With the rapid development of low-voltage DC technology, "Photovoltaic, Energy storage, Direct current and Flexibility (PEDF)" has become an important path to achieve carbon neutrality in the field of civil buildings. The large-scale application of DC appliances will become an important support for PEDF. In the process of realizing the commercialization of DC appliances, it is not only necessary to solve key technical problems, but also need to synchronously build design standards and evaluation systems. Analyzes the problems caused by the conversion of AC power supply to DC power supply to the design and evaluation of household appliances, draws on the experience of the standard framework system of the household appliances industry, analyzes the adaptability of the terms under the standard framework, lists the revision scheme of key technical indicators, focuses on the discussion of the significance and challenges of the DC appliance standard, and puts forward suggestions for the construction of the DC appliance system standard.

IEC 60335-2-40:2022 was issued in May, 2022. The new standard has revised the requirements for flammable refrigerant charge limit, ventilation and so on. Introduces the requirements for flammable refrigerant charge limit and ventilation in IEC 60335-2-40:2022 in detail, and compares the new standard with IEC 60335-2-40:2018, GB 4706.32-2012 for the difference of flammable refrigerant charge limit for reference.

Since the advancement of technology and the rising demand of users, merchants provide users with various home drinking water solutions, such as water purifiers, drinking purifiers, pipeline machines, central water treatment systems, and more. Drinking water health and safety are the basic needs. Now the drinking water product industry has relatively complete safety standard requirements, but there has been no clear standards for sensory evaluation. Studies on the establishment of a quantifiable sensory evaluation method in addition to the water quality, hygiene and safety standards for drinking water. By comparing a variety of sensory evaluation methods through desktop research and combining the feasibility of enterprise quality control, a quantitative evaluation method has been formed and a control standard has been established, which has been applied in enterprises to achieve a good effect of controlling the quality of drinking water products.

The rated power input is marked on the nameplate for impeller washing machine. It is an important safety parameter to the customer. But the power input is unstable throughout the operating cycle, it's difficult to measure the stable power input during representative period. Therefore, how to measure the power input of the impeller washing machine during representative period is the topic of this article. According to the clause 10 of IEC 60335-2-7(8.0th edition) and IEC 60335-1(5.1th & 6.0th edition), do the power input tests of impeller washing machine. The result of test data show that the requirement of chapter 10.1 in IEC 60335-2-7(8.0th edition) and IEC 60335-1(5.1th edition) is reasonable and precise for the Impeller washing machine.

The electric storage water heater is equipped with a thermostat and a thermal protector to control the temperature, and has the advantages of high safety performance and convenient use. With the popularity of electric storage water heaters, as a common high-power household appliance, its energy consumption has attracted much attention. The coefficient of standing per 24 h is one of the important energy consumption indicators of electric storage water heaters, and it is an important parameter for people to compare electric water heater products. Analyzes the uncertainty for the coefficient test of standing loss per 24 h of electric water heaters, and provides a reference for improving the accuracy of energy efficiency testing of electric water heaters.

The stator is one of the main components of the motor. When machining, the winding direction of a slot is opposite, which is called reverse embedding. Aiming at the bad phenomenon of anti embedding, a detection system based on current magnetic effect is designed. By applying a constant current source to the stator coil to generate a magnetic field, the hall sensor reads the magnetic field intensity of the coil, and then the software algorithm calculates the magnetic pole generated by the coil, and determines the anti embedding position according to the magnetic pole. The experimental results show that the system can accurately judge the defective products.

With the continuous development of information technology, smart home, especially smart home scenes, has become more and more popular in people's family life, people have higher requirements for smart home scenes, when users use scenarios, their functional defects seriously affect the experience. In the process of scenario function testing, there are some situations of imperfect test dimensions and unscientific case design. To improve the quality of scene function test in smart home industry. Proposes a method to improve scenario test dimensions and scientifically design test cases, and takes the home-coming scenario as an example, the analysis fully considers the completeness, correctness, suitability and compliance of functions in the process of functional testing, and integrates scenario method, equivalence class division method, boundary value analysis method and other technologies into the process of designing test cases in an orderly and efficient manner. Illustrates the method of scenario function test case design, which can effectively and orderly design a group of functional test cases with high reliability and strong execution, thus improving the test efficiency and ensuring the confidence of smart home scenario function and software quality.

Through the collection of user status product operation parameters of a certain type of range hood, through data analysis, the difference in performance between the hood and the main operating conditions of the laboratory state. The digital human foreman was used to measure the sound pressure level and the loudness of the sound quality of the user's ears under different working conditions in the kitchen, and the range of the noise value was clarified. Then the voltage distribution of user state and the difference of test voltage stipulated by laboratory standard are analyzed statistically, and the performance and development and design suggestions of subsequent products are given.

Low-carbon manufacturing is an inevitable way for sustainable development. Low-carbon manufacturing technology is an important method and means to realize the transformation of China's manufacturing industry. In view of the application status of carbon footprint assessment methods, collects and analyzes the relevant literatures at home and abroad, summarizes the current research results, and analyzes the core technology points and existing problems of carbon footprint assessment, so as to further promote the development and application of low-carbon manufacturing technology for mechanical and electrical products.

The enthalpy difference method is used to test the performance of R290 variable frequency air conditioning under varying working conditions. MATLAB software is used to fit the performance curve of the air conditioning system. Energy Plus software is used to build the air conditioning room model and the fitted air conditioning model. The results show that when the air conditioner is set at 20℃, the annual power consumption of refrigeration is the highest in Guangzhou, which is 2.18 times of that in Chengdu. In Shanghai, Chengdu and Guangzhou, the power consumption of air conditioning system decreases by about 19.2%, 17.1% and 20.1% when the set temperature of air conditioning rises by 2℃ respectively. The simulation of the use habit of office workers to turn on air conditioning from 6 PM to 6 AM shows that the power consumption of Beijing, Shanghai and Chengdu is the same, and Guangzhou is the highest, which is about 1.6 times of Beijing.

The existing smart flowerpot design has disadvantages such as low degree of automation and relatively simple plant applicability. Studying and improving such problems will improve the user experience and open up the smart flowerpot market. Based on the TRIZ theory, the intelligent flowerpot system is decomposed, and the problems that should be considered in the design process are summarized. Select the general parameters suitable for this study to establish a TRIZ contradiction matrix, select the applicable invention principles in the matrix according to the feasibility principle analysis table, and solve the contradictions existing in the solution design according to the invention principles. Finally, through the use of semiconductor condensation technology, a smart flowerpot solution with high resource utilization, low cost and high degree of automation is obtained, which provides a valuable reference for application research in the field of smart flowerpots.

Due to the influence of water hardness, wastewater valve blockage and other factors, the improvement of water efficiency was restricted. In order to further improve the water efficiency of the existing RO water purifier, the softened water technology is applied to the water purifier. Through comparative tests, this technology can reduce the hardness of water, increase the total water purification of the RO water purifier by about 20.6%, and increase the water purification rate by about 15%, so as to effectively improve the water efficiency of the RO water purifier. In addition, the self-cleaning technology of wastewater valve can reduce the risk of valve blockage, reduce the discharge of flushing water and concentrated water, increase the water purification rate by about 5%, and also improve the water efficiency of the RO water purifier.

During the foaming and cooling process of the refrigerator door, all parts contraction with the decrease of temperature, which is easy to produce thermal deformation. Excessive deformation will lead to problems such as door bending, cold leakage, condensation, etc. The cooling deformation properties of rigid polyurethane foam, as the key factor affecting the deformation of door, can be improved by adjusting the formula and improving the processing technology. It is low cost and easy to realize. So, it is particularly important to study the influence of rigid polyurethane foamproperty on the thermal deformation of refrigerator door. Uses CAE simulation method to calculate the deformation of door under foaming condition, meanwhile, the influence of rigid polyurethane foam with different property on the deformation of door is compared and analyzed. The results show that the thermal deformation is greatly affected by the elastic modulus and thermal expansion coefficient of the rigid polyurethane foam, and the deformation increases with the increase of elastic modulus, decreases with the decrease of thermal expansion coefficient.

The thermal comfort of the air duct mechanism has attracted more and more attention from users. In order to improve the heating comfort, a simulated user laboratory has been established, which can test the temperature of the main area of the room space. The position of air outlet, coupling angle of air outlet and air volume, increase of electric auxiliary heat and increase of wind speed were simulated experimentally. By sorting out the room stratification situation through each test data, it is concluded that the room stratification temperature can be made to about 2℃ by using the lower outlet and coupled air outlet angle and air volume. The overall room temperature can be raised by adding electric auxiliary heat and increasing air volume, but the stratification improvement of room temperature is very small. Attention should be paid to these problems in the subsequent design of the ducted type air conditioner and avoid design risks.

Since the development of household air conditioners, the traditional way of air outlet is that the cold air blows directly when cooling, and the head and feet are cold when heating. The comfort experience of the human body is poor, which has become a criticism of the industry. Taking the cabinet air conditioner as an example, CFD software is used to simulate the cooling and heating temperature field of a cabinet air conditioner with upper and lower cooling and heating air outlets that has been mass produced, taking the height of Chinese people as the experimental object. By observing the sweeping trajectory curve of the cold air, it is found that the experimental cabinet will not directly blow to people. In addition, through the analysis of the vertical temperature difference change and temperature uniformity of the simulation space. This cabinet machine can reduce the indoor temperature to a comfortable temperature within 30 minutes. At the same time, the cabinet machine and the traditional cabinet machine are tested for thermal comfort. Through the analysis of experimental data, it is verified that the vertical temperature difference changes less when hot air is delivered from top to bottom at the same time, and the heating temperature uniformity of the whole space is higher. Comprehensive simulation results show that the upper and lower cold and hot air outlet cabinet air conditioner have the best cooling and heating comfort.

Air fryer, as a new cooking tool, has good characteristics of strong convection, low oil and smokeless heating. If the function of hot air frying can be integrated into the existing electric oven, the function and practicability of the oven can be increased. Taking the common cooking of French fries as an example, the heat transfer mechanism of French fries in the convection environment is analyzed. And the chroma of French fries was determined by time-lapse photography and image segmentation technology, so as to optimize the heating rate of the cavity of the existing hot air oven, providing some guidance for the design of hot air oven.

The refrigerator reciprocating compressor usually has many different design methods on the ratio of piston-stroke to cylinder-diameter (stroke-to-diameter ratio for short). Based on influences on different stroke-to-diameters of reciprocating compressor, investigates the mechanism of shaft-connecting rod-piston on reciprocating compressor, analyses the dynamic characteristics on the influence of different stroke-to-diameters ratio. It is observed that the stroke-to-diameter has no influence on the resist-torque. Increasing the stroke-to-diameter appropriately can reduce the side-force of piston and the friction force of piston, enhances the refrigeration capacity and the coefficient of performance.

Studies user collaborative filtering control recommendation based on behavior curve, and creatively proposes an optimized UBC-based CF algorithm: Collaborative Filtering Based on User Of Behavior Curve. This algorithm uses more fine-grained behavior curves to represent users and the similarity of behavior curves to calculate the user's previous similarity, so as to provide customers with a more precise air conditioning control recommendation service. The method mainly includes the following steps: Firstly, extract the user's historical operation behavior and generate a behavior curve to represent the user; Then, calculate the Jaccard similarity of each two behavior curves to evaluate the similarity between each two users; Next, for the recommended user, select a certain number (K) of neighbors closest to the user and combine with the current control parameters to generate the user's parameter recommendation; Finally, several experiments are conducted and the effect is verified. It can be seen from the experimental results that the accuracy of this method can reach 91% and the effect is optimized.

Refrigerated display cabinets are widely used. Due to the existence of wind curtains, their energy consumption is high. During operation, the performance of refrigerated display cabinets will be affected by many factors. Therefore, using the validated model and response surface method (RSM), fully discussed the influence of operating conditions parameters (evaporation temperature, flow rate, ambient temperature and ambient humidity) on thermal entrainment factor (TEF), energy consumption and temperature uniformity, and carried out multi-objective optimization. The results show that evaporation temperature has great influence on TEF, energy consumption and temperature uniformity; The interaction between flow rate and evaporation temperature has a significant impact on the three performance indicators, while the interaction between flow rate and ambient temperature only has a significant impact on TEF. Compared with the basic conditions, the optimized parameters can reduce TEF by 22.07%, energy consumption by 37.06%, and temperature uniformity by 0.48℃.

Due to the different drying principles of the washer-drying machine, there will be huge differences in structural design, drying control algorithm, drying judgment logic, and drying effect. In order to solve the problems that the traditional water cooling system needs to use a large amount of water for condensation and the drying efficiency is low, based on the analysis of the water cooling and fresh air drying principles and system resistance, the drying structure of the system is optimized to reduce the system resistance by 45%, making the system air volume increased by 50%. At the same time, a temperature and humidity sensor is introduced to intelligently determine the drying of the system, so as to achieve precise control of the moisture content of the clothes. And through the closed-loop temperature control of the damper mechanism, the drying temperature of the load is intelligently controlled to meet the user's drying temperature requirements for different materials. Through the above technologies, the research on an intelligent drying system with high efficiency, water saving, intelligent temperature control, and clothes drying is completed, and the feasibility and reliability of the system are verified through theoretical analysis and experiments.

The structural parameters of the motor bracket of commercial duct type air conditioner are optimized. According to the actual force and constraints, the statics analysis was carried out to obtain the stress and strain cloud map of the motor support, and the danger point of the motor support was determined near the ring of the motor support. Through the sensitivity analysis of the structural parameters of the motor support, it is concluded that the main parameters affecting the mechanical properties of the motor support are the width of the backplane, the length of the beam, the length of the first vertical plate, the length of the second vertical plate, the diameter of the fixed motor circle and the rounded corner of the vertical plate. Finally, six parameters affecting the mechanical properties of the motor support are optimized. The optimization results show that the maximum deformation of the motor bracket is reduced by 6.7%, the maximum stress is reduced by 7.3%, and the model mass is reduced by 8.1%. The optimization design of the motor support based on the response surface method improves the speed and efficiency of the optimization work, improves the strength and reliability of the motor support, and also provides a method for the optimization of structural parts.