In recent years, in order to resist the air duct resistance of tall buildings, large air volume and high air pressure have become a key direction in the development of range hood. In order to design a range hood product with large air volume and high air pressure under the national standard noise limit, it is necessary to study the noise reduction technology of range hood. By using the hybrid CAA method, Fluent fluid simulation combined with Actran sound radiation simulation, the flow field data under the same fan, same air volume and different range hood platforms were used as noise sources to simulate the average sound power levels detected by noise monitoring points in four directions under the full free sound field. It is concluded that the sound power level of T-type range hood platform under the same air volume and the same fan is about 2 dB higher than that of 7-type range hood platform, indicating that different range hood platforms have different radiation effects on sound, which provides a new direction for the noise reduction design of range hood with large air volume and pressure.

With the development of refrigerator noise to ultra quiet level, higher requirements are put forward for pneumatic noise control. Taking the refrigerator fan of household refrigerator as the research object, the tail edge structures of different mixing forms are designed, and the noise reduction mechanism is studied by using acoustic analogy FW-H calculation method and experiments. The results show that both the acceleration channel and the bionic structure can improve the pressure gradient at the trailing edge of the blade and the vorticity of the blade and blade tip, so as to reduce the noise of the fan blade. For the prototype fan with 7 blades and a diameter of 41.8 mm, on the premise of ensuring performance, when the speed is constant at 1980 r/min, the maximum noise reduction of the acceleration channel blades can reach 1.7 dB(A), and the noise reduction effect is better than that of bionic blades. When the maximum pressure on the blade surface is extracted as the sound source, the calculation result of sound propagation will be inaccurate. This is because the location of the extracted sound source is contrary to the noise reduction design. Considering the limitations of the sound analogy calculation method, modifies the sound source surface extraction method, and carries out experimental verification to obtain better results.

To solve the problem of jet flow noise in refrigeration system, two kinds of noise reduction technologies with vortex generator and laminar flow generator were proposed. The characteristics of turbulence field and radiation sound field in vortex generator and laminar flow generator were studied based on the LES/CAA technology. The results show that the vortex generator can regulate the turbulent vortex structure inside jet flow and reduce the noise by 7 dB in the frequency range of 0~6400 Hz. The laminar flow generator can obtain high-speed laminar flow by suppressing the turbulent vortex structure. The noise level is further reduced by 4.3 dB compared with the vortex generator, which can achieve better noise reduction effect. The flow regulation technology proposed can provide theoretical guidance for the jet flow noise reduction in refrigeration system and has a good application prospect with the experimental validation.

With the rapid development of the home appliance manufacturing industry, the modernization of home appliance production lines, the gradual improvement of information technology, and artificial intelligence technology have become hot topics in the industry. The traditional method of manually distinguishing abnormal sounds in the production line of household appliances cannot meet the needs of rapid development. To address this issue, proposes a new method based on artificial intelligence for online recognition of abnormal and noisy household appliances, and has successfully applied it to the actual production line of air conditioning compressors, achieving good results. Expanding the application scope of this method can not only improve the efficiency and quality of household appliance production, but also reduce labor costs and shorten production cycles. At the same time, this technology also has broad application prospects and can be applied to other fields, such as the automotive manufacturing industry.

For cost reasons, the opplication of single cylinder rotor compressors almost cover all air conditioners below 1.5 P. Due to the structural structure and load characteristics, the traditional sensorless position presumption used in the internal PMSM motor drive control can't keep up with the pulsating load and there are shortcomings of detection error, leading to the speed and phase current ripple. Extracted the rotating ripple component containing the position error in the phase-locked loop control, and it is made to be 0 to correct the frequency conversion. In the speed loop control, the rotation pulsation component contained in the velocity feedback is removed, which greatly improves the precision of position detection, inhibits the fluctuation of speed and phase current, and improves the performance of the whole machine. The effectiveness of the control method is verified by simulation calculation and whole machine test.

Due to the high filtration accuracy, reverse osmosis water purifier needs high pressure for reverse osmosis, and the terminal water output of pure water is restricted. In order to improve the terminal water yield based on the current technology, large flow technology is adopted to improve the terminal water yield parameters. Through testing and analysis, the large flow technology can significantly improve the terminal water output (to 4 L/min), greatly reduce the product noise (≤51 dB(A)), and ensure that the effluent quality meets the health and safety standards, in addition, the large flow technology also has a considerable reduction in the cost of water purifiers. Therefore, the large flow technology in drinking water experience, pure water quality, product cost, etc., are more in line with consumer demand, and play a positive role in promoting the development of reverse osmosis water purifier industry.

In order to improve the experience of opening and closing refrigerator doors, an automatic door opening and closing actuator for refrigerators was designed. The actuator is driven by just one motor. The push rod and the rotating system were highly realized through a linkage wheel, and the cost is greatly reduced. The innovative design of clutch system, hover system, drive motor reducer, and rotating system makes the actuator widely applicable to cross door refrigerator, French refrigerator, and side by side refrigerator. And the actuator is compatible with traditional single-axis hinges, biaxial hinges, and Multi-link hinges. Through simulation analysis and calculation, material of the lower shell and size of shaft was determined, material and thickness of the connecting rod was determined, and other key structures and sizes were also determined. The designed automatic refrigerator door opening and closing actuator passed 100,000 cycle reliability tests. It has high reliability. Most of the parts in the actuator are injection molded, which greatly reduces the cost while ensuring reliability. This is conducive to the promotion and popularization of automatic refrigerator door opening and closing technology.

The door self-locking of refrigerator makes the door body have a certain pre-tightening force after it is closed, it makes the door seals on the door body and the box body can be tightly pressed. The reasonable design can make the user close the door more gently and smoothly under the premise of ensuring the preload; the unreasonable design will lead to a poor experience of opening and closing the door, the door body cannot be closed well and so on. In view of the problem that the door self-locking of a certain refrigerator has excessive pushing force during the door closing process, analyzes the self-locking part in the process of closing the door with the help of simulation software, improves the structure of suction assisting device, and the final design scheme was formed. The results show that the final improved self-locking part can greatly reduce the pushing force during the door closing process under the premise of ensuring the preload, the self-locking force in the self-closing stage is moderate at the same time, satisfies the needs of users, this provides a reference for designing and optimizing self-locking structure.

Aiming at the collision and displacement caused by the strong vibration in the dehydration stage of drum washing machine, applies the LMS vibration test system to vibration tests on the cylinder of a certain drum washing machine. The analysis on the test data proves the reason is the design of the glass bowl is unreasonable, and increasing the taper of the glass bowl is put forward as an optimized scheme. By increasing the taper of the glass bowl, the movement space of the roller during dehydration can be enlarged from 24 mm to 35 mm horizontally and vertically and the roller won't collide with the glass bowl, so as to effectively alleviate the collision and displacement of drum washing machine during dehydration.

The refrigerator suction assisting device can effectively help people close the door, which solves the problem of cold leakage caused by the door hovering or not closing tightly during the door closing process. In the process of repeatedly opening and closing the door of the refrigerator, the suction assisting device is constantly subjected to alternating loads. The suction assisting device may be fatigued and fractured, which affects the normal opening and closing of the refrigerator door. Therefore, it is necessary to analyze the fatigue life of the refrigerator suction assisting device to make it meet the reliability requirements. Firstly, a three-dimensional static structure simulation model of the suction assisting device is established. The distribution and variation trend of the strain of the suction assisting device in the process of opening and closing the refrigerator door are calculated. Then, the variation trend of the strain of the suction assisting device during the refrigerator door opening and closing process is experimentally tested. During the 100000 refrigerator door opening and closing experimental test, the strain curve of the suction assisting device in the process of closing and opening the refrigerator door shows a symmetrical distribution, and the strain shows a trend of increasing first and then decreasing. The simulated strain values are calibrated against experimentally strain values to provide accurate fatigue loads for fatigue life calculations. Finally, the fatigue life of the suction assisting device is calculated, and the locations most prone to fatigue fracture are found to guide the reliability design of the suction assisting device.

Studies the application of non heavy rare earth NdFeB magnet in the motor of household air-conditioning variable frequency compressor. On the basis of fully analyzing the demagnetization mechanism of NdFeB magnet, the strong demagnetization resistance structure design such as multi slot pole design and rotor magnetic circuit optimization is adopted, which greatly improves the demagnetization resistance of the motor and reduces the demand for the coercive force of the demagnetized iron of the motor. A motor scheme that can realize the application of non heavy rare earth magnet in air-conditioning compressor (the measured demagnetization rate is 2.51%) is proposed, it provides technical reference for the household appliance industry to realize the de heavy rare earth transformation, and provides essential reference for the improvement of the demagnetization resistance of permanent magnet motors.

With the advancement of industry and technology, the evaluation of air conditioner performance in China has transitioned from a "point" assessment based on rated operating conditions to a more "comprehensive" evaluation of seasonal performance. This evaluation takes into account the seasonal performance factors by analyzing the distribution of bin-hours through steady-state measurements conducted under limited indoor and outdoor working conditions. However, the existing methods fail to adequately reflect the dynamic control quality of direct expansion air conditioning equipment, such as air conditioners. To address this issue, proposes an enhanced method for dynamic environment and load-based seasonal performance testing, referred to as the load-based seasonal performance testing method. The core principle of this method involves simulating the outdoor conditions of air conditioning equipment over a specific measurement period within a performance laboratory. On the indoor side, heat and humidity loads corresponding to the outdoor operating conditions are applied, and the test air conditioning equipment is utilized to maintain the indoor temperature and humidity within the specified operating conditions and accuracy range. Based on the indoor load compensation method, two distinct approaches can be distinguished: the static compensation method and the dynamic compensation method. Presents a thorough examination and analysis of these two testing methods and their respective applicability.

Assembling an electrochemical oxygen control unit and simulating a fruit and vegetable box can achieve an oxygen conversion rate of 80.1 mL/min at a constant current of 22.5 A (50 mA/cm²), and control the oxygen concentration in a 30 L fruit and vegetable box below 15% within 23 minutes, which meets the technical requirements of commercial oxygen control and preservation. After industrial assembly testing by a large household appliance enterprise, the oxygen control unit can achieve long-term operation of over 2000 hours sat a constant current of 80 mA/cm².

The household central electric heating system conforms to the relevant national policies and is the future development trend of the household heating field. Due to the interdisciplinary characteristics of the central electric heating system, the standardization work and industry management are challenged. The importance and urgency of the standardization work of the central electric heating system is obvious, and industry standardization work requires a scientific and reasonable standard system. To build a scientific and reasonable standard system, by combing the application status and standard status of the central electric heating system, referring to the standard system of light industry, household appliances and smart home systems and corresponding national standards, the standard architecture of the central electric heating system is built. It provides the basis for the planning, formulation and revision of the industrial standard of central electric heating system. The standard architecture of the central heating system is divided into 4 levels and 31 series, which is comprehensive and complete, with clear levels and clear objectives. At the same time, it takes into account the requirements related to light industry, household appliances, and smart home systems. Provides basis for the planning and revision of industry standards for the central heating system.

Using superfine silver powder as conductive filling phase, the effects of morphology and dosage of four different kinds of silver powders on rheological properties, developing resolution and electrical properties of photosensitive conductive silver paste were studied. The results show that the smaller the particle size of silver powder in the silver paste system, the stronger the thixotropy of the paste, the higher the accumulation density of silver powder is easy to form a dense sintering conjunctival layer, good electrical conductivity, the minimum square resistance of silver paste can reach 3.1 mΩ/□. The selection of silver powder with high density, low specific surface area, high dispersion, uniform distribution and high surface smoothness is helpful for the fabrication of high resolution electrode. Considering the electrode resolution and conductivity of photosensitive conductive silver paste comprehensively, the requirements can be met when the mass fraction of silver powder is 80%.

Traditional quantification methods for measuring microfibers in water, including weighing method and microscopic counting method, are time-consuming and laborious. To improve this, a UV-Vis method has been developed to measure the two most common types of microfibers (cotton and polyester) released in household washing. Microfiber suspensions was prepared with different mass concentrations, and then the corresponding absorbance was measured at a wavelength of 500 nm to study the correlation between concentration and absorbance. The results show that there is a linear correlation between the absorbance and the mass concentration, and build the linear regression equation for cotton and polyester.

In view of the risks of thermostat meltdown and excessive temperature on the surface of the electrically heated boiler during dry burning, as well as the problem that the water temperature near the NTC temperature sensing element and the water temperature at the outlet may be too different when the boiler is boiling water, a coffee electromechanical heated boiler is taken as an example, and the shell wall temperature and the water temperature at the outlet are numerically simulated under dry burning, static conditions and dynamic conditions, respectively. The accuracy of the numerical model is verified by experimental tests. The results show that under dry burning condition, the temperature rise rate of the shell wall gradually accelerates and the temperature reaches 150℃ after 92 seconds of heating. Under static and dynamic conditions, the boiler water temperature continues to rise and then declines, finally reaches the dynamic equilibrium state, with the temperature stabilizing at about 67℃. Through comparative analysis, the maximum relative error between the simulated value and the experimental value is less than 5%, which indicates that the numerical model has high accuracy and can be used as a reference for the design of the boiler automatic control system.

To solve the problem of excessive water temperature in summer, the segmented combustion technology with a generous load ratio is used to widen the load output range of the wall-hung boilers, improve their ability to adapt to different load requirements and avoid the occurrence of excessive water temperatures in summer. The key parameters of the sectional burner are determined using a combination of theoretical calculations and experimental tests, and the performance tests are completed on the installation stage. The results show that: compared to atmospheric wall-hung boilers, the minimum heat load value of the sectional burner is widened by 60% downwards to 4.0 kW without affecting the maximum heat load output, and the small fire row load output can effectively solve the problem of water temperature being too hot due to excessive load output and improve the user's comfort experience with water.

Drying performance is one of the basic indicators of dishwasher. Analyzes the fan drying technology and its system commonly using in dishwashers, and sums up the problems including fixed air flow state, uneven drying efficiency, insufficient condensation of exhaust gas, etc. Then it puts forward the air inlet and exhaust two-way ventilation technology including double fans mixing condensation technology, which realizes the integration of air inlet mode and exhaust mode through the switchable air duct design and the combined use of double fans. In the exhaust mode, through the mixing condensation in the air duct, the moisture content of the exhaust air is effectively reduced, so as to solve the problem of "dishwasher outlet condensate". Furthermore, designs the two-way ventilation system with double fans and the multi-mode ventilation system with multi-fans. Inside the dishwasher chamber, there forms the continuously changing air flow, which can achieve the even drying efficiency everywhere and the better drying performance.

In order to improve the problem of poor cooking effect caused by the various sizes and amounts of ingredients in the cooking process of users using the steam oven, taking steamed sponge cakes as the example, the cooking model of which are steamed by the steam oven is studied. Through experimental research, the regularity of cooking time required for steamed sponge cakes of different sizes and amounts to reach the same cooking end point was obtained, and SPSS software was used for linear regression analysis. And after verification experiments, the cooking model suitable for Chinese pastries such as steamed sponge cakes of different sizes and amounts has been obtained, which provides solutions for intelligent cooking of kitchen appliances.

COMSOL Multiphysics 5.4 software was used to dynamically simulate the water tank heating process of the heat pump water heater. The measured temperature of the condenser was assumed to be the input parameter for the tank heating. The reliability of the simulation was verified by comparing the average temperature of the water tank with the experimental values of the sensors. Results show that the water near the wall is heated and flows upwards by natural convection, then turns to flow downwards along the central axis after the topmost confluence. The bottom water is heated by the copper tube condenser and flows upwards. After the two streams of water converge, they flow to either side of the tank wall, forming two circulation zones on either side of the tank, so that the water temperature is distributed in homogeneously in the horizontal and vertical directions. Along the vertical direction, the water temperature is higher on the top and lower at the bottom, and the temperature difference between the upper and lower is 3~6℃. The water temperature decreases sharply along the horizontal direction from the wall to the center and then rises slowly. There is a temperature boundary layer of 0.005 m near the wall, and the temperature in the boundary layer drops more than 5℃. The present work can serve as a theoretical reference for improving the heating performance of the heat pump water heater tank.