from polyglycols, including polyethylene glycol and/or polypropylene glycol.
In recent years, in the field of research on phase change materials, research using polyethylene glycol (PEG) as a phase change material has become an important branch in the field of research on novel phase change materials. The main reasons are that PEG has proper phase transition temperature and higher phase transition latent heat, and the phase transition process is stable and controllable, and supercooling phenomenon and phase separation are not easy to occur. According to different polymerization degrees, PEG can form a series of polymers with average molecular weights ranging from 200 to 24000, and the phase transition temperature of the polymers ranges from 4 ℃ to 70 ℃ and is suitable for the temperature of human bodies and the environment. The energy storage material with a series of phase transition temperatures can be obtained by controlling the molecular weight of polyethylene glycol or blending polyethylene glycols with different molecular weights, and the PEG has the advantages of higher phase transition enthalpy, no toxicity, no pungent smell, no hydrolysis, stable performance and the like. The phase change material in the present invention is therefore preferably polyethylene glycol (PEG), more preferably a blend of polyethylene glycols of different relative molecular masses.
In the present invention, the polyglycol includes polyethylene glycol I having a relative molecular mass of not more than 1000. Polyethylene glycol I is selected from at least one of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600 and polyethylene glycol 800, preferably polyethylene glycol I is selected from polyethylene glycol 600.
Wherein, the melting temperature of the polyethylene glycol 600 is about 21 ℃, the crystallization temperature is 11-16 ℃, and the chemical property is safer.
Preferably, the polyglycol further comprises polyethylene glycol II having a relative molecular mass of 2000 or more.
According to research, polyethylene glycol II with the relative molecular mass of more than or equal to 2000 is added into polyethylene glycol I, so that on one hand, the high-temperature peak proportion of the polyethylene glycol I in the crystallization stage can be increased, and the aim of improving the night temperature is fulfilled. This is probably because polyethylene glycol II acts as a nucleating agent during the night cooling process, promoting the crystallization of polyethylene glycol I to increase the proportion of high temperature peaks at the crystallization sites. On the other hand, the addition of polyethylene glycol II makes the melting peak of polyethylene glycol I move towards the low temperature direction, which is more beneficial to solar energy utilization.
In the present invention, polyethylene glycol II is selected from at least one of polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 6000, polyethylene glycol 15000 and polyethylene glycol 20000, more preferably, polyethylene glycol II is selected from polyethylene glycol 20000.
The temperature of the melting point of polyethylene glycol 20000 is 62 ℃, and polyethylene glycol 20000 does not melt during normal day time. The addition of polyethylene glycol 20000 makes the effect of polyethylene glycol 600 more pronounced.
Among them, polyethylene glycol 600 and polyethylene glycol 20000 of the present invention are commercially available, and are, for example, available from Nanjing chemical reagent Co., ltd.
In the invention, the mass ratio of polyethylene glycol I to polyethylene glycol II is 1: (0.01 to 0.20), preferably 1: (0.05-0.10).
Wherein, as the amount of polyethylene glycol II increases, the duty ratio of the high temperature peak in the crystallization stage of polyethylene glycol I also gradually increases, but when the mass ratio of polyethylene glycol I to polyethylene glycol II is 1: at 0.20, the amount of polyethylene glycol II is continuously increased, and the ratio of the high temperature peak in the crystallization stage of polyethylene glycol I is not substantially changed, probably due to the fact that the melting point temperature of polyethylene glycol II is higher, and polyethylene glycol II and polyethylene glycol I cannot be sufficiently mixed at high temperature. According to the invention, the addition of polyethylene glycol II makes the mixed system show gel state, even if polyethylene glycol I is completely melted, the mixed system still does not flow, which creates conditions for stabilizing the suspended heat conducting network in the polyethylene glycol mechanism.
In the present invention, the thermally conductive reinforcing material comprises ceramic particles and/or graphite, preferably comprises graphite. In order to accelerate the thermal conductivity of the phase change material, ceramic particles and/or graphite can be added into the phase change material, so that the thermal conduction phase change material can improve the local heat preservation and energy storage capacity.
According to the research, as the content of graphite increases, the heat conduction efficiency of a mixed system of polyethylene glycol I and polyethylene glycol II increases, and the higher the graphite consumption is, the greater the heat conduction efficiency is improved, but because the price of graphite is higher, in order to save the cost, the mass ratio of polyethylene glycol I to graphite is preferably 1: (0.01 to 0.20), more preferably 1: (0.01-0.10).
Preferably, the graphite is preferably at least one selected from the group consisting of expanded graphite, thermally exfoliated graphene, mechanically exfoliated graphene, liquid phase exfoliated graphene, high temperature carbonized graphene, oxidized graphene, reduced oxidized graphene, and graphite powder.
Among them, expanded graphite cannot be stably dispersed in a mixed system due to a difference in specific gravity when polyethylene glycol II and polyethylene glycol I are mixed at a high temperature. And the graphite powder can be uniformly dispersed in the system due to small sedimentation and low suspension speed of particles. That is to say, graphite powder can suspend in solution in the initial preparation process, and a certain amount of graphite powder can form a heat conduction channel, thereby being more beneficial to heat conduction. And the cost of the graphite powder is lower than that of graphene, so the graphite powder is preferably selected in the invention. Among these, graphite powder is commercially available, for example, qingdao morning sun graphite Co.
In order to improve the controllability in the production of the product, the invention prefers the graphite powder with high mesh number. Preferably, the mesh number of the graphite powder is 6000-20000. Since the price is correspondingly increased with the increase of the number of graphite powder, the number of graphite powder is more preferably 8000-15000 for cost saving.
According to research, the graphite powder can be filled in network gaps after crystallization of the crystalline phase-change material, and heat conduction can be better promoted when the material is heated. The graphite powder with higher mesh number can be uniformly suspended in the phase change material, and is better in favor of heat conduction.
In a preferred embodiment of the invention, the heat conduction reinforcing material further comprises steel wool, wherein the steel wool occupies not more than 10% of the volume of the inner cavity of the heat preservation wall, or the mass ratio of polyethylene glycol I to steel wool is 1: (0.05-0.15).
Wherein, the steel wool is preferably stone polishing steel wool, and more preferably the size is 17 inches; the stone materials of model #0- #4 are polished and ground with steel wool. The steel wool may be commercially available, for example, from Hubei Chemicals abrasive grinding stock Co.
The invention needs to pretreat the steel wool, preferably cuts the steel wool into a proper size of the cavity of the heat-insulating wall, thereby leading the formed heat-conducting network to further improve the heat-conducting efficiency.
The more the steel wool quantity is, the more the heat conduction can be effectively improved, but the volume of the steel wool is not more than 10% of the volume of the inner cavity in consideration of the volume proportion of the heat preservation wall cavity and the cost problem, or the mass ratio of polyethylene glycol I to steel wool is 1: (0.05 to 0.15), for example, 1: (0.08-0.12).
According to the phase change material, graphite and steel wool are further added, so that the thermal stability and the heat conduction capacity of the phase change material can be improved.
In the invention, the preparation process of the composite phase change material can comprise the following steps:
(1) Weighing polyethylene glycol 600, polyethylene glycol 20000, graphite powder and steel wool according to a certain proportion, and mixing;
(2) Heating the mixture obtained in the step (1) to fully liquefy the polyethylene glycol 600 and the polyethylene glycol 20000, stirring the mixture until the mixture is uniformly mixed, and naturally cooling the mixture to obtain the composite phase change material.
In a preferred embodiment of the invention, the insulating wall is made up of at least one metal sheet and a corresponding wall body.
In the present invention, the wall body is generally a conventional concrete wall or brick wall. The invention adopts the composite phase change material filled in the inner cavity of the wall body, so that the temperature of the surrounding environment in the shed can be kept at a proper temperature. Wherein the composite phase change material is selected to be non-corrodible or reactive with at least one of the metal plates.
To further enhance the thermal conductivity of the thermal insulation wall, the metal plate is selected from stainless steel plate, aluminum plate, iron plate or galvanized pipe. When the heat-insulating wall is used as a greenhouse wall, the aluminum plate is preferably selected as the wall of the heat-insulating wall in consideration of certain corrosiveness of the environment (humidity) in the greenhouse.
Wherein the thickness of the aluminum plate is 0.1-3 cm. The thickness of the aluminum plate is not particularly limited, and a person skilled in the art selects the thickness of the aluminum plate according to the actual situation of the greenhouse.
In a preferred embodiment of the present invention, in order to increase the stability of the insulation wall, the insulation wall further comprises a caulking agent for bonding at least one metal plate to the corresponding wall body;
preferably, the caulking agent is selected from neutral silicone adhesive (the neutral silicone adhesive takes polydimethylsiloxane as a main raw material). The neutral silicone adhesive may be commercially available, for example, from Shanghai Lianbao building materials Inc. The neutral silicone adhesive is suitable for weather-proof sealing of aluminum-plastic plate curtain walls and stone dry hanging, and the neutral pH silicone adhesive cannot be dissolved by polyethylene glycol to cause leakage of phase change materials, so that the stability and safety of the heat preservation wall are ensured.
The composite phase change material is injected into the inner cavity of the heat preservation wall, and when the temperature of the heat preservation wall is higher than the phase change temperature of the composite phase change material, the composite phase change material stores heat. When the temperature of the heat preservation wall is lower than the phase change temperature of the composite phase change material, the composite phase change material releases heat, so that the temperature in the shed can be effectively maintained; on the other hand, graphite and steel wool are further added into the composite phase-change material, so that the heat conduction efficiency of the system can be improved, and the greenhouse can be suitable for different regional environments. Meanwhile, the greenhouse has the service life of 15 years, the investment recovery period of about 10 years and remarkable economic benefit.
In a second aspect, the present invention provides a method for manufacturing a greenhouse using a phase change material according to the first aspect, including a step of manufacturing a heat insulation wall, wherein the step of manufacturing the heat insulation wall includes:
step 1, constructing the side surface and the bottom surface of a heat-insulating wall by utilizing at least one metal plate and a corresponding wall main body;
in the invention, a framework of the heat-insulating wall is constructed, and at least one metal plate and a corresponding wall body are bonded by using a joint compound. Preferably, a metal plate is disposed on the south side so that it can sufficiently contact irradiation of sunlight, the remaining surface is a brick wall or a concrete wall, and the metal plate is fixed with the corresponding brick wall or concrete wall with a caulking agent.
Step 2, injecting a composite phase change material;
the method mainly comprises the following substeps in step 2:
step 2-1, adding polyethylene glycol 600, polyethylene glycol 20000, graphite powder and steel wool into a container, heating to completely liquefy the polyethylene glycol 600 and the polyethylene glycol 20000, and uniformly mixing to obtain a liquid composite phase change material;
step 2-2, pouring the liquid composite phase change material into an inner cavity of the heat preservation wall until the inner cavity is filled; and naturally cooling the heat-insulating wall or cooling by using a cooling device until the composite phase change material completely presents a solid state.
And 3, packaging the top surface of the heat preservation wall.
In the invention, the top surface of the heat preservation wall is encapsulated by a cover plate or bricks or concrete. In order to strengthen the firmness of the heat-insulating wall, the gap between the heat-insulating wall and the metal plate can be filled with a gap filler.
The greenhouse disclosed by the invention is simple in manufacturing method, low in manufacturing cost and suitable for manufacturing greenhouses with different sizes.
In order to further understand the present invention, the greenhouse provided by the present invention will be described with reference to the following examples, and the scope of the present invention is not limited by the following examples.
Examples
Example 1 preparation of composite phase change Material
Mixing 100g of polyethylene glycol 600, 8g of polyethylene glycol 20000, 4g of 15000 mesh graphite powder and 10g of steel wool, heating to completely liquefy the polyethylene glycol 600 and the polyethylene glycol 20000, and uniformly mixing to obtain a liquid composite phase change material;
and naturally cooling the liquid composite phase-change material until the composite phase-change material completely presents a solid state.
Example 2 preparation of greenhouse Using phase Change Material
A heat preservation wall with the length of 43 meters, the width of 6.3 meters and the height of 3 meters is arranged in a greenhouse with the length of 43 meters, the height of 1.5 meters and the width of 0.05 meter, the south (facing surface) of the heat preservation wall is an aluminum plate, and the rest surface is a brick wall;
constructing the side surfaces and the bottom surfaces of the heat-insulating walls by using the aluminum plates and the brick walls, and fixing the aluminum plates and the corresponding brick walls by using neutral silicone adhesive;
the injection of the composite phase change material comprises the following specific processes:
2932g of polyethylene glycol 600, 293g of polyethylene glycol 20000, 117g of 15000 mesh graphite powder and 293g of steel wool are mixed and heated, so that the polyethylene glycol 600 and the polyethylene glycol 20000 are all liquefied and uniformly mixed to obtain a liquid composite phase change material;
filling the liquid composite phase change material into an inner cavity of the heat preservation wall until the inner cavity is filled with the liquid composite phase change material; naturally cooling the heat-insulating wall until the composite phase-change material completely presents a solid state;
and (3) packaging the top surface of the heat-insulating wall by using a brick wall, and filling up the pores of the heat-insulating wall and the aluminum plate by using neutral silicone adhesive.
Example 3
The preparation process similar to example 1 is different only in that the composite phase change material only comprises polyethylene glycol 600 and polyethylene glycol 20000, and graphite powder and steel wool are not added.
Example 4
The preparation process similar to example 1 is different only in that the composite phase change material only comprises polyethylene glycol 600, polyethylene glycol 20000 and graphite powder, and no steel wool is added.
Examples 5 to 7
The preparation process similar to example 3 is different only in that the mass of polyethylene glycol 20000 in the composite phase change material is different, and the mass of polyethylene glycol 20000 is 1%, 3% and 5% of the mass of polyethylene glycol 600, respectively.
Examples 8 to 9
The preparation process similar to example 4 differs only in that the mass of graphite powder in the composite phase change material is different, and the mass of graphite powder is 1% and 8% of the mass of polyethylene glycol 600, respectively.
Example 10
The preparation process similar to example 1 differs only in that the mass of steel wool in the composite phase change material is different, the mass of steel wool being 5% of the mass of polyethylene glycol 600.
Comparative example 1
The preparation process similar to example 1 is different only in that only polyethylene glycol 600 is included in the composite phase change material.
Experimental example
Experimental example 1 test of crystallization Properties of polyethylene glycol 600
FIG. 1 is a graph showing the change in crystallization temperature of polyethylene glycol 600 in examples 1, 3, examples 5 to 7 and comparative example 1. As can be seen from fig. 1, as the amount of polyethylene glycol 20000 increases, the proportion of the high Wen Fengzhan crystallization peak of polyethylene glycol 600 in the crystallization stage increases overall, which means that polyethylene glycol 600 is crystallized at a higher temperature when polyethylene glycol 20000 is added, thereby being able to absorb more heat.
Experimental example 2 test of thermal conductivity of composite phase-change Material
Fig. 2 is a graph showing temperature change of the composite phase change materials of examples 3 to 4 and examples 8 to 9 under irradiation of sunlight at different times. As can be seen from fig. 2, at the same time, the self temperature of the composite phase change material increases as the mass of the graphite powder increases. This means that the addition of graphite powder allows the composite phase change material to improve its own heat conduction efficiency after absorbing sunlight.
Experimental example 3 test of thermal conductivity of composite phase-change Material
Fig. 3 is a graph showing the temperature change at the same time of the different mass steel wool of the composite phase change materials in examples 1, 4 and 10.
As can be seen from fig. 3, the more the quality of the steel wool, the faster the self temperature of the composite phase change material rises, thereby indicating that the steel wool can improve the heat conduction efficiency of the composite phase change material.
Experimental example 4 testing of thermal insulation Property of greenhouse Using phase Change Material
In northern areas of China, the temperature in the greenhouse is reduced to be lower than 10 ℃ at night and the duration is longer than 8 hours, standard coal heating is needed at the moment, and in the greenhouse in the embodiment 2, the lower limit of the temperature at night in the greenhouse is 12 ℃ by using a heat-insulating wall and the duration is 8 hours, so that the standard coal heating is reduced in the period, the cost of the greenhouse is saved, and the pollution of waste gas is reduced;
meanwhile, the total amount of the standard coal is calculated,
the enthalpy of polyethylene glycol 600 and polyethylene glycol 20000 is 118J/g, the capacity of 1 gram of standard coal is 7000cal×4.18= 29260J, the mass of the composite phase-change material required by the heat-insulating wall is 3225kg, the total enthalpy of the composite phase-change material in one day is 38055000000J, which is equivalent to 13000g of standard coal, the total amount of the composite phase-change material in 5 days replaces the standard coal to be 0.065t, and the total amount of the standard coal 0.2936t required by the conventional planting greenhouse with the same size in 5 days, so that the standard coal saved by the heat-insulating wall accounts for 22.14% of the total energy consumption. Therefore, the greenhouse can meet the normal growth of crops by using less standard coal, thereby saving the cost of the greenhouse and reducing the pollution of waste gas.
The invention has been described in detail in connection with the specific embodiments and exemplary examples thereof, but such description is not to be construed as limiting the invention. It will be understood by those skilled in the art that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, and these fall within the scope of the present invention.
Claims (10)
1. A greenhouse using phase change materials, comprising:
the heat preservation wall is characterized in that a composite phase change material is filled in an inner cavity of the heat preservation wall, wherein the composite phase change material comprises a phase change material and a heat conduction reinforcing material, and the phase change temperature of the composite phase change material is between 5 and 35 ℃.
2. The greenhouse adopting the phase-change material according to claim 1, wherein the phase-change material comprises an organic phase-change material and/or an inorganic hydrated salt phase-change material,
preferably an organic phase change material, more preferably the organic phase change material comprises an alkane, carboxylic acid, ester or alcohol;
preferably, the alkane is selected from the group consisting of medium-long chain alkanes, preferably C 5 H 12 、C 9 H 20 、C 14 H 30 、C 16 H 34 、C 17 H 36 And C 18 H 38 At least one of (a) and (b);
preferably, the carboxylic acid is selected from the group consisting of medium-long chain acids, preferably C 8 -C 11 Acids, more preferably octanoic acid and/or nonanoic acid;
preferably, the alcohol is selected from medium-long chain mono-alcohols and/or polyols, preferably C 10 -C 13 Alcohols, more preferably undecanol and/or dodecanol, and/or
The polyhydric alcohol is selected from polyglycols, and the polyglycols comprise polyethylene glycol and/or polypropylene glycol.
3. The greenhouse using phase change material according to claim 2, wherein the organic phase change material is selected from polyglycols of different relative molecular masses,
the polyglycol comprises polyethylene glycol I with a relative molecular mass of not more than 1000;
the polyethylene glycol I is selected from at least one of polyethylene glycol 200, polyethylene glycol 400, polyethylene glycol 600, and polyethylene glycol 800.
4. The greenhouse adopting the phase-change material according to claim 3, wherein the polyglycol further comprises polyethylene glycol II with a relative molecular mass of 2000 or more,
more preferably, the polyethylene glycol II is selected from at least one of polyethylene glycol 2000, polyethylene glycol 4000, polyethylene glycol 6000, polyethylene glycol 15000 and polyethylene glycol 20000,
more preferably, the mass ratio of the polyethylene glycol I to the polyethylene glycol II is 1: (0.01-0.20).
5. Greenhouse using phase change material according to claim 4, characterized in that the heat conducting reinforcement material comprises ceramic particles and/or graphite, preferably graphite;
more preferably, the mass ratio of polyethylene glycol I to graphite is 1: (0.01-0.20),
the graphite is preferably at least one selected from the group consisting of expanded graphite, thermally exfoliated graphene, mechanically exfoliated graphene, liquid phase exfoliated graphene, high temperature carbonized graphene, oxidized graphene, reduced oxidized graphene and graphite powder, more preferably from the group consisting of graphite powder,
preferably, the mesh number of the graphite powder is 6000-20000.
6. The greenhouse using phase change material according to claim 1, wherein the heat conductive reinforcing material further comprises steel wool.
7. The greenhouse using phase change material according to claim 1, wherein the heat preservation wall is composed of at least one metal plate and a corresponding wall body.
8. The greenhouse using phase change material according to claim 7, wherein the metal plate is selected from stainless steel plate, aluminum plate, iron plate or galvanized pipe.
9. The greenhouse using phase change material according to claim 7, wherein the at least one metal plate and the corresponding wall body are adhered by using a caulking agent;
preferably, the caulking agent is selected from neutral silicone gums.
10. A method for manufacturing a greenhouse using a phase change material according to any one of claims 1 to 9, comprising a step of manufacturing a heat-insulating wall, wherein the step of manufacturing the heat-insulating wall comprises:
step 1, constructing the side surface and the bottom surface of a heat-insulating wall by utilizing at least one metal plate and a corresponding wall main body;
step 2, injecting a composite phase change material;
and 3, packaging the top surface of the heat preservation wall.
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