Refrigerant for cold-chain transportation as well as preparation method and application of refrigerant

Abstract

The invention belongs to the technical field of temperature control materials, and particularly discloses a refrigerant for cold-chain transportation and a preparation method and application thereof. The refrigerant for cold-chain transportation comprises monopotassium phosphate, sodium bicarbonate and water, wherein the molar ratio of the monopotassium phosphate to the sodium bicarbonate is 1: (1-1.8); the addition amount of the monopotassium phosphate to the water is (22.1 to 44.2) mmol: 20mL. When the monopotassium phosphate and the sodium bicarbonate are dissolved in water, the monopotassium phosphate and the sodium bicarbonate can react immediately to absorb heat, so that the surrounding temperature is reduced, when the packaging is closed, carbon dioxide generated by the reaction can promote circulating cooling, the material is environment-friendly and safe, the refrigeration process is mild, non-toxic and pollution-free, and the requirement for medium-low-temperature cold chain transportation of medicines, fresh food and the like can be met.

Description

Technical Field

[0001] This invention relates to the field of temperature control materials technology, and in particular to a refrigerant for cold chain transportation, its preparation method and application. Background Technology

[0002] Cold chain transportation, as a crucial link in the modern logistics system, directly impacts food safety, pharmaceutical preservation, and energy efficiency through innovation in its core refrigeration technology. Currently, HFCs (hydrofluorocarbons) remain the dominant refrigerant. While their refrigeration performance is stable, they suffer from environmental drawbacks, with GWP (Global Warming Potential) thousands of times higher than their actual value. Furthermore, their use is being strictly limited as relevant regulations are implemented. Traditional ammonia refrigeration systems, while environmentally friendly, are flammable and explosive. CO2 transcritical cycle systems, while promising, face technical bottlenecks such as high-pressure equipment costs and low energy efficiency. In addition, current technologies rely heavily on empirical formulas for optimizing the proportions of composite refrigerants, lacking precise control over phase change heat transfer mechanisms, leading to a surge in energy consumption in cold chain equipment under extreme operating conditions.

[0003] Against this backdrop, a green and controllable endothermic system based on potassium dihydrogen phosphate, sodium bicarbonate, and water is being developed as a disposable or controllable low-temperature refrigerant for cold chain applications, exhibiting good environmental friendliness, material availability, and safety. This system relies on the principle of endothermic CO2 release through the thermal decomposition of NaHCO3, combined with pH regulation and a buffer system using KH2PO4, to achieve a mild, non-toxic, and pollution-free release of cold energy. It is suitable for medium- and low-temperature cold chain transportation scenarios such as pharmaceuticals and fresh produce, demonstrating significant application potential. Summary of the Invention

[0004] In view of this, the present invention provides a refrigerant for cold chain transportation, its preparation method and application. The material is environmentally friendly and safe, and the refrigeration process is mild, non-toxic and pollution-free, which can meet the requirements of medium and low temperature cold chain transportation of pharmaceuticals, fresh food and other products.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A refrigerant for cold chain transportation, comprising the following components:

[0007] Potassium dihydrogen phosphate, sodium bicarbonate, and water;

[0008] The molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1 to 1.8.

[0009] The amount of potassium dihydrogen phosphate added to water is 22.1–44.2 mmol: 20 mL.

[0010] Preferably, the molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1.4.

[0011] Preferably, the ratio of potassium dihydrogen phosphate, sodium bicarbonate and water is 44.2 mmol: 61.88 mmol: 20 mL.

[0012] Another object of the present invention is to provide a method for preparing a refrigerant for cold chain transportation, comprising the following steps:

[0013] Potassium dihydrogen phosphate, sodium bicarbonate, and water are mixed to obtain a refrigerant for cold chain transportation.

[0014] Another object of the present invention is to provide an application of a refrigerant for cold chain transportation, wherein the application method involves placing the freshly prepared refrigerant for cold chain transportation and the transported goods in the same enclosed space for refrigeration.

[0015] Reaction principle:

[0016] Reaction 1: Na₂CO₃ + H₂O → NaHCO₃ + NaOH

[0017] Reaction 2: NaHCO3 + KH2PO4 → NaKHPO4 + CO2↑ + H2O

[0018] Reaction 3: Na₂CO₃ + CO₂ + H₂O → 2NaHCO₃

[0019] Reaction 2 is the main reaction within the system and is endothermic, thus achieving heat absorption. During the process, sodium bicarbonate partially decomposes to produce sodium carbonate, which further reacts with carbon dioxide and water to produce sodium bicarbonate, forming a gas-liquid balance regulation mechanism. The reaction of sodium carbonate with water to produce sodium hydroxide can buffer the environment, stabilize the pH value, and regulate the reaction rate and heat transfer efficiency. This achieves a long-term heat preservation effect through cyclic reaction.

[0020] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention uses potassium dihydrogen phosphate and sodium bicarbonate as the main raw materials. Under the specified addition amounts, the reaction proceeds fully, ensuring stable CO2 release and endothermic effect during the acid-base neutralization reaction. Compared to other ratios, the addition ratio specified in this invention maximizes the system's endothermic efficiency and provides superior refrigeration performance. Furthermore, the raw materials are all common, non-toxic, and harmless inorganic salts, resulting in a mild and environmentally safe reaction, suitable for food and pharmaceutical transportation where high cold chain logistics safety is required. This formulation optimizes the system's cold release rate and duration, achieving a more efficient and stable refrigeration effect, and possesses significant potential for engineering applications. Attached Figure Description

[0022] 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 embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0023] Figure 1 This is a graph showing the temperature drop of refrigerants with different ratios of potassium dihydrogen phosphate and sodium bicarbonate in Example 1.

[0024] Figure 2 This is a graph showing the percentage temperature reduction of refrigerants with different ratios of potassium dihydrogen phosphate and sodium bicarbonate in Example 1.

[0025] Figure 3 This is a graph showing the temperature drop of the refrigerant in Example 2 with different amounts of potassium dihydrogen phosphate and sodium bicarbonate.

[0026] Figure 4 This is a graph showing the percentage decrease in temperature of the refrigerant in Example 2 with different amounts of potassium dihydrogen phosphate and sodium bicarbonate.

[0027] Figure 5 The image shows the EDS spot scan results of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:1.4.

[0028] Figure 6 This is a thermal image of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:0.4 before the reaction. Figure 6 In the equation 'a' corresponds to before the reaction, Figure 6 b corresponds to the reaction after;

[0029] Figure 7 This is a thermal image of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:0.6 before the reaction. Figure 7 In the equation 'a' corresponds to before the reaction, Figure 7 b corresponds to the reaction after;

[0030] Figure 8 This is a thermal image of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:0.8 before the reaction. Figure 8 In the equation 'a' corresponds to before the reaction, Figure 8 b corresponds to the reaction after;

[0031] Figure 9 This is a thermal image of the refrigerant before the reaction of potassium dihydrogen phosphate and sodium bicarbonate in Example 1 with a molar ratio of 1:1. Figure 9 In the equation 'a' corresponds to before the reaction, Figure 9 b corresponds to the reaction after;

[0032] Figure 10 This is a thermal image of the refrigerant before reaction in Example 1, where the molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1.2. Figure 10 In the equation 'a' corresponds to before the reaction, Figure 10 b corresponds to the reaction after;

[0033] Figure 11 This is a thermal image of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:1.4 before the reaction, wherein... Figure 11 In the equation 'a' corresponds to before the reaction, Figure 11 b corresponds to the reaction after;

[0034] Figure 12 This is a thermal image of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:1.6 before the reaction, wherein... Figure 12 In the equation 'a' corresponds to before the reaction, Figure 12 b corresponds to the reaction after;

[0035] Figure 13 This is a thermal image of the refrigerant in Example 1 with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:1.8 before the reaction, wherein... Figure 13 In the equation 'a' corresponds to before the reaction, Figure 13 b corresponds to the reaction afterward. Detailed Implementation

[0036] This invention provides a refrigerant for cold chain transportation, comprising the following components: potassium dihydrogen phosphate, sodium bicarbonate, and water.

[0037] In this invention, the molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1 to 1.8, preferably 1:1.2 to 1.6, and more preferably 1:1.3 to 1.5; the amount of potassium dihydrogen phosphate and water added is 22.1 to 44.2 mmol: 20 mL, preferably 33.15 to 44.2 mmol: 20 mL, and more preferably 39.78 to 44.2 mmol: 20 mL.

[0038] In this invention, the molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1.4.

[0039] In this invention, the ratio of potassium dihydrogen phosphate, sodium bicarbonate and water is 44.2 mmol: 61.88 mmol: 20 mL.

[0040] This invention also provides a method for preparing a refrigerant for cold chain transportation, comprising the following steps:

[0041] Potassium dihydrogen phosphate, sodium bicarbonate, and water are mixed to obtain a refrigerant for cold chain transportation.

[0042] The present invention also provides an application of a refrigerant for cold chain transportation, wherein the application method involves placing the freshly prepared refrigerant for cold chain transportation and the transported goods in the same enclosed space for refrigeration.

[0043] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] Dissolve 22.1 mmol of potassium dihydrogen phosphate and 30.94 mmol of sodium bicarbonate in 20 mL of deionized water to obtain a refrigerant for cold chain transportation.

[0046] By determining the amount of potassium dihydrogen phosphate and changing the amount of sodium bicarbonate added (the molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.6, and 1:1.8 respectively), different refrigerants can be obtained.

[0047] The cooling effect of refrigerants with different molar ratios of potassium dihydrogen phosphate and sodium bicarbonate was tested (cooling effect includes temperature drop and percentage temperature drop; the temperature drop test method was real-time monitoring with an infrared thermal imager (fixed time 3 minutes, monitoring the liquid center temperature), and the percentage temperature drop was calculated as: percentage drop = (initial liquid temperature - equilibrium temperature after cooling) / initial temperature); the temperature drop graph is shown below. Figure 1 As shown in the graph, the percentage of temperature decrease is as follows: Figure 2 As shown, through Figure 1 and Figure 2 It can be seen that when the amount of potassium dihydrogen phosphate is fixed, as the amount of sodium bicarbonate added increases from 1:0.4 to 1:1.4, the temperature difference (ΔT) of the system shows a continuous upward trend, indicating that the endothermic effect of the reaction is enhanced with the increase of sodium bicarbonate concentration. When the ratio exceeds 1:1.4, the temperature difference tends to stabilize (ΔT fluctuation ≤ 0.1℃), indicating that the reaction is close to equilibrium at this point, and further increasing the amount of sodium bicarbonate no longer significantly improves the refrigeration effect. Based on the principle of balancing "efficiency" and "cost", the optimal ratio range of potassium dihydrogen phosphate to sodium bicarbonate is determined to be 1:1 to 1.8.

[0048] Example 2

[0049] Based on Example 1, while maintaining the molar ratio of potassium dihydrogen phosphate to sodium bicarbonate at 1:1.4, the concentrations of potassium dihydrogen phosphate and sodium bicarbonate were scaled up proportionally by 1.5 times and 2 times, and the cooling effect was tested (as above); the temperature drop graph is shown below. Figure 3As shown in the graph, the percentage of temperature decrease is as follows: Figure 4 As shown (labeled accordingly as 1x group, 1.5x group, and 2x group based on magnification). Through Figure 3 and Figure 4 It can be seen that the cooling effect of the refrigerant increases significantly with the increase of potassium dihydrogen phosphate and sodium bicarbonate dosage. Specifically, the cooling effect of the 2x group of refrigerant is approximately 1.7 times that of the 1x group. However, due to the limitation of deionized water solvent, excessive reagents can lead to supersaturation of the solution and incomplete reaction.

[0050] Experimental Example 1

[0051] Electron microscopy (EDS) spot scanning was performed on a refrigerant with a molar ratio of potassium dihydrogen phosphate to sodium bicarbonate of 1:1.4. The results are as follows: Figure 5 As shown, according to theoretical derivation, the ratio of C to Na atoms in the sample before the reaction should be 1:1. Experimental results show that the number of C atoms in the system significantly decreases after the reaction, a phenomenon consistent with the prediction that "CO2 is generated and leaves the system." Combining the above experimental phenomena with theoretical logic, the rationality of the inferred reaction formula "NaHCO3 + KH2PO4 → NaKHPO4 + CO2↑ + H2O" can be verified.

[0052] Experiment Example 2

[0053] Thermal images of the refrigerant before and after the reaction were tested for refrigerant ratios of 1:0.4, 1:0.6, 1:0.8, 1:1, 1:1.2, 1:1.6, 1:1.4, and 1:1.8 in Example 1, respectively, and were respectively corresponding to Figures 6-13 ,in, Figures 6-13 In the diagram, 'a' corresponds to the thermal image of the refrigerant before the reaction. Figures 6-13 In the diagram, 'b' corresponds to the thermal imaging image after the refrigerant reaction. (Through...) Figures 6-13 Experimental results show that as the proportion of NaHCO3 increases, the cooling effect of the refrigerant significantly improves, and the temperature drop gradually increases. Particularly at a ratio of 1:1.4, the refrigerant exhibits the best cooling effect, with the fastest cooling rate and the most significant temperature reduction. Further observation revealed that when the proportion of sodium bicarbonate exceeds this value, the cooling effect tends to stabilize, and the release of cold energy reaches saturation. This indicates that this ratio has reached the optimal equilibrium point for the system reaction, effectively avoiding the problems of reduced energy efficiency or runaway reaction caused by excessive reactants.

[0054] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A refrigerant for cold chain transportation, characterized in that, It includes the following components: Potassium dihydrogen phosphate, sodium bicarbonate, and water; The molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1 to 1.

8. The amount of potassium dihydrogen phosphate added to water is 22.1–44.2 mmol: 20 mL.

2. The refrigerant for cold chain transportation according to claim 1, characterized in that, The molar ratio of potassium dihydrogen phosphate to sodium bicarbonate is 1:1.

4.

3. The refrigerant for cold chain transportation according to claim 2, characterized in that, The ratio of potassium dihydrogen phosphate, sodium bicarbonate, and water used is 44.2 mmol: 61.88 mmol: 20 mL.

4. A method for preparing a refrigerant for cold chain transportation according to any one of claims 1 to 3, characterized in that, Includes the following steps: Potassium dihydrogen phosphate, sodium bicarbonate, and water are mixed to obtain a refrigerant for cold chain transportation.

5. The application of the refrigerant for cold chain transportation according to any one of claims 1 to 3, characterized in that, The application method involves placing the pre-mixed refrigerant for cold chain transportation and the transported goods in the same enclosed space for refrigeration.

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