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CN-121970805-A - Low-temperature high-humidity air treatment system and method for fruit and vegetable fresh-keeping based on ice slurry spraying

CN121970805ACN 121970805 ACN121970805 ACN 121970805ACN-121970805-A

Abstract

The invention provides a low-temperature high-humidity air treatment system and a method for fruit and vegetable fresh-keeping based on ice slurry spraying, which are characterized in that air is in direct contact with ice slurry to carry out heat and mass exchange to obtain low-temperature high-humidity air, and then the low-temperature high-humidity air is sent to the position of fruit and vegetable to realize the fresh-keeping of fruit and vegetable, the invention avoids the conflict of cooling and humidification in the traditional refrigeration mode, avoids the risk of surface condensation and decay caused by direct spraying, satisfies the cooling in the fresh-keeping process, and carries out direct contact countercurrent heat exchange between the ice slurry and the air, the invention does not directly spray fruits and vegetables, but processes air into a low-temperature high-humidity state close to saturation and then sends the state into a storage space, thereby avoiding condensation on the surfaces of the fruits and vegetables, obviously reducing the decay rate and improving the fresh-keeping safety.

Inventors

  • LIU HAOZHE
  • TANG YIFANG
  • LIN YUNFEI
  • LUO CHUN
  • HAN SHUANG
  • LIU RUXIN

Assignees

  • 湖南科技大学

Dates

Publication Date
20260505
Application Date
20260206

Claims (10)

  1. 1. The low-temperature high-humidity air treatment system for fruit and vegetable fresh-keeping based on ice slurry spraying is characterized by comprising a shell (1), a guide plate (2), a spray pipe (3), a nozzle (4), a water baffle (6), an air inlet (8), an air outlet (9), a water return pipe (10), a water collecting tank (11), an ice slurry supply pipe (13), a water supply pump (P-1), a water return pump (P-2), a first temperature sensor (T-1), a second temperature sensor (T-2), a first humidity sensor (H-1) and a second humidity sensor (H-2), wherein the guide plate (2), the spray pipe (3), the nozzle (4), the water baffle (6) and the water collecting tank (11) are all arranged inside the shell (1), one end of the ice slurry supply pipe (13) is connected with an external ice slurry preparation unit, the other end of the water supply pipe is connected with the spray pipe (3), the water return pipe (P-1) is connected with the ice slurry supply pipe (13) in series, the water return pump (P-2) is arranged below the water collecting tank (11), one end of the water return pipe (10) is connected with the water return pipe (11), the other end of the water return pipe (10) is connected with the external ice slurry preparation unit (P-2), the water return pipe (P-2) is connected with the first humidity sensor (H-1) in series The second temperature sensor (T-2) and the second humidity sensor (H-2) are arranged at the air inlet (8) and the air outlet (9).
  2. 2. The low-temperature high-humidity air treatment system for fruit and vegetable fresh-keeping based on ice slurry spraying according to claim 1 is characterized in that the shell (1) is of a cuboid structure, the inner wall of the shell is made of stainless steel, a sealing overhaul port (5) is formed in the side wall of the shell (1), a blow-down valve (12) is arranged at the bottom of the shell, the blow-down valve (12) is communicated with a water collecting tank (11), an air inlet (8) and an air outlet (9) are respectively formed in two opposite side walls of the shell (1), and a flow equalizer and a filtering device are arranged at the air inlet (8).
  3. 3. The low-temperature high-humidity air treatment system for fresh-keeping of fruits and vegetables based on ice slurry spraying according to claim 1 is characterized in that the guide plate (2) is of a multi-layer snake-shaped structure which is obliquely arranged, an included angle between the guide plate and a horizontal plane is 55-65 degrees, the plate material of the guide plate (2) is stainless steel, the surface of the guide plate is subjected to hydrophilic modification treatment, and the guide plate (2) is used for spreading sprayed ice slurry to form a continuously updated low-temperature liquid film and forcing air to generate turbulence so as to improve gas-liquid contact efficiency.
  4. 4. The low-temperature high-humidity air treatment system for fresh-keeping of fruits and vegetables based on ice slurry spraying according to claim 1 is characterized in that the spray pipe (3) is formed by welding heat-insulation stainless steel pipes and comprises a main distribution main pipe and a plurality of spray branch pipes which are transversely connected in parallel, wherein a liquid inlet of the main distribution main pipe is close to one side of an air outlet (9), ice slurry is distributed from the main distribution main pipe to the spray branch pipes which are close to one side of an air inlet (8) in sequence, the spray nozzles (4) are large-caliber spiral or solid conical spray nozzles, the spray pipes are uniformly distributed with the spray nozzles (4), and the spray direction of the spray nozzles (4) faces the guide plate (2).
  5. 5. The low-temperature high-humidity air treatment system for fresh-keeping of fruits and vegetables based on ice slurry spraying according to claim 1 is characterized in that the water baffle (6) is of a folded plate type or a silk screen type structure and is arranged between the guide plate (2) and the air outlet (9), tiny liquid drops in air are separated by the water baffle (6) through the principle of inertial collision and absorption, and the collected liquid drops flow into the water collecting tank (11).
  6. 6. The low-temperature high-humidity air treatment system for fruit and vegetable fresh-keeping based on ice slurry spraying according to claim 1 is characterized in that the water collecting tank (11) is positioned at the bottom of the shell (1), the bottom surface is obliquely arranged to facilitate water return collection, the ice slurry supply pipe (13) and the water return pipe (10) are subjected to heat preservation treatment, and the water supply pump (P-1) and the water return pump (P-2) are positive displacement pumps or non-blocking centrifugal pumps specially designed for slurry.
  7. 7. The ice slurry spray-based low-temperature high-humidity air treatment system for fruit and vegetable fresh-keeping according to claim 1, further comprising a state monitoring screen (7), wherein the state monitoring screen (7) integrates display, alarm, recording and interaction functions, is electrically connected with the first temperature sensor (T-1), the second temperature sensor (T-2), the first humidity sensor (H-1), the second humidity sensor (H-2), the water supply pump (P-1) and the water return pump (P-2) and is used for displaying operation parameters in real time and sending alarm signals when in failure.
  8. 8. The low-temperature high-humidity air treatment method for fruit and vegetable fresh-keeping based on ice slurry spraying is characterized in that the low-temperature high-humidity air treatment system for fruit and vegetable fresh-keeping based on ice slurry spraying according to any one of claims 1-7 comprises the following steps: s1, preprocessing, namely preparing ice slurry at 0 ℃ in advance through an external ice slurry preparation unit according to the required storage temperature, so as to ensure that the ice slurry is free of impurities and uniform in ice crystal particles; S2, ice slurry spraying, namely starting a water supply pump (P-1), conveying the ice slurry at the temperature of 0 ℃ to a nozzle (4) through an ice slurry supply pipe (13) and a spray pipe (3), and uniformly spraying the ice slurry to the surface of a guide plate (2) through the nozzle (4) to form a low-temperature liquid film; S3, heat and mass exchange, namely introducing air to be treated through an air inlet (8), uniformly distributing the air through a flow equalizer, and then enabling the air to be treated to be in countercurrent contact with ice slurry and a low-temperature liquid film on the surface of a guide plate (2), quickly cooling by utilizing the phase change latent heat of the ice slurry, and simultaneously realizing air humidification by water evaporation to obtain low-temperature high-humidity air; s4, gas-liquid separation and output, namely, after the low-temperature high-humidity air is subjected to liquid drop removal through a water baffle (6), the low-temperature high-humidity air is sent to a fruit and vegetable storage from an air outlet (9); S5, backwater circulation, namely enabling backwater on the surface of the guide plate (2) to flow into the water collecting tank (11), starting the backwater pump (P-2), conveying the backwater to an external ice slurry preparation unit through the backwater pipe (10) to prepare ice slurry again, and realizing recycling.
  9. 9. The method for treating low-temperature and high-humidity air for fresh-keeping of fruits and vegetables based on ice slurry spraying according to claim 8, wherein in the step S1, the particle diameter of ice crystals in the prepared ice slurry is 0.5-2mm, and in the step S3, the temperature of the treated low-temperature and high-humidity air is 2+/-0.5 ℃ and the relative humidity is 90% -95%.
  10. 10. The method for treating the low-temperature high-humidity air for the fresh-keeping of the fruits and vegetables based on the ice slurry spraying according to claim 8 is characterized by further comprising a fault judging step of acquiring temperature and humidity data of the air inlet and the air outlet in real time through a state monitoring screen (7), judging that equipment has a fault and sending out an alarm signal if the temperature and the humidity of the air outlet exceed a set range or the temperature and humidity difference value of the air inlet and the air outlet is abnormal, and opening a drain valve (12) to drain liquid and dirt in a water collecting tank (11) when the system is maintained or stopped for a long time.

Description

Low-temperature high-humidity air treatment system and method for fruit and vegetable fresh-keeping based on ice slurry spraying Technical Field The invention relates to the technical field of fruit and vegetable fresh-keeping, in particular to a low-temperature high-humidity air treatment system and method for fruit and vegetable fresh-keeping based on ice slurry spraying. Background An ice slurry is a homogeneous mixture of solid and liquid phases consisting of tiny ice crystals (typically 0.1-1 mm in diameter), a carrier liquid (water or aqueous solutions such as ethylene glycol, brine) and possibly additives (e.g., surfactants, anti-caking agents). Has the advantages of large phase transition latent heat, large specific surface area and the like. The ice slurry is used as an efficient binary phase change cold accumulation working medium, and has the core advantages of high energy storage density, phase change latent heat (about 335 kJ/kg) which is far larger than apparent cold and lower energy consumption when the same cold quantity is conveyed, high heat exchange efficiency, high specific surface area of ice crystal particles, and capability of realizing rapid cooling when the ice crystal particles are in direct contact with air for heat exchange, accurate temperature regulation and control, capability of realizing regulation and setting of phase change temperature by adjusting the types and proportion of additives in the ice slurry so as to meet the fresh-keeping requirements of different fruits and vegetables, and good fluidity and capability of realizing flexible conveying and distribution of cold quantity. The characteristics make the device become ideal media for realizing efficient, accurate and flexible refrigeration, especially break through the bottleneck of 'cooling' and 'dehumidification' mutual restriction in the traditional refrigeration, and provide a brand new technical path by constructing a direct contact type cooling and humidifying integrated system. The core of the fruit and vegetable fresh-keeping is to maintain a low-temperature (usually 0-4 ℃) and high-humidity (the relative humidity is more than 90% -95%) storage environment so as to inhibit respiration and water transpiration. The prior preservation technology is mainly divided into the following paths: the traditional mechanical refrigeration and independent humidification adopts a finned tube evaporator (an air cooler) for cooling, and then the independent humidification is carried out through humidifiers such as ultrasonic wave, high-pressure spraying and the like. The method has the advantages of mature technology, accurate temperature control and wide application. Disadvantages: 1. the energy consumption is high, the humidity is uneven, the fruit and vegetable 'dry consumption' is easy to cause, and particularly, the surface temperature of an air cooler is far lower than the dew point of air, and a large amount of dehumidification is performed while the temperature is reduced, so that the air in a warehouse is dried. 2. The subsequent moisturizing has high energy consumption, is difficult to be uniform, and is easy to form a local water film on the surfaces of fruits and vegetables to cause decay. Direct spraying method, direct water spraying/spraying. The advantages are that: 1. the humidification is direct and efficient, can rapidly supplement moisture on the surfaces of fruits and vegetables, and reduces 'dry consumption'. 2. The system is simple, and the initial investment and the running cost are relatively low. Disadvantages: 1. The risk of rot is high, free water film exists on the surface of fruits and vegetables for a long time, conditions are created for mold and bacteria to grow, and rot and deterioration are easy to cause. 2. The temperature and humidity control precision is low, the temperature of spray water is generally limited with that of a warehouse Wen Xiangjin, the cooling effect is extremely limited, and the accurate low-temperature control cannot be realized. Uneven humidification is likely to cause local excessive humidity. 3. The fresh-keeping period is short, and the fresh-keeping period is generally only used for pretreatment before short-term storage or transportation and is difficult to meet the long-term fresh-keeping requirement. Spraying or soaking the antistaling agent, namely preparing the bactericide (such as chlorine water and chlorine dioxide) and the biological antistaling agent into solution, and spraying or soaking the fruits and vegetables. Disadvantages: 1. With chemical residue problems, consumer concerns about food safety are easily raised and the use of some medicaments is subject to strict regulations. 2. The spray coverage is difficult to be completely uniform, and the integral fresh-keeping effect is affected. 3. Failing to solve the fundamental requirements of low temperature and high humidity in the storage environment, the refrigerator is usually used in combination with ot