Liquid dairy product sterilization apparatus and method

Abstract

The present disclosure provides a liquid dairy product sterilization device and method, the liquid dairy product sterilization device comprising: at least one heat exchange device, the heat exchange device comprising a substrate, the substrate being made of SiC material and internally formed with a flow channel for the circulation of liquid dairy products, the flow channel having a characteristic width of 100-500 microns and a characteristic depth of 100-500 microns; a heating source, the heating source being in thermal connection with the substrate and used for heating the flow channel; and a delivery pump, the delivery pump being used to drive the flow of liquid dairy products in the flow channel; wherein the heat flux provided by the heating source and the flow rate of the delivery pump are configured such that the temperature rise time of the liquid dairy products flowing through the flow channel from a preheating temperature to a sterilization temperature is not more than 0.5 seconds, the preheating temperature being 65-75 DEG C, and the sterilization temperature being 138 DEG C + / - 0.5 DEG C.

Description

Technical Field

[0001] This disclosure relates to a sterilization apparatus and method for liquid dairy products. Background Technology

[0002] Ultra-high temperature (UHT) sterilization of liquid dairy products (such as milk) is a key process to ensure product biosafety and extend shelf life. A typical UHT process requires rapidly heating liquid dairy products to 135°C to 142°C and holding for several seconds to kill heat-resistant spores while preserving as much of the product's nutrition and flavor as possible.

[0003] During the aforementioned high-temperature processing, heat-sensitive components in liquid dairy products, such as whey protein and casein, are highly susceptible to thermal denaturation and deposition on the heat exchange wall surface, forming milk residue. Milk residue has extremely poor thermal conductivity, leading to decreased heat transfer efficiency and significantly increasing the flow resistance of liquid dairy products. To ensure stable sterilization temperatures, manufacturers must frequently shut down the equipment for online cleaning to remove milk residue, severely hindering continuous production and efficiency.

[0004] Traditional UHT sterilization equipment typically uses stainless steel tube or plate heat exchangers. The flow channel dimensions of these heat exchangers are usually on the order of millimeters to centimeters, resulting in a significant temperature difference between the fluid's core region and the flow channel wall region. To ensure that the fluid's core temperature meets sterilization requirements, the wall surface often needs to be heated to a level far exceeding the sterilization temperature. This excessively high wall temperature further exacerbates the scaling of milk proteins onto the wall surface.

[0005] Therefore, how to inhibit the scaling of milk proteins on the walls during UHT sterilization is a technical problem that urgently needs to be solved in the field of liquid dairy processing equipment. Summary of the Invention

[0006] This disclosure provides a sterilization apparatus and method for liquid dairy products.

[0007] According to one aspect of this disclosure, a liquid dairy product sterilization apparatus is provided, comprising: at least one heat exchange device including a substrate made of SiC material and having a flow channel formed therein for the flow of liquid dairy product, the flow channel having a characteristic width of 100 μm to 500 μm and a characteristic depth of 100 μm to 500 μm; a heating source thermally connected to the substrate for heating the flow channel; and a delivery pump for driving the liquid dairy product to flow in the flow channel; wherein the heat flux density provided by the heating source and the flow rate of the delivery pump are configured such that the time for the liquid dairy product flowing through the flow channel to rise from a preheating temperature to a sterilization temperature does not exceed 0.5 seconds, the preheating temperature being 65°C-75°C and the sterilization temperature being 138°C ± 0.5°C.

[0008] According to one aspect of the technical solution of this disclosure, liquid dairy products flow through a channel within a substrate made of SiC material, driven by a delivery pump. A heating source provides heat to the substrate via a thermal connection, thereby heating the liquid dairy products within the channel. Because the characteristic width and depth of the channel are limited to the micrometer scale range of 100 μm to 500 μm, the channel has a very large specific surface area, resulting in a highly uniform temperature distribution of the liquid dairy products within the channel cross-section. The fluid core can reach the sterilization temperature without significant overheating of the wall surface. Simultaneously, the heat flux density provided by the heating source and the flow rate of the delivery pump are configured to rapidly raise the liquid dairy products from a preheating temperature of 65℃-75℃ to a sterilization temperature of 138℃±0.5℃ in an extremely short time of no more than 0.5 seconds. This rapid heating process allows the liquid dairy products to quickly traverse the sensitive temperature range where milk proteins undergo thermal denaturation, fundamentally inhibiting the deposition and scaling of milk proteins on the channel wall surface. This avoids the decrease in heat transfer efficiency and frequent shutdowns for cleaning caused by scaling, ensuring continuous operation and efficiency of the sterilization process.

[0009] According to at least one embodiment of the liquid dairy product sterilization apparatus of the present disclosure, the substrate includes a chip layer, a first cover plate and a second cover plate, the chip layer is provided with a flow channel, and the first cover plate and the second cover plate are respectively sealed and connected to opposite ends of the chip layer and cover the flow channel.

[0010] In this embodiment, the flow channel is integrated within an independent chip layer. The upper and lower ends of the chip layer are sealed by a first cover plate and a second cover plate, forming a closed fluid passage. The layered structure formed by the chip layer, the first cover plate, and the second cover plate facilitates the flow channel processing of the chip layer and the surface treatment of the first and second cover plates, reducing manufacturing complexity while ensuring the sealing reliability of the flow channel under high temperature and high pressure conditions.

[0011] According to at least one embodiment of the liquid dairy product sterilization apparatus of the present disclosure, the flow channel is arranged in a serpentine pattern, including a plurality of parallel extensions arranged in a straight line and a bent section connecting the ends of two adjacent parallel extensions.

[0012] In this embodiment, the flow channel is arranged in a serpentine pattern, repeatedly zigzagging within the substrate. This achieves a longer flow path within a limited substrate area, extending the residence distance of the liquid dairy product within the channel. Simultaneously, the flow control of the delivery pump ensures that the liquid dairy product undergoes a complete heating process and sterilization temperature maintenance time within the channel. Furthermore, the bends in the serpentine arrangement cause periodic changes in the fluid flow direction, enhancing micro-mixing within the channel cross-section and further promoting the uniformity of temperature distribution in the liquid dairy product.

[0013] According to at least one embodiment of the liquid dairy product sterilization apparatus of the present disclosure, the heating source includes a ceramic heating element attached to the back side of a substrate.

[0014] In the technical solution of this embodiment, the heating source is a ceramic heating element, which is attached to the back of the substrate and forms a direct contact thermal connection with the substrate. The heat is efficiently transferred to the substrate by thermal conduction, and then to the liquid dairy product in the flow channel.

[0015] The liquid dairy product sterilization apparatus according to at least one embodiment of the present disclosure further includes a first manifold and a second manifold, and a plurality of heat exchange devices are provided, each heat exchange device having an inlet end and an outlet end. The inlet ends of the plurality of heat exchange devices are connected in parallel through the first manifold, and the outlet ends of each heat exchange device are connected in parallel through the second manifold.

[0016] In this embodiment, liquid dairy products are evenly distributed to multiple parallel heat exchange devices via a first manifold. After each heat exchange device independently completes sterilization, the liquid dairy products are collected and output via a second manifold. This parallel structure allows each heat exchange device to maintain the same flow channel structure and process parameters, ensuring the consistency and predictability of sterilization effects after capacity expansion.

[0017] The liquid dairy product sterilization apparatus according to at least one embodiment of the present disclosure further includes two electrodes, which are respectively disposed at both ends of a substrate. The heating source is a DC power supply, which applies DC current to the substrate through the electrodes. The substrate provides heat to the liquid dairy product in the flow channel through its own Joule heating effect.

[0018] In this embodiment, the heating source uses a DC power supply, and DC current is applied to the substrate through electrodes disposed at both ends of the substrate. Since the substrate is made of SiC material and is conductive, Joule heating is generated when current flows through the substrate, and the substrate itself becomes a heating element. Heat is directly transferred from the substrate body to the liquid dairy product in the flow channel, eliminating the need for an external independent heating element. The heat source and heat exchange structure are integrated, shortening the heat transfer path and improving the speed of thermal response.

[0019] The liquid dairy product sterilization apparatus according to at least one embodiment of the present disclosure further includes a countercurrent heat recovery device disposed upstream of the transfer pump for receiving liquid dairy products and transferring the liquid dairy products to the transfer pump. The countercurrent heat recovery device is configured to exchange heat with the liquid dairy products output from the heat exchange device.

[0020] In this embodiment, the countercurrent heat recovery device is located upstream of the delivery pump. Before the liquid dairy products enter the heat exchange device, they undergo countercurrent heat exchange with the sterilized high-temperature liquid dairy products output from the heat exchange device. The residual heat released by the high-temperature liquid dairy products before cooling is recovered and used to preheat the incoming low-temperature liquid dairy products. This reduces the amount of heat required by the heating source to further raise the liquid dairy products from the preheating temperature to the sterilization temperature, thereby reducing the overall energy consumption of the liquid dairy product sterilization device.

[0021] According to another aspect of this disclosure, a method for sterilizing liquid dairy products is provided, comprising: driving liquid dairy products through a flow channel in a substrate made of SiC material via a delivery pump; the flow channel having a characteristic width of 100 μm to 500 μm and a characteristic depth of 100 μm to 500 μm; and providing heat to the liquid dairy products in the flow channel via a heating source thermally connected to the substrate, such that the liquid dairy products flowing through the channel rise from a preheating temperature to a sterilization temperature within a time not exceeding 0.5 seconds, wherein the preheating temperature is 65℃-75℃ and the sterilization temperature is 138℃±0.5℃.

[0022] According to another aspect of this disclosure, liquid dairy products flow through micron-scale channels within a SiC substrate driven by a delivery pump. A heating source provides heat to the channels via a thermal connection with the substrate. Because the characteristic width and depth of the channels are limited to the range of 100 μm to 500 μm, the channels have a very large specific surface area, resulting in a highly uniform temperature distribution of the liquid dairy products within the channel cross-section, eliminating the need for significant overheating of the substrate walls. The heat flux density provided by the heating source is coordinated with the flow rate of the delivery pump, enabling the liquid dairy products to rapidly rise from a preheating temperature of 65°C-75°C to a sterilization temperature of 138°C ± 0.5°C in an extremely short time of no more than 0.5 seconds. The aforementioned rapid heating process allows liquid dairy products to quickly pass through the sensitive temperature range where milk proteins undergo thermal denaturation, fundamentally inhibiting the deposition and scaling of milk proteins on the flow channel walls. At the same time, the inherent high wall shear force within the micron-scale flow channel peels off the already attached trace protein aggregates, further reducing the degree of scaling. This reduces the attenuation of heat transfer efficiency caused by scaling, extends the continuous operating time of the device, and improves the processing efficiency of liquid dairy products.

[0023] The method for sterilizing liquid dairy products according to at least one embodiment of the present disclosure further includes: detecting the electrical conductivity of the liquid dairy products flowing through the substrate during the process of the liquid dairy products flowing through the flow channel.

[0024] In this embodiment, while the liquid dairy product is being heated and sterilized as it flows through the flow channel, online conductivity detection is performed on the liquid dairy product flowing through the substrate. In normal liquid dairy products, lactose and inorganic salts dissolve in molecular and ionic form, forming a relatively stable concentration of free ions, resulting in a stable conductivity. When the raw milk (before sterilization) is adulterated or has abnormal quality, its ion concentration deviates from the normal range, and the conductivity changes accordingly. By detecting conductivity online, the quality of the raw milk can be simultaneously determined during the sterilization process, eliminating the need for a separate offline detection step.

[0025] According to at least one embodiment of the present disclosure, the method for sterilizing liquid dairy products includes providing heat by applying direct current to the substrate through electrodes disposed at both ends of the substrate, thereby causing the substrate to generate heat through its own Joule heating effect.

[0026] In this embodiment, the heating source uses a DC power supply, and the heat is supplied by applying DC current to the substrate through electrodes at both ends. Since the substrate is made of SiC material and is conductive, Joule heating is generated when current flows through it, making the substrate itself a heating element. This self-heating method allows heat to be directly transferred from the substrate to the liquid dairy product within the flow channel, resulting in a shorter heat transfer path and a faster thermal response. Attached Figure Description

[0027] The accompanying drawings illustrate exemplary embodiments of the present disclosure and, together with the description thereof, serve to explain the principles of the present disclosure. These drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification.

[0028] Figure 1 This is a schematic diagram of a liquid dairy product sterilization apparatus and method according to one embodiment of the present disclosure.

[0029] Figure 2 This is a schematic diagram of the structure of a substrate according to one embodiment of the present disclosure.

[0030] Figure 3 This is a schematic diagram of the structure of a substrate according to one embodiment of the present disclosure from a top view.

[0031] Figure 4 This is a schematic diagram of the structure of a chip layer according to one embodiment of the present disclosure.

[0032] Figure 5 This is a schematic diagram of the connection between a ceramic heating element and a substrate according to one embodiment of the present disclosure.

[0033] Figure 6 This is a schematic diagram showing the connection between a first branch manifold, a second branch manifold, and a plurality of heat exchange devices according to one embodiment of the present disclosure.

[0034] Figure label: 100 heat exchanger 110 base 111 Chip Layer 112 First cover plate 113 Second cover plate 120 flow channel 121 Parallel extension 122 bending section 130 Entry Point 140 Export end 200 heating source 210 electrode 220V DC power supply 230 Ceramic heating element 300 transfer pump 400 First branch manifold 500 Second branch manifold 600 Countercurrent Heat Recovery Unit 700 Raw Material Balance Storage Tank 800 Cooling Module 900 Control Unit 1000 Aseptic Cold Filling Workshop. Detailed Implementation

[0035] The present disclosure will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure. Furthermore, it should be noted that, for ease of description, only the parts relevant to the present disclosure are shown in the accompanying drawings.

[0036] It should be noted that, where there is no conflict, the embodiments and features described in this disclosure can be combined with each other. The technical solutions of this disclosure will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] Unless otherwise stated, the exemplary implementations / embodiments shown are to be understood as providing exemplary features of various details that provide ways in which the technical concepts of this disclosure can be implemented in practice. Therefore, unless otherwise stated, the features of various implementations / embodiments may be additionally combined, separated, interchanged and / or rearranged without departing from the technical concepts of this disclosure.

[0038] In existing technologies, ultra-high temperature instantaneous sterilization of liquid dairy products typically employs stainless steel tube or plate heat exchangers, with flow channel dimensions ranging from millimeters to centimeters. In these macroscopically sized channels, a significant temperature difference exists between the fluid core region and the near-wall region. To ensure the fluid core reaches the sterilization temperature, the wall surface must be heated to a level far exceeding the sterilization temperature. However, heat-sensitive components in liquid dairy products, such as whey protein and casein, are highly susceptible to thermal denaturation and deposition on the overheated wall surface, forming milk residue. This leads to decreased heat transfer efficiency and increased flow resistance, forcing manufacturers to frequently shut down for cleaning, thus hindering continuous production.

[0039] To this end, the present disclosure proposes the following technical solution, wherein by reducing the flow channel size of the heat exchange device to the micrometer level to eliminate the need for wall overheating, and by coordinating the heat flux density of the heating source with the flow rate of the delivery pump, the liquid dairy products can pass through the sensitive temperature range of protein denaturation in a very short time, thereby inhibiting wall fouling from the source.

[0040] Figure 1 This is a schematic diagram of a liquid dairy product sterilization apparatus and method according to one embodiment of the present disclosure.

[0041] like Figure 1 As shown, this disclosure provides a sterilization device for liquid dairy products, including at least one heat exchange device 100, a heating source 200 and a transfer pump 300.

[0042] Figure 2 This is a schematic diagram of the structure of a substrate according to one embodiment of the present disclosure. Figure 3 This is a schematic diagram of the structure of a substrate according to one embodiment of the present disclosure from a top view. Figure 4 This is a schematic diagram of the structure of a chip layer according to one embodiment of the present disclosure.

[0043] Combination Figures 2 to 4 As shown, the heat exchange device 100 includes a substrate 110 made of SiC material, and has flow channels 120 formed inside for the flow of liquid dairy products. The characteristic width of the flow channels 120 is 100 μm to 500 μm, and the characteristic depth is 100 μm to 500 μm. The function of the heat exchange device 100 is to provide a closed space for the heated flow of liquid dairy products. The characteristic width refers to the maximum inner wall spacing of the cross-section of the flow channels 120 in the direction parallel to the surface of the substrate 110, and the characteristic depth refers to the maximum inner wall spacing of the cross-section of the flow channels 120 in the direction perpendicular to the surface of the substrate 110. SiC material refers to silicon carbide, which has a thermal conductivity higher than 350 W / (m·K) and possesses high thermal conductivity and chemical inertness.

[0044] The heating source 200 is thermally connected to the substrate 110 and is used to heat the flow channel 120. The function of the heating source 200 is to provide the heat required for heating the liquid dairy product in the flow channel 120. The thermal connection means that the heating source 200 and the substrate 110 form a heat transfer path through direct contact or through an intermediate heat-conducting medium layer.

[0045] The transfer pump 300 is used to drive the liquid dairy product to flow in the flow channel 120. The function of the transfer pump 300 is to provide a controlled flow driving force for the liquid dairy product, causing it to pass through the heat exchange device 100 at a predetermined flow rate.

[0046] The heat flux density provided by the heating source 200 and the flow rate of the delivery pump 300 are configured such that the time for the liquid dairy product flowing through the flow channel 120 to rise from the preheating temperature to the sterilization temperature does not exceed 0.5 seconds. The preheating temperature is 65℃-75℃, and the sterilization temperature is 138℃±0.5℃. Heat flux density refers to the amount of heat passing through a heat transfer surface per unit area per unit time. The preheating temperature refers to the initial temperature of the liquid dairy product before entering the area of ​​action of the heating source 200. The sterilization temperature refers to the target temperature to which the liquid dairy product is heated within the flow channel 120, a temperature sufficient to kill the target microorganisms within a predetermined time.

[0047] The working principle of the liquid dairy product sterilization device described above is as follows: Liquid dairy products enter the flow channel 120 of the heat exchanger 100 at a controllable flow rate, driven by the delivery pump 300. Since the characteristic width and depth of the flow channel 120 are limited to the micrometer scale range of 100 μm to 500 μm, the hydraulic diameter of the flow channel 120 is correspondingly limited to the micrometer scale. According to the theory of convective heat transfer, the convective heat transfer coefficient h between the fluid and the wall is inversely proportional to the hydraulic diameter Dh, i.e., h = Nu·k / Dh, where Nu is the Nusselt number and k is the thermal conductivity of the liquid dairy product. The smaller the hydraulic diameter Dh, the larger the convective heat transfer coefficient h. Within the characteristic scale of 100 μm to 500 μm, the specific surface area of ​​the flow channel 120 can reach the order of 10,000 m² / m³ to 30,000 m² / m³, and the convective heat transfer coefficient is 1 to 2 orders of magnitude higher than that of traditional flow channels with a diameter of millimeters or larger. The extremely high convective heat transfer coefficient means that heat can be transferred from the wall to the fluid very quickly, and the radial temperature difference within the fluid cross-section is compressed to a minimum, almost zero temperature gradient. Therefore, the wall temperature only needs to be slightly higher than the fluid temperature to drive heat transfer, and the wall does not need to be heated to a level far above the sterilization temperature. There is no physical basis for the increased fouling of milk proteins due to overheating of the wall in traditional macroscopic flow channels.

[0048] Assuming an environment free from overheating on the wall surface, the heat flux density provided by the heating source 200 and the flow rate of the delivery pump 300 are coordinated to control the residence time and heating rate of the liquid dairy product within the flow channel 120. The heat flux density determines the amount of heat input to a unit area of ​​the wall surface per unit time, while the flow rate of the delivery pump 300 determines the speed at which the liquid dairy product flows through the flow channel 120. Together, they determine the temperature rise profile of the liquid dairy product along the length of the flow channel 120. By matching the heat flux density and flow rate to predetermined values, the liquid dairy product rapidly rises from a preheating temperature of 65℃-75℃ to a sterilization temperature of 138℃±0.5℃ within less than 0.5 seconds. This rapid heating process allows the liquid dairy product to traverse the sensitive temperature range where milk proteins undergo heat-induced denaturation in a very short time. The milk proteins leave the high-temperature zone before they have fully expanded and cross-linked, thus preventing effective deposition on the wall surface to form milk residue. Meanwhile, the high wall shear force within the micron-scale flow channel 120 exerts a continuous peeling effect on any micro-protein aggregates that may have already adhered, further reducing the degree of scaling. Thus, the above technical solution, through the synergistic effect of eliminating wall overheating and shortening protein heating time, fundamentally inhibits wall scaling, avoiding the heat transfer efficiency degradation and frequent shutdowns for cleaning caused by scaling, and ensuring continuous operation and high efficiency of sterilization work.

[0049] In some embodiments of this disclosure, the delivery pump 300 is a high-pressure pump. The output pressure of the high-pressure pump can meet the driving head required for the liquid dairy product to flow in the micron-scale flow channel 120. Since the characteristic width and characteristic depth of the flow channel 120 are 100 μm to 500 μm, and the hydraulic diameter of the flow channel 120 is on the order of microns, the wall friction resistance is relatively large when the liquid dairy product flows in the flow channel 120, requiring a high inlet end 130 pressure to maintain a predetermined flow rate. The high-pressure pump can provide a stable high-pressure output, allowing the liquid dairy product to pass through the heat exchange device 100 at a constant flow rate, avoiding flow fluctuations caused by pressure pulsation, and ensuring the stability of the configuration relationship between the heat flux density provided by the heating source 200 and the flow rate of the delivery pump 300. In a specific example, the delivery pump 300 is a high-pressure non-pulsating delivery pump, whose output pressure pulsation amplitude is lower than a predetermined threshold, further reducing the interference of flow fluctuations on the accuracy of heating time control.

[0050] In some embodiments of this disclosure, the substrate 110 includes a chip layer 111, a first cover plate 112 and a second cover plate 113. The chip layer 111 is provided with a flow channel 120. The first cover plate 112 and the second cover plate 113 are respectively sealed and connected to the opposite ends of the chip layer 111 and cover the flow channel 120.

[0051] In terms of installation method, the chip layer 111 can be independently fabricated using micro-nano processing technology. First, high-density reaction-sintered SiC is selected as the substrate for the chip layer 111. A nickel hard mask is coated on its surface. The flow channel 120 pattern is transferred to the mask layer using photolithography. Subsequently, dry deep silicon etching is performed in an inductively coupled plasma (ICP-PAP) system under a fluorine-based gas atmosphere to obtain a microchannel array with an inner wall roughness Ra of less than 0.1 μm for the flow channel 120. After the mask is removed, the flow channel 120 of the chip layer 111 is fabricated. The first cover plate 112 and the second cover plate 113 can be made of SiC material of the same composition as the chip layer 111 or a high-temperature special inorganic glass material. The sealing connection between the first cover plate 112 and the second cover plate 113 and the chip layer 111 can be achieved by high-temperature molten solid-phase bonding of special microcrystalline sealing glass powder at 1050℃, or by compression sealing using precision mechanical tooling. The aforementioned layered structure exposes the processing surface of the flow channel 120 to the surface of the chip layer 111, which facilitates the inspection of etching quality before bonding and reduces the overall manufacturing difficulty. At the same time, the first cover plate 112 and the second cover plate 113 provide sealing for the flow channel 120 in both the upper and lower directions, ensuring that the liquid dairy products do not leak under high temperature and high pressure conditions.

[0052] For example, the flow channel 120 is arranged in a serpentine pattern, including a plurality of parallel extensions 121 that are parallel to each other and arranged in a straight line direction, and a bent section 122 connecting the ends of two adjacent parallel extensions 121.

[0053] In the serpentine arrangement of the flow channel 120, multiple parallel extension segments 121 are arranged sequentially in the plane of the base 110 along a first direction (as shown in the left-right direction). Each parallel extension segment 121 extends along a second direction perpendicular to the first direction (as shown in the up-down direction). In two adjacent parallel extension segments 121, the end of one parallel extension segment 121 and the beginning of the other parallel extension segment 121 are located on the same side, and a bending segment 122 connects the end and the beginning, forming a 180° flow direction bend. After the liquid dairy product enters from the inlet end 130, it flows sequentially through the first parallel extension segment 121, the first bending segment 122, the second parallel extension segment 121, the second bending segment 122, and so on, until it flows out from the outlet end 140. The above arrangement allows the total length of the flow channel 120 to be extended within the limited area of ​​the base 110. Taking a single parallel extension segment 121 with a length of 120 mm as an example, if 10 parallel extension segments 121 are set, the total length of the flow channel 120 can reach about 1.2 m, providing sufficient heating residence distance for liquid dairy products within the micron-scale flow channel 120. The bending segment 122 causes a periodic change in the fluid flow direction, promoting the uniformity of temperature in various areas of the liquid dairy product.

[0054] For example, the flow channel 120 can be divided into a heating section and a constant temperature maintenance section along the flow direction. In the heating section, the liquid dairy product is heated from the preheating temperature to the sterilization temperature, and in the constant temperature maintenance section, the liquid dairy product is maintained at the sterilization temperature for a predetermined time. The constant temperature maintenance section can be achieved by continuously providing a heating source 200 with a low heat flux density to compensate for heat loss, or by a passive insulation design of the flow channel 120.

[0055] Figure 5 This is a schematic diagram of the connection between a ceramic heating element and a substrate according to one embodiment of the present disclosure.

[0056] Combination Figure 5 As shown, as an example, the heating source 200 includes a ceramic heating element 230 attached to the back surface of the substrate 110. The ceramic heating element 230 can be an aluminum nitride ceramic heating element, which has high thermal conductivity and a coefficient of thermal expansion similar to that of the SiC substrate 110, resulting in lower interfacial thermal stress during repeated thermal cycling. The ceramic heating element 230 is attached to the back surface of the substrate 110, i.e., the outer surface of the substrate 110 opposite to the plane containing the flow channel 120. In embodiments where the substrate 110 includes a chip layer 111, a first cover plate 112, and a second cover plate 113, the ceramic heating element 230 can be attached to the outer surface of either the first cover plate 112 or the second cover plate 113, with heat conducted to the chip layer 111 via the cover plate. The bonding method can employ a thermally conductive interface material to fill the contact gaps to reduce contact thermal resistance. When the heating source 200 is working, the ceramic heating element 230 receives external electrical power input and converts electrical energy into heat energy. The heat enters the substrate 110 through the bonding interface via thermal conduction, and is then transferred to the wall of the flow channel 120 via the substrate 110 body. Finally, it is transferred to the liquid dairy product in the flow channel 120 through convection heat transfer. Because the ceramic heating element 230 and the substrate 110 form a surface contact, the heat flow is evenly distributed in the plane of the substrate 110, which is conducive to achieving the same heating temperature in each flow channel 120.

[0057] Figure 6 This is a schematic diagram showing the connection between a first branch manifold, a second branch manifold, and a plurality of heat exchange devices according to one embodiment of the present disclosure.

[0058] like Figure 4 and Figure 6As shown, in some embodiments of this disclosure, the liquid dairy product sterilization device further includes a first manifold 400 and a second manifold 500. Multiple heat exchange devices 100 are included, each with an inlet end 130 and an outlet end 140. The inlet ends 130 of the multiple heat exchange devices 100 are connected in parallel via the first manifold 400, and the outlet ends 140 of each heat exchange device 100 are connected in parallel via the second manifold 500. The inlet of the first manifold 400 is connected to the outlet of the transfer pump 300. The cross-sectional area of ​​the inner cavity of the first manifold 400 gradually contracts along the flow direction or is provided with guide vanes to ensure a uniform distribution of the flow rate of liquid dairy products entering each heat exchange device 100. The second manifold 500 acts as a confluencer in the fluid flow direction, collecting the liquid dairy products flowing out of the outlet ends 140 of each heat exchange device 100 into a single outlet pipeline. In the parallel architecture, each heat exchanger 100 maintains the same flow channel 120 geometry and operating parameters; that is, the characteristic width, characteristic depth, flow channel 120 length, heat flux density, and flow rate of each heat exchanger 100 are identical. The outlet end 140 of each heat exchanger 100 is connected to a second manifold 500, which collects the sterilized liquid dairy products output from each heat exchanger 100 and channels them to downstream pipelines. This parallel structure ensures that the total throughput of the liquid dairy product sterilization system equals the throughput of a single heat exchanger 100 multiplied by the number of parallel units. For example, if the throughput of a single heat exchanger 100 is 200 mL / min, connecting 84 heat exchangers 100 in parallel yields a total throughput of approximately 1000 L / h. Because each heat exchanger 100 performs sterilization independently with consistent parameters, the sterilization effect after capacity expansion corresponds proportionally to the sterilization effect of a single laboratory-level heat exchanger 100, eliminating the need for redevelopment of process parameters.

[0059] In some embodiments of this disclosure, the liquid dairy product sterilization device further includes two electrodes 210, which are respectively disposed at both ends of the substrate 110. The heating source 200 is a DC power supply 220, which applies DC power to the substrate 110 through the electrodes 210. The substrate 110 provides heat to the liquid dairy product in the flow channel 120 through its own Joule heating effect.

[0060] For example, the substrate 110 is made of conductive SiC material. The conductive SiC material can be obtained by doping nitrogen into reaction-sintered SiC to obtain N-type conductive SiC, whose resistivity can be tuned to the order of 10⁻²Ω·cm to 10¹Ω·cm. Two electrodes 210 are respectively disposed at both ends of the substrate 110 along the extension direction of the flow channel 120, forming conductive contact with the substrate 110. The positive and negative terminals of the DC power supply 220 are respectively connected to the two electrodes 210, forming a current path inside the substrate 110 along the extension direction of the flow channel 120. According to Joule's law of heating, when current flows through the conductive SiC substrate 110 with a certain resistance, electrical energy is converted into heat energy, with a heating power P=I²R, where I is the current flowing through the substrate 110 and R is the resistance of the substrate 110 in the direction of current flow. Since the heating element is the substrate 110 itself, heat is uniformly generated inside the substrate 110 and directly transferred to the wall of the flow channel 120. The heat transfer path is shorter than that of external bonding heating, resulting in a faster thermal response speed. The output voltage and current of the DC power supply 220 can be closed-loop regulated by the control unit 900 according to the preset temperature curve.

[0061] In some embodiments of this disclosure, the liquid dairy product sterilization apparatus further includes a countercurrent heat recovery device 600, which is located upstream of the transfer pump 300 and is used to receive liquid dairy products and transfer them to the transfer pump 300. The countercurrent heat recovery device 600 is configured to exchange heat with the liquid dairy products output from the heat exchange device 100.

[0062] Exemplarily, the countercurrent heat recovery device 600 has a first flow path and a second flow path, with the flow directions of the first and second flow paths being opposite. The inlet of the first flow path receives low-temperature liquid dairy products from a raw material source, and the outlet of the first flow path is connected to the inlet of the transfer pump 300. The inlet of the second flow path is connected to the outlet end 140 of the heat exchange device 100, receives sterilized high-temperature liquid dairy products, and the outlet of the second flow path is connected to a downstream cooling section. The first and second flow paths are separated by a partition wall, through which heat is transferred from the high-temperature liquid dairy products in the second flow path to the low-temperature liquid dairy products in the first flow path. During the heat exchange process, the low-temperature liquid dairy products are preheated to 65°C-75°C before entering the heat exchange device 100, and the high-temperature liquid dairy products are initially cooled before entering the cooling section. Since the heat absorbed by the low-temperature liquid dairy products comes from the residual heat released by the high-temperature liquid dairy products, the heating source 200 only needs to provide the heat required to further raise the liquid dairy products from 65℃-75℃ to 138℃±0.5℃, thereby reducing the heating energy consumption of the device.

[0063] In some embodiments of this disclosure, the liquid dairy product sterilization apparatus further includes a raw material balancing tank 700. The raw material balancing tank 700 is located upstream of the transfer pump 300 and is used to store the liquid dairy products to be sterilized and provide a stable feed level to the transfer pump 300. The outlet of the raw material balancing tank 700 can be connected to the first flow path inlet of the countercurrent heat recovery device 600, or, when the apparatus does not have the countercurrent heat recovery device 600, the outlet of the raw material balancing tank 700 is directly connected to the inlet of the transfer pump 300. The raw material balancing tank 700 provides a buffer volume for the apparatus, mitigating the impact of upstream material fluctuations on the inlet pressure of the transfer pump 300, ensuring a stable output flow rate of the transfer pump 300, and thus ensuring that the configuration relationship between the heat flux density provided by the heating source 200 and the flow rate of the transfer pump 300 does not deviate from the preset value due to material fluctuations during continuous operation.

[0064] In some embodiments of this disclosure, the liquid dairy product sterilization apparatus further includes a cooling module 800. The cooling module 800 is located downstream of the heat exchange device 100 and is used to receive the sterilized high-temperature liquid dairy products and rapidly cool them to below 25°C. When the apparatus is equipped with a countercurrent heat recovery device 600, the cooling module 800 is located downstream of the second flow path outlet of the countercurrent heat recovery device 600, meaning the high-temperature liquid dairy products are first initially cooled by the countercurrent heat recovery device 600 before entering the cooling module 800 for further cooling. The cooling module 800 can employ an ice-water bath heat exchanger or a refrigerant plate heat exchanger, using a partitioned heat exchange method to reduce the temperature of the liquid dairy products to a temperature range suitable for aseptic cold filling.

[0065] In some embodiments of this disclosure, the liquid dairy product sterilization apparatus further includes a control unit 900. The control unit 900 is signal-connected to the heating source 200 and the transfer pump 300. The control unit 900 is configured to receive temperature and flow signals collected by various sensors in the system, and, according to preset sterilization process parameters, send output power commands to the heating source 200 and flow commands to the transfer pump 300. During the stable operation phase of the apparatus, the control unit 900 performs closed-loop feedback regulation of the output power of the heating source 200 and the flow rate of the transfer pump 300, so that the liquid dairy product flowing through the flow channel 120 rises from a preheating temperature of 65°C-75°C to a sterilization temperature of 138°C ± 0.5°C within no more than 0.5 seconds, and maintains this temperature for 2.5 seconds. When it is necessary to switch product lines to handle liquid dairy products with different process requirements, the control unit 900 is configured to adjust the output parameters of the heating source 200 to the new process steady state within 2 seconds according to the newly preset liquid dairy product type, minimizing waste during the transition period. The control unit 900 can use a programmable logic controller (PLC) as the control hardware.

[0066] According to another aspect of this disclosure, a method for sterilizing liquid dairy products is provided. This method can be implemented using the liquid dairy product sterilization apparatus described in any of the foregoing embodiments.

[0067] The sterilization method for liquid dairy products includes the following steps: Liquid dairy products are driven by a delivery pump 300 to flow through a channel 120 in a substrate 110 made of SiC material. The channel 120 has a characteristic width of 100 μm to 500 μm and a characteristic depth of 100 μm to 500 μm. Heat is supplied to the liquid dairy product in the flow channel 120 by the heating source 200 which is thermally connected to the substrate 110, so that the liquid dairy product flowing through it rises from the preheating temperature to the sterilization temperature in no more than 0.5 seconds. The preheating temperature is 65℃-75℃ and the sterilization temperature is 138℃±0.5℃.

[0068] In some embodiments of this disclosure, the sterilization method for liquid dairy products further includes: detecting the conductivity of the liquid dairy product flowing through the substrate 110 during the flow of the liquid dairy product through the flow channel 120. The conductivity detection is performed simultaneously with the heating and sterilization of the liquid dairy product. In normal liquid dairy products, lactose and inorganic salts are dissolved in the liquid phase in molecular and ionic forms, respectively. Since the content of lactose and inorganic salts is relatively stable in normal milk, the concentration of free ions formed in the liquid phase is basically constant, therefore normal liquid dairy products have a stable conductivity value. When the raw milk (before sterilization) is adulterated or has abnormal quality, its ion concentration deviates from the normal range, and the conductivity changes accordingly. By detecting the conductivity online and comparing the detected value with the normal range, the quality of the raw milk can be simultaneously determined during the sterilization process, eliminating the need for a separate offline sampling and testing step outside the sterilization process. In implementation, a pair of detection electrodes can be disposed on the wall of the flow channel 120. The detection electrode pair is electrically connected to an AC bridge measurement circuit. The AC bridge measurement circuit measures the resistance value of the liquid dairy product flowing through the flow channel 120 and converts it into conductivity. The detection electrode pair is electrically isolated from the heating source 200 to avoid interference of the heating current with the conductivity measurement signal. In embodiments where the heating source 200 includes a ceramic heating element 230, electrical isolation is naturally achieved through the substrate 110 body.

[0069] In some embodiments of this disclosure, the step of providing heat in the sterilization method for liquid dairy products includes: applying direct current to the substrate 110 through electrodes 210 disposed at both ends of the substrate 110, causing the substrate 110 to heat up through its own Joule heating effect. The substrate 110 is made of conductive SiC material. The conductive SiC material can be obtained by doping nitrogen into reaction-sintered SiC to obtain N-type conductive SiC, and its resistivity is tuned to a range suitable for the Joule heating effect. A direct current power supply 220 applies direct current to the substrate 110 through electrodes 210 disposed at both ends of the substrate 110 along the extension direction of the flow channel 120, and the current forms a path inside the conductive SiC substrate 110 along the extension direction of the flow channel 120. According to Joule's law of heating, when current flows through the conductive SiC substrate 110 with a certain resistance, electrical energy is converted into heat energy, and the heating power P=I²R, where I is the current through the substrate 110 and R is the resistance of the substrate 110 in the direction of the current. Heat is uniformly generated within the substrate 110 and directly transferred from the substrate 110 to the wall of the flow channel 120, and then to the liquid dairy product within the flow channel 120. This method uses the substrate 110 itself as the heating element, resulting in a shorter heat transfer path and faster thermal response compared to externally attached heating elements. In practice, the output voltage and current of the DC power supply 220 are regulated by the control unit 900 through closed-loop feedback based on a preset sterilization temperature. By changing the DC power applied to the substrate 110, the temperature of the substrate 110 is controlled, thereby controlling the heating rate and sterilization temperature of the liquid dairy product.

[0070] The working process of the liquid dairy product sterilization device and method described above is as follows: In the embodiment where a ceramic heating element 230 is used as the heating source 200, high-density reaction-sintered SiC is selected as the substrate material 110. In the embodiment where a DC power supply 220 and an electrode 210 are used for heating via the Joule heating effect, nitrogen-doped conductive reaction-sintered SiC is selected as the substrate material 110, with its resistivity tuned to the order of 10⁻²Ω·cm to 10¹Ω·cm. A parallel serpentine microchannel matrix is ​​drawn using computer-aided design software, with the design dimensions of a single channel 120 being: feature width 300μm, feature depth 400μm, and length 120mm. A nickel hard mask is coated on the cleaned substrate 110 surface, and the channel 120 pattern is transferred to the mask layer using standard photolithography. Subsequently, the substrate 110 is placed in an inductively coupled plasma (ICP-PAP) machine, and high-selectivity dry deep silicon etching is performed in a fluorine-based gas atmosphere, where a mixture of sulfur hexafluoride and oxygen can be used. After etching, the mask is removed to obtain a microchannel array with an inner wall roughness Ra of less than 0.1 μm for the channel 120. Finally, a special microcrystalline sealing glass powder is used for high-temperature molten solid-state bonding at 1050℃ to seal the first cover plate 112 and the second cover plate 113 to the chip layer 111, forming a closed chip. Based on a feature width of 300 μm and a feature depth of 400 μm, the hydraulic diameter Dh of the channel 120 is 343 μm.

[0071] In terms of system integration and assembly, the aforementioned chips are tightly sealed within a stainless steel insulated housing. A ceramic heating element 230, which can be a high-power-density aluminum nitride ceramic heating element, is attached to the back of the substrate 110. The thermal conductivity of the SiC chip substrate 110 is 420 W / (m·K) to ensure rapid instantaneous heat transfer and reduce the internal temperature gradient of the substrate 110. The rated flow rate of a single chip at the liquid dairy product inlet 130 is 50 mL / min to 200 mL / min. For industrial scale-up, multiple chips can be connected in parallel to expand the throughput to tons per hour. The preheating section output temperature of the countercurrent heat recovery device 600 is set to 65°C to 75°C to recover high-temperature heat and reduce the overall energy consumption of the system. The temperature of the microchannel instantaneous sterilization section is set to 138°C ± 0.5°C, and the time from the preheating temperature to the sterilization temperature does not exceed 0.5 seconds. The isothermal sterilization maintenance section is set to 2.5 seconds to efficiently kill pathogenic spores and achieve commercial aseptic requirements. Taking raw milk sterilization as an example, the configuration relationship of the above engineering parameters is shown in the table below: In the continuous dynamic sterilization production process, the raw liquid dairy product enters the first flow path of the countercurrent heat recovery device 600 from the refrigerated source tank, where it undergoes countercurrent heat exchange with the high-temperature liquid dairy product flowing through the second flow path from the outlet 140 of the heat exchange device 100, rapidly raising its temperature to approximately 70°C. Subsequently, the delivery pump 300 pressurizes the preheated liquid dairy product into the flow channel 120 of the heat exchange device 100. Under the closed-loop feedback control of the control unit 900, the output power of the ceramic heating element attached to the back of the substrate 110 is adjusted in real time based on the flow rate of the delivery pump 300. Under constant high heat flux density, the heat transfer equation q=h·(T) is satisfied. wall -T fluid ), where q is the heat flux density, h is the convective heat transfer coefficient, and T wall T is the wall temperature of the flow channel at 120°C. fluid The temperature of the liquid dairy product is determined by the extremely high convective heat transfer coefficient h provided by the micron-scale flow channel 120. Within 0.4 seconds, the liquid dairy product rapidly crosses the sensitive temperature zone prone to protein fouling, directly reaching 138°C. The liquid dairy product then flows through the isothermal maintenance section of the serpentine flow channel 120, where it is maintained at 138°C ± 0.5°C for 2.5 seconds to achieve efficient sterilization. Subsequently, the high-temperature liquid dairy product flows through the second flow path of the counter-current heat recovery device 600, releasing heat to the low-temperature liquid dairy product in the first flow path for initial cooling. It then enters the cooling module 800, where it is rapidly cooled to below 25°C before being sent to the aseptic cold filling workshop 1000 for filling. When it is necessary to temporarily adjust the product line to produce liquid dairy products with different process requirements, such as setting the sterilization temperature to 130°C and the constant temperature maintenance time to 4 seconds, the control unit 900 can smoothly transition the output parameters of the heating source 200 and the flow rate of the delivery pump 300 to the new process steady state within 2 seconds, reducing the generation of waste during the transition period.

[0072] The parameters in the above-mentioned working process may include: feature width 300 μm, feature depth 400 μm, hydraulic diameter 343 μm, thermal conductivity 420 W / (m·K), flow rate 50 mL / min to 200 mL / min, preheating temperature 65℃ to 75℃, sterilization temperature 138℃±0.5℃, and isothermal holding time 2.5 seconds. Those skilled in the art should understand that, within the scope defined in the claims, the above parameters can be adjusted according to actual production needs. For example, the feature width and feature depth can be selected within the range of 100 μm to 500 μm, and the flow rate can be designed to match the number of parallel chips and the target processing throughput.

[0073] In summary, the liquid dairy product sterilization apparatus and method provided in this disclosure have the following advantages and innovations compared to existing technologies: First, it inhibits wall fouling at its source. This disclosure limits the characteristic width and depth of the flow channel 120 to the micrometer scale of 100 μm to 500 μm. Utilizing the extremely high specific surface area and convective heat transfer coefficient of the micrometer-scale flow channel 120, it eliminates the physical prerequisite of significant wall overheating required to heat the fluid core in traditional macroscopic flow channels. Simultaneously, by coordinating the heat flux density provided by the heating source 200 with the flow rate of the delivery pump 300, liquid dairy products can rapidly cross the sensitive temperature range for heat-induced denaturation of milk proteins from the preheating temperature in an extremely short time of no more than 0.5 seconds. The synergistic effect of eliminating wall overheating and shortening protein heating time inhibits the deposition and fouling of milk proteins on the walls of the flow channel 120 at its source. Combined with the inherent high wall shear force within the micrometer-scale flow channel 120, which effectively removes trace amounts of deposited substances, it effectively avoids the decrease in heat transfer efficiency and increase in flow resistance caused by fouling, significantly extending the continuous operation time of the liquid dairy product sterilization device.

[0074] Secondly, the SiC substrate 110 possesses both high thermal conductivity and chemical inertness. Made of SiC material, the substrate 110 boasts a thermal conductivity exceeding 350 W / (m·K), more than 20 times that of stainless steel. This ensures rapid heat transfer from the heating source 200 to the wall of the flow channel 120, minimizing the internal temperature gradient of the substrate 110. Simultaneously, SiC exhibits high physical hardness and excellent chemical inertness. Under the long-term, complex alternating effects of ultra-high temperatures, strong acid and alkali cleaning, and high-salt food components, it exhibits virtually no trace leaching of chemical elements, ion migration, or material aging, eliminating the risk of heavy metal contamination that may exist with stainless steel.

[0075] Third, production capacity can be scaled up proportionally using the principle of quantity scaling. Multiple heat exchange devices 100 are integrated in parallel through a first manifold 400 and a second manifold 500. Each heat exchange device 100 maintains the same flow channel 120 geometry and operating parameters, allowing laboratory-level sterilization process parameters to be directly scaled up proportionally to industrial production capacity at the ton-per-hour level without the need to redevelop process parameters, thus reducing the risk of process scale-up.

[0076] Fourth, process parameters can be switched rapidly within seconds. Due to the small total volume of the micron-scale flow channel 120, the device has a small dead volume and thermal inertia close to zero. The control unit 900 can smoothly transition the output parameters of the heating source 200 and the flow rate of the delivery pump 300 to the newly preset sterilization process steady state within 2 seconds, meeting the flexible production needs of multi-variety, small-batch liquid dairy products and minimizing waste during the transition period.

[0077] Fifth, it can integrate online conductivity detection. Utilizing the stable conductivity characteristics imparted by the relatively stable free ion concentration formed by lactose and inorganic salts in liquid dairy products, online conductivity detection can be performed on liquid dairy products flowing through channel 120 during sterilization, simultaneously determining whether the raw milk is adulterated or has abnormal quality, without the need for an additional independent offline detection process.

[0078] In the description of this specification, the references to terms such as "one embodiment / mode," "some embodiments / modes," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment / mode or example is included in at least one embodiment / mode or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment / mode or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments / modes or examples. Furthermore, without contradiction, those skilled in the art can combine and integrate the different embodiments / modes or examples described in this specification, as well as the features of different embodiments / modes or examples.

[0079] Those skilled in the art should understand that the above embodiments are merely for illustrating the present disclosure and are not intended to limit the scope of the disclosure. Those skilled in the art can make other changes or modifications based on the above disclosure, and these changes or modifications still fall within the scope of the present disclosure.

Claims

1. A sterilization device for liquid dairy products, characterized in that, include: At least one heat exchange device, the heat exchange device comprising a substrate made of SiC material and having a flow channel formed therein for the flow of liquid dairy products, the flow channel having a characteristic width of 100 μm to 500 μm and a characteristic depth of 100 μm to 500 μm; A heating source, thermally connected to the substrate, is used to heat the flow channel; as well as A delivery pump for driving the liquid dairy product to flow in the flow channel; The heat flux density provided by the heating source and the flow rate of the delivery pump are configured such that the time for the liquid dairy product flowing through the flow channel to rise from the preheating temperature to the sterilization temperature does not exceed 0.5 seconds, wherein the preheating temperature is 65℃-75℃ and the sterilization temperature is 138℃±0.5℃.

2. The liquid dairy product sterilization device according to claim 1, characterized in that, The substrate includes a chip layer, a first cover plate, and a second cover plate. The chip layer is provided with the flow channel. The first cover plate and the second cover plate are respectively sealed and connected to opposite ends of the chip layer and cover the flow channel.

3. The liquid dairy product sterilization device according to claim 1, characterized in that, The flow channel is arranged in a serpentine pattern, including multiple parallel extension segments that are parallel to each other and arranged in a straight line, and a bent segment connecting the ends of two adjacent parallel extension segments.

4. The liquid dairy product sterilization device according to claim 1, characterized in that, The heating source includes a ceramic heating element attached to the back of the substrate.

5. The liquid dairy product sterilization device according to claim 1, characterized in that, It also includes a first branch manifold and a second branch manifold. There are multiple heat exchange devices, each with an inlet end and an outlet end. The inlet ends of the multiple heat exchange devices are connected in parallel through the first branch manifold, and the outlet ends of each heat exchange device are connected in parallel through the second branch manifold.

6. The liquid dairy product sterilization device according to claim 1, characterized in that, It also includes two electrodes, which are respectively disposed at both ends of the substrate. The heating source is a DC power supply, which applies DC current to the substrate through the electrodes. The substrate provides heat to the liquid dairy product in the flow channel through its own Joule heating effect.

7. The liquid dairy product sterilization device according to claim 1, characterized in that, It also includes a countercurrent heat recovery device, which is located upstream of the delivery pump and is used to receive liquid dairy products and deliver them to the delivery pump. The countercurrent heat recovery device is configured to exchange heat with the liquid dairy products output by the heat exchange device.

8. A method for sterilizing liquid dairy products, characterized in that, include: Liquid dairy products are driven by a delivery pump to flow through channels within a substrate made of SiC material, and the channels have a characteristic width of 100 μm to 500 μm and a characteristic depth of 100 μm to 500 μm. Heat is supplied to the liquid dairy product in the flow channel by a heating source that is thermally connected to the substrate, so that the liquid dairy product flowing through it rises from the preheating temperature to the sterilization temperature in no more than 0.5 seconds. The preheating temperature is 65℃-75℃ and the sterilization temperature is 138℃±0.5℃.

9. The method for sterilizing liquid dairy products according to claim 8, characterized in that, Also includes: During the flow of the liquid dairy product through the channel, the electrical conductivity of the liquid dairy product flowing through the substrate is detected.

10. The method for sterilizing liquid dairy products according to claim 8, characterized in that, The provision of heat includes: A direct current is applied to the substrate by electrodes located at both ends, causing the substrate to heat up through its own Joule heating effect.

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