Phase change cold storage container with high space utilization, design method and installation method

Abstract

The application discloses a phase change cold storage container with high space utilization, a design method and an installation method, wherein the design method comprises the following steps: setting a plurality of groups of thermal insulation layer thicknesses, obtaining the cold quantity requirement of the container through a container heat load multi-physical field coupling mathematical model, and calculating the phase change cold storage layer thickness corresponding to each group of thermal insulation layer thicknesses according to the cold quantity requirement to obtain a mapping set of the thermal insulation layer thickness and the phase change cold storage layer thickness; and determining a group of thermal insulation layer thickness and the corresponding phase change cold storage layer thickness from the mapping set with the principle of minimizing the sum of the thermal insulation layer thickness and the phase change cold storage layer thickness, so as to realize the cold quantity requirement of the container and maximize the utilization rate of the inner and outer spaces of the container. The combination of the thermal insulation layer thickness and the phase change cold storage layer thickness obtained through the embodiment realizes the cold quantity requirement of the container and maximizes the utilization rate of the container space, improves the cargo transportation efficiency, and solves the problem that the prior art blindly increases the cold storage layer thickness to meet the cold storage requirement.

Description

Technical Field

[0001] This invention relates to the field of cold chain logistics technology, and in particular to a phase change cold storage container with high-efficiency space utilization, its design method, and its installation method. Background Technology

[0002] In the cold chain logistics sector, the pain points of traditional refrigeration systems are becoming increasingly apparent. Firstly, energy consumption is a major issue; continuous and substantial energy consumption keeps operating costs high for cold chain logistics companies, significantly squeezing profit margins. Secondly, large temperature fluctuations are a persistent problem with traditional refrigeration systems. Maintaining a stable low-temperature environment for goods during transportation is difficult, posing a serious threat to the quality and safety of temperature-sensitive goods such as pharmaceuticals and fresh food, easily leading to damage and economic losses. Thirdly, the high dependence of traditional refrigeration systems on continuous power supply is a significant operational vulnerability. A power outage will drastically reduce refrigeration efficiency and may even cause goods to spoil.

[0003] Phase change materials (PCMs), with their superior latent heat storage properties, have become an ideal solution to many of the aforementioned problems. By absorbing and storing cold energy within containers using PCMs, and releasing the cold energy through the latent heat of phase change in the absence of continuous power supply, passive temperature control within the container is achieved. This alleviates, to some extent, the high energy consumption and power dependence issues of traditional refrigeration systems, while also reducing temperature fluctuations. However, current technologies that blindly increase the thickness of the cold storage layer to meet cold storage demands significantly reduce the effective cargo space of the container, decreasing cargo transportation efficiency. Summary of the Invention

[0004] This invention provides a phase change cold storage container with high-efficiency space utilization, a design method, and an installation method, which solves the problem that blindly increasing the thickness of the cold storage layer to meet cold storage needs can significantly reduce the effective cargo space of the container and reduce cargo transportation efficiency.

[0005] The efficient space utilization phase change cold storage container design method provided in this invention includes:

[0006] S1. Set multiple sets of insulation layer thicknesses, obtain the container's cooling demand through a multi-physics coupling mathematical model of container heat load, and calculate the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses based on the cooling demand, thereby obtaining the mapping set between the insulation layer thickness and the phase change cold storage layer thickness.

[0007] S2. Based on the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness, determine a set of insulation layer thicknesses and their corresponding phase change cold storage layer thicknesses from the mapping set, so as to meet the cooling capacity requirements of the container while maximizing the utilization rate of the container's internal and external space.

[0008] Furthermore, the process after step S1 and before step S2 includes: establishing a nonlinear coupled database of the insulation layer thickness, the phase change cold storage layer thickness, and the cold storage maintenance time requirement of the container based on the mapping set and combined with three-dimensional multiphysics dynamic simulation.

[0009] Step S2 includes:

[0010] Based on the aforementioned nonlinear coupling database, and in accordance with the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness, a fitting formula is established through a dynamic mapping algorithm.

[0011] By fitting the formula, based on the required cold storage duration of the container, the final insulation layer thickness and the final phase change cold storage layer thickness are determined, so that the container can meet the required cold storage duration while maximizing the utilization rate of the container's internal and external space.

[0012] Further, the step of obtaining the cooling demand of the container through a multi-physics coupled mathematical model of container heat load, and calculating the thickness of the phase change cold storage layer corresponding to each group of insulation layer thicknesses based on the cooling demand, includes:

[0013] Calculate the heat conduction on the bottom surface of the container;

[0014] Calculate the heat transfer on the non-bottom surface of the container body;

[0015] The cooling capacity requirement of the container is determined based on the sum of heat conduction on the bottom surface of the container and heat transfer on the non-bottom surface of the container.

[0016] The required mass of cold storage material is calculated based on the cold load requirements of the container.

[0017] The thickness of the phase change cold storage layer is calculated based on the required mass of the cold storage material.

[0018] Furthermore, the calculation formula for the heat conduction on the bottom surface of the enclosure includes:

[0019] , ;

[0020] in, λ represents the heat conduction at the bottom of the enclosure; λ represents the thermal conductivity of the insulation material; δ1 represents the thickness of the insulation layer; A1 represents the area of ​​the bottom of the enclosure; and ΔT1 represents the temperature difference between the inside and outside of the enclosure.

[0021] Furthermore, the calculation formula for heat transfer on the non-bottom surface of the enclosure includes:

[0022] 1, ;

[0023] Where Q2 is the heat transfer on the non-bottom surface of the box; Q21 is the heat transfer on the non-bottom surface of the box at night; h1 is the forced convection heat transfer coefficient of the outer wall of the box; h2 is the natural convection heat transfer coefficient of the inner wall of the box; A2 is the total surface area of ​​the box excluding the bottom surface.

[0024] or:

[0025] 2, , ;

[0026] Where Q22 is the daytime heat transfer of the non-bottom surface of the enclosure; α is the solar radiation absorption rate of the enclosure; This represents the solar radiation intensity at sea during the summer.

[0027] An embodiment of the present invention provides a phase change cold storage container, comprising: an insulation layer, a phase change cold storage layer, and a cold charging pipe. The thickness of the insulation layer and the thickness of the phase change cold storage layer are determined by any of the above-described design methods. The insulation layer is disposed on the outer wall of the container, the phase change cold storage layer is disposed on the inner wall of the container, and the cold charging pipe is disposed on the side of the phase change cold storage layer away from the inner wall of the container.

[0028] Furthermore, the insulation layer includes multiple phase change cold storage modules, which are distributed throughout the inner wall of the container and are fixed together by sealing connectors.

[0029] Furthermore, an L-shaped angle steel bracket is welded to the inner wall of the container, which is used to support the phase change cold storage module.

[0030] Furthermore, the insulation layer includes multiple insulation modules, which are adhered to the outer wall of the container by expanding foam.

[0031] An installation method for the phase change cold storage container provided in this embodiment of the invention includes:

[0032] The container pretreatment: After the inner and outer walls of the container are derusted and degreased, the L-shaped angle steel bracket is welded to the inner wall of the container to support the phase change cold storage module, and the surface of the L-shaped angle steel bracket is coated with anti-rust paint.

[0033] The insulation layer construction: First, the outer wall of the box is sprayed with expanding foam, and then the prefabricated insulation modules are pasted on. The joints of the insulation modules are filled with sealant and covered with protective cloth to ensure that no thermal bridges are generated.

[0034] The cold charging tube assembly: The cold charging tube is first fixed to the inner surface of each phase change cold storage module;

[0035] The filling and encapsulation of the phase change cold storage module: Molten phase change cold storage material is injected into the cavity of the phase change cold storage module through the top filling port of the phase change cold storage module. Each phase change cold storage module is reserved for expansion space. After filling, the filling port is sealed and allowed to cool naturally to room temperature for curing.

[0036] The phase change cold storage module is hoisted and fixed by using a vacuum suction cup hoist to hoist multiple phase change cold storage modules one by one onto the L-shaped angle steel bracket, and then fixed with bolts through the pre-drilled holes on the side of the phase change cold storage module.

[0037] Piping connection: The charging pipes of each phase change cold storage module are connected in series using tee elbows. After connection, a water pressure test is performed. After passing the test, the pipes are wrapped with insulation cotton.

[0038] The installation of the phase change cold storage container has been completed.

[0039] As can be seen from the above technical solutions, the present invention has the following advantages:

[0040] This embodiment obtains the cooling capacity requirement of the container through a multi-physics coupled mathematical model of container thermal load, and calculates the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses based on the cooling capacity requirement. This yields a mapping set of insulation layer thicknesses and phase change cold storage layer thicknesses, ensuring that all combinations of insulation layer thicknesses and phase change cold storage layer thicknesses within this mapping set meet the container's cooling capacity requirement. Furthermore, based on the principle of minimizing the sum of insulation layer thicknesses and phase change cold storage layer thicknesses, a set of insulation layer thicknesses and their corresponding phase change cold storage layer thicknesses is determined from the mapping set that meets the container's cooling capacity requirement. This combination of insulation layer thicknesses and phase change cold storage layer thicknesses is extracted from the mapping set, meets the cooling capacity requirement, and minimizes the total thickness of the insulation layer thickness and phase change cold storage layer thickness, which is beneficial for maximizing the utilization rate of the container's internal and external space. Therefore, the combination of insulation layer thicknesses and phase change cold storage layer thicknesses obtained through the method of this embodiment satisfies the container's cooling capacity requirement while maximizing container space utilization, improving cargo transportation efficiency, and solving the problem of blindly increasing the thickness of the cold storage layer to meet cold storage requirements in existing technologies. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 A schematic diagram of a phase change cold storage container design method for efficient space utilization provided by an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of a design method for a phase change cold storage container with high-efficiency space utilization, provided for another embodiment of the present invention;

[0044] Figure 3 A COMSOL simulation diagram obtained from a phase change cold storage container design method for efficient space utilization provided in another embodiment of the present invention;

[0045] Figure 4 In another embodiment of the present invention, a nonlinear coupled database obtained by three-dimensional multiphysics dynamic simulation is provided in a phase change cold storage container design method with high space utilization (using the valence surface fitting-radial basis function method).

[0046] Figure 5 In another embodiment of the present invention, a phase change cold storage container design method for efficient space utilization is provided, which combines a nonlinear coupled database obtained by three-dimensional multiphysics dynamic simulation (comparing the relationship between insulation layer, maintenance days, and total thickness using different surface fitting methods).

[0047] Figure 6 The figure shows a three-dimensional fitting curve obtained from a phase change cold storage container design method for efficient space utilization provided in another embodiment of the present invention. Detailed Implementation

[0048] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0049] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the present application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0050] Please see Figure 1 The present invention provides a space-efficient phase change cold storage container design method, comprising:

[0051] S1. Set multiple sets of insulation layer thicknesses, obtain the container's cooling demand through the multi-physics coupling mathematical model of container heat load, and calculate the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses based on the cooling demand, so as to obtain the mapping set between insulation layer thickness and phase change cold storage layer thickness.

[0052] S2. Based on the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness, determine a set of insulation layer thicknesses and their corresponding phase change cold storage layer thicknesses from the mapping set to meet the cold load requirements of the container while maximizing the utilization rate of the container's internal and external space.

[0053] Understandably, in specific implementation, this embodiment obtains the cooling demand of the container through a multi-physics coupling mathematical model of container heat load, and calculates the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses based on the cooling demand, thereby obtaining a mapping set of insulation layer thicknesses and phase change cold storage layer thicknesses, so that all combinations of insulation layer thicknesses and phase change cold storage layer thicknesses within the mapping set meet the cooling demand of the container.

[0054] This embodiment further determines a set of insulation layer thicknesses and their corresponding phase change cold storage layer thicknesses from the mapping set that meets the container's cooling capacity requirements, based on the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness. This combination of insulation layer thickness and phase change cold storage layer thickness is extracted from the mapping set, thus meeting the cooling capacity requirements. At the same time, this combination minimizes the total thickness of the insulation layer thickness and the phase change cold storage layer thickness, which is beneficial for maximizing the utilization rate of the container's internal and external space.

[0055] Therefore, the combination of insulation layer thickness and phase change cold storage layer thickness obtained by the method of this embodiment can solve the problem of blindly increasing the thickness of the cold storage layer in order to meet the cold storage demand in the prior art, so as to maximize the utilization rate of container space while meeting the cold capacity demand of the container and improve the efficiency of cargo transportation.

[0056] It should be noted that, compared to the principle of minimizing the thickness of the phase change cold storage layer, determining the final insulation layer thickness and the final phase change cold storage layer thickness from the mapping set based on minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness can maximize the effective internal volume of the container while minimizing the overall structural space occupied, thus avoiding excessive external volume that would restrict transportation / installation. In other words, it maximizes the utilization rate of the container's internal and external space. For example, when the container in this embodiment is used for maritime transport, the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness simultaneously optimizes the thickness of the external insulation layer, effectively controlling the external volume of the container. This maximizes the loading efficiency of standard containers or shipping space and reduces the unit cargo volume cost in maritime transport.

[0057] It should be further explained that the required cooling capacity of a container is obtained through a multi-physics coupling mathematical model of container heat load. This cooling capacity requirement refers to the total heat load (including conduction, convection, and radiation heat) that needs to be removed from the container per unit time or throughout the entire transportation cycle (such as sea voyages, port loading and unloading, and land transshipment) to maintain a stable internal temperature within a preset range. Meeting the cooling capacity requirement means that throughout the entire container transportation cycle, the cooling capacity provided by the cold storage system through the phase change cold storage layer and insulation layer can completely offset the container's heat load and stably maintain the internal temperature within the preset range.

[0058] In a more specific embodiment, such as Figure 2 As shown, the design methods for phase change cold storage containers with high space utilization efficiency include:

[0059] S01. Set multiple sets of insulation layer thicknesses, obtain the container's cooling demand through the multi-physics field coupling mathematical model of container heat load, and calculate the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses based on the cooling demand, so as to obtain the mapping set between insulation layer thickness and phase change cold storage layer thickness.

[0060] S02. Based on the mapping set and combined with three-dimensional multiphysics dynamic simulation, establish a nonlinear coupled database of insulation layer thickness, phase change cold storage layer thickness, and cold storage maintenance time requirements of the container.

[0061] S03. Based on the nonlinear coupling database and the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness, a fitting formula is established through a dynamic mapping algorithm.

[0062] S04. By fitting the formula, based on the required cold storage duration of the container, determine the final insulation layer thickness and the final phase change cold storage layer thickness, so as to achieve the container meeting the cold storage duration requirement while maximizing the utilization rate of the container's internal and external space.

[0063] Understandably, in specific implementation, on the one hand, this embodiment establishes a nonlinear coupled database of insulation layer thickness, phase change cold storage layer thickness, and container cold storage maintenance duration requirements based on the mapping set and combined with three-dimensional multiphysics dynamic simulation (see subsequent specific embodiments for details). Figure 4 and Figure 5 Based on the nonlinear coupling database and the principle of minimizing the sum of the insulation layer thickness and the final phase change cold storage layer thickness, a fitting formula is established through a dynamic mapping algorithm (refer to formulas (7) and (8) in the subsequent specific embodiments). This directly establishes a continuous mapping relationship between the thickness parameter (the combination of the insulation layer thickness and the phase change cold storage layer thickness) and the cold storage duration requirement. That is, the thickness parameter corresponding to any cold storage duration requirement not listed in the mapping set can be obtained through the fitting formula. Therefore, this embodiment directly establishes a continuous mapping relationship between the thickness parameter and the cold storage duration requirement through the fitting formula, without the need to preset discrete values. It can solve the optimal solution in the continuous domain, which not only ensures the accuracy of the solution but also avoids the computational burden of high-dimensional discrete sets.

[0064] On the other hand, this embodiment establishes a nonlinear coupled database of insulation layer thickness, phase change cold storage layer thickness, and cold storage duration requirements through three-dimensional multiphysics dynamic simulation, and obtains fitting formulas to determine the final insulation layer thickness and the final phase change cold storage layer thickness based on the cold storage duration requirements. This embodiment uses the cold storage duration requirement as the dependent variable; container designers only need to modify the value of the target cold storage duration requirement to quickly solve for the optimal combination of insulation layer thickness and phase change cold storage layer thickness in the corresponding scenario (ensuring the sum of the insulation layer thickness and the phase change cold storage layer thickness is minimized). It should be noted that if the thickness combination designed with the cold capacity requirement as the dependent variable needs additional verification of "whether the cold capacity can support the preset transportation duration," problems may arise such as "sufficient cold capacity but insufficient duration" or "duration far exceeding the requirement leading to over-design," requiring secondary adjustment of the thickness parameters. Compared to using cooling demand as the dependent variable, this embodiment uses the required duration of cold storage as the dependent variable. The thickness combination obtained by fitting the formula directly matches the usage scenario, eliminating the need for subsequent duration verification and significantly reducing the design rework rate.

[0065] It should be noted that dynamic mapping algorithms are a class of algorithms that adjust the correspondence rules between inputs and outputs in real time under scenarios where the mapping relationship changes dynamically with the environment, data, or task requirements. The core objective is to maintain the effectiveness, accuracy, and efficiency of the mapping under dynamic conditions. The essence of mapping is establishing an element correspondence between two sets (e.g., input set X and output set Y). The key difference between dynamic mapping algorithms and static mapping algorithms is that the correspondence is not fixed in advance but can be automatically adjusted according to real-time changing constraints. In this embodiment, the input set is the container's cold storage duration, and the output set is the combination of insulation layer thickness and phase change cold storage layer thickness determined based on the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness. This embodiment can establish the fitting formula using existing greedy dynamic mapping algorithms, reinforcement learning-based dynamic mapping algorithms, graph theory-based dynamic mapping algorithms, or adaptive threshold dynamic mapping algorithms.

[0066] In a more specific embodiment, the three-dimensional multiphysics dynamic simulation is implemented using COMSOL three-dimensional dynamic simulation, and the COMSOL simulation diagram is shown below. Figure 3 As shown.

[0067] Understandably, in specific implementation, the thickness design in this embodiment is based on a multi-physics coupling model of box heat conduction, solar radiation heat gain, and forced convection heat transfer. Combined with COMSOL three-dimensional dynamic simulation, a nonlinear coupling database of insulation layer thickness (δ1), phase change cold storage layer thickness (δ2), and system maintenance time (τ) is established to form a dynamic mapping algorithm of "cold energy demand-thickness ratio". It can automatically match the optimal thickness combination according to the transportation time (10-50 days) and derive the fitting formula.

[0068] In a more specific embodiment, the required cooling capacity for the container is obtained through a multiphysics coupling model of the container's heat load, including:

[0069] A multi-physics coupled mathematical model of container heat load is used to obtain the container's cooling demand, and the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses is calculated based on the cooling demand, including:

[0070] Calculate the heat conduction on the bottom surface of the container;

[0071] Calculate the heat transfer on the non-bottom surface of the container body;

[0072] The cooling capacity requirement of the container is determined based on the sum of heat conduction on the bottom surface and heat transfer on the non-bottom surface of the container.

[0073] The required mass of cold storage material is calculated based on the container's cooling capacity requirements;

[0074] The thickness of the phase change cold storage layer is calculated based on the required mass of cold storage material.

[0075] Understandably, in practical implementation, this embodiment determines the container's cooling capacity requirements by separately calculating heat conduction on the bottom surface and heat transfer on the non-bottom surfaces of the container, thus accurately separating the sources of heat load: firstly, the bottom surface of the container directly contacts objects, resulting in solid-to-solid heat conduction; secondly, heat transfer on the non-bottom surfaces includes air convection heat transfer and external heat infiltration through gaps. The heat transfer mechanisms and influencing factors (such as thermal conductivity and temperature difference) of these two methods are completely different. Separate calculations clearly define the heat load proportion of each path, avoiding design deviations in cooling capacity due to neglecting any heat transfer path. This embodiment, by accurately separating the sources of heat load, avoids both overestimating the heat load, which could lead to waste of cold storage materials and increased costs, and underestimating the heat load, which could result in substandard insulation performance of the cold storage box and uncontrolled internal temperature. This facilitates obtaining accurate cooling capacity requirements for the container, and consequently, accurate thicknesses for the phase change cold storage layer and insulation layer.

[0076] In a more specific embodiment, the formula for calculating heat conduction on the bottom surface of the enclosure includes:

[0077] , (1)

[0078] Q1 represents the heat conduction at the bottom of the enclosure, in kJ.

[0079] Where λ is the thermal conductivity of the insulation material. δ1 is the insulation layer thickness, mm; A1 is the bottom surface area of ​​the enclosure, m². 2 ΔT1 is the temperature difference between the inside and outside of the chamber, in K.

[0080] Understandably, in specific implementation, this embodiment fully considers the influence of the thermal conductivity of the insulation layer material, the thickness of the insulation layer, the bottom surface area of ​​the container, and the temperature difference between the inside and outside of the container on the heat conduction of the bottom surface of the container. This is beneficial to obtain accurate heat conduction of the bottom surface of the container, and thus obtain the precise cooling requirements of the container.

[0081] In a more specific embodiment, the calculation formula for heat transfer on the non-bottom surface of the enclosure includes:

[0082] 1, ; (2)

[0083] Where Q2 represents heat transfer on the non-bottom surface of the enclosure (KJ); Q21 represents heat transfer on the non-bottom surface of the enclosure (KJ); and h1 represents the forced convection heat transfer coefficient of the outer wall of the enclosure. h2 is the natural convection heat transfer coefficient of the inner wall of the box. A2 is the total surface area of ​​the box excluding the bottom surface, in meters. 2 .

[0084] or:

[0085] 2, , ; (3)

[0086] Where Q22 is the daytime heat transfer of the non-bottom surface of the container, in KJ; α is the solar radiation absorption rate of the container.

[0087] Summer solar radiation at sea, W / m 2 .

[0088] Understandably, this embodiment fully considers the differences in heat transfer characteristics under different environmental conditions during the day and night, which is beneficial for obtaining accurate heat transfer data of the non-bottom surface of the enclosure. During the day, the ambient temperature is high and there is solar radiation, so the non-bottom surface of the enclosure mainly absorbs heat and dissipates heat outward; at night, the ambient temperature is low and there is no solar radiation, so heat transfer is mainly the dissipation of heat from the enclosure to the outside. The heat transfer direction, rate, and influencing factors are significantly different between the two periods. Calculating them separately more accurately reflects the actual heat transfer situation at different times.

[0089] As can be seen from the above embodiments, determining the cooling capacity requirement of a container based on the sum of heat conduction on the bottom surface and heat transfer on the non-bottom surface includes:

[0090] (4)

[0091] Where Q represents the cooling capacity requirement of the cold storage box, in KJ.

[0092] In a more specific embodiment, the required mass of cold storage material is calculated based on the container's cooling capacity requirements:

[0093] (5)

[0094] Where M is the required mass of cold storage material, in kJ / kg; ΔH is the latent heat of the phase change material, in kJ / kg;

[0095] The thickness of the phase change cold storage layer is calculated based on the required mass of cold storage material:

[0096] (6)

[0097] Where δ2 is the thickness of the phase change cold storage layer, KJ / kg; B is the density of the cold storage material, kg / L; B is the installation area of ​​the cold storage material, m². 2 .

[0098] In summary, this embodiment determines the thickness of the phase change energy storage layer by varying the thickness of the insulation layer. The nonlinear coupling relationship between the insulation layer thickness (δ1), the phase change energy storage layer thickness (δ2), and the required cold storage duration (τ) is quantitatively analyzed. The optimal combination of insulation layer thickness (δ1) and phase change energy storage layer thickness (δ2) is selected to control heat flux density and temperature uniformity. Simultaneously, COMSOL simulation analysis is performed on the temperature changes inside the container. Maximizing space utilization is achieved when the total thickness of the container's insulation layer and phase change energy storage layer is minimized.

[0099] This invention also provides a phase change cold storage container, including an insulation layer, a phase change cold storage layer, and a cold charging pipe. The thickness of the insulation layer and the thickness of the phase change cold storage layer are determined by the design method of the above embodiments. The insulation layer is disposed on the outer wall of the container, the phase change cold storage layer is disposed on the inner wall of the container, and the cold charging pipe is disposed on the side of the phase change cold storage layer away from the inner wall of the container.

[0100] Understandably, in practical implementation, this embodiment determines the final thickness of the insulation layer and the final thickness of the phase change cold storage layer based on the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness. By placing the insulation layer on the outer wall of the container and the phase change cold storage layer on the inner wall, while the cold charging pipes are arranged on the side of the phase change cold storage layer away from the inner wall of the container, it is possible to maximize the effective internal volume of the container while minimizing the overall structural space occupied, thus avoiding excessive external volume that would restrict transportation / installation. If the container of this embodiment is used in maritime transportation, the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness simultaneously optimizes the external insulation layer thickness of the container, effectively controlling the external volume of the container. This maximizes the loading efficiency of standard containers or ocean freight space and reduces the unit cargo volume cost in ocean freight.

[0101] It should be noted that the container in this embodiment does not consume electrical energy during use. It utilizes phase change materials (PCMs) for cooling at specific temperatures. This phase change process effectively regulates the temperature, ensuring that the container's interior remains at a stable low temperature. PCMs can undergo a phase change under specific temperature conditions, absorbing or releasing a large amount of latent heat during this process. When the temperature inside the container fluctuates, the PCMs can respond rapidly, effectively regulating the temperature through the phase change process, thus ensuring that the container's interior remains at a stable low temperature.

[0102] Phase Change Material (PCM), with its superior latent heat energy storage properties, is utilized in this embodiment to provide an independently operating PCM cold storage container, deeply integrating PCM cold storage technology with the container structure. Energy storage units for the PCM cold storage layer are cleverly embedded in the container's inner wall, and a driving refrigeration unit efficiently stores the cold energy within the PCM cold storage layer. During maritime transport, the PCM cold storage layer releases cold energy, precisely maintaining a constant temperature environment within the container. In terms of cooling, this system exhibits significant energy consumption advantages. Firstly, it can fully utilize the difference between peak and off-peak electricity prices for cooling. During off-peak electricity periods, the refrigeration equipment is activated to centrally cool the PCM cold storage layer, as electricity costs are lower at this time, effectively reducing energy consumption costs in the cooling process. Specifically, the cooling process involves centrally cooling the PCM cold storage layer with a low-temperature refrigerant, allowing the layer to rapidly absorb cold energy and efficiently complete the cold storage.

[0103] In a more specific embodiment, the cooling tube is a partitioned serpentine cooling tube.

[0104] Understandably, in practical applications, the indirect-wall serpentine charging pipe has significant advantages when used in the phase change cold storage layer of containers: First, the serpentine structure maximizes the extension of the heat exchange pipe length within the limited space of the container, significantly increasing the contact area with the phase change cold storage material, accelerating the charging rate and the uniformity of cold storage; Second, the indirect-wall design effectively isolates the refrigerant inside the pipe from the phase change cold storage medium outside the pipe, avoiding refrigerant leakage and contamination or deterioration of the phase change material composition, ensuring the safety and stability of the cold storage system; Third, the structure has a mature manufacturing process, is easy to install and maintain, can be flexibly adapted to the internal layout of containers of different specifications, and can withstand the vibration and impact during container transportation, with strong structural reliability; Fourth, compared with other heat exchange structures, the refrigerant flow resistance inside the serpentine charging pipe is controllable, can be adapted to the output pressure of conventional refrigeration units, and does not require additional pressurization equipment, reducing the overall system modification cost.

[0105] In a more specific embodiment, the insulation layer includes multiple phase change cold storage modules, which are distributed throughout the inner wall of the container and fixed together by sealing connectors.

[0106] Understandably, in specific implementation, on the one hand, by preparing the phase change cold storage layer in sections, the thickness of each phase change cold storage module can be precisely controlled, so that the installed phase change cold storage layer can meet the phase change cold storage layer thickness design requirements obtained in the above embodiment; on the other hand, the phase change cold storage room is fixed by a sealing connector to achieve fault isolation.

[0107] In a more specific embodiment, multiple phase change cold storage modules are distributed throughout the inner walls of the container, excluding the bottom surface, i.e., throughout the front, back, left, right, and top of the container.

[0108] In a more specific embodiment, the dimensions of a single phase change cold storage module are 1.2m × 0.8m × 0.06-0.145m, and the phase change cold storage modules are fixed together by a sealed connector to achieve fault isolation.

[0109] In a more specific embodiment, the phase change cold storage layer uses a high latent heat phase change cold storage material that conforms to the phase change temperature range, ensuring the efficient cold storage of the box. This not only significantly reduces the use of Freon refrigerants and actively responds to the "dual carbon" goal, but also provides an innovative approach to green refrigeration and efficient energy utilization, offering a new generation solution that integrates economy, reliability, and environmental friendliness for the cold chain logistics field.

[0110] In a more specific embodiment, the inner wall of the container is welded with an L-shaped angle steel bracket, which is used to support the phase change cold storage module.

[0111] L-shaped angle steel brackets are welded on the inside to support the phase change cold storage modules. Multiple phase change cold storage modules are hoisted one by one into the L-shaped angle steel brackets inside the box using vacuum suction cups. The modules are then fixed with bolts through the pre-drilled holes on the side of the phase change cold storage modules, reducing the thickness required for installation.

[0112] In a more specific embodiment, the insulation layer includes multiple insulation modules that are adhered to the outer wall of the container by expanding foam.

[0113] Understandably, in practice, expanding foam is used to bond the insulation modules. The expanding foam mainly fills the gaps between the insulation modules and does not take up any thickness space.

[0114] In a more specific embodiment, the insulation layer material is selected as polyurethane (thermal conductivity of ). .

[0115] In a more specific embodiment, the phase change cold storage layer material is selected from composite modified inorganic hydrated salts (density ρ = 1.3 kg / l, latent heat of phase change ... ).

[0116] In a more specific embodiment, the refrigerant in the cooling tube is a 40% aqueous solution of ethylene glycol.

[0117] This invention also provides an installation method for a phase change cold storage container, comprising:

[0118] Container pretreatment: After the inner and outer walls of the container are derusted and degreased, L-shaped angle steel brackets are welded to the inner wall of the container to support the phase change cold storage module. The surface of the L-shaped angle steel brackets is coated with anti-rust paint.

[0119] Insulation layer construction: First, spray expanding foam onto the outer wall of the box, then attach the prefabricated insulation modules. Fill the joints of the insulation modules with sealant and cover them with protective cloth to ensure that no thermal bridges are generated.

[0120] Cold charging tube assembly: The cold charging tube is first fixed to the inner surface of each phase change cold storage module;

[0121] The filling and encapsulation of the phase change cold storage module: The molten phase change cold storage material is injected into the cavity of the phase change cold storage module through the top filling port of the phase change cold storage module. Each phase change cold storage module is reserved for expansion space. After filling, the filling port is sealed and naturally cooled to room temperature for curing.

[0122] Lifting and fixing of phase change cold storage modules: Vacuum suction cup lifting tools are used to lift multiple phase change cold storage modules one by one onto the L-shaped angle steel bracket, and bolts are used to fix them through the reserved holes on the side of the phase change cold storage modules;

[0123] Piping connection: The charging pipes of each phase change cold storage module are connected in series using tee elbows. After connection, a water pressure test is performed. After passing the test, the pipes are wrapped with insulation cotton.

[0124] The installation of the phase change cold storage container has been completed.

[0125] Understandably, in practice, L-shaped angle steel brackets are welded on the inside to support the phase change cold storage modules. Vacuum suction cups are used to lift multiple phase change cold storage modules one by one into the L-shaped angle steel brackets inside the box. Bolts are used to fix the modules through the pre-drilled holes on the side of the phase change cold storage modules, thus reducing the thickness required for installation.

[0126] On the other hand, using expanding foam to bond the insulation layer, the expanding foam mainly fills the gaps in the insulation layer and does not take up thickness space.

[0127] In a more specific embodiment, the installation method of the phase change cold storage container specifically includes:

[0128] S11. Container pretreatment: After the container body is derusted and degreased, L-shaped angle steel brackets (0.4m×0.4m spacing) are welded on the inside to support the PCM module. The bracket surface is coated with anti-rust paint (epoxy zinc-rich primer).

[0129] S12. Insulation layer construction: On-site foaming + prefabricated panel splicing is adopted. A 20mm foam layer is first sprayed on the outside of the box, and then a 60mm prefabricated insulation board (thickness δ1=60mm) is pasted. The splicing seam is filled with polyurethane sealant and covered with aluminum foil cloth for protection to ensure that no thermal bridge is generated.

[0130] S13. Cooling tube assembly: First fix the serpentine cooling tube in each PCM module (tube clamp spacing 0.3m).

[0131] S14, PCM module potting and encapsulation: Molten composite modified PCM (temperature 80℃) is injected through the top potting port of the PCM module at a potting speed of 5L / min. Each PCM module is reserved with 5% expansion space. After potting, the potting port is sealed and allowed to cool naturally to room temperature (25℃) for curing.

[0132] S15. PCM Module Lifting and Fixing: Use a vacuum suction cup lifting tool (load capacity 500kg) to lift 32 PCM modules one by one into the bracket inside the box. The gap between PCM modules is ≤5mm. Use high-strength bolts (M8×30) to fix them through the reserved holes on the side of the PCM modules. Add rubber pads to the bolt connection to reduce shock.

[0133] S16. Pipeline connection and pressure test: Each PCM module's cooling pipe uses copper tees and elbows connected in series. The main pipe diameter is 32mm. After connection, a water pressure test is performed (pressure 1.2MPa, pressure holding for 30min, pressure drop ≤0.05MPa). After passing the test, the pipeline is wrapped with insulation cotton (thickness 20mm).

[0134] This invention provides a cooling and operation control process, including:

[0135] S21, Pre-charge and cooling preparation (30 minutes):

[0136] The control unit initiates a self-test: it detects all sensor signals, valve status, and unit operating parameters. If a fault such as sensor signal loss or valve jamming occurs, it immediately issues an audible and visual alarm (alarm sound level ≥ 85dB, indicator light flashing red).

[0137] S22. Refrigerant pretreatment: 40% ethylene glycol aqueous solution (freezing point -35℃) is injected into the storage tank, and the air in the pipeline is purged by the circulation pump. The initial temperature of the refrigerant is set to -26℃.

[0138] S23, Dynamic Cooling (Duration 5 hours):

[0139] Hour 1: Flow control valve fully open, refrigerant flow rate 1.5m / s, rapidly reduce PCM temperature to 10℃;

[0140] Hours 2-4: Adjust the flow rate based on the liquid phase fraction feedback (reduce to 1.2 m / s when the liquid phase fraction is 50%), maintain the refrigerant temperature at -10℃, and ensure uniform solidification of PCM;

[0141] 5th hour: When the liquid phase fraction is ≤10%, the flow rate is reduced to 0.8m / s, the refrigerant temperature rises to -22℃, and the temperature is maintained for 30 minutes to complete the cooling process (PCM final temperature -18℃).

[0142] This invention also provides a fault handling and maintenance method, including:

[0143] For PCM module leakage fault types, the detection method is to use the humidity sensor at the bottom of the module to trigger an alarm (humidity ≥80%RH). The handling procedure is as follows:

[0144] S31, Unit Automatic Fault Isolation PCM Module;

[0145] S32. Replace the PCM module after the transportation is completed.

[0146] For the fault type of blockage in the cooling pipeline, the detection method is to use an internal differential pressure sensor to detect a differential pressure ≥ 0.3 MPa. The handling procedure is as follows:

[0147] S41. The control unit automatically switches to backwash mode (refrigerant flows in reverse, flow rate 1.8m / s, lasting 5min).

[0148] S42. If the differential pressure still exceeds the standard after backflushing, an alarm will be triggered.

[0149] Emergency measures: If backflushing is ineffective, isolate the module corresponding to the blocked pipeline, while the remaining PCM modules operate normally.

[0150] It should be noted that the PCM module in the above embodiments is a phase change cold storage module.

[0151] In a more specific embodiment, the space-efficient phase change cold storage container design method specifically includes:

[0152] Taking a 20-inch standard container (external dimensions: 6.058m × 2.438m × 2.591m, internal clearance: 5.898m × 2.352m × 2.393m) as an example, the design method for the thickness of the insulation layer and the phase change cold storage layer is as follows:

[0153] S51. Selection and specification confirmation of core components. The selection and specifications of core components are shown in Table 1.

[0154] Table 1 Selection and Specifications of Core Components

[0155]

[0156] S52. Parameter Acquisition and Calculation:

[0157] Assuming the interior of the container is maintained at -18℃ and the average daily temperature at sea in summer is 30℃, the following parameters are obtained from the table of container, materials, and working environment:

[0158] External wall forced convection heat transfer coefficient The natural convection heat transfer coefficient of the inner wall Thermal conductivity of insulation layer material The latent heat of the phase change material ΔH = 285 KJ / kg, the density of the phase change cold storage material ρ = 1.3 kg / l, and the bottom area A1 of the box is 14.77 (m²).2 The total surface area A2 of the non-bottom surface of the box is 58.796 (m²). 2 The temperature difference between the inside and outside of the container is ΔT1=48°C, the solar radiation absorptivity of the container is α=0.3, and the summer marine solar radiation intensity is... =850W / m 2 ΔT2=65.

[0159] S53. Set multiple sets of insulation layer thicknesses, which may include:

[0160] δ1=200mm, δ1=190mm, δ1=180mm, δ1=170mm, δ1=160mm, δ1=150mm, δ1=140mm, δ1=130mm, δ1=120mm, δ1=1 10mm, δ1=100mm, δ1=90mm, δ1=80mm, δ1=70mm, δ1=60mm, δ1=50mm, δ1=40mm, δ1=30mm, δ1=20mm, δ1=10mm.

[0161] S54. Using a multi-physics coupled mathematical model of container heat load, the cooling demand of the container is obtained, and the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses is calculated based on the cooling demand (as shown in Table 2). The mapping set of insulation layer thickness and phase change cold storage layer thickness is obtained as shown in Table 3. Taking δ1=200mm and δ1=190mm as examples, as shown in Table 2. Wherein, K=0.02 / δ1; H=1 / (1 / 15+1 / 3+δ1 / 0.02); ΔT1=48; ΔT2=65; A1=14.77m 2 A2 = 58.796 m 2 ;

[0162] Table 2 Calculation Table for Phase Change Cold Storage Layer Thickness

[0163]

[0164] Table 3 Partial Mapping Sets

[0165]

[0166] It should be noted that the total thickness in Table 3 is the sum of the thickness of the insulation layer and the thickness of the phase change cold storage layer. The bolded items indicate that the sum of the thickness of the insulation layer and the thickness of the phase change cold storage layer is minimized.

[0167] S55. Based on the mapping set and combined with three-dimensional multiphysics dynamic simulation, establish a nonlinear coupled database (e.g., for insulation layer thickness, phase change cold storage layer thickness, and container cold storage duration) Figure 4 and Figure 5 (As shown).

[0168] S56. Based on the nonlinear coupling database and the principle of minimizing the sum of the insulation layer thickness and the final phase change cold storage layer thickness, a three-dimensional fitting curve is obtained through a dynamic mapping algorithm (e.g., Figure 6 (as shown), and establish the fitting formula:

[0169] Using MATLAB to fit the optimal points for each of the 10-50 day periods, we can obtain two fitting formulas:

[0170] a. Fitting formula for the number of days of maintenance (x) and the optimal phase change cold storage layer thickness (y, mm):

[0171] (7)

[0172] b. Fitting formula for maintenance days (x) and minimum total thickness (z, mm):

[0173] (8)

[0174] The minimum total thickness is the sum of the optimal phase change cold storage layer thickness and the optimal insulation layer thickness.

[0175] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A design method for a phase change cold storage container with high-efficiency space utilization, characterized in that, Including the following steps: S1. Set multiple sets of insulation layer thicknesses, obtain the container's cooling demand through a multi-physics coupling mathematical model of container heat load, and calculate the phase change cold storage layer thickness corresponding to each set of insulation layer thicknesses based on the cooling demand, thereby obtaining the mapping set between the insulation layer thickness and the phase change cold storage layer thickness. S2. Based on the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness, determine a set of insulation layer thicknesses and their corresponding phase change cold storage layer thicknesses from the mapping set, so as to meet the cooling capacity requirements of the container while maximizing the utilization rate of the container's internal and external space. The process after step S1 and before step S2 also includes: establishing a nonlinear coupled database of the insulation layer thickness, the phase change cold storage layer thickness, and the cold storage maintenance time requirement of the container based on the mapping set and combined with three-dimensional multiphysics dynamic simulation. Step S2 includes: Based on the aforementioned nonlinear coupling database, and in accordance with the principle of minimizing the sum of the insulation layer thickness and the phase change cold storage layer thickness, a fitting formula is established through a dynamic mapping algorithm. By fitting the formula, based on the required cold storage duration of the container, the final insulation layer thickness and the final phase change cold storage layer thickness are determined, so that the container can meet the required cold storage duration while maximizing the utilization rate of the container's internal and external space. The process of obtaining the container's cooling demand through a multi-physics coupled mathematical model of container heat load, and calculating the phase change cold storage layer thickness corresponding to each group of insulation layer thicknesses based on the cooling demand, includes: Calculate the heat conduction on the bottom surface of the container; Calculate the heat transfer on the non-bottom surface of the container body; The cooling capacity requirement of the container is determined based on the sum of heat conduction on the bottom surface of the container and heat transfer on the non-bottom surface of the container. The required mass of cold storage material is calculated based on the cold load requirements of the container. The thickness of the phase change cold storage layer is calculated based on the required mass of the cold storage material.

2. The design method for a phase change cold storage container with high-efficiency space utilization according to claim 1, characterized in that, The calculation formula for heat conduction on the bottom surface of the enclosure includes: ， ； in, λ represents the heat conduction at the bottom of the enclosure; λ represents the thermal conductivity of the insulation material; δ1 represents the thickness of the insulation layer; A1 represents the area of ​​the bottom of the enclosure; and ΔT1 represents the temperature difference between the inside and outside of the enclosure.

3. The design method for a phase change cold storage container with high-efficiency space utilization according to claim 2, characterized in that, The calculation formula for heat transfer on the non-bottom surface of the enclosure includes: 1， ； Where Q2 is the heat transfer on the non-bottom surface of the box; Q21 is the heat transfer on the non-bottom surface of the box at night; h1 is the forced convection heat transfer coefficient of the outer wall of the box; h2 is the natural convection heat transfer coefficient of the inner wall of the box; A2 is the total surface area of ​​the box excluding the bottom surface. or: 2， ， ； Where Q22 is the daytime heat transfer of the non-bottom surface of the enclosure; α is the solar radiation absorption rate of the enclosure; This represents the solar radiation intensity at sea during the summer.

4. A phase change cold storage container, characterized in that, include: The container includes an insulation layer, a phase change cold storage layer, and a cold charging pipe. The thickness of the insulation layer and the thickness of the phase change cold storage layer are determined by the design method described in any one of claims 1-3. The insulation layer is disposed on the outer wall of the container, the phase change cold storage layer is disposed on the inner wall of the container, and the cold charging pipe is disposed on the side of the phase change cold storage layer away from the inner wall of the container.

5. A phase change cold storage container according to claim 4, characterized in that, The insulation layer includes multiple phase change cold storage modules, which are distributed throughout the inner wall of the container and fixed together by sealing connectors.

6. A phase change cold storage container according to claim 5, characterized in that, The inner wall of the container is welded with an L-shaped angle steel bracket, which is used to support the phase change cold storage module.

7. A phase change cold storage container according to claim 6, characterized in that, The insulation layer comprises multiple insulation modules, which are adhered to the outer wall of the container by means of expanding foam.

8. A method for installing the phase change cold storage container as described in claim 7, characterized in that, include: The container pretreatment: After the inner and outer walls of the container are derusted and degreased, the L-shaped angle steel bracket is welded to the inner wall of the container to support the phase change cold storage module, and the surface of the L-shaped angle steel bracket is coated with anti-rust paint. The insulation layer construction: First, the outer wall of the box is sprayed with expanding foam, and then the prefabricated insulation modules are pasted on. The joints of the insulation modules are filled with sealant and covered with protective cloth to ensure that no thermal bridges are generated. The cold charging tube assembly: The cold charging tube is first fixed to the inner surface of each phase change cold storage module; The filling and encapsulation of the phase change cold storage module: Molten phase change cold storage material is injected into the cavity of the phase change cold storage module through the top filling port of the phase change cold storage module. Each phase change cold storage module is reserved for expansion space. After filling, the filling port is sealed and allowed to cool naturally to room temperature for curing. The phase change cold storage module is hoisted and fixed by using a vacuum suction cup hoist to hoist multiple phase change cold storage modules one by one onto the L-shaped angle steel bracket, and then fixed with bolts through the pre-drilled holes on the side of the phase change cold storage module. Piping connection: The charging pipes of each phase change cold storage module are connected in series using tee elbows. After connection, a water pressure test is performed. After passing the test, the pipes are wrapped with insulation cotton. The installation of the phase change cold storage container has been completed.

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