Due to the multi-terminal characteristics of the VRF system, the individual performance metering technology for each terminal is of great significance for building energy management and fair billing, etc. However, it is currently difficult to achieve a low-cost, high-precision performance measurement method with built-in sensors. This paper investigates related existing research, and proposed three methods to realize individual performance metering. In cooling conditions, the measurement method is validated and discussed on the water-cooled VRF test bench. In this way, the accuracy and applicability of the proposed methods are analyzed.

By installing a set of water circulation air source heat pump heating system and a heat pipe type air source heat pump heating system on the user's site, the heating characteristics of the two heating systems are studied. The experimental results show that the power consumption of the heat pipe air source heat pump system is 4% less than that of the water cycle air source heat pump system when the outdoor ambient temperature is the same and the indoor temperature is the same; when the outdoor ambient temperature is the same, the indoor ambient temperature rises from 15℃ to 20℃, and the time consumption of the heat pipe air source heat pump system is only 37.5% of that of the water cycle air source heat pump system; when the outdoor ambient temperature is the same When the temperature of the indoor heat exchanger rises from 13.5℃ to 30℃, the time consumption of the heat pipe air source heat pump system is only 24.5% of that of the water circulation air source heat pump heating system; the operation analysis of defrosting is also carried out, which provides the experimental basis for the design of the heat pipe air source heat pump heating system.

The low ambient temperature air source heat pump air heaters with vapor-injection technique can still provide thermal comfort even though under less than -25℃ ambient temperature condition. However, it is found that the control strategy of refrigerant mass flow rate at injection path significantly affects the system stability. Consequently, to prevent the compressor liquid hummer and improve system stability, refrigerant flow characteristic of the electronic expansion valve (EEV) was improved with an approximate linear relationship, meanwhile, the corresponding EEV control strategy was optimized. The experimental results shows that for the systems with related heating capacities of 3 kW and 4 kW, the compressor liquid hummer was prevented by optimizing the EEV flow characteristic and control strategy. Additionally, the COP deviation for various systems was within ±2% under both -12℃ and -20℃ ambient temperature conditions. Generally, applying the proposed optimization method is a promising way for enhancing the system stability.

Under severe operating conditions (high load, low temperature conditions, poor heat exchange), the air conditioner is prone to fall into the situation of poor lubricating oil and refrigerants return, and that will cause fatal damage to the operation of the compressor, leading to abnormal condition of the air conditioner system or even unable to run. The purpose of this paper is studying and analyzing the principles of the circulation of compressor oil and the migration of system refrigerants, based on the actual operating process of the air conditioner. Then, according to the test results of the lubricating oil return and refrigerants return of the air conditioner under different operating conditions, the results show that low-temperature sleep start up items, low-temperature defrost operation items, and high-load operation items are prone to poor oil and liquid return, then analyze the specific reasons for each item. It will provide guidance on household air conditioners and problem analysis.

Due to the difference of heat exchanger in split air-source heat punp, it is difficult to give consideration to refrigerant charging amount of both cooling throttling by indoor unit and heating throttling by outdoor unit. This problem can be solved by adjusting the size of piping connection between indoor unit and outdoor unit, and throttling by outdoor unit in both cooling and heating conditions, without adding other refrigerant receivers. According to the experiment and calculation of 8kW unit using R32, the optimal refrigerant amount in indoor unit and outdoor unit can be obtained. Then the correlation between the refrigerant amount in piping connection and length of piping connection were carried out, and optimal refrigerant charging amount can be determined. Finally, the optimal piping connection and refrigerant charging amount were verified by experiment, which were suitable for both cooling and heating.

Refrigerator energy efficiency and floor area ratio is a key indicator in refrigerator design. The cooling capacity coupling calculation can realize the optimized design of refrigerator energy efficiency and floor area ratio. This paper uses computational fluid dynamics software ANSYS and heat exchanger test equipment to simulate and experiment on refrigerator evaporators, and study the effect of heat exchange of evaporator on the energy efficiency of refrigerators from the side of evaporative air circulation. The results show that the standard energy efficiency index can be kept unchanged by changing the three-row oblique-insertion evaporator to two-row oblique-insertion evaporator, and at the same time adjusting the fan speed under the power consumption state of 16℃ and 32℃. Effectively increase the floor area ratio of the refrigerator by 1.9%.

In recent years, smart appliances have developed rapidly. It is more and more common to use App to remotely control smart appliances. Besides, voice interaction can realize better control experience and improve the convenience of use. With the wide application of remote control and voice interaction, its safety is worth discussing. This paper analyzes the main forms of remote control and voice interaction of smart appliances, analyzes the safety risks of remote control and voice interaction of smart appliances based on the actual test results and specific application scenarios, and gives security application suggestions for remote control and voice interaction functions in combination with the standard requirements.

In response to the current demand of market for indoor personnel dynamic detection, a 60 GHz millimeter-wave radar-based human sensory detection system is designed. The system uses IWR6843 as a processor for data signal processing and algorithm implementation, and PMICLP87524 as a multi-channel programmable The high-precision power supply system, combined with the on-board three-transmit and four-receive antenna design, uses a high-frequency 6-layer PCB to realize the design plan, which can accurately detect the distance, angle, speed, acceleration and other information of indoor activities. The system does not involve privacy issues, is not affected by light, has fast response speed, high positioning accuracy, and wide detection range. The test proves that the horizontal detection range of the system can reach ±75°, the upper and lower detection range is ±40°, the detection distance can reach 8 m, the distance output accuracy can reach 0.1 m, the angle output accuracy can reach 1°, and the comprehensive detection of some scenes is accurate The rate can reach more than 90%.

Since the outbreak of novel coronavirus, the safe drinking water has become a topic of concern to prevent viruses from entering the mouth. How to ensure the safety of drinking water and which water treatment technology is suitable for China's water quality? Through the reverse osmosis technology in the membrane filter element has the direct flow type and the side flow type two kinds of structure forms, as well as the reverse osmosis membrane filter element in the water purifier application research, the reverse osmosis water purifier technical can solve the water purification question. After testing, the purified water by the reverse osmosis water purifier can meet the requirements of drinking water health and safety standards. The reverse osmosis purifier can deeply purify water and is one of the best choices for people to realize the safety of drinking water.

With spinach and strawberries as research objects, the effect of high voltage electrostatic filed on the preservation of fruit and vegetable stored in refrigerator was investigated. The results illustrate that high voltage electrostatic filed environment of refrigerator has a positive effect on the fresh-keeping quality of spinach and strawberries during storage. The high-voltage electrostatic field treatment can effectively reduce the quality loss of spinach and strawberries, inhibit the degradation of vitamin C and chlorophyll, and delay the consumption of soluble solid form, thereby improving the storage quality of fruit and vegetable.

The chicken breast was taken as the research object to study the salt reduction process of the steam oven. On the basis of single factor experiment, the orthogonal optimization method was used to optimize the salt reduction process of the steam oven. The effects of baking time, temperature and steam consumption on the salt content of chicken breast meat were investigated. The results showed that the best salt reduction technology of steam content was 50%, baking temperature was 210℃, and the time was 15 minutes. Under these conditions, the salt reduction rate of chicken breast meat was 37.96% higher than that of single roasting.

In this paper, based on the three factors of the power of the deep ultraviolet lamp, the working time of the ultraviolet lamp, and the distance between the ultraviolet lamp and the bacterial solution, four different combinations of working conditions of the deep ultraviolet lamp are set to study its effect on the sterilization rate of E. coli. The experimental results show: Within a certain range, the change of irradiation time is more sensitive to the sterilization rate of E. coli. The difference between the power of the UV lamp and the irradiation distance is not sensitive to the effect of E. coli sterilization rate. Based on the above results, the refrigerator sterilization zone was designed. The ultraviolet light irradiation intensity was greater than 5.5μW/cm², and the killing rate of Salmonella was greater than 99%.

In this paper, a novel EMFi piezoelectric thin film sensor based sleep monitoring health mattress was made to monitor and evaluate the sleep quality of users during sleep without load. With modern signal processing method, respiratory wave and heart rate can be real time monitored. Through the combination of the two signals statistical analysis, the health mattress is expected to achieve sleep related health data analysis, and emergency response.

The spray system is very important to a dishwasher, and the design of the spray arm has impact on the cleaning efficiency of the dishwasher. So it is necessary to study the mode and status of the spray and the rotation impact to the cleaning efficiency. At the same time, the well designed spray could improve the cleaning efficiency and lower the energy consumption and water consumption. We got the values between the tangent of rotation and the vertical water spraying pressure by analysis the working process of the spray, virtual simulation and testing. We got the distribution of the water spraying by virtual images. We got the line chart by analysing different cleaning efficiency from different spray rotation. We got all the information about how the spray is working and gave reference for future dishwasher design.

Through case analysis of dehumidifier corrosion failure, combined with electrochemical research methods, the possibility of failure caused by crevice corrosion and galvanic corrosion and the feasibility of implementing cathodic protection by changing materials are studied. The results show that the corrosion failure of the dehumidifier is caused by the ant nest corrosion caused by low molecular carboxylic acid in the condensed water environment; Although there is crevice corrosion acceleration at the crevices, the acceleration effect is not large; In the solution environment, it interacts with active metals Coupled cathodic protection can slow down the corrosion of red copper.

The mechanical noise produced by the discharge valve flapping the discharge stopper is one of the main noise sources of the refrigeration compressor. In order to reduce the noise of this part, the natural frequency simulation analysis and experimental research were carried out after the material of the compressor discharge stopper was changed. Through the analysis of natural frequency of PEEK material discharge stopper by ANSYS software, it can be seen that the natural frequency of PEEK material limit plate is lower than that of metal limit plate, which is not easy to excite response. At the same time, the frequency response area is avoided. It can be concluded that PEEK material discharge stopper has lower noise. It is found that PEEK material discharge stopper can not only improve the mechanical noise of the compressor, but also improve the efficiency of the compressor, and prolong the service life of the discharge valve.

Inner round-tube evaporator is commonly used in horizontal direct cooling freezers, and evaporator is in line contact with the inner. The flat-tube evaporator is in surface contact with the inner, which effectively increases the heat exchange area. It is found that the product energy consumption can be reduced by 8.5% when the flat-tube evaporator is used instead of the round-tube evaporator.

Through the finite element analysis method, the wind speed distribution of two kinds of air conditioning heat exchanger corresponding to the axial fan suction air supply and the blowing air supply is modeled, solved and analyzed, and the flow path is designed based on the wind field distribution characteristics of the heat exchanger. This paper innovatively proposes a scheme to design the flow path of heat exchanger based on the distribution characteristics of flow field at the outlet side of the heat exchanger. The solution of the flow field distribution law of the heat exchanger formed by the two air supply forms shows that the velocity field distribution law of the two air supply forms is opposite, and the suction air supply has better uniformity, which can directly design the flow path evenly. The blowing type velocity field distribution is poor, so the blowing type is selected the flow path of the heat exchanger is designed in the form of air supply, and the heat exchange effect is equivalent to the uniform distribution of wind speed.

Flow simulation analysis was conducted to solve the turbulent noise of a closed inlet chamber multi-blade centrifugal fan when running, it has been found that the uneven flow state inside the fan especially impeller area is the main cause of subjective hearing noisy. Pre-rotating guide vane was targeted designed according to the flow characteristics of this kind of fan, the subjective sense of hearing has been confirmed to be significantly improved by experimental verification. Compared to the original plan, the air volume under same rotating speed was improved by 5%, the sound pressure level under same air volume was reduced by 0.4~0.5 decibel, and the flow uniformity was highly improved.

With the upgrading of the new national energy efficiency standard in 2020, thus new demands have been placed on compressor for high performance and low noise. By introduce the high efficiency innovative design technology of compressors in terms of the improvement of volume efficiency, mechanical efficiency and motor efficiency. And by optimized the structure of muffler internal and reservoir bracket, the compressor's noise and vibration have been greatly improved. Moreover, with the oil tank optimization scheme were proposed,the reliability of the compressor is further improved and guaranteed. By adopting these innovative technologies, the quality and competition of new generation inverter compressor has been greatly improved, which can meet the new national energy efficiency standard.

Oil pump lubrication system is an essential portion of the rotary compressor for its reliability. Utilizing numerical simulation and experiment, this paper studies the oil supply system. Firstly, based on the theoretical analysis, this paper summarizes and gives out the estimation method for the oil level inside the crankshaft. Then, the simulation framework based on VOF multiphase model is established for the oil supply system. After that, the experimental equipment is designed and built, in order to validate the simulation model. The simulation shows good agreement with the experiment. Finally,based on the multiphase model, the key factors of the oil pump system are studied.

There is a direct relationship between the surface temperature of the steel tube heater and the surface emissivity of the steel. In this paper, the surface emissivity of 304, 316L, 310S, 840 kinds of steel used in the steel tube heater are measured and analyzed by using Fourier spectrum analyzer. When the use environment and surface power are the same, the heat radiation efficiency of the steel tube heaters of 840 and 310S materials is higher than that of the steel tube heaters of 304 and 316L materials. Through Ansys Icepak software simulation and temperature test of steel tube heater, the safety design limits of surface load of different materials of steel tube heater are obtained.

The vibration performance defects of the suspension system of the automatic top load washing machine have been summarized in this paper after the vibration principle of the suspension system had been analyzed. According to the washing machine vibration performance and the quasi-zero-stiffness vibration isolation theory is used. An new suspension system with high-static and low-dynamic stiffness of the top load washing machine would be design. The feasibility of the new suspension system is verified by the numerical simulation and experiment. The vibration performance of the washing machine is greatly improved by adopting the quasi-zero stiffness suspension system.

The flow-induced vibration of the structural parts of the air conditioner can cause abnormal noise problems, which greatly affect the user experience and the improvement of the sound quality of the product, and even damage the strength of the structure and cause safety problems. By studing the flow-induced vibration and noise problem of guard filter on air-conditioner air outlet. First, the CFD is used to study the vortex characteristics of the flow around the cylindrical guard filter. And then the modal analysis of the cylindrical guard filter is completed by CAE. Modal analysis determined that the abnormal noise of the guard filter was caused by structural resonance caused by flow-induced excitation. Finally, the structure of the guard filter is optimized to improve the abnormal noise problem.

Heating efficiency is an important performance index of electric kettles, and the test process is greatly affected by factors such as testers' ability, test methods, and test equipment. Discusses the heating efficiency test of the electric kettle from the factors that affect the test and the uncertainty evaluation, the comparison test shows that the water quantity has a great influence on the thermal efficiency of the electric kettle, while the initial water temperature and the end water temperature have little influence on the thermal efficiency of the electric kettle.

The application of Wi-Fi communication in smart homes and the influence factors of microwave ovens on Wi-Fi communication are introduced. Select household microwave oven products as the interference source, and carry out the radiated electromagnetic field disturbance test under the Wi-Fi communication connection state. Through the test data, the influence of different angles and different distances of the microwave oven on Wi-Fi communication is obtained. The results show that the microwave oven works the power, distance and placement direction in the state will all bring different degrees of electromagnetic disturbance to the work of smart home appliances.

Permanent magnet synchronous motor drive system with small DC-link capacitor has advantages such as low cost and good reliability. However, DC-link voltage pulsation, a side effect of the system, reduces the control system's performance. To improve the system's input power factor and reduce harmonics in input currents, an improved power control strategy is put forward in this paper. Differing from traditional speed feedback control method, this strategy uses power as the input control variable. An improved PID controller is selected to reduce control error. Additionally, an active suppression strategy is applied in the system to suppress the integral saturation and achieve the goal of precise control effect. This improved motor drive system was tested in simulation platform and its control performance proved that the control system improved by power control strategy can maintain a high input power factor and suppress integral saturation effectively.

MCU is the core component of variable frequency driving system. As vector control need a large number of complicated calculating and has a high requirement for real-time, the operation requirement of MCU for variable frequency driving control is analyzed firstly. The Cordic hardware coprocessor is applied for the complicated calculating of trigonometric function and square root. And to settle the problems of single resistance sampling and frequency reduction, which are unique in variable frequency driving of air-conditioning, some functions are designed, including double trigger and sampling delay of AD, flexible phase shift of PWM, interval skip of interrupt, etc. The basic resources and functions of MCU are also analyzed and designed for the general requirements. At last, the custom designed MCU is applied in air-conditioner products, through which related functions are verified.

The heat dissipation of the heating elements inside the induction cooker will seriously affect the performance, operation safety and reliability of the induction cooker. Therefore, it is necessary to design a reasonable heat dissipation structure to realize the cooling of the heating elements. By using the computational fluid dynamics (CFD) based on Fluent, an idea of the heat dissipation structure design, which is based on the wind energy accumulation and stratified air supply, is proposed, and the accuracy of the simulation model is verified by the experiment. The simulation results show that the position and height of the air duct in the heat dissipation structure have great influences on the heat dissipation of the heating elements. Therefore, a reasonable use of the space inside the induction cooker, i.e. properly reducing the space on both sides of the air duct, and controlling the distance of the gap between the exciting coil and glass-ceramics, can gather more air into the air duct, which will improve the effective utilization of the entering wind, and then improve the effect of the air duct on the heat dissipation of the heating elements.

By comparing the change trend of indoor CO₂ concentration in different scenarios of power on and power off, the positive influence of the fresh fan on reducing CO₂ concentration in the room was proved. Indoor different initial concentration of indoor CO₂ concentration had a greater influence on the change trend, the initial concentration higher than that of dynamic balance, during using it the display of CO₂ concentration shows the reduce of the trend, while the initial concentration is lower than the dynamic balance, CO₂ concentration shows rising trend, which may cause complaints by market consumers. Based on the theoretical calculation and experimental data to provide data support for market complaints, reduce use erroneous zone. Different fresh air volumes have a great influence on the decline trend of indoor CO₂ concentration and the dynamic equilibrium point, so users need to choose the use scene with appropriate fresh air volume according to the use demand. It is of great significance to promote the application of fresh fans and improve people's cognition.

Comfortable, healthy and energy efficient are the main design goals of room air conditioners (RACs). Due to the difference between the field test and laboratory test results, this paper carried out the subjective questionnaire survey, tested the indoor thermal environment of two residential buildings in the cooling season, and determined the actual operation performance of the RAC through the all-condition compressor energy balance method. The results show that the indoor thermal environment can basically meet the requirements of comfort for RAC in cooling mode, and the draft may be slightly higher; when the RAC operates, the indoor air quality is poor, and the CO₂ concentration is increased. In terms of the energy performance of the RAC, and the fluctuation of indoor environment is coupled with the performance of the unit. According to the results of comprehensive test and subjective questionnaire survey, the draft and fresh air demand are the direction of improvement of RAC operation in cooling mode.

An ideal cycle model of air refrigeration with water injection is established to analyze the influence of pressure ratio and water injection amount on the thermal performance of the system and to compare with the ordinary air refrigeration cycle. The research results show that: the air cooling cycle with water injecting can not only improve the cooling capacity of the system, but also not lead to a significant reduction in the air supply temperature, which is more suitable for air-conditioning, Compared with the ordinary air refrigeration cycle, when the circulating pressure ratio of the system is greater than 2, the COP of the system after injecting water is about 2 times of the former, and the air refrigeration cycle with spraying water has more advantages

Vapour-Injected Heat pump (VIHP) can improve the efficiency and reliability of the heat pump system, and the heat pump system using R290 as the working fluid has a good prospect. In this paper, a thermodynamic model of VIHP with a subcooler using R290 is established and the influence of the evaporation temperature, condensation temperature, relative intermediate pressure and relative vapour injection mass flow on the performance of the system is analyzed. The results show that under the maximum allowable relative vapour injection mass flow, reducing the condensation temperature and increasing the evaporation temperature during cooling will reduce the cooling capacity, while reducing the evaporation temperature during heating is conducive to the improvement of COP. The relative intermediate pressure has a significant effect on the maximum allowable relative vapour injection mass flow.In addition, an increase in relative intermediate pressure will reduce heating capacity and power consumption, but will increase COP. The system performance parameters under the maximum relative vapour injection mass flow are studied, which provides a reference for greatly reducing the system exhaust temperature and improving system performance.

As a new porous material with high heat conductivity, metal foam owns unique advantages in heat exchanging enhancement. The heat transfer and flow characteristics in gas-liquid two-phase refrigerants are different from those of single phase working fluid. Considering various refrigerants, the heat transfer and flow performances of metal foam in refrigeration and air conditioning systems were analyzed including single pipe, heat exchanger and phase-change energy storage. The further study suggestions were also proposed, which are important to the energy efficiency improvement of systems and charging quality reduction of refrigerants.

There are important applications of low temperature refrigeration function in some special scenarios such as equipment heat dissipation in winter. Through the research and analysis of outdoor ambient temperature, outdoor fan speed and wind baffle, the research shows that the refrigeration capacity, condensation pressure and evaporation pressure will decrease with the decrease of outdoor ambient temperature. Within a certain range, the performance of low temperature refrigeration can be improved by reducing the speed of outdoor fan, and the performance of low temperature refrigeration can be improved rapidly with the decrease of speed of outdoor fan. The installation of the wind baffle can also improve the performance of low temperature refrigeration, condensation pressure and evaporation pressure. By reducing outdoor fan speed and installing the wind baffle, it can substantially improve the performance of low temperature refrigeration.

The research object of this paper is the air duct of a commercial heat pump water heater. In order to achieve a refined design and reduce the early design of the detour, we have carried out a simulation analysis on the fan duct part of this product and optimized the design of the heat exchanger. In this paper, the flow field distribution of the original product was obtained through CFD simulation analysis, and Suggestions on improving the flow field of the evaporator were given to improve the heat transfer effect of the evaporator and improve airflow uniformity, so as to realize the improvement of energy efficiency of the capacity under the same air volume. Finally, experiments were carried out on the products according to the improvement Suggestions, and the effectiveness of some structural improvements was verified, which proved that the CFD simulation analysis could indeed guide the product design.

At present, the power supply is becoming increasingly severe, many enterprises are carrying out technology innovation for energy saving of wall hung electric water heaters. The heat pump technology has a good energy saving effect, but the traditional heat pump components are many and the system is complex. If heat pump is simply applied to the wall hung electric water heater, it will cause problems such as large size of the machine and difficult installation of the toilet. Subvert the traditional design idea, through the optimization and modular design of the heat pump system, break through the bottleneck that the energy efficiency of the traditional electric water heater does not exceed 100%, further improve the energy efficiency of the electric water heater, and form a new generation of energy-saving wall hung electric water heater.

When the air-cooled refrigerator is used in a high temperature and high humidity environment, the consumer opens the refrigerator to store food, it is easy to cause condensation and freezing in the refrigerator compartment. Through simulation research and analysis of the refrigerated air supply duct of a certain refrigerator, it is found that the air supply form of the air duct and the air outlet speed have a greater influence on condensation. The research results show that by optimizing and improving the air supply form of the air supply duct, the condensation problem has been significantly improved.

Because the wall-mounted air conditioning system used for truck parking is not beautiful enough, and there is a risk of violating traffic regulations. In order to solve the above problems, a kind of air conditioning system for truck parking and its application compressor are studied and analyzed. The air conditioning system is installed on the top of the truck compartment. Due to the high national requirements on motor vehicle restrictions, the system needs to be designed as low as possible. To solve the problem of large vibration during truck operation, the system designed in this paper is connected with the compressor with a flexible hose, which has a strong anti-vibration capability. At the same time, the vibration reduction system, motor system and heat dissipation system of the compressor are optimized for the special application environment of the truck parking air conditioning. A horizontal compressor for truck parking air conditioning with good vibration reduction effect and high reliability was designed.

In the era of big data, digitalization has a profound impact on our study, life and work. Digital design also gradually forms norms in daily work, and has a subtle influence on rapid product design and innovative design. This paper analyzes several kinds of product design scenarios based on data and Cpk tolerance analysis, and arranges the methods of defect control, process control and module selection in product design, so as to promote how to combine Cpk tolerance analysis tools with new product design and guide us to design optimization, process control and quality inspection in the process of new product development, so as to improve the efficiency of product digital design.

The quality changes of salmon stored at -18℃ and -60℃ in refrigerator for 56 days were studied by measuring TBA value, myofibrillar protein content, total bacterial count, sensory evaluation and microstructure. The results showed that with the extension of frozen storage time, the indicators of salmon changed significantly. Lipid oxidation was delayed, myofibrillar protein degradation rate was reduced and microbial growth and reproduction was significantly inhibited under the condition of -60℃ freezing storage compared with -18℃. The original flavor and quality of salmon can be better maintained with lower temperature.

Sauce beef were stored at 4℃ in refrigerator with vacuum pump technology. The fresh-keeping effects of two different packaging were compared by measuring sensory evaluation, chromatic aberrations, total number of bacteria, pH value and MDA value of sauce beef. The results show that vacuum package storage lengthened for about 4 days compared with ordinary package. Vacuum package storage has a positive influence on the flavor and inhibit the reproduction microorganisms of sauce beef. In addition, vacuum package storage can delay the oxidation of sauce beef.

Magnetic field assisted preservation technology is a new type of food preservation method. It has been widely concerned by academic and industrial field due to its advantages of non-toxic and high nutrient retention rate. Previous studies have shown that the effect of magnetic field on the activity of organisms and the phase transition process of water does exist, but there is no consensus on its mechanism and influence law. The theoretical research and application of magnetic field assisted preservation technology were summarized and analyzed, and the future development was prospected.

In order to solve the electromagnetic sound,this paper has researched the starting force and the electromagnetic sound. Via theoretical calculation of the electromagnetic force and deflection for eccentric rotor, comparing the starting performance of the compressor and the system at different coaxiality clearance, the relationship between stator/rotor clearance and starting performance is obtained in this paper. By comparing the reinforced structure of the shaft system of the pump, an optimized pump scheme solving the electromagnetic sound during starting is obtained. The paper can be used as a reference for the design and development to be made in the future.

The frosting of frost-free refrigerator fin evaporator has a great influence on the performance of refrigerator. In order to study the method of restraining frosting, we treat the fin evaporator with hydrophobic coating. The frosting on the surface of finned evaporator was experimentally studied, and the influence of hydrophobic materials on the frosting of finned evaporator was analyzed. The results show that the surface of hydrophobic fin evaporator has a certain inhibition effect on frost layer.

In order to meet the requirements of the latest edition of GB/T 23137 for the temperature measurement of static heat pump water heater, a movable water mixing device was developed. The processes of water injection, heating and water mixing can be conducted automatically, and energy efficiency calculation can be performed by the test device. Therefore,it is effectively to save time, reduce manual operation, and improve the accuracy of test results.

When the content of indoor air conditioning unit is too small or too large, it will cause adverse effects on the heat exchanger. In order to find a suitable range of internal and external machine volume to maximize the common and replacement design, uses the experimental method to test the matching of internal machine with different volume of 24K model, and carries on the actual verification to many brands of internal machine. The results show that when the content product ratio of frequency conversion products is between 50% and 91%, the output capacity of the products is the same, and the products can be interchanged, so as to meet the performance requirements of the North American products.

Polyurethane foam is the most important insulation material for fridge freezer. It can be regarded as homogeneous thermal insulation material. With the change of temperature, humidity and pressure, the thermal conductivity also changes. When the refrigerator is working, the room temperature is different, leading to different insulation properties of polyurethane foam, so we need a more reasonable method to evaluate polyurethane foam insulation performance. At the same time, different room temperature of the refrigerator is different, the foam insulation performance between the rooms is different, so the thickness of the foam layer should also be different, so as to draw a reasonable thickness of the foam layer.

Hot gas defrosting technology is conducive to energy saving, and more and more light commercial products are beginning to use hot gas defrosting technology to improve energy efficiency. This article proposes a series of solutions to the use of hot gas defrosting compressors that are prone to liquid hammer, overload or even jamming, and proposes a series of solutions such as valve group pressure relief, optimizing elastic pins, limit plates, motors and refrigerating oil, and proposes reliability Operate the SOA area, and conduct targeted reliability tests based on the inflection point of the SOA operating area, which can greatly improve the reliability of the compressor and make the compressor suitable for hot gas defrosting systems.

By investigating roller chamfer influence on performance of rolling piston compressor. Combining theoretical analysis and test verification, we explained importance of roller chamfer, made reasonable design requirements to chamfering of roller edges, set quantitative expression requirements and methods, and effectively improved consistency and reliability of compressor performance.

In order to analyze the variation of indoor carbon dioxide concentration with various parameters,the theoretical formula and orthogonal experimental design method are used to theoretically analyze the indoor CO₂ concentration. Based on the relevant hypotheses, the relationship between indoor CO₂ concentration and indoor initial CO₂ concentration, outdoor CO₂ concentration, fresh air volume, exhaust air volume, indoor number of people, CO₂ concentration produced by human and other parameters are derived. Four factors including outdoor air CO₂ concentration, number of indoor people, fresh air volume and exhaust air volume are selected, and three levels of each factor are selected for orthogonal experimental design. Through the mean and range analysis, the exhaust air volume has the greatest impact on the stable value of indoor CO₂ concentration and the time required to reach the stable value in these four factors. According to the final optimization scheme determined by orthogonal analysis, the stable value of indoor CO₂ concentration is 109 ppm, and the time required to reach the stable value is 3.2 h. Therefore, in addition to ensuring sufficient fresh air volume, it is also necessary to exhaust the indoor dirty air as soon as possible in the design of fresh air function.

The evaluation method of intelligent degree of intelligent household electrical appliances is an important part of the evaluation standard system of intelligent appliances. It is the basis for identifying the intelligent appliances and non intelligent appliances. It is also an important basis for distinguishing the "intelligence quotient" between different intelligent appliances. This paper designs a kind of intelligent degree evaluation method of intelligent household electrical appliances, which is the combination of qualitative and quantitative evaluation,and the combination of subjective and objective. In particular, this paper proposed an index system based on intelligent index, and then forms a subsystem of the "evaluation system" of intelligent household appliances, which is an important standardization task after GB/T 28219-2018.

In traditional smart home wireless communication networks, smart devices access to channels according to carrier-sense multiple access mechanisms. Contention back-off mechanism easily causes long communication, resulting in low channel resource utilization. For the above problems, a channel access mechanism of random access and packet access algorithm is proposed. The time is dynamically divided into different slices in the light of the priority of the station, and stations randomly access the channel in turn according to the divided time slices. As the simulation shows, the proposed algorithm effectively reduces the number of avoidance of devices, in the meanwhile, single device communication delay is effectively reduced. The proposed algorithm also improves system throughput performance effectively.

With the development of artificial intelligence, speech interaction technology has made great progress in smart home, intelligent assistant and other fields. The semantic understanding technology of oral short text has become the research focus. There are some characteristics in spoken text, such as nonstandard syntax, less key information and small differences between sentences, which affect the accuracy of semantic recognition. In this paper, the hierarchical theory is combined with the voice interaction application in smart home field to form a multi-layer semantic analysis framework, which realizes the transformation from text data to structured knowledge. On the basis of a small amount of text data, the training time is less than 10 seconds, and the average accuracy rate is more than 96%. A distributed model training system is designed to meet the industrial application requirements.

After experiencing a new crown pneumonia epidemic, people's hygiene concepts and health awareness have been unprecedentedly high, which has further promoted people's attention to healthy home appliances. At present, the health functions of home appliances in the market mainly include antibacterial, odor removal, virus killing and purification technology. This study mainly introduces the functions of refrigerator preservation, washing machine sterilization, air conditioning purification and water dispenser filtration. The refrigerator can control the spoilage of food by controlling temperature, humidity and anti-bacterial technology. The level of antibacterial and sterilization has become an important indicator to reflect the health function of washing machine. The air conditioner purifies the air and the drinking water purifies the domestic water. These functions meet people's needs for healthy life in all aspects. By introducing the health function of home appliances, and provides a theoretical reference for consumers to better understand the health appliances.

In recent years, cooking oil fume has not only endangered human health, but also caused air pollution due to its complex composition, toxicity and carcinogenicity. Therefore, people have gradually paid enough attention to it. The unique way of making food in China, including frying, is no doubt produce a lot of cooking fume. This article mainly summarizes the formation mechanism, emission characteristics, composition, toxicity analysis, environmental pollution and other aspects of cooking fume, which is intended to provide a reference for future in-depth research.

The health performance of vacuum cleaner mainly includes the function of Eliminating mites, Eliminating bacterial, Antibacterial and Allergen removal. In order to better evaluate the health performance of vacuum cleaners, several vacuum cleaners with different structures were tested. The results show that: (1) the ultraviolet lamp has nothing to do with the performance of eliminating mites; (2) the rated power also has nothing to do with the performance of eliminating mites; (3) the ultraviolet lamp has a significant influence on the performance of eliminating bacterial, and the eliminating bacterial rate of the vacuum cleaners with the ultraviolet lamp is significantly higher than that of the vacuum cleaner without ultraviolet lamp; (4) the rated power has nothing to do with the performance of eliminating bacterial; (5) the rated power has also nothing to do with the performance of allergen removal. Therefore, the research on the health performance of vacuum cleaners can guide consumers to shop rationally and meet their daily needs.

Health problems are problems that everyone cannot escape, whether it is the middle-aged and elderly people or children. In daily life, hypertension and obesity are the most overlooked health problems that greatly affect our health. Hypertension and obesity are prone to cause cardiovascular and cerebrovascular diseases. If we do not pay attention to our physical condition, it will cause major health hazards. Everyone needs to strengthen their knowledge of hypertension and obesity, and continually pay attention to their own blood pressure and weight status. Therefore, it is necessary to build an integrated health platform to integrate smart blood pressure monitors and body fat scales into unified management. Through the analysis of the user's blood pressure and weight information, it prompts the user's current health status and corresponding life suggestions to improve the user's daily habits , Thereby reducing the incidence of various health problems.

In order to study the crushing effect degree and its influencing factors of the cell wall-broken blender, laser particle size analyzer was used to test the particle size of carrot stirred by cell wall-broken blender at different rotating speed and working time. The software was used to analyze the test data. The results show that rotating speed and working time are the two factors affecting the crushing effect of the cell wall-broken blender.

Electronic toilet industry in China has huge market potential. National Standard GB/T 23131-2019 “Household and similar electrical toilets” released in March 2019 and implemented on October 1, 2019, electronic toilet odor removal performance detection method was added. By testing the odor-removing function of 32 electronic toilet seats of different brands and models, and analyzing and comparing the test results, it was found that the odor removal performance of electronic toilet is generally poor at present, but there are still high performance products with odor removal effect over 80%. The reason of low odor removal performance of electronic toilet is analyzed and the reason of poor performance is summarized. In order to help manufacturers to improve the performance of electronic toilet odor removal level.

Aiming at the problem of reflow soldering voids in the home appliance industry, using ANSYS software to simulate the process and difference of bubble escape under different air pressures. The study found that the escape of bubbles in the molten tin liquid is divided into two stages. In the first stage, the bubbles are subjected to inertial forces, and the tin liquid moves downward until the entire system is balanced. In the second stage, the bubbles are affected by the surface tension of the tin liquid , Escape outwards until the bubbles overflow; as the air pressure increases, the longer the time required for the bubbles to escape, the two have a nonlinear relationship, so adjusting the air pressure can effectively reduce the occurrence of voids. Through the design experiment, the vacuum welding experiment was carried out using 6 kinds of air pressure environments, and the welding points were detected by X-ray. The smaller the welding air pressure, the smaller the cavity size, which has the effect of suppressing the occurrence of cavity.

The research object was the ultrathin drum washing machine, Firstly, the case was simulated by Simcenter3D simulation software, to got the natural frequency and mode of vibration. Secondly, the modal test of the case was designed, to verified the accuracy of simulation analysis. Last but not the least, the case structure was topologically optimized and verified by simulation. According to the research, the reasonable reinforcement structure was designed, the first natural frequency of the case was increased from 36 Hz to 70.9 Hz, to improve the rigidity of the case, to avoided resonance phenomena caused by external excitation, and to reduced vibration and noise of the whole machine.

With the impact of COVID-19 and the unprecedented increase of consumers' attention to healthy home environment, the design of health materials is becoming more and more important in the design of household appliances. Mining the latest innovation achievements in product, material and technology to cope with the emerging global health crisis and meet the consumer's focus has become the key research direction and work content of refrigerator material design. Steel plate is widely used in refrigerators as the appearance of metal materials, its surface added antibacterial function can greatly improve the market competitiveness of products as health appliances. By analysising the existing refrigerator steel plate surface treatment process, steel plate to increase the antibacterial function of the implementation technology path, the antibacterial industry is currently suitable for the refrigerator surface to increase the antibacterial function of the implementation method, suitable for the refrigerator environment requirements of the type of antibacterial agent, suitable for antibacterial steel plate color and decorative texture implementation process, the promotion and application of health materials in refrigerators are analyzed and expounded.

The structure of the power transformer has a great influence on the safety structure of the power adapter product, so the power adapter must be clear about the structure of the power transformer in the design and production, and carry out a reasonable component layout and structure design of the product, so as to avoid the adverse impact of the power transformer structure. Taking the power adapter (including travel charger) and the power transformer commonly used in the extension cord socket with USB adapter as examples, this paper analyzes the structure and requirements of different power transformers, and the influence of power transformer structure on the product safety structure of power adapter (or including adapter module).

The side range hood with automatic opening and closing guide plate is prone to open and close failure in low temperature environment. By means of test design, force analysis and theoretical calculation, the fault is repeated and the fault mechanism is analyzed. The unreasonable gap design between the screw rod and the screw sleeve transmission pair of the push rod motor is found, the solution of increasing the design clearance of the transmission pair and modifying the software logic to increase the load capacity of the push rod is put forward, through the actual verification, the improvement of the solution is effective.

The main function of the air-conditioning air guide driving mechanism is to drive the transmission mechanism rack to expand and contract through the forward and reverse operation of the stepper motor, and to complete the direction change through the trigger signal of the micro switch component to complete the air guide switch and air supply purpose. In the front end of the design, three-dimensional tolerance simulation and other analysis methods were used to analyze the theoretical reliability of the wind guide and drive mechanism, so as to solve the FC fault, abnormal sound, jitter and other problems occurred in the operation of the mechanism, and meet the quality development requirements

The electrical conductivity and temperature changes of water not only have a great impact on the electrochemical state of water heater tank, but also influence the output of the impressed current cathodic protection system. In order to evaluate the corrosion resistance of water heater tank under different water temperatures and electrical conductivities, open circuit potential and polarization curves of enamel steel were analyzed under the condition of 400~2000 μS/cm and 25~75℃. On this basis, the output voltage as well as the output current of the impressed current cathodic protection system were calculated. CP Manager simulation software was used to optimize the installed form of anodes. The experiments and simulation studies provide a reference for the application design of impressed current cathodic protection system.

Compressor usually has a large noise problem in the frequency range of 2000 Hz~4000 Hz. In order to further explore its production mechanism and improvement measures, relevant researches are carried out by combining theory with experiment. Through theoretical analysis and simulation, the causes of compressed noise are clarified, and the resonant chamber is proposed to improve the frequency band noise. Based on the method of half power bandwidth, the existing resonance chamber design is optimized, and the noise attenuation effect of the resonance chamber is improved by improving the quality factor of the resonance chamber. Finally, the effectiveness of the method is verified by experiments, which provides theoretical guidance for the subsequent design of resonance chamber.

From the view of the demand performance of household cooking stove, this paper makes a comparative analysis of the advantages and disadvantages of the cooking stove that different technology currently used. At the same time, it points out the technical bottleneck of low energy efficiency and slow thermal corresponding of the radiant electric range adopting electric heating technology. The solution and feasibility to break through the technical bottleneck is revealed by the theoretical analysis and test results.

At present, compressor noise source optimization has reached the bottleneck; therefore, the main direction of noise reduction of vibration is to optimize the noise transmission path. The compressor rubber pads are most important defense of preventing spread the compressor vibration source to the refrigerator plate and side panel, etc. It plays a vital role in preventing spread the noise. The paper optimizes the structure of the rubber pads from the two indexes of natural frequency and vibration isolation rate. The experimental results show that reasonable optimization of the compressor rubber pads can effectively avoid the compressor resonance zone and improve refrigerator noise and vibration.

Factor analysis confirms that impact velocity is the main factor affecting the refrigerator drawer impact noise. According to the second law of classical mechanics, the calculation formula for crash speed of drawer is derived. The relationship between impact velocity and impact noise is obtained experimentally, and we use the logarithmic equation [A×ln(v+B)+C] to fit the prediction formula. Comparing with the experiment, the fitting result has a high coincidence. Theoretical and fitting formulas can be used in the design of refrigerator drawers to quantitatively predict the impact noise. The corresponding parameters can be optimized at the beginning of product design.

At high speed, the outer drum vibrates because of eccentricity of clothes, which causes vibration and noise of the drum Washing machine. The natural frequency and vibration mode of the box are obtained through the modal analysis of the box shell. The structure of the box shell is optimized to improve the natural frequency of the box shell. Through the experimental verification, the maximum vibration of the box body is reduced by more than 66.8%.

Combined with the cases of the refrigerants flow noise of two kind pipes, which happened at Series Parallel Connection Node of Multi-System Refrigerator, the reasons of causing refrigerants flow noise are analyzed. And above two kinds of pipe are optimized, respectively. The result shows that fluctuation noise of two pipe style decline from 4 dB to 1 dB. In order to reduce the fluctuation of eruption noise, enough eruption space should be ensured at outlet side of capillary, where capillary and suction pipe connect. About the pipe of capillary inserted suction pipe directly, capillary need locating at center of suction pipe. Above result of the refrigerants flow noise at Series Parallel Connection Node of Multi-System Refrigerator can supply one direction for refrigerants flow noise improvement.

Household appliances have been widely introduced into consumers' home. The production, use, and recycling will have an impact on the natural environment, human health, energy consumption and other aspects. Some of the impacts involve environmental damage, ecological imbalance and other issues, which are all disturbing the healthy development of economy and people's production and living activities. From national policies to consumers' demands, people are paying more attention to green home appliances. The public's understanding of green concept is deepening, and consumers and manufacturers are simultaneously promoting the development of green home appliances. The standards of green home appliances are constantly improving and upgrading, the functions of green home appliances are becoming richer, and the relevant policies are becoming more comprehensive, all these are pushing green home appliances moving forward along the direction of more environmental protection, more health, and more intelligent.

The national standard GB 38383-2019 "The minimum allowable values of the energy, water consumption and grades for dishwashers" had been released. For the introduction of Chinese standard tableware,the related contents of energy efficiency and water efficiency grades, technical requirements, and test methods of dishwashers are introduced. The differences between Chinese and Western tableware, dishwasher-related energy efficiency water efficiency standards are compared and analyzed. Machine product standards and testing have a more comprehensive understanding, to provide a basis for dishwasher product design and consumer purchase.

IEC 60335 is the basic safety standard for household appliances. The main difference between the newly released IEC 60335-1 version 6.0 and 5.2. Including the measurement of input power and rated current changes during the entire working cycle, battery-powered appliances, metal ion battery charging, user-accessible appliance sockets and output sockets, optical radiation hazards, external communication software management, etc. A brief analysis of the differences between the two editions of IEC 60335-1 and the new requirements of the new version of the standard is provided for reference by testers and designers from home appliance related enterprises and testing institutions.

Due to its small volume ,it is easy to be short of water in the process of using kitchen water heater. In order to provide as much hot water as possible without changing the volume, by recording the actual water temperature change of the tank of the water heater during the heating process, and the rise of the actual water temperature of the tank after the power failure. It is found that there is a big difference between the water temperature of the cupboard container and the set temperature, and the water temperature of the cupboard container will rise for a period of time after the heating stops. Finally, the improvement plan is provided according to the actual situation after analysis.

China's electronic and electrical products occupy most of the market share in the world's electronic products trade. However, the REACH regulations and RoHS directives make it extremely difficult for Chinese enterprises to export to the EU. Until now, many electronic enterprises will confuse REACH regulations with ROHS directives. By analyzing and comparing the differences between REACH regulations and RoHS directives on electronic and electrical products from the aspects of regulations, helps Chinese electrical and electronic products manufacturers to clarify the differences between REACH regulations and RoHS directives, and puts forward strategic suggestions for manufacturers, so as to help them cope with the situation calmly and break the barrier of Chinese electronic and electrical enterprises exporting to EU.

In order to analyzes and verifies the refrigeration and preservation performance indexes of household refrigerators, quantitatively detects their preservation performance from two indexes, namely weight loss rate and vitamin C retention rate, and forms the characteristic quantitative indexes of product performance. The indexes are formulated as "Implementation Rules for Characteristic Appliance Certification" and "Technical Specifications for Characteristic Appliance Certification - Technical Requirements for Certification of Fresh-keeping Refrigerators", which are used for quality activities of product performance certification.

This article analyzes the calculation method of CSPF/HSPF seasonal energy efficiency ratio in Australian room air conditioner standard AS/NZS 3823.4-2014; analyzes the impact of various working conditions on energy efficiency and discusses the analysis of performance improvement methods. In the Australian room air conditioner cooling CSPF and heating HSPF test, the focus was on the energy efficiency of low temperature refrigeration and low temperature heating. According to the influencing factors of each test point, adjust the energy efficiency of inverter products, such as compressor frequency, fan speed, expansion valve step and other parameters, so that the comprehensive energy efficiency is optimized.

The application of image processing technology in household electric appliances performance test can achieve clearer and more intuitive results, taking the oil smoke test of automatic cooker as an example, the composition and frame of the whole system were designed. TMS320DM6437 as the core component of data processing in the system, background difference method as the main method to extract feature targets and the system focuses on the design of feature target extraction process and related algorithms. In addition, the application of image processing technology in household electric appliances test was discussed through the analysis of the oil smoke test of automatic cooker.

Electric blanket is a kind of electric heating appliance directly contacting with human body, which belongs to CCC compulsory product certification catalogue. The determination of the control type of electric blanket is a difficulty in the detection process. This paper compares the working conditions of several kinds of typical electric blankets, and analyzes how to correctly confirm the control types of electric blankets through the power curve.

This article delves into the problems that occurs when we are testing power input of the pedestal pan. According to the analysis of the electric safety standard terms of electric toilet, and the explanation of typical cases, this article standardizes form of labeling the rated power input of electric toilet, improves the test method of the power input of electric toilet, and guides significance to test the power input of electric toilet.

Differential scanning calorimetry (DSC) is an important method of thermodynamic research, which has the characteristics of accuracy and speed, small sample amount and easy operation. Aiming at the testing principles and characteristics of differential scanning calorimetry, PA, PP, ABS are taken as examples to illustrate the application of qualitative and quantitative analysis of materials in non-metallic materials.

This article starts with the analysis of two currently valid national standards for testing energy-saving indicators for electric Hobs,compare which of the two test methods to more scientifically reflect the actual energy-saving performance indicators of electric Hobs,propose whether it is possible to have a unified energy-saving performance test standard.

Poor indoor air quality can cause discomfort and even affect people's health. Fresh air conditioning solves the impact of indoor and outdoor air circulation on indoor air quality in the operation of traditional air conditioning. However, due to the lack of standards, it can not be scientifically evaluated. Through the analysis of the fresh air conditioner function and practical verification, determine the CO₂ removal efficiency, the new air volume, the impact on the indoor temperature as evaluation test project of fresh air conditioner; The actual testing methods of the above tests in household environment are introduced. Through the above several test items, the performance of fresh air conditioning products can be evaluated comprehensively in the household environment.

By analyzing the performance from the result of a spot check of air cleaners in the circulation domain in Beijing in the last 3 years, the common non-conforming items are summarized as non-standard nominal value, confusing the conception of sterilization, releasing harmful chemicals and exaggerated propaganda. Altogether about 300 samples have been tested and analyzed to acquire the regulation and characteristics of the non-conforming items especially the elimination of noise and formaldehyde to help the enterprises improving the qualities of their air cleaners.