Method for measuring liquid material temperature using solubility of low-temperature agar gel particles

Abstract

The present invention relates to a method for measuring the temperature of a liquid material by utilizing the solubility of low-temperature agar gel particles, comprising S1, preparing low-temperature fast-dissolving agar gel particles; S2, measuring the temperature of the liquid material; and S3, measuring the temperature distribution of the liquid material. The present invention utilizes low-temperature fast-dissolving agar to prepare agar gel particles, places the particles into a hollow container and places the particles in a constant-temperature water bath, heats the particles at different temperatures, calculates the agar dissolution rates corresponding to different dissolution times at a fixed temperature, and establishes a mathematical model of agar dissolution rate, dissolution time, and dissolution temperature. The established model is used to calculate the liquid temperature and temperature distribution according to the dissolution rates corresponding to the different dissolution times actually measured. The temperature measurement effect is good, and the effect of quickly and conveniently measuring the liquid temperature can be achieved. The measurement cost is low, the preparation process is simple, and the requirements for process equipment conditions are not high. The production cost of the enterprise can be effectively reduced, and large-scale production is convenient, which has practical application significance.

Description

Technical Field

[0001] The invention belongs to the technical field of temperature measurement, relates to temperature measurement of liquid materials, and particularly relates to a method for measuring the temperature of liquid materials by utilizing the solubility of low-temperature agar gel particles. Background Art

[0002] Sterilization is a critical technology in liquid food processing. To ensure sterilization efficiency while maximizing nutrient retention, improving heating uniformity is crucial. Underheating increases microbial risk, while overheating can cause significant nutritional loss and diminish sensory value. Accurate temperature and temperature distribution measurement methods are necessary to determine the temperature and temperature distribution of liquid foods during heating. Currently, commonly used temperature measurement devices for measuring liquid temperatures include thermocouples, fiber optic temperature sensors, and thermal imagers. However, these devices have several drawbacks in determining the heating status of liquid materials. First, the temperature measurement points are fixed, failing to effectively reflect the overall heating status of the liquid. Second, to obtain more accurate temperature and temperature distribution, a sufficient number of temperature probes must be installed, which not only increases costs but also limits the structure of the heating equipment. Third, some technologies, such as microwave and induction heating, cannot use metal probes for temperature measurement due to inherent limitations. Therefore, finding a convenient and reliable method for measuring liquid temperature is crucial in liquid heating applications.

[0003] At present, there are many research reports on liquid temperature measurement methods and systems. Through searching the public patent documents, the following similar public patent documents are found:

[0004] 1. Patent publication number CN113701906A discloses a method for measuring liquid temperature in a liquid cooling circuit. A tee is connected to the pipeline to be measured in the liquid cooling circuit. The thermocouple wire is introduced into the pipeline to be measured through the interface of the tee that is different from the interface connected to the pipeline to be measured, thereby realizing the measurement of the liquid temperature in the cooling circuit.

[0005] 2. Patent publication number CN109708773A discloses a method, processor, and system for measuring liquid temperature. By accurately calculating the loading capacity by analyzing the pressure fluctuations of saturated steam in the sterilization chamber, the temperature fluctuations of the chamber wall, or the sampling temperature fluctuations of the sample container, the comprehensive thermal conductivity coefficient of the container loaded in the chamber is derived. Finally, the average temperature value of the liquid load can be calculated based on the two obtained parameters.

[0006] 3. Patent publication number CN103926018A discloses a device and method for detecting liquid temperature using sound waves, which converts multiple sound wave signals into multiple digital waveform signals, calculates multiple frequencies corresponding to the multiple digital waveform signals based on the received multiple digital waveform signals; compares the calculated frequencies and amplitudes with the stored correspondence table to obtain the real-time temperature.

[0007] The liquid temperature measurement disclosed in the above patent documents is costly and has a complicated process, and the temperature measurement accuracy is not high enough.

[0008] Agar is a hydrophilic colloid extracted from red algae, also known as agar-agar and agar-agar. Its molecular formula is (C12H18O9)n. It has excellent plasticity, and when made into agar gel, it is firmer, less prone to collapse, and more elastic. Furthermore, agar is recognized as a generally recognized safe food additive by the U.S. Food and Drug Administration, with no restrictions on its use in food. Low-temperature, instant agar has excellent temperature-responsiveness, rapidly responding to temperature changes and exhibiting excellent solubility within the 75-100°C temperature range, meeting pasteurization temperature requirements. The present invention proposes a method for measuring the temperature of liquid materials using the solubility of low-temperature agar gel particles. Summary of the Invention

[0009] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for measuring the temperature of liquid materials by utilizing the solubility of low-temperature agar gel particles. The method can accurately measure the temperature distribution within the liquid material and effectively solve the problem of accurately reflecting the temperature of the liquid material during heating and the uniformity of the temperature distribution.

[0010] The present invention solves the technical problem by the following technical solutions:

[0011] A method for measuring the temperature of a liquid material by utilizing the solubility of low-temperature agar gel particles, characterized in that the method comprises the following steps:

[0012] S1. Preparation of low-temperature fast-dissolving agar gel particles

[0013] 1) Weigh a quantity of low-temperature instant agar and place it in a beaker. Add deionized water and stir until the low-temperature instant agar is evenly dispersed to obtain an agar solution.

[0014] 2) heating the agar solution in 1) in a microwave oven. To prevent the liquid from boiling over, remove the liquid and stir it every 30 seconds until a clear solution is obtained.

[0015] 3) Cooling the solution in 2) to room temperature (25°C) to obtain a gel-like agar gel;

[0016] 4) Cut the agar gel prepared in 3) above into 5 mm × 5 mm × 5 mm agar gel particles;

[0017] S2. Liquid material temperature measurement

[0018] Agar gel particles that dissolve at a set temperature are placed in the liquid material. When heated to a certain temperature, the remaining amount of agar gel particles is measured to obtain the average temperature of the liquid material.

[0019] 1) Establish the solubility characteristics of agar, which refers to the change in the dissolution rate of agar at a certain concentration at a certain temperature over time;

[0020]

[0021] Where: X is the agar dissolution rate, %

[0022] m t is the remaining mass of agar at dissolution time t, g

[0023] m0 is the initial mass of agar, g;

[0024] 2) Setting the temperatures of a constant temperature water bath to 85°C, 87.5°C, 90°C, 92.5°C, 95°C, and 97.5°C, respectively, the prepared agar gel particles were placed on a hollow container and heated in a constant temperature water bath. The dissolution rate X of the agar gel particles at different temperatures and different dissolution times t was recorded, and a curve of the change of agar dissolution rate over time at different temperatures was obtained;

[0025] 3) Perform linear fitting on the above curve,

[0026] X=Kt (2)

[0027] K=f(T) (3)

[0028] T is the dissolution temperature; K is the coefficient;

[0029] Further fitting of K and T, according to the values ​​on the change curve, we can get:

[0030] K=3.827-0.08721T+0.000499T 2 (4)

[0031] Substituting formula (4) into formula (2), the relationship between the dissolution rate X of agar gel and the dissolution temperature T and dissolution time t is obtained, as shown in formula (5):

[0032] X=(3.827-0.08721T+0.000499T 2 )×t (5)

[0033] By transforming formula (5), we can obtain the expressions of dissolution temperature, K and t:

[0034] T=85.11+33.00X-0.3216t-16.29X 2 +0.002435t 2 -0.1957X×t (6)

[0035] Place agar gel particles in a heated liquid material, and measure the agar dissolution rate X at a certain heating time t. The temperature T of the liquid material at this time can be calculated using formula (6). This temperature is the average temperature of the liquid material measured using the agar gel particles.

[0036] S3. Liquid material temperature distribution measurement

[0037] 1) Determine the temperature distribution by single measurement: Determine the dissolution temperature T1 at which the agar gel particles are completely dissolved at the dissolution time t1 using formula (6). If the actual measured dissolution rate is X1, that is, X1 agar gel particles are dissolved, then the temperature of the portion of the measured liquid with X1 particles reaching or exceeding temperature T1 is said to have reached or exceeded temperature T1.

[0038] (2) Continuous measurement to determine temperature distribution: Place agar gel particles in the heated liquid material and continuously measure the temperature distribution at certain heating times t1, t2, t3, ..., t n , the agar solubility rates are X1, X2, X3, ...X n ,(X n ≤100%); Determine the corresponding time t1, t2, t3, ..., t n The complete dissolution temperature of agar gel particles is T1, T2, T3, ..., T n The temperature of the portion of the liquid X1 that is measured reaches or exceeds the temperature T1, the temperature of the portion of the liquid X2 that is measured reaches or exceeds the temperature T2, the temperature of the portion of the liquid X3 that is measured reaches or exceeds the temperature T3, ..., the ...3 that is measured reaches or exceeds the temperature T3, ... n The temperature of the part reaches or exceeds the temperature T n ;

[0039] At the same time, the liquid temperature distribution of (X2-X1) is within the interval T2~T1, the liquid temperature distribution of (X3-X2) is within the interval T3~T2, ..., the liquid temperature distribution of (X n -X n-1 ) of the liquid temperature distribution in the interval T n ~T n-1 Within.

[0040] Moreover, in step S1, the heating power of the microwave oven is 500W to 1000W; and the cooling time is 2 to 4 hours.

[0041] Furthermore, in step S3, food coloring can be added to the liquid material, and the temperature of the water bath heating is 80° C. to 100° C.

[0042] The advantages and beneficial effects of the present invention are:

[0043] Compared with the prior art, the present invention establishes a mathematical model for the solubility of low-temperature fast-dissolving agar particles, thereby utilizing the solubility of agar gel to measure the liquid temperature. The temperature measurement effect is good, and the effect of quickly and conveniently measuring the liquid temperature can be achieved.

[0044] At the same time, the measurement process is low-cost, the preparation process is simple, and the requirements for process equipment conditions are not high. It can be applied to the liquid food industry and related industries in the future. It can effectively reduce the production costs of enterprises and facilitate large-scale production, which has practical application significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The dissolution rate curves of agar gel particles with a concentration of 1% at different temperatures according to an embodiment of the present invention are as follows; (a) represents the dissolution rate of agar gel particles at a temperature of 87.5°C; (b) represents the dissolution rate of agar gel particles at a temperature of 90°C; (c) represents the dissolution rate of agar gel particles at a temperature of 92.5°C; and (d) represents the dissolution rate of agar gel particles at a temperature of 95°C.

[0046] Figure 2 This is a comparison chart of the dissolution rates of agar gel particles with a concentration of 1% at different temperatures according to an embodiment of the present invention;

[0047] Figure 3 1 is a comparison chart of the measured temperatures according to Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the scope of protection of the present invention cannot be limited thereto.

[0049] A method for measuring the temperature of liquid materials by utilizing the solubility of low-temperature agar gel particles is innovative in that the method comprises the following steps:

[0050] S1. Preparation of low-temperature fast-dissolving agar gel particles

[0051] 1) Weigh 1 g of low-temperature instant agar and place it in a 250 mL beaker. Add 100 mL of deionized water and stir until the low-temperature instant agar is evenly dispersed to obtain an agar solution.

[0052] 2) heating the agar solution in 1) in a microwave oven at 1000 W. To prevent the liquid from boiling over, remove the liquid and stir it every 30 seconds until a clear solution is obtained.

[0053] 3) Cooling the solution in 2) to room temperature (25°C) to obtain a gel-like agar gel;

[0054] 4) Cut the agar gel prepared in 3) above into 5 mm × 5 mm × 5 mm agar gel particles;

[0055] S2. Liquid material temperature measurement

[0056] Agar gel particles that dissolve at a set temperature are placed in the liquid material. When heated to a certain temperature, the remaining amount of agar gel particles is measured to obtain the average temperature of the liquid material.

[0057] 1) Establish the solubility characteristics of agar, which refers to the change in the dissolution rate of agar at a certain concentration at a certain temperature over time;

[0058]

[0059] Where: X is the agar dissolution rate, %

[0060] m t is the remaining mass of agar at dissolution time t, g

[0061] m0 is the initial mass of agar, g;

[0062] 2) The temperatures of the constant temperature water bath are set to 85°C, 87.5°C, 90°C, 92.5°C, 95°C and 97.5°C respectively. The prepared agar gel particles are placed on a hollow container and placed in a constant temperature water bath for heating. At the same time, the dissolution rate X of the agar gel particles at different temperatures and different dissolution times t is recorded to obtain the change curve of the agar dissolution rate at different temperatures over time, as shown in FIG. Figure 1 、 2 As shown;

[0063] 3) Perform linear fitting on the above curve,

[0064] X=Kt (2)

[0065] K=f(T) (3)

[0066] T is the dissolution temperature; K is the coefficient;

[0067] According to the attached Figure 1 The K value at different temperatures T can be obtained, as shown in Table 1.

[0068] Table 1 Relationship between K value and temperature at different temperatures T

[0069] K T / ℃ 0.0183 87.5 0.0253 90 0.0341 92.5 0.0454 95 0.073 97.5

[0070] Further fitting of K and T in Table 1, according to the values ​​on the change curve, we can get:

[0071] K=3.827-0.08721T+0.000499T 2 (4)

[0072] Substituting formula (4) into formula (2), the relationship between the dissolution rate X of agar gel and the dissolution temperature T and dissolution time t is obtained, as shown in formula (5):

[0073] X=(3.827-0.08721T+0.000499T 2 )×t (5)

[0074] By transforming formula (5), we can obtain the expressions of dissolution temperature, K and t:

[0075] T=85.11+33.00X-0.3216t-16.29X 2 +0.002435t 2 -0.1957X×t (6)

[0076] Place agar gel particles in a heated liquid material, and measure the agar dissolution rate X at a certain heating time t. The temperature T of the liquid material at this time can be calculated using formula (6). This temperature is the average temperature of the liquid material measured using the agar gel particles.

[0077] S3. Liquid material temperature distribution measurement

[0078] 1) Single measurement to determine the temperature distribution: The dissolution temperature T1 at which the agar gel particles are completely dissolved at the dissolution time t1 is determined by formula (6). If the actual measured dissolution rate is X1, that is, X1 agar gel particles are dissolved, then the temperature of the measured liquid with X1 particles reaching or exceeding the temperature T1 is said to be reached. (2) Continuous measurement to determine the temperature distribution: The agar gel particles are placed in the heated liquid material, and the temperature distribution is determined by continuously measuring the temperature at certain heating times t1, t2, t3, ..., t n , the agar solubility rates are X1, X2, X3, ...X n ,(X n ≤100%); Determine the corresponding time t1, t2, t3, ..., t n The complete dissolution temperature of agar gel particles is T1, T2, T3, ..., T nThe temperature of the portion of the liquid X1 that is measured reaches or exceeds the temperature T1, the temperature of the portion of the liquid X2 that is measured reaches or exceeds the temperature T2, the temperature of the portion of the liquid X3 that is measured reaches or exceeds the temperature T3, ..., the ...3 that is measured reaches or exceeds the temperature T3, ... n The temperature of the part reaches or exceeds the temperature T n ;

[0079] At the same time, the liquid temperature distribution of (X2-X1) is within the interval T2~T1, the liquid temperature distribution of (X3-X2) is within the interval T3~T2, ..., the liquid temperature distribution of (X n -X n-1 ) of the liquid temperature distribution in the interval T n ~T n-1 As shown in Table 2.

[0080] Table 2 Measurement principle of temperature distribution using agar

[0081] Temperature range ratio <![CDATA[>T1]]> <![CDATA[X1]]> <![CDATA[T2-T1]]> <![CDATA[X2-X1]]> … … <![CDATA[T n -T n-1 ]]> <![CDATA[X n -X n-1 ]]>

[0082] Record the dissolution rate of the added agar at 5s, 10s, and 15s; substitute 5s, 10s, 15s and X as 1 into the resulting mathematical model T = 85.11 + 33.00X - 0.3216t - 16.29X 2 +0.002435t 2 -0.1957X×t, the temperatures at which the agar particles are completely dissolved in 5s, 10s, and 15s are 94℃, 93.2℃, and 92℃, respectively.

[0083] The measurement results show that the dissolution rate is 13.8% at 5s. According to formula (6), the temperature required for the complete dissolution of agar after heating for 5s is 94℃. Therefore, 13.8% of the overall temperature of the measured liquid material reaches or exceeds 94℃, and correspondingly, 86.2% of the temperature is below 94℃. Similarly, the dissolution rate of 26% at 10s reflects that 74% of the temperature of the measured liquid material is below 93.2℃. The dissolution rate of 40% at 15s reflects that 60% of the temperature of the measured liquid material is below 92℃.

[0084] Based on the two descriptions that 86.2% of the measured liquid has a temperature below 94°C and 74% has a temperature below 93.2°C, we can see that 12.2% of the measured liquid has a temperature between 93.2°C and 94°C. Similarly, 14% of the measured liquid has a temperature between 92°C and 93.2°C. Based on the above discussion, the partial temperature distribution range of the measured liquid can be determined, as shown in Table 4.

[0085] Comparative Example 1: Thermocouple Temperature Measurement Method

[0086] Place 100mL of water in a 250mL beaker, and place the beaker in the microwave cavity of a ZDM-2B microwave multifunctional heating platform for heating (set power to 1000w, heating time 3min). After heating, use a thermocouple sensor to measure the water temperature in the cup. The measurement results are as follows: Figure 3 , as shown in Table 3.

[0087] like Figure 3 As shown in Table 3, in the Examples of the present invention and Comparative Example 1, the results show that the maximum temperature difference between the temperature measurement using agar and the temperature measurement using a thermocouple is 0.3° C., and the maximum error is within 5%, indicating that the temperature measurement results using the agar dissolution model are accurate.

[0088] Table 3 Comparison of measured temperatures of the embodiment of the present invention and comparative example 1

[0089] Time / s Dissolution rate / % Agar fitting temperature / ℃ Thermocouple measurement temperature / ℃ 30 10％ 80 79.8±0.2 50 21％ 79.27 78.8±0.2 70 21％ 77.73 77.4±0.1 90 59％ 79.25 78.9±0.1

[0090] Comparative Example 2: Fiber Optic Probe Measuring Temperature Distribution

[0091] 100 mL of water was placed in a 250 mL beaker, and the beaker was placed in the microwave cavity of a ZDM-2B microwave multifunctional heating platform for heating (the set power was 500 W and the heating time was 4 min). After the heating was completed, two sets of fiber optic probes were used to continuously change their positions to measure the temperatures of the cold and hot spots in the beaker to obtain the maximum temperature difference in the water. The experimental results are shown in Table 5.

[0092] As shown in Tables 4 and 5, in Comparative Example 2, the temperature distribution measured using agar is within the range of the highest and lowest temperatures measured by the optical fiber probe, which indirectly proves the accuracy of the temperature distribution range measured using agar. Although the actual measured range is limited by the solubility properties of agar, this provides a new idea for measuring the uneven distribution of liquids and can effectively reflect the proportion of liquid within certain specific temperature ranges to the total liquid volume. It is a new means of measuring temperature distribution.

[0093] Table 4 Temperature distribution of liquid materials in the embodiment of the present invention

[0094] Temperature range ratio ＞94℃ 13.8％ 93.2℃-94℃ 12.2％ 92℃-93.2℃ 14％ ＜92℃ 60％

[0095] Table 5 Measurement temperature distribution table of the embodiment of the present invention and comparative example 2

[0096] Time / s Minimum temperature / ℃ Maximum temperature / ℃ 5s 88.03 96.8 10s 88.43 96.3 15s 88.53 95.9

[0097] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A method for measuring the temperature of a liquid material by utilizing the solubility of low-temperature agar gel particles, characterized in that: The steps of the method include: S1. Preparation of low-temperature fast-dissolving agar gel particles 1) Weigh a certain amount of low-temperature instant agar and place it in a beaker. Add deionized water and stir until the low-temperature instant agar is evenly dispersed to obtain an agar solution. 2) Heat the agar solution from 1) in a microwave oven. To prevent violent boiling, remove the liquid and stir it every 30 seconds until a clear solution is obtained. 3) Cooling the solution in step 2) to room temperature (25°C) to obtain a gel-like agar gel; 4) Cut the agar gel prepared in step 3) above into 5 mm × 5 mm × 5 mm agar gel pellets; S2. Liquid material temperature measurement Agar gel particles that dissolve at a set temperature are placed in the liquid material. When heated to a certain temperature, the remaining amount of agar gel particles is measured to obtain the average temperature of the liquid material. 1) Establish the solubility characteristics of agar, which refers to the change in the dissolution rate of agar at a certain concentration at a certain temperature over time; Where: X is the agar dissolution rate, %; m t is the mass of agar remaining at the dissolution time t, g; m0 is the initial mass of agar, g; 2) Set the temperature of a constant temperature water bath to 85°C, 87.5°C, 90°C, 92.5°C, 95°C, and 97.5°C, respectively. Place the prepared agar gel particles on a hollow container and heat it in the constant temperature water bath. Simultaneously, record the dissolution rate X of the agar gel particles at different temperatures and different dissolution times t to obtain a curve of the change of agar dissolution rate over time at different temperatures. 3) Perform a linear fit on the above curve, X = Kt (2) K = f (T) (3) T is the dissolution temperature; K is the linear coefficient; Further fitting of K and T, according to the values ​​on the change curve, we can get: Substituting formula (4) into formula (2), we can obtain the relationship between the dissolution rate X of agar gel and the dissolution temperature T and dissolution time t, as shown in formula (5): X = (3.827-0.08721T+0.000499T²)×t (5) By transforming formula (5), we can obtain the expressions of dissolution temperature, X, and t: T=85.11+33.00X-0.3216t-16.29X²+ 0.002435t²-0.1957X×t (6) Place agar gel particles in a heated liquid material, and measure the agar dissolution rate X at a certain heating time t. The temperature T of the liquid material at this time can be calculated using formula (6). This temperature T is the average temperature of the liquid material measured using the agar gel particles. S3. Liquid material temperature distribution measurement 1) Determine the temperature distribution by single measurement: Determine the dissolution temperature T1 at which the agar gel particles are completely dissolved at the dissolution time t1 using formula (6). If the actual measured dissolution rate is X1, that is, X1 agar gel particles are dissolved, then the temperature of the portion of the measured liquid with X1 particles reaching or exceeding temperature T1 is said to have reached or exceeded temperature T1. (2) Continuous measurement to determine temperature distribution: Place agar gel particles in the heated liquid material and continuously measure the temperature distribution at certain heating times t1, t2, t3, ..., t n , the agar solubility rates are X1, X2, X3, ..., X n , X n ≤100%; determine the corresponding time t1, t2, t3, ..., t n The complete dissolution temperature of agar gel particles is T1, T2, T3, ..., T n The temperature of the portion of the liquid X1 that is measured reaches or exceeds the temperature T1, the temperature of the portion of the liquid X2 that is measured reaches or exceeds the temperature T2, the temperature of the portion of the liquid X3 that is measured reaches or exceeds the temperature T3, ..., the ...3 that is measured reaches or exceeds the temperature T3, ... n The temperature of the part reaches or exceeds the temperature T n ; At the same time, the liquid temperature distribution of (X2-X1) is within the interval T2~T1, the liquid temperature distribution of (X3-X2) is within the interval T3~T2, ..., the liquid temperature distribution of (X n -X n-1 ) of the liquid temperature distribution in the interval T n ~T n-1 Within.

2. The method for measuring the temperature of a liquid material by utilizing the solubility of low-temperature agar gel particles according to claim 1, wherein: In step S1, the heating power of the microwave oven is 500W to 1000W; and the cooling time is 2 to 4 hours.

3. The method for measuring the temperature of a liquid material by utilizing the solubility of low-temperature agar gel particles according to claim 1, wherein: In step S3, food coloring is added to the liquid material, and the temperature of the water bath is heated at 80° C. to 100° C.

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