34 results about "Freezing Point Temperature" patented technology

The invention discloses a nitrochlorobenzene freezing point detection device and a test method. The device comprises a base, and a test device, a power supply and control module and a freezing module are arranged on the base. A refrigerator is arranged in the freezing module and is used for providing cooling capacity for the test device; the power supply and control module comprises a power supply and a controller; the power supply is used for supplying power to the freezing module and the test device; the test device comprises a fixed table, a lifting driving device, a lifting table, a test container and a bath. The test container comprises a test bottle, a stirrer, a temperature sensor, a torque sensor, a test bottle cap and a dropwise adding meter. The controller judges whether the test sample reaches a freezing point or not according to the torque value of the stirring shaft, when the test sample reaches the freezing point, the controller stores the measured temperature of the temperature sensor, and the temperature is the freezing point temperature of the test sample. The nitrochlorobenzene freezing point detection device can replace manual work to automatically detect the nitrochlorobenzene freezing point, and is high in detection efficiency, high in detection precision and good in repeatability.

The invention discloses a low-temperature plasma cold sterilization and fresh-keeping method for a chilled poultry meat product, and particularly relates to a low-temperature plasma cold sterilization and fresh-keeping method for the chilled poultry meat product by virtue of low-temperature plasma activated water (PAW) and dielectric barrier (DBD). The method comprises the following steps: spraying and sterilizing the whole slaughtered and eviscerated poultry meat by virtue of PAW with the temperature close to the freezing point temperature of-1.5 to-2.5 DEG C of the product; the fresh-keeping method comprises the following steps: soaking the fresh-keeping materials in PAW at the temperature of less than or equal to-1.50 DEG C, cooling to the temperature of-1.5 + / -0.5 DEG C, cutting and packaging, carrying out DBD low-temperature plasma cold sterilization under the working voltage of 120-160 kV, and carrying out cold-chain logistics under the condition of the fresh-keeping temperature of-1.0 to-1.5 DEG C, so that the fresh-keeping period is prolonged from 4 days to 15 days. According to the method, PAW and DBD plasma cold sterilization and preservation are adopted at the temperature of the chilled products, the shelf life of the poultry meat chilled products is effectively prolonged on the premise of ensuring the freshness, safety and high quality of the poultry meat chilled products, and industrial innovation and sustainable development are promoted.

The invention relates to an equipment defrosting method and device, air conditioning equipment and a storage medium. The method comprises the steps that multiple environment parameter values of the environment where target equipment is located and the surface temperature value of the target equipment are collected; determining a freezing point temperature value corresponding to the current environment according to the plurality of environment parameter values; and under the condition that it is determined that the target equipment meets a preset defrosting condition based on the surface temperature value and the freezing point temperature value, defrosting operation is conducted on the target equipment. Therefore, whether the equipment meets the frosting condition or not can be efficiently and accurately judged, and the defrosting efficiency of the equipment is improved.

A method for cooling a device, the device comprising a heat sink (1), electronic components connected to the heat sink (1), a heat pipe (2) connected to or integrated with the heat sink (1), an inlet air temperature measuring device and a cooling fan (3), wherein - the device determines whether the inlet air temperature is below a first temperature threshold (T EinlassluftNiedrig1 ) is close to the freezing point temperature of the working fluid of the heat pipe, and - the device operates the cooling fan (3) with a low inlet air temperature speed regime when the inlet air temperature is below the first temperature threshold (T EinlassluftNiedrig1 ), characterized in that - the device determines whether the inlet air temperature is above a second temperature threshold (T EinlassluftNiedrig2) and operates the cooling fan (3) with a high inlet air temperature speed regime when the inlet air temperature is above the second temperature threshold (T EinlassluftNiedrig2 ) and the device has previously been operated with the low intake air temperature speed regime and that - the second temperature threshold (T EinlassluftNiedrig2 ) higher than the first temperature threshold (T EinlassluftNiedrig1 ) is.

The invention relates to the technical field of metal purification, in particular to a method and system for purifying a gallium liquid phase based on temperature field disturbance crystallization. The purity of the metal gallium liquid phase is larger than or equal to 99.99%, and the method comprises the steps that cooling water is used for conducting first temperature field disturbance on the metal gallium liquid phase, and meanwhile a heat source is used for conducting second temperature field disturbance on the metal gallium liquid phase; under the action of the first temperature field disturbance and the second temperature field disturbance, the gallium liquid phase is separated out and crystallized, and gallium crystals are obtained; wherein the disturbance direction of the second temperature field disturbance is perpendicular to the disturbance direction of the first temperature field disturbance; the temperature of the cooling water is lower than the freezing point temperature of the metal gallium liquid phase; the temperature of the heat source is higher than the freezing point temperature of the metal gallium liquid phase. According to the method, on the basis of three-dimensional heat flow field cooperative regulation and control and vector superposition of an orthogonal disturbance field, the solute redistribution coefficient is increased before solidification, the impurity separation efficiency of a metal gallium liquid phase is improved, and the purity of a final metal gallium crystal solid phase reaches 7N.

The application provides a vehicle air intake cooling control method, system and storage medium. The vehicle comprises an engine, an intercooler, a first pipeline, a second pipeline and a first control valve. The method comprises the following steps: acquiring an ambient temperature of the vehicle, a treatment temperature of gas after passing through the intercooler and a dew point temperature; if the ambient temperature is less than or equal to a freezing point temperature threshold, the treatment temperature is less than or equal to the freezing point temperature threshold and the treatment temperature is less than or equal to a condensation threshold, and the condensation threshold is greater than or equal to the dew point temperature, then the first control valve is controlled to close the first pipeline and open the second pipeline, so that the gas directly enters the engine from the second pipeline without passing through the condenser to reduce the gas temperature, the gas temperature entering the engine is improved, the condensation risk of the gas is reduced, the probability of water accumulation or icing near the outlet of the intercooler is reduced, the probability of throttle sticking is reduced, and the driving safety of the vehicle is improved.

The utility model discloses a refrigerant dewatering and drying device which comprises a tunnel type instant freezer and a separation box, and the separation box is installed on one side of the tunnel type instant freezer. The utility model has the beneficial effects that the tunnel type instant freezer and the separation mesh belt are adopted, a refrigerant flows in the liquid conveying pipe, when the refrigerant passes through the tunnel type instant freezer, the low temperature in the tunnel type instant freezer enables moisture in the refrigerant to be frozen to form ice crystals, the freezing point temperature of the refrigerant is far lower than the freezing point temperature of water, and the refrigerant is still in a liquid state; and when the ice crystals and the refrigerant flow out of the liquid conveying pipe, the ice crystals and the refrigerant flow into the top surface of the separation mesh belt, the ice crystals stay on the top surface of the separation mesh belt, the refrigerant flows into the bottom of the separation box on the left side of the partition plate and is discharged along the liquid discharging pipe, and water removal and drying are completed. The problem that the enterprise cost is increased due to the adoption of consumables such as a drying agent is solved, and the working efficiency and the economical efficiency are remarkably improved.

The utility model discloses a separated heat pipe molten salt heat exchanger which comprises an evaporator, the output end of the evaporator is connected with one end of a steam pipe, the other end of the steam pipe is connected with a steam box, a condenser is arranged at the top of the steam box, and the bottom of the steam box is connected with one end of a condensed water drain pipe. The other end of the condensed water sewer pipe is connected with a separator, the output end of the separator is connected with one end of a water return pipe, and the other end of the water return pipe is connected with the input end of the evaporator. The device can prevent molten salt from being solidified, even if the temperature of cold fluid is lower than the freezing point temperature of the molten salt, the unique condenser structure enables the temperature of working medium liquid to be close to the saturation temperature, heat transfer density is large, arrangement is convenient, and the device is not limited by the positions of the molten salt and the cold fluid.

The invention provides an airport pavement freezing point temperature real-time monitoring method, device and system, and relates to the technical field of airport pavement monitoring. The method comprises the following steps: identifying a ponding area included in each acquisition area in an airport pavement image, and determining a ponding distribution main axis of the ponding area, each acquisition area including a water film sensor; determining the ponding position influence degree based on the ponding total area change trend of the collection area and the distance between each ponding area and the ponding distribution main axis, and determining the ponding area sensitivity by combining the area ratio of each ponding area to the collection area; determining the water film thickness sensitivity of the water film sensor based on the ponding area sensitivity, the pavement water film thickness, the average value and the change rate, and determining the water film thickness sensitivity consistency by combining the average water film thickness sensitivity; and determining the parameter sensitivity of the water film sensor, determining the data accuracy by combining the average parameter sensitivity, correcting the pavement water film thickness, and determining the freezing point temperature. The freezing point temperature monitoring accuracy can be improved.

The invention discloses a hydrated salt phase separation suppression system, comprising: a heat storage device and a liquid medium layer composed of a liquid medium; the heat storage device comprises: a circulation pipe, an inner tank filled with a hydrated salt phase change material, and a jet nozzle arranged at the bottom of the inner tank; the melting point and density of the liquid medium are lower than those of the hydrated salt phase change material, and the boiling point is higher than the highest heat storage temperature of the heat storage device; the liquid medium layer covers the surface of the hydrated salt phase change material; the circulation pipe is connected to the jet nozzle; when the hydrated salt phase change material is in the heat release stage, and the temperature is between the freezing point temperature and the heat release starting temperature, the circulation pipe intermittently transports the liquid medium to the jet nozzle and then sprays it out, so as to form a forced turbulent dispersion effect in the hydrated salt phase change material. The invention effectively realizes the cyclic phase separation suppression of the hydrated salt phase change material without adding any additives.

This invention discloses a control method and apparatus for a refrigeration system. The control method includes: acquiring the freezing point temperature of the refrigerant in the refrigeration system; determining the relationship between the freezing point temperature and a preset temperature value; and controlling the operating states of a solenoid valve and an evaporation pressure regulating valve in the refrigeration system based on this relationship. The control method and apparatus for the refrigeration system provided by this invention can ensure the reliability of the refrigeration system's operation.

The invention provides a road black ice detection method and device, and the method comprises the steps: collecting a road surface temperature value, an air humidity value, a wind speed value and a vehicle flow value in real time for a target road under the condition of no rainfall; determining a dew point temperature value based on the road surface temperature value and the air humidity value, and judging whether the road surface temperature value and the duration at the current moment meet a dew formation condition or not; if yes, determining a dew freezing index based on the dew point temperature value, the road surface temperature value and the duration time, and judging whether the dew freezing index is greater than or equal to a dew freezing threshold value or not; if yes, whether the road surface temperature value at the target moment is larger than or equal to the freezing point temperature value is judged; and if yes, determining a black ice freezing index based on the freezing point temperature value, the road surface temperature value, the wind speed value and the vehicle flow value so as to determine whether the black ice exists on the target road at the target moment. According to the method, the accuracy and efficiency of black ice detection and the road safety are improved.

The invention discloses a method for testing the supercooling degree of nano-liter liquid drops by a differential scanning calorimetry. The method comprises the following steps: taking a liquid sample with the mass of more than 0.2 mg or the volume of more than 0.2 mu L, then placing the liquid sample in a crucible to form a plurality of sub-droplets, then carrying out DSC test to obtain the phase change enthalpy of the plurality of sub-droplets, and calculating to obtain the degree of supercooling of the plurality of sub-droplets; wherein the volume of at least one sub-droplet is less than 0.1 mu L. The method provided by the invention can accurately measure the freezing point temperature of the liquid drop below 50 nanoliters and even 5 nanoliters, widens the measurement range of the quantitative relationship between the liquid drop size and the supercooling behavior, and lays a technical foundation for researching the liquid coating dominated liquid drop phase change behavior.

The invention provides a refrigerator and an unfreezing control method of the refrigerator. The refrigerator comprises an unfreezing chamber and an unfreezing device, a to-be-unfrozen object is put into the unfreezing chamber, the unfreezing process is controlled through the unfreezing device, the unfrozen object is unfrozen in the unfreezing chamber according to the preset unfreezing temperature, and the surface temperature of the to-be-unfrozen object is always lower than or equal to the freezing point temperature of the to-be-unfrozen object in the unfreezing process. According to the thawing control method of the refrigerator, the surface of the to-be-thawed object is not thawed in the whole thawing process by controlling the preset thawing temperature or the surface temperature of the to-be-thawed object. The occurrence of surface phase change is avoided, and the phenomenon that the efficiency of re-conducting heat outside the to-be-unfrozen object to the to-be-unfrozen object due to surface melting is reduced is improved. Finally, the problems that the to-be-unfrozen object is unfrozen unevenly, the outside is melted, and the inside hardness is high and cannot be cut are solved.

The application provides a control method of an air conditioning system and an air conditioner, wherein the control method of the air conditioning system comprises the following steps: the air conditioning system operates in a heating mode; when a first outdoor heat exchanger reaches a defrosting condition, the opening degree of a first electronic expansion valve is controlled so that the outer surface temperature of the first outdoor heat exchanger is above the freezing point temperature, and the opening degree of a second electronic expansion valve is controlled so that the second outdoor heat exchanger keeps normal heating; or when the second outdoor heat exchanger reaches the defrosting condition, the opening degree of the second electronic expansion valve is controlled so that the outer surface temperature of the second outdoor heat exchanger is above the freezing point temperature, and the opening degree of the first electronic expansion valve is controlled so that the first outdoor heat exchanger keeps normal heating. According to the application, during the whole defrosting process, one outdoor heat exchanger is always in normal heating, and the other outdoor heat exchanger is defrosted in the case of participating in the heating of the air conditioning system, so the indoor environment temperature basically does not fluctuate, and therefore the comfort of people is not affected.

The present invention relates to the technical field of high-salt sewage treatment, and in particular to a device and method for achieving zero discharge of high-salt and high-COD wastewater by using a freezing method. The device comprises a bottom plate and an upper shell which can be separated from the bottom plate upwards, a refrigerator is arranged at the top of the upper shell, a water storage ring is fixedly connected to the top of the bottom plate, a container is formed between the water storage ring and the top of the bottom plate, and six extensions are evenly arranged on the outside of the water storage ring. When the present invention is used, it is necessary to first sample and measure the freezing point of the contaminated water. After obtaining the freezing point temperature of the contaminated water, the present invention discharges the sewage into the inner side of the water storage ring through a water inlet pipe on the bottom plate, and then controls the refrigerator to start cooling, so that the cooling temperature is slightly lower than the freezing point temperature of the contaminated water, and the temperature difference between the cooling temperature and the freezing point temperature of the contaminated water is reduced, which, on the one hand, plays a role in prolonging the freezing time, and on the other hand, reduces energy consumption by reducing the temperature difference between the inside and outside of the upper shell.

The utility model discloses a nitrochlorobenzene freezing point detection device which comprises a base, and a test device, a power supply and control module and a freezing module are arranged on the base. A refrigerator is arranged in the freezing module and is used for providing cooling capacity for the test device; the power supply and control module comprises a power supply and a controller; the power supply is used for supplying power to the freezing module and the test device; the test device comprises a fixed table, a lifting driving device, a lifting table, a test container and a bath. The test container comprises a test bottle, a stirrer, a temperature sensor, a torque sensor, a test bottle cap and a dropwise adding meter. The controller judges whether the test sample reaches a freezing point or not according to the torque value of the stirring shaft, when the test sample reaches the freezing point, the controller stores the measured temperature of the temperature sensor, and the temperature is the freezing point temperature of the test sample. The nitrochlorobenzene freezing point detection device can replace manual work to automatically detect the nitrochlorobenzene freezing point, and is high in detection efficiency, high in detection precision and good in repeatability.

The invention relates to the technical field of 3D printing, and discloses an unsupported photocuring 3D printing system and method.The system comprises a laser module and a printing module, the laser module comprises a laser and is used for generating scanning laser beams to cure printing raw materials, and the printing module comprises a raw material bin, a double-scraper unit and a forming bin; the raw material bin is used for containing printing raw materials, the double-scraper unit comprises a first scraper and a second scraper, and the second scraper is used for heating the surfaces of the printing raw materials to be in a liquid state and scraping the printing raw materials to a forming platform in the forming bin. The first scraper is used for cooling the printing raw material on the surface layer of the forming platform below a freezing point temperature to solidify the printing raw material; the forming bin comprises a second lifting platform. By arranging the double-scraper unit, combining the physical characteristics of the printing material and finely controlling the heating and cooling of the printing material, the 3D object containing the complex geometric structure is printed under the condition that no supporting structure needs to be constructed.

The invention relates to a low-temperature multi-directional forging process and device for an alloy material. The low-temperature multi-directional forging process comprises the steps that S1, the device is assembled; s2, preparing a low-temperature medium solution; s3, placing and compressing the forging blank; s4, liquid nitrogen cooling and temperature control; and S5, multi-pass compression forging is conducted. The alcohol-water mixed solution is used as a cooling medium, the temperature stability of the alloy material in the multidirectional forging process is guaranteed by means of the freezing point temperature, and the continuity of the low-temperature state in the forging process is guaranteed; refining of material grains can be effectively promoted through low-temperature multidirectional forging, the mechanical property of the alloy is improved, and the tensile strength and the yield strength are improved.

The present invention discloses a method for electrolytic grinding of honeycomb materials based on the freezing point temperature difference characteristics of a medium. The method is as follows: fill the cell grids of the honeycomb material to be processed with a liquid medium, then place the honeycomb material to be processed in an environment with a temperature not higher than the freezing point of the liquid medium, and perform electrolytic grinding after the liquid medium filled in the honeycomb material has solidified; wherein, the freezing point temperature of the electrolyte is lower than the freezing point temperature of the liquid medium. The method of the present invention realizes the mechanical and electrochemical protection of the cell structure by filling the pores of the honeycomb material with a high freezing point medium and solidifying it, so that the cell will not be deformed or damaged due to a large grinding force, nor will over-corrosion occur in the cell due to stray current.

The application provides a printed circuit board type heat exchanger, and belongs to the technical field of heat exchangers, and specifically comprises a heat exchange plate, a cold fluid channel, a hot fluid channel and a heating assembly, wherein the heating assembly is used for directly or indirectly heating the hot fluid medium of the fluid channel when the temperature of the hot fluid medium in the hot fluid channel is lower than a preset temperature. Through the processing scheme, when the temperature of the heat exchanger plate approaches the freezing point temperature of molten salt or liquid metal and its alloy, the heating mode is quickly started, the temperature of the heat exchange plate is raised, and the heat exchange channel is prevented from being blocked.

According to the device and method for preventing the water conveying pipeline from freezing, a mounting frame is arranged in the water conveying pipeline, a driving motor coaxial with the water conveying pipeline is mounted on the mounting frame, a paddle assembly is arranged on the driving motor, and when the interior of the water conveying pipeline may be frozen due to the air temperature, the driving motor drives the paddle assembly to rotate; therefore, water spirally flows in the water conveying pipeline, water at different temperatures is mixed, and freezing caused by continuous reduction of the temperature of water close to the wall surface of the water conveying pipeline is prevented. After the water flow is stable, water which is influenced by centrifugal force, has higher density and is above the freezing point temperature is in contact with the wall surface of the water conveying pipeline, exchanges heat with the outside of the water conveying pipeline, and returns to the center of the water conveying pipeline after the temperature is reduced. Moreover, the water spirally flows in the water conveying pipeline, so that the water flow speed can be increased, the growth of ice crystals is inhibited, more friction heat can be generated, the water temperature is increased to a certain extent, and the purpose of preventing the water conveying pipeline from being frozen is achieved.

The invention discloses an ice food making time determination method, an ice food machine and a storage medium, and relates to the technical field of refrigeration systems, the disclosed ice food making time determination method comprises the following steps: determining a target freezing point temperature of an ice food raw material according to a target component content in the ice food raw material; based on the relationship between the raw material temperature and the making time, predicting first making time when the ice food raw material is changed from the initial temperature to the target freezing point temperature and second making time when the ice food raw material is changed from the target freezing point temperature to the set temperature, and obtaining ice food making completion time; according to the ice food making completion time, determining the remaining ice food making time; and displaying the remaining ice food making time. According to the technical scheme, the ice food making completion time is accurately predicted, so that the feedback precision of the remaining ice food making time is improved.

The invention discloses a temperature regulation and control method, a temperature regulation and control device and refrigeration fresh-keeping equipment thereof.The freezing point temperature of a food material is judged in the food material cooling process, and when the temperature of the food material is stable within a preset duration in the cooling process, the upper limit of the refrigeration temperature is determined according to the stable temperature value within the preset duration; the upper limit of the refrigeration temperature represents the freezing point temperature of the food material, and then the lower limit of the refrigeration temperature is determined according to the upper limit of the refrigeration temperature, so that the ice-water proportion of the food material is kept stable within the range of the upper limit of the refrigeration temperature and the lower limit of the refrigeration temperature, namely, the temperature of the food material is kept in a stable interval of the ice-water proportion; then the refrigeration fresh-keeping equipment regulates and controls the temperature of the fresh-keeping space according to the refrigeration temperature upper limit and the refrigeration temperature lower limit, ice glaze can be formed on the surfaces of the food materials, microorganisms are prevented from invading the food materials, the proportion of ice water in the food materials is kept, and ice crystals in the food materials are prevented from being repeatedly frozen and thawed, so that the fresh-keeping nutritional effect of the food materials is guaranteed; and a good partial freezing fresh-keeping effect is achieved.

The utility model relates to a snow making system technical field especially is concerned about a kind of snow making machine terminal auxiliary device and snow making system.The snow making machine terminal auxiliary device includes double fluid nuclear, condenses snow subassembly and refrigeration subassembly.Wherein, double fluid nuclear has high pressure water and high pressure air in flow circulation.Condenses snow subassembly including shell and condenses snow screen, condenses snow screen is set on the inner wall of shell, shell has mutually communicating import and export, import is communicated with double fluid nuclear, export is configured as the snow crystal group that sprays out.Refrigeration subassembly is communicated with shell, or, refrigeration subassembly is attached on the outer wall of shell.Refrigeration subassembly provides low temperature environment for condenses snow subassembly, the temperature of this low temperature environment is lower than freezing point temperature, so that water mist can evaporate condensation crystallization rapidly, and through condenses snow screen on shell inner wall, adhere to gather, form the snow crystal group of cluster or flocculate and finally be sprayed out from condenses snow subassembly, to improve snow quality, improve the snow making snow rate, save cost.

The present application relates to a kind of photonic crystal indicating label for cryogenic monitoring, belong to indicating material field.It is characterized in that with photonic crystal as temperature response material, after being uniformly mixed with phase transition temperature adjustable solvent, directional freezing is carried out at the freezing point temperature of solvent, the principle that ice crystal formation and melting caused by temperature fluctuation change photonic crystal arrangement and cause label discoloration is used, temperature monitoring of low-temperature storage product is realized.The indicating label produced by the present application has the advantages of simple preparation method, wide monitoring temperature range, high sensitivity, etc., as indicating label to monitor the temperature fluctuation of cold chain logistics product.

The present application provides a crude oil electromagnetic field comprehensive modification method. The method comprises the following steps: heating crude oil to a first predetermined temperature above its wax precipitation point temperature and constant temperature for a first time; then cooling to a second predetermined temperature and constant temperature for a second time; then performing magnetic field treatment at the second predetermined temperature; then constant temperature at a third predetermined temperature between the wax precipitation point temperature and the freezing point temperature of the crude oil for a third time; then performing electric field treatment at the third predetermined temperature to obtain modified crude oil. The method of the present application is not a simple combination of magnetic field and electric field, but uses the effect of magnetic field on key components in crude oil to enhance the electric field viscosity reduction effect of crude oil and improve the flowability of crude oil.

The application discloses a temperature regulation method, a temperature regulation device and refrigeration and preservation equipment thereof. The freezing point temperature of food is determined during the cooling process of the food. When the temperature of the food is stable within a preset time period during the cooling process, the upper limit of the refrigeration temperature is determined according to the stable temperature value within the preset time period. The upper limit of the refrigeration temperature represents the freezing point temperature of the food. Then, the lower limit of the refrigeration temperature is determined according to the upper limit of the refrigeration temperature. The ice-water ratio of the food is kept stable within the range of the upper limit of the refrigeration temperature and the lower limit of the refrigeration temperature, that is, the temperature of the food is kept in the interval where the ice-water ratio is stable. Then, the refrigeration and preservation equipment regulates the temperature of the preservation space according to the upper limit of the refrigeration temperature and the lower limit of the refrigeration temperature. The ice coat is formed on the surface of the food, the invasion of microorganisms into the food is prevented, the ice-water ratio in the food is kept, and the repeated freezing and thawing of ice crystals in the food is avoided. Therefore, the preservation and nutrition effect of the food is ensured, and good micro-freezing preservation effect is realized.

The invention discloses a sample freezing point temperature detection device and method.The air outlet end of an air pump communicates with a cold and hot air flow separation device through an electronic pressure regulating valve, the electronic pressure regulating valve is electrically connected with the first control end of a controller, the second control end of the controller is electrically connected with a temperature sensor, and the temperature sensor is arranged at the cold end of a refrigeration device; and the cold and hot air flow separation device is communicated with the refrigeration device. Compressed air is conveyed into the vortex tube through the air pump, and after a vortex chamber in the vortex tube is expanded and accelerated, airflow is divided into a cold stream and a hot stream. The hot air flow is released to the external environment, and the cold air flow enters the hot end of the Peltier refrigerator. The Peltier refrigerator is powered on for refrigeration, and the hot end absorbs heat from the ultralow-temperature cold air flow, so that the cold end of the Peltier is kept in an ultralow-temperature state. After the sample is placed on the vortex tube, the current direction of the Peltier can be adjusted to switch to a heating mode, meanwhile, airflow of the vortex tube is reduced or stopped, and the freezing point temperature of the sample is observed in the temperature rising process.

The invention belongs to the technical field of construction dust fall, and particularly discloses a highway engineering construction site dust fall device which comprises a protection plate, a water supply main pipe horizontally fixed to one side of the protection plate and water supply branch pipes communicated to the upper side of the water supply main pipe in an array mode. The upper end of the water supply branch pipe extends out of the heat preservation sleeve and is not wrapped, a spray head is installed at the top end of the water supply branch pipe, and a liquid supply bent pipe, a phase change driving assembly, a liquid control system and a liquid supply assembly are further included. The anti-freezing solution is automatically injected and filled into the spray head by using the driving force generated by phase change of the temperature-sensitive phase change material when the temperature is close to the freezing point temperature of water, and the spray head is automatically reset and new anti-freezing solution is stored after the temperature rises, so that full-automatic and circulating anti-freezing protection of the spray head is realized, electric energy consumption and manual intervention are not needed, and the working efficiency is improved. And the problems of ice blockage and frost heaving damage of the spray head are solved, so that the operation cost is effectively reduced.