Ice slurry spraying-based low-temperature high-humidity air treatment system and method for fresh keeping of fruits and vegetables

Abstract

According to the low-temperature and high-humidity air treatment system and method for fruit and vegetable preservation based on ice slurry spraying, air makes direct contact with ice slurry for heat and mass transfer, low-temperature and high-humidity air is obtained, then the low-temperature and high-humidity air is sent to the positions where fruits and vegetables are located, and fruit and vegetable preservation is achieved; according to the invention, the conflict between cooling and humidifying in a traditional refrigeration mode is avoided, the risk of surface condensation and decay caused by direct spraying is avoided, the requirement for cooling in the fresh-keeping process is met, cooling and humidifying are synchronously realized through direct contact type countercurrent flow heat exchange of ice slurry and air, and the structural conflict that dehumidification is required for cooling in a traditional system is avoided; the air is sent into the storage space after being treated to be in a low-temperature and high-humidity state close to saturation, dew condensation on the surfaces of the fruits and vegetables is avoided, the rotting rate is remarkably reduced, the fresh-keeping safety is improved, only ice slurry is used as a treatment medium, no chemical additive exists, potential safety hazards of food are avoided, and the method conforms to the green and healthy food storage trend.

Description

Technical Field

[0001] This invention relates to the field of fruit and vegetable preservation technology, and more specifically, to a low-temperature, high-humidity air treatment system and method for fruit and vegetable preservation based on ice slurry spray. Background Technology

[0002] Ice slurry is a homogeneous solid-liquid two-phase mixture consisting of tiny ice crystals (typically 0.1-1 mm in diameter), a carrier liquid (water or aqueous solution, such as ethylene glycol or brine), and possible additives (such as surfactants and anti-caking agents). It has advantages such as high latent heat of phase change and large specific surface area.

[0003] Ice slurry, as a highly efficient binary phase change cold storage medium, has the following core advantages: First, it has a high energy density; its latent heat of phase change (approximately 335 kJ / kg) is far greater than its sensible heat, resulting in lower energy consumption when delivering the same amount of cooling. Second, it has high heat exchange efficiency; the large specific surface area of ​​ice crystal particles allows for rapid cooling when directly contacting air for heat exchange. Third, its temperature can be precisely controlled; by adjusting the types and proportions of additives in the ice slurry, the phase change temperature can be adjusted to meet the preservation needs of different fruits and vegetables. Fourth, it has good fluidity, enabling flexible delivery and distribution of cooling capacity. These characteristics make it an ideal medium for achieving efficient, precise, and flexible refrigeration, especially breaking through the bottleneck of the mutual constraint between "cooling" and "dehumidification" in traditional refrigeration, and providing a new technical path for constructing a direct contact integrated cooling and humidification system.

[0004] The key to preserving fruits and vegetables lies in maintaining a low-temperature (usually 0-4℃) and high-humidity (relative humidity above 90%-95%) storage environment to inhibit respiration and water evaporation.

[0005] Existing preservation technologies can be mainly categorized into the following approaches: Traditional mechanical refrigeration + independent humidification: It uses a finned tube evaporator (air cooler) for cooling, and then uses humidifiers such as ultrasonic or high-pressure spray for separate humidification.

[0006] Advantages: Mature technology, precise temperature control, and wide application.

[0007] shortcoming: 1. High energy consumption, uneven humidity, and easy to cause fruits and vegetables to "dry out". Specifically, the surface temperature of the air cooler is much lower than the dew point of the air. While cooling, it will dehumidify a lot, resulting in dry air inside the warehouse.

[0008] 2. Subsequent humidification consumes a lot of energy and is difficult to achieve evenly, which can easily lead to the formation of local water films on the surface of fruits and vegetables, causing them to rot.

[0009] Direct spraying method: Direct water spraying / spraying.

[0010] advantage: 1. Humidification is direct and efficient, quickly replenishing the surface moisture of fruits and vegetables and reducing "dry loss".

[0011] 2. The system is simple, and the initial investment and operating costs are relatively low.

[0012] shortcoming: 1. High risk of rotting: The presence of a free water film on the surface of fruits and vegetables creates conditions for the growth of mold and bacteria, which can easily lead to rotting and spoilage.

[0013] 2. Low temperature and humidity control precision: The temperature of the spray water is usually close to the temperature of the storage room, resulting in extremely limited cooling effect and making precise low-temperature control impossible. Uneven humidification can easily lead to localized overhumidity.

[0014] 3. Short shelf life: It is usually only used for short-term storage or pre-treatment before transportation, and it is difficult to meet the needs of long-term preservation.

[0015] Preservative spraying / soaking: Prepare a solution of bactericides (such as chlorine water, chlorine dioxide), biological preservatives, etc., and spray or soak the fruits and vegetables. Advantages: It can directly inhibit the growth of surface microorganisms and has a certain auxiliary preservation effect.

[0016] shortcoming: 1. It has chemical residue issues, which can easily raise consumer concerns about food safety, and the use of some drugs is subject to strict regulations.

[0017] 2. Spraying coverage is difficult to achieve completely even coverage, affecting the overall preservation effect.

[0018] 3. It fails to address the fundamental requirement of low temperature and high humidity in the storage environment, and usually needs to be used in combination with other refrigeration technologies.

[0019] In summary, existing fruit and vegetable preservation technologies have the following limitations: 1. Traditional mechanical refrigeration + independent humidification: has problems such as conflicting cooling and humidification, complex system, and high energy consumption; 2. Indirect heat exchange using ice slurry storage: The potential of ice slurry is not fully utilized, resulting in poor heat exchange efficiency; 3. Direct spraying of water or preservatives: While direct, this method easily leads to fruit and vegetable spoilage, poses food safety risks, and makes it impossible to precisely control the storage environment. Therefore, a low-temperature, high-humidity air treatment system and method for fruit and vegetable preservation based on ice slurry spraying is proposed. Summary of the Invention

[0020] The purpose of this invention is to address the above-mentioned shortcomings by proposing a low-temperature, high-humidity air treatment system and method for fruit and vegetable preservation based on ice slurry spraying. This system involves direct contact between air and ice slurry for heat and mass exchange, resulting in low-temperature, high-humidity air. This air is then delivered to the location of the fruits and vegetables, thus preserving their freshness. This invention avoids the conflict between cooling and humidification in traditional refrigeration methods and also avoids the risks of surface condensation and spoilage associated with direct spraying, thus meeting the dual needs of cooling and humidification in the fruit and vegetable preservation process.

[0021] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a low-temperature, high-humidity air treatment system for fruit and vegetable preservation based on ice slurry spray, comprising a shell, a guide plate, a spray pipe, a nozzle, a baffle plate, an air inlet, an air outlet, a return water pipe, a water collection tank, an ice slurry supply pipe, a water supply pump, a return water pump, a first temperature sensor, a second temperature sensor, a first humidity sensor, and a second humidity sensor; the guide plate, spray pipe, nozzle, baffle plate, and water collection tank are all disposed inside the shell; one end of the ice slurry supply pipe is connected to an external ice slurry preparation unit, and the other end is connected to the spray pipe; the water supply pump is connected in series with the ice slurry supply pipe; the return water pump is disposed below the water collection tank; one end of the return water pipe is connected to the water collection tank, and the other end is connected to the external ice slurry preparation unit; the first temperature sensor, the first humidity sensor, the second temperature sensor, and the second humidity sensor are all disposed at the air inlet and the air outlet.

[0022] As a preferred technical solution of the present invention, the outer shell is a cuboid structure with the inner wall made of stainless steel; the side wall of the outer shell is provided with a sealed maintenance port, and the bottom is provided with a drain valve, which is connected to the water collection tank; the air inlet and air outlet are respectively provided on the opposite side walls of the outer shell, and the air inlet is provided with a flow equalizer and a filter device.

[0023] As a preferred technical solution of the present invention, the guide plate is a multi-layered inclined serpentine structure with an angle of 55°-65° with the horizontal plane; the plate material of the guide plate is stainless steel and the surface is treated with hydrophilic modification; the guide plate is used to spread the sprayed ice slurry to form a continuously renewed low-temperature liquid film and force the air to generate turbulence to improve the gas-liquid contact efficiency.

[0024] As a preferred technical solution of the present invention, the spray pipe is welded from insulated stainless steel pipe, including a longitudinally arranged main distribution pipe and multiple horizontally connected spray branch pipes; the liquid inlet of the main distribution pipe is close to the air outlet side, and the ice slurry is sequentially distributed from the main distribution pipe to the spray branch pipes close to the air inlet side; the nozzles are large-diameter spiral or solid cone nozzles, and multiple nozzles are evenly distributed on the spray branch pipes, and the spraying direction of the nozzles is towards the guide plate.

[0025] As a preferred technical solution of the present invention, the baffle plate adopts a folded plate or wire mesh structure and is set between the guide plate and the air outlet; the baffle plate uses the principle of inertial collision and adsorption to separate tiny droplets in the air, and the collected droplets flow into the water collection pool.

[0026] As a preferred technical solution of the present invention, the water collection tank is located at the bottom of the shell, and the bottom surface is inclined to facilitate the collection of return water; both the ice supply pipe and the return water pipe are insulated; the water supply pump and the return water pump are both positive displacement pumps or non-clogging centrifugal pumps designed specifically for slurry.

[0027] As a preferred technical solution of the present invention, it also includes a status monitoring screen, which integrates display, alarm, recording and interactive functions, and is electrically connected to the first temperature sensor, the second temperature sensor, the first humidity sensor, the second humidity sensor, the water supply pump and the return water pump, for real-time display of operating parameters and issuing alarm signals in case of failure.

[0028] The low-temperature, high-humidity air treatment method for fruit and vegetable preservation based on ice slurry spraying includes the following steps: S1. Pretreatment: Based on the required storage temperature, 0℃ ice slurry is prepared in advance by an external ice slurry preparation unit to ensure that the ice slurry is free of impurities and has uniform ice crystal particles; S2. Ice Slurry Spraying: Start the water supply pump and deliver 0℃ ice slurry through the ice slurry supply pipe and spray pipe to the nozzle, which will then spray it evenly onto the surface of the guide plate to form a low-temperature liquid film. S3. Heat and mass exchange: The air to be treated is introduced through the air inlet, and after being evenly distributed by the flow equalizer, it comes into countercurrent contact with the ice slurry and low-temperature liquid film on the surface of the guide plate. The latent heat of phase change of the ice slurry is used to quickly cool the air, while the air is humidified by water evaporation, resulting in low-temperature and high-humidity air. S4. Gas-liquid separation and output: Low-temperature, high-humidity air is sent to the fruit and vegetable storage room through the air outlet after the water baffle removes the liquid droplets. S5. Water return circulation: The water returning from the surface of the guide plate flows into the water collection tank. The water return pump is started, and the water return is transported through the water return pipe to the external ice slurry preparation unit to re-prepare ice slurry, so as to realize recycling.

[0029] As a preferred technical solution of the present invention, in step S1, the diameter of the ice crystal particles in the prepared ice slurry is 0.5-2 mm; in step S3, the temperature of the treated low-temperature and high-humidity air is 2±0.5℃ and the relative humidity is 90%-95%.

[0030] As a preferred technical solution of the present invention, it also includes a fault judgment step: real-time acquisition of temperature and humidity data of the air inlet and outlet through the status monitoring screen; if the temperature and humidity of the air outlet exceed the set range, or the temperature and humidity difference between the air inlet and outlet is abnormal, the equipment is judged to be faulty and an alarm signal is issued; when the system is under maintenance or shut down for a long time, the drain valve is opened to drain the liquid and dirt in the water collection tank.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Integrated solution for low temperature and high humidity environments Traditional fruit and vegetable preservation systems typically employ a "mechanical refrigeration plus independent humidification" mode. During the refrigeration process, the surface temperature of the evaporator is far below the air dew point, resulting in severe dehumidification. Subsequent additional humidification is required, leading to high energy consumption.

[0032] This solution achieves simultaneous cooling and humidification within the same device through countercurrent heat exchange between ice slurry and air in direct contact. This avoids the structural contradiction of "cooling must be followed by dehumidification" in traditional systems, resulting in a simpler system and significantly reduced energy consumption.

[0033] 2. It avoids the risk of condensation and rotting on the surface of fruits and vegetables, thus improving the safety of preservation. While existing direct spraying methods can quickly humidify, they easily form a free water film on the surface of fruits and vegetables, creating conditions for microbial growth and leading to rot and spoilage.

[0034] This solution does not directly spray fruits and vegetables. Instead, it treats the air to a near-saturated low-temperature, high-humidity state before sending it into the storage space. This fundamentally avoids condensation on the surface of fruits and vegetables, significantly reduces the rate of decay, and improves the safety of preservation.

[0035] 3. High-efficiency utilization of ice slurry cooling capacity, energy saving and environmental protection Traditional ice slurry cold storage systems mostly use indirect heat exchange methods, which have limited heat exchange efficiency. In this solution, ice slurry serves as both a cold source and a humidifying medium, forming a uniform liquid film on the surface of the guide plate. This allows for full contact with the air, resulting in more complete release of cooling capacity, a significant improvement in system energy efficiency, and a reduction in operating costs.

[0036] Significantly improved heat exchange efficiency and speed: The ice slurry has a huge latent heat of phase change and heat exchange surface area. Combined with a specially designed baffle plate (multi-layer inclined corrugated packing), the gas-liquid contact area and time are maximized. This makes the heat and mass transfer efficiency of the air handling process extremely high, the cooling and humidification speed fast, and the warehouse can quickly reach and stabilize at the set operating conditions.

[0037] High energy efficiency and low operating costs: Ice slurry can be used as a cold storage medium, prepared and stored during off-peak hours and used during peak hours, achieving "peak shaving and valley filling" and reducing electricity costs. At the same time, the integrated design eliminates the need for a separate humidifier and its energy consumption, significantly improving the overall system energy efficiency ratio (COP).

[0038] 4. No chemical additives, meets food safety standards Compared to spraying methods that use chemical treatments such as preservatives and bactericides, this solution uses only ice slurry as the treatment medium, without any chemical additives, thus avoiding food safety hazards and conforming to the trend of green and healthy food storage. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the low-temperature and high-humidity air treatment system for fruit and vegetable preservation based on ice slurry spray provided by the present invention.

[0040] The image shows: 1-Outer casing, 2-Guide plate, 3-Spray pipe, 4-Nozzle, 5-Sealed inspection port, 6-Water baffle, 7-Status monitoring screen, 8-Air inlet, 9-Air outlet, 10-Return water pipe, 11-Water collection tank, 12-Drain valve, 13-Ice supply pipe, P-1-Water supply pump, P-2-Return water pump, T-1-First temperature sensor, T-2-Second temperature sensor, H-1-First humidity sensor, H-2-Second humidity sensor. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention.

[0042] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely illustrates some embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. It should be noted that, in the absence of conflict, the embodiments and features and technical solutions in the embodiments of the present invention can be combined with each other. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0043] Example 1: A low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray, comprising a shell 1, a guide plate 2, a spray pipe 3, nozzles 4, a baffle plate 6, an air inlet 8, an air outlet 9, a return water pipe 10, a water collection tank 11, an ice slurry supply pipe 13, a water supply pump P-1, a return water 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; the guide plate 2, spray pipe 3, nozzles 4, baffle plate 6, and water collection tank 11 are all located on the shell. Inside the shell 1, one end of the ice slurry supply pipe 13 is connected to the external ice slurry preparation unit, and the other end is connected to the spray pipe 3. The water supply pump P-1 is connected in series with the ice slurry supply pipe 13. The return water pump P-2 is located below the water collection tank 11. One end of the return water pipe 10 is connected to the water collection tank 11, and the other end is connected to the external ice slurry preparation unit. The return water pump P-2 is connected in series with the return water pipe 10. The first temperature sensor T-1, the first humidity sensor H-1, the second temperature sensor T-2, and the second humidity sensor H-2 are all located at the air inlet 8 and the air outlet 9.

[0044] The outer shell 1 is a cuboid structure with an inner wall made of stainless steel. The side wall of the outer shell 1 is provided with a sealed inspection port 5, and the bottom is provided with a drain valve 12, which is connected to the water collection tank 11. The air inlet 8 and the air outlet 9 are respectively provided on the opposite side walls of the outer shell 1. The air inlet 8 is provided with a flow equalizer and a filter.

[0045] The guide plate 2 is a multi-layered inclined serpentine structure with an angle of 55°-65° with the horizontal plane; the plate material of the guide plate 2 is stainless steel, and the surface is treated with hydrophilic modification; the guide plate 2 is used to spread the sprayed ice slurry to form a continuously renewed low-temperature liquid film and force the air to generate turbulence to improve the gas-liquid contact efficiency.

[0046] The spray pipe 3 is welded from insulated stainless steel pipe, including a longitudinally arranged main distribution pipe and multiple horizontally connected spray branch pipes; the liquid inlet of the main distribution pipe is close to the air outlet 9, and the ice slurry is distributed from the main distribution pipe to the spray branch pipes close to the air inlet 8 in sequence; the nozzle 4 is a large-diameter spiral or solid cone nozzle, and multiple nozzles 4 are evenly distributed on the spray branch pipes, and the spraying direction of the nozzles 4 is towards the guide plate 2.

[0047] The baffle plate 6 adopts a folded plate or wire mesh structure and is set between the guide plate 2 and the air outlet 9. The baffle plate 6 uses the principle of inertial collision and adsorption to separate tiny droplets in the air, and the collected droplets flow into the water collection pool 11.

[0048] The water collection tank 11 is located at the bottom of the outer shell 1, and the bottom surface is inclined to facilitate the collection of return water; the ice supply pipe 13 and the return water pipe 10 are both insulated; the water supply pump P-1 and the return water pump P-2 are both positive displacement pumps or non-clogging centrifugal pumps designed specifically for slurry.

[0049] It also includes a status monitoring screen 7, which integrates display, alarm, recording and interactive functions. It is electrically connected to 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 return water pump P-2. It is used to display operating parameters in real time and issue alarm signals in case of failure.

[0050] The low-temperature, high-humidity air treatment method for fruit and vegetable preservation based on ice slurry spraying includes the following steps: S1. Pretreatment: Based on the required storage temperature, 0℃ ice slurry is prepared in advance by an external ice slurry preparation unit to ensure that the ice slurry is free of impurities and has uniform ice crystal particles; S2. Ice Slurry Spraying: Start the water supply pump P-1 to deliver 0℃ ice slurry through the ice slurry supply pipe 13 and the spray pipe 3 to the nozzle 4, and spray it evenly onto the surface of the guide plate 2 to form a low temperature liquid film. S3. Heat and mass exchange: The air to be treated is introduced through the air inlet 8, and after being evenly distributed by the flow equalizer, it comes into countercurrent contact with the ice slurry and low-temperature liquid film on the surface of the guide plate 2. The latent heat of phase change of the ice slurry is used to quickly cool down the air, and at the same time, the air is humidified by water evaporation to obtain low-temperature and high-humidity air. S4. Gas-liquid separation and output: Low-temperature and high-humidity air is sent to the fruit and vegetable storage room from the air outlet 9 after the water baffle 6 removes the liquid droplets. S5. Water return circulation: The water return from the surface of the guide plate 2 flows into the water collection tank 11. The water return pump P-2 is started, and the water return is transported through the water return pipe 10 to the external ice slurry preparation unit to re-prepare ice slurry, so as to realize recycling.

[0051] In step S1, the ice crystal particles in the prepared ice slurry have a diameter of 0.5-2 mm; in step S3, the temperature of the treated low-temperature and high-humidity air is 2±0.5℃ and the relative humidity is 90%-95%.

[0052] It also includes fault diagnosis steps: real-time temperature and humidity data of the air inlet and outlet are obtained through the status monitoring screen 7. If the temperature and humidity of the air outlet exceed the set range, or the temperature and humidity difference between the air inlet and outlet is abnormal, the equipment is determined to be faulty and an alarm signal is issued. When the system is under maintenance or shut down for a long time, the drain valve 12 is opened to drain the liquid and dirt in the water collection tank 11.

[0053] Example 2: A low-temperature and high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray, including a shell 1, a guide plate 2, a spray pipe 3, a nozzle 4, a sealed inspection port 5, a water baffle 6, a status monitoring screen 7, an air inlet 8, an air outlet 9, a return water pipe 10, a water collection tank 11, a drain valve 12, an ice slurry supply pipe 13, a water supply pump P-1, a return water 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.

[0054] During operation, the nozzles evenly spray customized low-temperature ice slurry onto the surface of the guide plate. The ice crystals in the slurry rapidly absorb heat and melt upon direct contact with the air, utilizing the latent heat of phase change to quickly cool the air. Simultaneously, the water in the ice slurry forms a uniform low-temperature liquid film on the guide plate surface, engaging in thorough heat and moisture exchange with the air: on one hand, it continues to cool the air through sensible heat exchange, and on the other hand, it rapidly brings the air close to saturation through moisture evaporation. Ultimately, the air is treated to meet the set requirements for low-temperature, high-humidity clean air.

[0055] Specifically, 0°C ice slurry is prepared in advance according to the required preservation temperature, such as 2°C. This slurry is then pumped by water pump P-1 through ice slurry pipe 13 to spray nozzles 4 at the top of spray pipe 3, where it is sprayed downwards. Air is introduced through air inlet 8, flowing from right to left through guide plate 2, forming a counter-current flow with the sprayed ice slurry for thorough heat and mass exchange, thus being processed into low-temperature, high-humidity air. Subsequently, water baffle 6 removes liquid droplets carried in the air, and finally, the air is discharged through air outlet 9. The ice slurry, after heat and mass transfer with the air, falls along the guide plate into water collection tank 11, and is then pumped by return water pump P-2 through return water pipe 10 back to the ice slurry preparation unit for reprocessing.

[0056] This device mainly includes the following components: Outer shell 1: The overall structure is a cuboid, with the inner wall made of stainless steel to prevent corrosion and contamination. The outer protective plate is made of stainless steel or galvanized steel plate, with polyurethane foam filling the space between the inner and outer layers for insulation, reducing heat loss and preventing condensation on the outer surface when the ambient humidity is high. As the pressure-bearing and sealing main body of the device, a controlled and near-insulated environment is constructed to ensure that the internal heat and mass exchange process is not disturbed by external factors and to guarantee operational safety.

[0057] Baffle 2: The baffle is the core component of this device for achieving efficient and uniform heat and mass exchange. Its core functions are to organize airflow, extend contact, and form a liquid film. Specifically, its special structure guides air to pass through uniformly, transforming disordered spray droplets into an ordered, large gas-liquid contact interface, thereby significantly increasing the contact area and time between air and ice slurry, and greatly enhancing the efficiency of heat transfer cooling and mass transfer humidification.

[0058] To achieve the above functions, the deflector adopts the following preferred structure: Configuration: The multi-layered, tilted serpentine guide plates are placed at an angle of 55°-65° to the horizontal plane, which facilitates the ice slurry to flow more evenly down the plate surface under the action of gravity and avoids vertical dripping.

[0059] Surface characteristics: The plate material is stainless steel, and its surface is hydrophilic modified to promote the rapid spread of ice slurry into a continuous and uniform liquid film on the surface of the guide plate, effectively preventing the "channeling" phenomenon caused by liquid accumulation.

[0060] Working principle: When ice slurry is sprayed onto the surface of the guide plates, the low-temperature water in the ice slurry rapidly forms a constantly renewed cryogenic liquid film. Air passes through the tortuous channels between the guide plates, is forcibly disturbed, and generates strong turbulence, breaking the boundary layer and allowing the cryogenic liquid film to make full contact with the airflow. Ultimately, this maximizes the contact area and prolongs the contact time, thereby achieving extremely high heat and mass transfer efficiency.

[0061] Spray pipe 3: Welded from insulated stainless steel pipe, it stably delivers ice slurry to each nozzle. The spray pipe includes a longitudinally arranged main distribution pipe and multiple horizontally parallel spray branch pipes connected to the main pipe. The liquid inlet of the main distribution pipe is located at one end near the air outlet, so that the ice slurry can be sequentially distributed from the air outlet side to the spray branch pipes at the air inlet side.

[0062] Nozzle 4: It consists of a spray header and multiple large-diameter spiral or solid cone nozzles to prevent ice slurry from clogging the nozzles and to facilitate the uniform dispersion and spraying of ice slurry.

[0063] Function: To distribute ice slurry at a specific temperature evenly and stably across the entire baffle plate, providing the initial cold source and medium for heat and mass exchange.

[0064] Sealed Inspection Port 5: The sealed inspection port is an openable and closureable structure located on the side wall of the outer casing 1. Its core function is to provide a channel for regular inspection, cleaning, maintenance, and troubleshooting of the core areas inside the device, especially the guide plate 2 and nozzles 4, while ensuring that the overall sealing integrity, thermal insulation performance, and structural strength of the device are not affected when closed. Additionally, the door is equipped with a double-layered hollow insulated observation window, facilitating observation of the internal spraying and airflow conditions when closed.

[0065] Water baffle 6: Utilizing a folded plate or wire mesh structure, it separates water droplets through inertial collision and adsorption principles, capturing and removing tiny droplets carried in the air after heat exchange with the ice slurry. This ensures that clean, low-temperature, high-humidity air is delivered, preventing water droplets from being carried away by the air and thus preventing the formation of a free water film on the surface of fruits and vegetables, which creates conditions for mold and bacteria growth, leading to spoilage. The collected condensate flows along the water baffle into the water collection tank 11.

[0066] Status monitoring panel 7: This is the local monitoring core of the device, integrating display, alarm, recording, and interactive functions, specifically including: 1. Core parameter monitoring: Real-time display of temperature and humidity at the air inlet and outlet to intuitively reflect whether the device has achieved the preset preservation conditions.

[0067] 2. Fault diagnosis and alarm: When the air outlet parameters are detected to deviate continuously from the set range or the sensor signal is abnormal, an audible and visual alarm is triggered, indicating "performance degradation" or "sensor failure", providing guidance for preventive maintenance.

[0068] 3. Operational data recording: Built-in memory can record historical data of key parameters and alarm logs, supporting trend query and fault tracing.

[0069] 4. Local interaction: Supports on-site viewing of parameters, setting of alarm thresholds, and manual start and stop of equipment, facilitating debugging and maintenance.

[0070] Water collection tank 11: Located at the bottom of the shell, it collects and temporarily stores the water flowing down from the guide plate. The bottom surface has a certain slope to facilitate water collection and return to the ice slurry preparation unit through the return water pump P-2.

[0071] Function: Serving as a "reservoir" and "sedimentation tank" for the entire ice slurry circulation system, it collects and buffers the water flowing down from the baffle plate. A filter is installed above the return water inlet to filter out impurities brought in by the air or falling off within the system, protecting the return water pump and nozzles.

[0072] Drain valve 12: Installed at the bottom of the water collection tank, used to drain the liquid and dirt in the water collection tank during system maintenance, cleaning or long-term shutdown.

[0073] Water supply pump P-1: Select a positive displacement pump such as a single screw pump or a non-clogging centrifugal pump designed specifically for slurry. It is the power interface connecting the external ice slurry preparation unit and this device, and delivers ice slurry at 0°C stably and adjustablely to nozzle 4.

[0074] Return water pump P-2: Located below the water collection tank, a positive displacement pump such as a single screw pump or a non-clogging centrifugal pump designed specifically for slurry is used to send the return water in the water collection tank to the ice slurry preparation unit for recycling.

[0075] Water supply line 13: Connects the ice slurry preparation unit to the main unit. The low-temperature ice slurry, supplied from the external system via the main water supply line, first reaches the leftmost spray branch pipe (air outlet side), then distributes sequentially to the right of the incoming air flow, finally reaching the rightmost spray branch pipe (air inlet side). This arrangement ensures that the coldest ice slurry encounters the coldest and closest to saturated air on the left, while the warmer ice slurry encounters the warmer and drier air on the right. This arrangement guarantees the largest possible temperature and humidity difference between the ice slurry and the air at any location, maintaining high efficiency in heat exchange and mass transfer, and maximizing overall energy efficiency. Additionally, the pipeline requires insulation.

[0076] Return water pipe 10: Connects the water collection tank to the ice slurry preparation unit, and returns the water, after heat and mass transfer with the air, to the ice slurry preparation unit to re-prepare ice slurry. The pipe needs to be insulated.

[0077] Air inlet 8: Located on the side of the casing, it is equipped with a grille or perforated plate as a flow distributor to introduce the air to be treated and ensure it enters the heat exchange zone evenly. Additionally, the air inlet has a filter to prevent impurities from the outside air from entering the equipment.

[0078] Air outlet 9: Located on the side of the casing, it delivers the low-temperature, high-humidity clean air that has been directly in contact with the ice slurry in the equipment and has been cooled and humidified to the fruit and vegetable storage room for cold storage and preservation of fruits and vegetables.

[0079] The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described herein. Although the present invention has been described in detail with reference to the above embodiments, the present invention is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present invention, as well as all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present invention.

Claims

1. A low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spraying, characterized in that, The system includes a housing (1), a guide plate (2), a spray pipe (3), a nozzle (4), a baffle plate (6), an air inlet (8), an air outlet (9), a return water pipe (10), a water collection tank (11), an ice slurry supply pipe (13), a water supply pump (P-1), a return water 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). The guide plate (2), spray pipe (3), nozzle (4), baffle plate (6), and water collection tank (11) are all located inside the housing (1) to supply ice slurry. One end of the pipe (13) is connected to the external ice slurry preparation unit and the other end is connected to the spray pipe (3). The water supply pump (P-1) is connected in series to the ice slurry supply pipe (13). The return water pump (P-2) is located below the water collection tank (11). One end of the return water pipe (10) is connected to the water collection tank (11) and the other end is connected to the external ice slurry preparation unit. The return water pump (P-2) is connected in series to the return water pipe (10). The first temperature sensor (T-1), the first humidity sensor (H-1), the second temperature sensor (T-2), and the second humidity sensor (H-2) are all located at the air inlet (8) and the air outlet (9).

2. The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray according to claim 1, characterized in that, The outer shell (1) is a cuboid structure with stainless steel material on the inner wall; the outer shell (1) has a sealed inspection port (5) on the side wall and a drain valve (12) at the bottom, which is connected to the water collection tank (11); the air inlet (8) and the air outlet (9) are respectively located on the opposite side walls of the outer shell (1), and the air inlet (8) is equipped with a flow equalizer and a filter.

3. The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray according to claim 1, characterized in that, The guide plate (2) is a multi-layered inclined serpentine structure with an angle of 55°-65° with the horizontal plane; the plate material of the guide plate (2) is stainless steel and the surface is hydrophilic modified; the guide plate (2) is used to spread the sprayed ice slurry to form a continuously renewed low temperature liquid film and force the air to generate turbulence to improve the gas-liquid contact efficiency.

4. The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray according to claim 1, characterized in that, The spray pipe (3) is welded from insulated stainless steel pipe, including a longitudinally arranged main distribution pipe and multiple horizontally connected spray branch pipes; the liquid inlet of the main distribution pipe is close to the air outlet (9), and the ice slurry is distributed from the main distribution pipe to the spray branch pipes close to the air inlet (8) in sequence; the nozzle (4) is a large-diameter spiral or solid cone nozzle, and multiple nozzles (4) are evenly distributed on the spray branch pipes, and the spraying direction of the nozzles (4) is towards the guide plate (2).

5. The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray according to claim 1, characterized in that, The baffle plate (6) adopts a folded plate or wire mesh structure and is set between the guide plate (2) and the air outlet (9). The baffle plate (6) uses the principle of inertial collision and adsorption to separate tiny droplets in the air, and the collected droplets flow into the water collection pool (11).

6. The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray according to claim 1, characterized in that, The water collection tank (11) is located at the bottom of the outer shell (1), and the bottom surface is inclined to facilitate the collection of return water; the ice supply pipe (13) and the return water pipe (10) are both insulated; the water supply pump (P-1) and the return water pump (P-2) are both positive displacement pumps or non-clogging centrifugal pumps designed specifically for slurry.

7. The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray according to claim 1, characterized in that, It also includes a status monitoring screen (7), which integrates display, alarm, recording and interactive functions. It is electrically connected to 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 return water pump (P-2) to display operating parameters in real time and issue alarm signals when there is a fault.

8. A low-temperature, high-humidity air treatment method for fruit and vegetable preservation based on ice slurry spraying, characterized in that, The low-temperature, high-humidity air handling system for fruit and vegetable preservation based on ice slurry spray as described in any one of claims 1-7 includes the following steps: S1. Pretreatment: Based on the required storage temperature, 0℃ ice slurry is prepared in advance by an external ice slurry preparation unit to ensure that the ice slurry is free of impurities and has uniform ice crystal particles; S2. Ice slurry spraying: Start the water supply pump (P-1) to deliver 0℃ ice slurry to the nozzle (4) through the ice slurry supply pipe (13) and the spray pipe (3), and spray it evenly onto the surface of the guide plate (2) to form a low temperature liquid film; S3. Heat and mass exchange: The air to be treated is introduced through the air inlet (8), and after being evenly distributed by the flow equalizer, it comes into countercurrent contact with the ice slurry and low-temperature liquid film on the surface of the guide plate (2). The latent heat of phase change of the ice slurry is used to quickly cool down the air, and at the same time, the air is humidified by water evaporation to obtain low-temperature and high-humidity air. S4. Gas-liquid separation and output: Low-temperature and high-humidity air is sent to the fruit and vegetable storage room from the air outlet (9) after the water baffle (6) removes the liquid droplets. S5. Water return circulation: The water return on the surface of the guide plate (2) flows into the water collection tank (11), the water return pump (P-2) is started, and the water return is transported through the water return pipe (10) to the external ice slurry preparation unit to re-prepare ice slurry and realize recycling.

9. The low-temperature, high-humidity air treatment method for fruit and vegetable preservation based on ice slurry spray according to claim 8, characterized in that, In step S1, the ice crystal particles in the prepared ice slurry have a diameter of 0.5-2 mm; in 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. The low-temperature, high-humidity air treatment method for fruit and vegetable preservation based on ice slurry spray according to claim 8, characterized in that, It also includes fault judgment steps: real-time temperature and humidity data of the air inlet and outlet are obtained through the status monitoring screen (7). If the temperature and humidity of the air outlet exceed the set range, or the temperature and humidity difference between the air inlet and outlet is abnormal, the equipment is judged to be faulty and an alarm signal is issued. When the system is under maintenance or shut down for a long time, the drain valve (12) is opened to drain the liquid and dirt in the water collection tank (11).

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