Multi-phase high-viscosity dish heat and mass transfer optimization method based on direct steam injection

Abstract

The invention relates to the technical field of food industrial processing and computer simulation, in particular to a multiphase high-viscosity dish heat and mass transfer optimization method based on CFD simulation steam direct injection. Firstly, a heat and mass transfer model of a steam-material system is established, and a steam flow path, a temperature field and heat transfer characteristics are simulated; and steam direct injection parameters are dynamically regulated and controlled based on a simulation result, so that the contact efficiency of the steam and the high-viscosity material is maximized. According to the method, the heat transfer efficiency is improved by 30% or above compared with that of a traditional process, the texture characteristics, color stability and nutritional ingredients of dishes are effectively kept by accurately controlling heat flow distribution, and it is ensured that the sterilization effect reaches the standard. According to the method, numerical simulation and process optimization are deeply combined, the technical bottleneck of low heat and mass transfer efficiency of a multi-phase high-viscosity system is solved, and an efficient and energy-saving steam direct injection regulation and control scheme is provided for industrial production of prefabricated dishes.

Description

Technical Field

[0001] The present invention relates to the field of food industrial processing (classification number: A23L) and computer simulation technology, and particularly relates to a method for optimizing heat and mass transfer of multi-phase high-viscosity dishes by simulating direct steam injection based on CFD (Computational Fluid Dynamics). Background Art

[0002] Steam heating technology is widely used in the food industry, especially in the processing of multi-phase high-viscosity foods. Traditional steam heating methods usually achieve heat transfer through direct contact between steam and materials. However, due to the poor fluidity of multi-phase high-viscosity foods, the contact efficiency between steam and materials is relatively low, resulting in slow heat transfer speed and large energy consumption. For high-viscosity and high-moisture dishes such as Yu-Shiang Shredded Pork, Sweet and Sour Pork Tenderloin, and Fish Maw Chicken Soup, the traditional steam heating method has the following problems: (1) Uneven heat transfer: Due to the viscosity of the materials, steam is difficult to quickly penetrate into the interior of the materials, resulting in faster external heating and slower internal heating. (2) Energy waste: The contact efficiency between steam and materials is relatively low. When the steam temperature and pressure are too high, heat waste is likely to occur, affecting the effective utilization of heat. (3) Fluctuation in dish quality: Due to inaccurate control of the heating process, the taste, color, and nutritional components of the dishes are easily affected. Especially during the heating process, if the steam temperature is too high or the heating time is too long, the quality of the dishes may decline.

[0003] Therefore, there is an urgent need for a technology that can optimize the conditions of direct steam injection, improve the heat transfer efficiency, and ensure high quality of prefabricated dishes. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention optimizes the heat transfer efficiency of multi-phase high-viscosity dishes by establishing a heat and mass transfer model based on CFD simulation and optimizing the process parameters of direct steam injection; by optimizing process conditions such as the temperature, pressure, injection angle, and flow rate of steam, the contact efficiency between steam and dish materials is improved, thereby increasing the heating speed, reducing heat loss, and ensuring the quality of the dishes.

[0005] The present invention provides a method for optimizing heat and mass transfer of multi-phase high-viscosity dishes based on direct steam injection, including the following steps:

[0006] S1. Establish a mathematical model of heat transfer and fluid dynamics through CFD software to simulate the heat and mass transfer process between steam and dish materials;

[0007] S2. Adjust the process parameters of steam injection according to the simulation results of step S1;

[0008] S3. Evaluate the rationality of the model through the heat transfer efficiency and the sterilization effect F value.

[0009] To accurately simulate the heat and mass transfer process between steam and highly viscous multiphase materials, a CFD mathematical model combining heat transfer and fluid dynamics is used. The conduction, convection, and phase change processes between steam and materials are considered.

[0010] Furthermore, in step S1, the mathematical model includes a heat convection model, a heat conduction model, and a phase change and steam-material heat exchange model. Through these models, the flow path of steam, the temperature distribution of materials, and the simulation of the heat transfer process are simulated; the contact time between the fluid and the materials, the injection speed of steam, and the heat exchange efficiency between steam and materials are calculated.

[0011] Furthermore, the heat convection model: is used to predict the heat convection transfer efficiency between steam and the material surface; the heat convection model: during the direct injection of steam, steam transfers heat to the material surface by convection. In the CFD model, the Navier-Stokes equations are used to describe the flow behavior of steam, and the heat conduction equation is combined to describe the heat transfer. The rate of convective heat transfer is determined by the Nusselt number, and the Nusselt number is related to the Reynolds number and the Prandtl number:

[0012] Nu = C * Re m * Pr n

[0013] where Nu is the Nusselt number, Re is the Reynolds number, Pr is the Prandtl number, and C, m, n are empirical constants.

[0014] The heat conduction model: predicts the heat distribution during the heating process by simulating the temperature change inside the material; the heat conduction model: after steam contacts the material, heat conducts from the steam through the material surface to the inside. In the CFD model, Fourier's law is used to describe the heat conduction process:

[0015]

[0016] where q is the heat flux density, k is the thermal conductivity of the material, is the temperature gradient.

[0017] Furthermore, the phase change and steam-material heat exchange model: in the CFD simulation, the energy equation is used to consider the latent heat exchange between steam and materials. Phase change and steam-material heat exchange: when steam is directly injected onto the surface of the dish, the steam will undergo a phase change, and part of the steam will condense into water, releasing a large amount of latent heat, which significantly improves the heat exchange efficiency. The heat release during the phase change can be described by the following formula:

[0018] Q = m * h f

[0019] Among them, m is the mass flow rate of steam condensation, and h f is the latent heat of the steam.

[0020] Furthermore, in step S2, the process parameters include but are not limited to steam temperature, steam pressure, steam injection angle, and steam flow rate.

[0021] Furthermore, in step S3, the heat transfer efficiency is calculated by the following formula:

[0022]

[0023] Where: Q 有效 is the heat effectively transferred to the material, that is, the heat actually raising the temperature of the material; Q 总 is the total input heat, that is, the total heat brought by the steam;

[0024] Q 总 = m 蒸汽 * c 蒸汽 *(T 蒸汽 - T 环境 )

[0025] Where: m 蒸汽 is the steam flow rate; c 蒸汽 is the specific heat capacity of the steam; T 蒸汽 is the temperature of the steam; T 环境 is the ambient temperature when the steam contacts the material.

[0026] Furthermore, in step S3, the calculation formula for the sterilization effect F value:

[0027]

[0028] Where: F is the F value of the sterilization process, in minutes; T (t) is the temperature at time t; T0 is the reference temperature; Z is the influence coefficient of temperature on the sterilization effect.

[0029] Furthermore, the multi-phase high-viscosity dish is a dish with a soup viscosity greater than 200 mPa·s;

[0030] In some embodiments of the present invention, the multi-phase high-viscosity dishes include but are not limited to shredded pork with fish flavor, chicken with fish maw, and sweet and sour pork tenderloin.

[0031] Furthermore, the physical properties of the main ingredients in the dish are simulated by setting the material size and material viscosity in the software.

[0032] In one embodiment, the multiphase high-viscosity dish is shredded pork with fish flavor. In the CFD software, the dimensions of the dish are set to 44.81 cm in length * 4.48 cm in width * 4.48 cm in height. The main ingredients (bamboo shoot shreds and meat) are set to strips with dimensions of 5 cm in length * 0.5 cm in width * 0.5 cm in height, accounting for 52.5%. The sauce accounts for 30% in the dish, and the sauce viscosity is 200 mPa·s.

[0033] In one embodiment, the multiphase high-viscosity dish is sweet and sour pork tenderloin. In the CFD software, the dimensions of the dish are set to 24.66 cm in length * 7.40 cm in width * 4.93 cm in height. The main ingredient is a meat strip, set to a strip with dimensions of 5 cm in length * 1.5 cm in width * 1.0 cm in height. The sauce accounts for 17.5% in the dish, and the sauce viscosity is 200 mPa·s.

[0034] In one embodiment, the multiphase high-viscosity dish is fish maw and chicken. In the CFD software, the dimensions of the dish are set to 9.66 cm in length * 9.66 cm in width * 9.66 cm in height. The main ingredient is a chicken piece, set to a piece with dimensions of 1.5 cm in length * 1.5 cm in width * 1.5 cm in height. The sauce accounts for 71.4% in the dish, and the sauce viscosity is 200 mPa·s.

[0035] In some embodiments, the process conditions of the multiphase high-viscosity dish optimized by the method are that the steam temperature is 100°C to 130°C, the pressure is 1.2 MPa to 1.5 MPa, the injection angle is direct injection, and the flow rate is 10 kg / h to 15 kg / h.

[0036] In some embodiments, the CFD software is ANSYS Fluent.

[0037] In some embodiments, in step S3, by comparing the improvement amplitude of the heat transfer efficiency of the comparative example, the optimized processing parameters are evaluated. Preferably, the improvement amplitude of the heat transfer efficiency ≥ 30%.

[0038] The beneficial effects produced by the present invention at least include:

[0039] 1. Through computer CFD simulation, the present invention establishes an optimization method for heat and mass transfer of multiphase high-viscosity dishes based on steam direct injection processing, which has universality and is applicable to the processing of various multiphase high-viscosity prefabricated dishes.

[0040] 2. By constructing a heat and mass transfer mathematical model: establishing a heat and mass transfer model between steam and dish materials, simulating the flow path, temperature distribution and heat transfer process of steam on the surface and inside of the materials; it can more accurately predict the physical property parameters of multiphase high-viscosity dish foods, avoiding the subjectivity and cumbersome nature of experiments.

[0041] 3. The method of the present invention can effectively improve the heat transfer efficiency and mass transfer efficiency during the processing of multi-phase high-viscosity dish-like foods, thereby improving the product quality. By controlling the process parameters of direct steam injection, optimizing the heat distribution, reducing heat loss, and ensuring that the taste, color, nutritional components, and sterilization effect of the dishes reach the best state.

[0042] 4. During the actual production process, the heat transfer efficiency is increased by 30% compared with the traditional method. For the optimized processing technology obtained, the F value of the sterilization process is 3.5 to 4.5, and the sterilization effect is significantly better than the traditional method. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings are used to provide a further understanding of the present application, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application, and do not constitute a limitation to the present application. In the drawings:

[0044] Figure 1 Flow chart of the optimized process of direct steam injection;

[0045] Figure 2 Heat transfer efficiency diagram of shredded pork with fish flavor under optimized conditions;

[0046] Figure 3 Heat transfer efficiency diagram of sweet and sour pork tenderloin under optimized conditions;

[0047] Figure 4 Heat transfer efficiency diagram of fish maw and chicken soup under optimized conditions. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention will be given in conjunction with the embodiments of the specification.

[0049] In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0050] Experimental apparatus: A fully automatic electric heating steam generator is used for direct steam injection; a cooking pot is used for the comparative example;

[0051] Model design of each embodiment: Referring to the high-viscosity dish formula and physical properties collected from the market below, the whole dish and the main ingredients are simulated.

[0052] Shredded pork with fish flavor: A total of 400 g, 120 g of sauce, 130 g of shredded bamboo shoots, 80 g of meat, 60 g of green peppers, 10 g of black fungus;

[0053] CFD simulation of the dish container size: 44.81 cm in length * 4.48 cm in width * 4.48 cm in height, the size of the main ingredients (bamboo shoot shreds and shredded meat): 5 cm in length * 0.5 cm in width * 0.5 cm in height.

[0054] Sweet and Sour Pork Tenderloin: A total of 400 g, with 70 g of sauce poured and 330 g of pork tenderloin;

[0055] CFD simulation of the dish container size: 24.66 cm in length * 7.40 cm in width * 4.93 cm in height, the size of the main ingredient (pork tenderloin): 5 cm in length * 1.5 cm in width * 1.0 cm in height

[0056] Fish Maw Chicken Soup: A total of 560 g, with 400 g of concentrated soup, 52 g of coix seed, 40 g of chicken, 33 g of mushrooms, 32 g of fish maw, and 3 g of abalone; the size of the dish container: 9.66 cm in length * 9.66 cm in width * 9.66 cm in height, the size of the main ingredient (chicken pieces): 1.5 cm in length * 1.5 cm in width * 1.5 cm in height.

[0057] Evaluation method: Input the physical properties of the collected multi-phase highly viscous dishes into the model of the CFD software, including the size of the heat and mass transfer area of the dishes (the dish size in the following text), the proportion of the highly viscous materials in the dishes, and the proportion / viscosity of the main ingredients; then adjust various process parameters based on the conventional heating method of the dishes; evaluate the rationality of the model according to the heat transfer efficiency and sterilization F value obtained from the simulation. After obtaining the optimal process conditions through the simulation, then conduct actual experiments according to the conditions obtained from the model to verify the effect of the model. Among them, the sterilization effect of the sterilization F value is compared with the time of spoilage during storage at room temperature.

[0058] Evaluation indicators:

[0059] 1. Heat transfer efficiency calculation formula

[0060] The heat transfer efficiency usually represents the effective utilization degree of heat during the heating process and is usually measured by "thermal efficiency" or "heat transfer efficiency". When calculating the heat transfer efficiency, the comparative analysis method of heat flow is often used, that is, comparing the heat input during the heating process and the heat effectively transferred. The heat transfer efficiency (η) can be calculated by the following formula:

[0061]

[0062] Where: Q 有效 is the heat effectively transferred to the material, that is, the heat actually raising the temperature of the material; Q 总 is the total heat input, that is, the total heat brought by the steam.

[0063] The effectively transferred heat can be obtained through simulation calculation, while the input heat can be calculated through parameters such as steam flow rate, temperature, and heat capacity:

[0064] Q总 = m 蒸汽 * c 蒸汽 *(T 蒸汽 - T 环境 )

[0065] Where: m 蒸汽 is the steam flow rate; c 蒸汽 is the specific heat capacity of the steam; T 蒸汽 is the temperature of the steam; T 环境 is the ambient temperature when the steam contacts the material.

[0066] The effective heat transfer needs to be calculated according to the heat capacity, specific heat and temperature change of the material.

[0067] 2. Calculation formula for the sterilization effect F value:

[0068] The F value (sterilization process F value) is a parameter used to describe the sterilization effect, especially during the heat treatment process. It is calculated based on different temperatures and treatment times, representing the time required at a specific temperature and the equivalent sterilization time at the standard temperature. The calculation formula for the sterilization effect F value is as follows:

[0069]

[0070] Where: F is the sterilization process F value, usually in minutes; T (t) is the temperature at time t (unit: °C); T0 is the reference temperature, usually selected as 121.1 °C; is the influence coefficient of temperature on the sterilization effect, usually 10 °C. It means that when the temperature increases by 10 °C, the sterilization effect (i.e., the F value) doubles.

[0071] Example 1: Heating experiment of Yu-Shiang Shredded Pork

[0072] Experimental conditions: Steam temperature: 100 °C, steam pressure: 1.4 MPa, flow rate: 12 kg / h;

[0073] Food material: Yu-Shiang Shredded Pork, viscosity about 200 mPa·s

[0074] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Yu-Shiang Shredded Pork respectively, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0075] The corresponding heat transfer efficiency is calculated by simulation: 45% for Yu-Shiang Shredded Pork; Sterilization F value: 3.5 for Yu-Shiang Shredded Pork.

[0076] Example 2: Heating experiment of Yu-Shiang Shredded Pork: Simulated container size: 44.81 cm in length * 4.48 cm in width * 4.48 cm in height, main ingredient (shredded pork) size: 5 cm in length * 0.5 cm in width * 0.5 cm in height;

[0077] Experimental conditions: Steam temperature: 110 °C, steam pressure: 1.4 MPa, flow rate: 12 kg / h;

[0078] Food material: Yu-Shiang Shredded Pork, viscosity approximately 200 mPa·s

[0079] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Yu-Shiang Shredded Pork, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0080] The corresponding heat transfer efficiency calculated by simulation: Yu-Shiang Shredded Pork is 55%; Sterilization F value: Yu-Shiang Shredded Pork is 3.8.

[0081] Example 3: Heating experiment of Yu-Shiang Shredded Pork

[0082] Experimental conditions: Steam temperature: 120 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h;

[0083] Food material: Yu-Shiang Shredded Pork, viscosity approximately 200 mPa·s

[0084] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Yu-Shiang Shredded Pork, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0085] The corresponding heat transfer efficiency calculated by simulation: Yu-Shiang Shredded Pork is 58%; Sterilization F value: Yu-Shiang Shredded Pork is 4.

[0086] Example 4: Heating experiment of Yu-Shiang Shredded Pork

[0087] Experimental conditions: Steam temperature: 130 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0088] Food material: Yu-Shiang Shredded Pork, viscosity approximately 200 mPa·s

[0089] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Yu-Shiang Shredded Pork, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0090] The corresponding heat transfer efficiency calculated by simulation: Yu-Shiang Shredded Pork is 57%; Sterilization F value: Yu-Shiang Shredded Pork is 3.9.

[0091] Comparative Example 1: Heating experiment of Yu-Shiang Shredded Pork (Dimensions of the dish container: 44.81 cm in length * 4.48 cm in width * 4.48 cm in height)

[0092] Experimental conditions: Heating temperature (boiling): 100 °C; Heating pressure: Standard atmospheric pressure 1 bar; Flow rate: 12 kg / h

[0093] Food material: Yu-Shiang Shredded Pork, viscosity about 200 mPa·s

[0094] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Yu-Shiang Shredded Pork under steaming and standard atmospheric pressure, ensuring that the steam can quickly penetrate the surface of the material and heat to the inside.

[0095] The corresponding heat transfer efficiency calculated by simulation: Yu-Shiang Shredded Pork is 35%; Sterilization F value: Yu-Shiang Shredded Pork is 2.

[0096] The heat transfer efficiency and sterilization F values of Examples 1-4 and Comparative Example 1 are as Figure 2 shown, among which for the optimized process conditions obtained in Example 3, the heat transfer efficiency is increased by 68.6% compared with Comparative Example 1; the sterilization F value is doubled.

[0097] Example 5: Experimental verification of the simulation conditions of Yu-Shiang Shredded Pork

[0098] Evaluation method: The heat transfer efficiency is reflected by the steaming duration speed of the food under different conditions. The sterilization F value is reflected by evaluating the duration of not getting contaminated and moldy when placed at room temperature. The sensory properties (such as color, smell, texture, taste) of the cooked Yu-Shiang Shredded Pork are evaluated to indirectly reflect whether microorganisms have affected the quality of the food. As the placement duration increases, the food may change, and the growth of bacteria is often accompanied by changes such as spoilage and off-odor.

[0099] The data obtained from the simulation in Example 3 and Comparative Example 1 are respectively verified by experiments. The dimensions of the dish containers for both are: 44.81 cm in length * 4.48 cm in width * 4.48 cm in height.

[0100] Experimental conditions refer to Example 3 and Comparative Example 1; Food material: Yu-Shiang Shredded Pork, viscosity about 200 mPa·s;

[0101] Under the conditions of Example 3, use a fully automatic electric heating steam generator to observe the steaming duration of Yu-Shiang Shredded Pork under the influence of steam, ensuring that the steam can quickly penetrate the surface of the material and heat to the inside.

[0102] In Comparative Example 1, use a cooking pot for heating to observe the steaming duration of Yu-Shiang Shredded Pork under the influence of steaming and standard atmospheric pressure, ensuring that the steam can quickly penetrate the surface of the material and heat to the inside.

[0103] Experimental results: Under the optimal simulation conditions, the heating and cooking time of Yu-Shiang Shredded Pork in the real experiment is 30 s, and the heating time in the real experiment under the comparative example conditions is 50 s. The heating and cooking time of the optimal Example 3 is just 66.7% higher than that of the comparative example, which is in line with the improvement of the mass transfer efficiency in the simulation ((58% - 35%) / 35% = 65.7%), indicating that the model is accurate. The cooked Yu-Shiang Shredded Pork of the optimal Example 3 can be placed at room temperature for 3 days, while the cooked Yu-Shiang Shredded Pork in the real experiment under the comparative example can be placed at room temperature for 1.5 days, and the fresh-keeping duration is doubled, which is consistent with the doubling of the simulated sterilization F value, indicating that the model is accurate and applicable to Yu-Shiang Shredded Pork.

[0104] Example 6: Heating experiment of Sweet and Sour Pork Tenderloin

[0105] Experimental conditions: Steam temperature: 100 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0106] Food material: Yu-Shiang Shredded Pork, viscosity about 200 mPa·s

[0107] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Sweet and Sour Pork Tenderloin, ensuring that the steam can quickly penetrate the surface of the material and heat to the inside. The corresponding heat transfer efficiency is simulated and calculated: Sweet and Sour Pork Tenderloin is 44%; Sterilization F value: Sweet and Sour Pork Tenderloin is 3.6.

[0108] Example 7: Heating experiment of Sweet and Sour Pork Tenderloin

[0109] Experimental conditions: Steam temperature: 110 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0110] Food material: Sweet and Sour Pork Tenderloin, viscosity about 200 mPa·s

[0111] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and Sweet and Sour Pork Tenderloin, ensuring that the steam can quickly penetrate the surface of the material and heat to the inside. The corresponding heat transfer efficiency is simulated and calculated: Sweet and Sour Pork Tenderloin is 52%; Sterilization F value: Sweet and Sour Pork Tenderloin is 3.7.

[0112] Example 8: Heating experiment of Sweet and Sour Pork Tenderloin

[0113] Experimental conditions: Steam temperature: 120 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0114] Food material: Sweet and Sour Pork Tenderloin, viscosity about 200 mPa·s

[0115] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and sweet and sour pork tenderloin, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside. Simulate and calculate the corresponding heat transfer efficiency: 55% for sweet and sour pork tenderloin; sterilization F value: 4.1 for sweet and sour pork tenderloin.

[0116] Example 9: Heating experiment of sweet and sour pork tenderloin

[0117] Experimental conditions: Steam temperature: 130 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0118] Food material: Sweet and sour pork tenderloin, viscosity about 200 mPa·s

[0119] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and sweet and sour pork tenderloin, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0120] Simulate and calculate the corresponding heat transfer efficiency: 56% for sweet and sour pork tenderloin; sterilization F value: 4.0 for sweet and sour pork tenderloin.

[0121] Comparative example 2: Heating experiment of sweet and sour pork tenderloin (Dish container size: 24.66 cm long * 7.40 cm wide * 4.93 cm high)

[0122] Experimental conditions: Heating temperature (boiling): 100 °C; Heating pressure: Standard atmospheric pressure 1 bar; Flow rate: 12 kg / h

[0123] Food material: Sweet and sour pork tenderloin, viscosity about 200 mPa·s

[0124] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and shredded pork with fish flavor under steaming and standard atmospheric pressure, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0125] Simulate and calculate the corresponding heat transfer efficiency: 36% for sweet and sour pork tenderloin; sterilization F value: 1.8 for sweet and sour pork tenderloin.

[0126] The heat transfer efficiency and sterilization F values of Examples 6 - 9 and Comparative example 2 are as Figure 3 shown, among which, under the optimized process conditions obtained in Example 9, the heat transfer efficiency is increased by 55.6% compared with Comparative example 2; under the optimized process conditions obtained in Example 9, the sterilization F value is increased by 1.28 times.

[0127] Example 10: Experimental verification of simulation conditions for sweet and sour pork tenderloin

[0128] The evaluation method refers to Example 5:

[0129] Example 9 and Comparative Example 2 were respectively verified by real experiments on simulated data. The sizes of the dish containers for both were: 24.66 cm in length * 7.40 cm in width * 4.93 cm in height

[0130] The experimental conditions refer to Example 9 and Comparative Example 2; Food material: Sweet and Sour Pork Tenderloin, with a viscosity of about 200 mPa·s

[0131] Under the conditions of Example 9, a fully automatic electric heating steam generator was used for heating. Observe the steaming duration of Sweet and Sour Pork Tenderloin under the influence of steam to ensure that the steam can quickly penetrate the surface of the material and heat it to the inside

[0132] Comparative Example 2 used a cooking pot for heating. Observe the steaming duration of Sweet and Sour Pork Tenderloin under the influence of cooking and standard atmospheric pressure to ensure that the steam can quickly penetrate the surface of the material and heat it to the inside

[0133] Experimental results: The heating and cooking time of Sweet and Sour Pork Tenderloin under the real experiment of the optimal simulation conditions was 28 s. The heating time of the real experiment under the conditions of Comparative Example 2 was 43 s. The heating and cooking time of the optimal Example 9 was just 53.6% shorter than that of Comparative Example, which was in line with the simulated mass transfer efficiency improvement ((56% - 36%) / 36% = 55.6%), indicating that the model was accurate. The cooked Sweet and Sour Pork Tenderloin of the optimal Example 9 could be placed at room temperature for 3.5 days, while the cooked Sweet and Sour Pork Tenderloin under the real experiment of Comparative Example could be placed at room temperature for 1.5 days. The preservation duration was increased by 1.33 times, which was consistent with the 1.28 - fold increase in the simulated sterilization F value, indicating that the model method was accurate and applicable to Sweet and Sour Pork Tenderloin

[0134] Example 11: Heating experiment of fish maw and chicken soup

[0135] Experimental conditions: Steam temperature: 100 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0136] Food material: Fish maw and chicken soup, with a viscosity of about 200 mPa·s

[0137] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and fish maw and chicken soup respectively, to ensure that the steam can quickly penetrate the surface of the material and heat it to the inside

[0138] The corresponding heat transfer efficiency was simulated and calculated: For fish maw and chicken soup, it was 47%; Sterilization F value: For fish maw and chicken soup, it was 3.5

[0139] Example 12: Heating experiment of fish maw and chicken soup

[0140] Experimental conditions: Steam temperature: 110 °C; Steam pressure: 1.4 MPa; Flow rate: 12 kg / h

[0141] Food material: Fish maw and chicken soup, with a viscosity of about 200 mPa·s

[0142] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and fish maw chicken soup, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0143] The corresponding heat transfer efficiency was simulated and calculated: for fish maw chicken soup, it is 53%; the sterilization F value: for fish maw chicken soup, it is 3.6.

[0144] Example 13: Heating experiment of fish maw chicken soup

[0145] Experimental conditions: Steam temperature: 120 °C; steam pressure: 1.4 MPa; flow rate: 12 kg / h

[0146] Food material: Fish maw chicken soup, viscosity about 200 mPa·s

[0147] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and fish maw chicken soup, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0148] The corresponding heat transfer efficiency was simulated and calculated: for fish maw chicken soup, it is 56%; the sterilization F value: for fish maw chicken soup, it is 4.2.

[0149] Example 14: Heating experiment of fish maw chicken soup

[0150] Experimental conditions: Steam temperature: 130 °C; steam pressure: 1.4 MPa; flow rate: 12 kg / h

[0151] Food material: Fish maw chicken soup, viscosity about 200 mPa·s

[0152] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and fish maw chicken soup, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0153] The corresponding heat transfer efficiency was simulated and calculated: for fish maw chicken soup, it is 58%; the sterilization F value: for fish maw chicken soup, it is 4.1.

[0154] Comparative Example 3: Heating experiment of fish maw chicken soup (dish container size: 9.66 cm long * 9.66 cm wide * 9.66 cm high)

[0155] Experimental conditions: Heating temperature (boiling): 100 °C; heating pressure: standard atmospheric pressure 1 bar; flow rate: 12 kg / h

[0156] Food material: Fish maw chicken soup, viscosity about 200 mPa·s

[0157] Steps: Use ANSYS Fluent for CFD simulation to simulate the heat exchange process between steam and fish maw chicken soup under cooking and standard atmospheric pressure, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0158] The corresponding heat transfer efficiency was simulated and calculated: for fish maw chicken soup, it is 34%; the sterilization F value: for fish maw chicken soup, it is 2.1.

[0159] The heat transfer efficiency and sterilization F values of Examples 11 - 14 and Comparative Example 3 are as Figure 4 shown. Among them, under the optimized process conditions obtained in Example 14, the heat transfer efficiency increased by 70.6% compared to Comparative Example 3; under the optimized process conditions obtained in Example 13, the sterilization F value doubled.

[0160] Example 15: Experimental verification of fish maw chicken soup under the optimal simulation conditions

[0161] The evaluation method refers to Example 5:

[0162] Real - experimental verification of the simulation data was carried out for Example 14, Example 13, and Comparative Example 3 respectively. The size of the dish container is: 9.66 cm long * 9.66 cm wide * 9.66 cm high

[0163] The experimental conditions refer to Example 13, Example 14, and Comparative Example 3; the food material: fish maw chicken soup, with a viscosity of about 200 mPa·s.

[0164] Experimental steps for Example 14 and Example 13: Use a fully automatic electric - heating steam generator for heating, observe the steaming duration of fish maw chicken soup under the influence of steam, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0165] Comparative Example 3 uses a cooking pot for heating, observe the steaming duration of fish maw chicken soup under the influence of cooking and standard atmospheric pressure, ensuring that the steam can quickly penetrate the surface of the material and heat it to the inside.

[0166] Experimental results: The heating and cooking time of fish maw chicken soup under the real - experiment of the optimal simulation Example 14 conditions is 31 s, and the heating time of the real - experiment under the comparative example conditions is 53 s. The heating and cooking time of the optimal Example 14 just increased by 70.9% compared to the comparative example, approximately in line with the improvement of the mass transfer efficiency in the simulation ((58% - 34%) / 34% = 70.6%), indicating that the model is accurate. And the cooked fish maw chicken soup of the optimal Example 13 can be placed at room temperature for 2 days, while the cooked fish maw chicken soup under the real - experiment of the comparative example can be placed at room temperature for 1 day. The preservation duration has doubled, which coincides with the doubling of the simulated sterilization F value, indicating that the model method is accurate and applicable to fish maw chicken soup.

[0167] Result analysis:

[0168] Heat transfer efficiency: Based on the optimization method of the present invention, the direct steam injection conditions are optimized; applied to three kinds of pre-made dishes, the heat transfer efficiency of Yuxiang shredded pork is increased from 45% in Example 1 to 58% in Example 3. The heat transfer efficiency of sweet and sour pork tenderloin is increased from 44% in Example 5 to 56% in Example 8. The heat transfer efficiency of fish maw chicken soup is increased from 47% in Example 9 to 58% in Example 12. All are increased by 20-30%. The quality of the dishes is also significantly improved: the optimized Yuxiang shredded pork has uniform color, better taste, and better preservation of nutrients. The sterilization effect of the three kinds of pre-made dishes also reaches an F value of 4.0, meeting the food safety standards.

[0169] The method of optimizing the direct steam injection conditions through CFD (Computational Fluid Dynamics) simulation is particularly applicable to the heat and mass transfer process of multiphase high-viscosity dishes, optimizes the direct steam injection process conditions, and improves the heating efficiency and dish quality. The optimized steam injection conditions make the heating process more uniform, reduce heat loss, improve the taste, color and nutrients of the dishes, ensure the high quality of the products, and ensure that the sterilization effect meets the standards. Compared with the traditional method, the optimized process greatly improves the production efficiency and reduces the energy consumption at the same time, having good industrial application prospects.

[0170] The present invention aims at the problems of uneven heat transfer, energy waste and dish quality fluctuation existing in the existing industrial dish production process, and proposes an innovative solution of collaborative optimization through CFD numerical simulation and process parameters. First, a heat and mass transfer model of the steam-material system is established to simulate the steam flow path, temperature field and heat transfer characteristics; based on the simulation results, the direct steam injection parameters (temperature 100-130 °C, pressure 1.2-1.5 MPa, direct injection angle, flow rate 10-15 kg / h) are dynamically adjusted to maximize the contact efficiency between the steam and the high-viscosity material. This method increases the heat transfer efficiency by more than 50% compared with the traditional process, and at the same time, by precisely controlling the heat flow distribution, effectively maintains the texture characteristics, color stability and nutrients of the dishes, and ensures that the sterilization effect meets the standards. The present invention deeply combines numerical simulation and process optimization, solves the technical bottleneck of low heat and mass transfer efficiency in multiphase high-viscosity systems, and provides an efficient and energy-saving direct steam injection control scheme for the industrial production of pre-made dishes.

[0171] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A method for optimizing heat and mass transfer of multiphase high-viscosity dishes based on direct steam injection, characterized in that: The steps include: S1. Establish heat transfer and fluid dynamics mathematical models through CFD software to simulate the heat and mass transfer process between steam and food materials; S2. Adjust the process parameters of steam injection according to the simulation results of step S1; S3. Evaluate the rationality of the model through heat transfer efficiency and sterilization effect F value; In step S1, the mathematical model includes a heat convection model, a heat conduction model, a phase change and a steam-material heat exchange model.

2. The heat and mass transfer optimization method for multi-phase high-viscosity dishes based on direct steam injection according to claim 1 is characterized in that: The heat convection model is used to predict the heat convection transfer efficiency between steam and the material surface; No=C*Re m *Pr n Nu is the Nusselt number, Re is the Reynolds number, Pr is the Prandtl number, and C, m, and n are empirical constants.

3. The heat and mass transfer optimization method for multi-phase high-viscosity dishes based on direct steam injection according to claim 1 is characterized in that: The heat conduction model simulates the temperature change inside the material, predicts the heat distribution during the heating process, and uses Fourier's law to describe the heat conduction process: q is the heat flux density, k is the thermal conductivity of the material, is the temperature gradient.

4. The heat and mass transfer optimization method for multi-phase high-viscosity dishes based on direct steam injection according to claim 1 is characterized in that: The phase change and steam-material heat exchange model: the energy equation is used to consider the latent heat exchange between steam and material; the heat release of phase change can be described by the following formula: Q=m*h f m is the mass flow rate of steam condensation, h f is the latent heat of steam.

5. The method for optimizing heat and mass transfer of multi-phase high-viscosity dishes based on direct steam injection according to claim 1, characterized in that: In step S2, the process parameters include but are not limited to steam temperature, steam pressure, steam injection angle, and steam flow rate.

6. The method for optimizing heat and mass transfer of multiphase high-viscosity dishes based on direct steam injection according to claim 1, characterized in that: In step S3, the heat transfer efficiency is calculated by the following formula: Where: Q 有效 It is the heat effectively transferred to the material, that is, the heat that actually raises the temperature of the material; Q 总 is the total heat input, that is, the total heat brought by the steam; Q 总 =m 蒸汽 *c 蒸汽 *(T 蒸汽 -T 环境 ) Where: m 蒸汽 is the steam flow rate; c 蒸汽 is the specific heat capacity of steam; T 蒸汽 is the temperature of steam; T 环境 It is the ambient temperature when steam comes into contact with the material.

7. The method for optimizing heat and mass transfer of multiphase high-viscosity dishes based on direct steam injection according to claim 1 is characterized in that: In step S3, the calculation formula of the bactericidal effect F value is: Where: F is the sterilization process F value, in minutes; T (t) is the temperature at time t; T0 is the reference temperature; z is the coefficient of influence of temperature on the sterilization effect.

8. The method for optimizing heat and mass transfer of multi-phase high-viscosity dishes based on direct steam injection according to claim 1, characterized in that: The viscosity of the soup of the multi-phase high-viscosity dish is ≥200mPa·s; The multi-phase high-viscosity dishes include, but are not limited to, shredded pork with fish flavor, chicken with fish maw, and sweet and sour pork tenderloin.

9. The method for optimizing heat and mass transfer of multi-phase high-viscosity dishes based on direct steam injection according to claim 1, characterized in that: By setting the material size and material viscosity in the software, the physical properties of the main ingredients in the dish can be simulated.

10. The heat and mass transfer optimization method for multi-phase high-viscosity dishes based on direct steam injection according to claim 1, characterized in that: The optimized process conditions for multiphase high-viscosity dishes are steam temperatures of 100°C-130°C; and / or, the steam pressure is 1.2 MPa to 1.5 MPa; And / or, the steam flow rate is 10kg / h-15kg / h.

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