Aiming at the problems of high power consumption and easy fouling of small steam generators used in various home appliances, this research improved the thermal efficiency of the traditional cavity structure by means of increasing the heat exchange area and enhancing the heat transfer coefficient and reduced energy consumption. At the same time, this design can avoid the problems of scale blocking the flow channel and the failure of the heat exchanger that are easily generated by the general pipeline heating method. The thermal calculation, numerical simulation and experimental verification of the improved steam generator structure were carried out. The heat transfer and flow characteristics of the upper and lower inlet water are compared by numerical simulation and results show that the upper inlet has better heat transfer and flow performance. According to the simulation results, the upper water inlet method is selected to test the steam generator before and after adding the foam metal copper. After the improved structure (adding metal foam), the thermal efficiency of the improved steam generator can be as high as 98.92%, which is about 5% higher than that before the improvement, and the improvement effect is obvious. According to the analysis of thermodynamic principle, the improvement of thermal efficiency comes from the reduction of heat leakage and the improvement of electrothermal efficiency.

Range hood is an important equipment to control kitchen contaminant, capture performance is a significant index to evaluate range hood, which has been widely recognized at home and abroad. Summarizes the typical parameters and test methods of the range hood's capture performance, and analyzes the influence of the mounting height, air supplement mode and heat source characteristics on the capture performance. The results show that in a certain extent, reducing the mounting height and heat source intensity, increasing the air volume and pressure, using the back heat source and taking appropriate air supplement can effectively improve the capture performance of the range hood. However, beyond this extent, the change of the capture performance is small, and the energy consumption and noise will be increased.

In this study, the internal circulation air cleaner was applied in the kitchen and integrated with the exhaust hood. CFD numerical simulation was utilized to find a rational recirculation parameter under different air outlet velocity: 1~4 m/s and the air outlet angle: horizontal air outlet and upward 45° air outlet under 100 m³/h circulating purification flowrate. The best purifying effect was realized under 3 m/s air outlet velocity and upward 45° air outlet angle in the scope of discussion. It is found that compared with a separate range hood, the concentration of the breathing zone and the kitchen space can be reduced by 66.5% and 86.7% using this range hood with a recirculating purification unit. In the scope of the discussion of circulatory purification parameters, the concentration reduction rate of the breathing zone is in the range: 35.1%~66.5%; the concentration reduction rate in the kitchen space is in the range: 26.2%~86.7%. The purification experiments verifies that with the 3 m/s air apply velocity and 45° air outlet angle, the PM_2.5 and TVOC concentrations in the breathing zone sampling points could be reduced by 53% and 28%, respectively.

In recent years, with the decrease of particle concentration in the China's atmospheric and the outbreak of COVID-19, consumers have higher requirements for the indoor air quality and the use of air cleaners. Therefore, GB/T 18801—2015 "Air Cleaner" national standard needs to be modified, especially modifications on requirements, gaseous pollutants removal evaluation, virus removal evaluation, and secondary odor evaluation, etc. Based on large amount of data analysis and several round robin tests, research work has been carried out on the establishment of correlation index, mixed loading test method of gaseous pollutants, virus removal evaluation method, simulated secondary odor evaluation and test method of dynamic balance test method. Based on this research results, the standard GB/T 18801—2015 is modified. These modifications makes the evaluation indexes of air cleaners are more standardized and the test methods are more suitable. The revised standard will play a significant leading role in the industry.

As the pace of life accelerates, people are prone to anxiety and other bad emotions. Therefore, household appliances with soothing function have appeared. But there is no suitable method for testing the soothing function. In order to fill this vacancy, taking aromatherapy air conditioners as an example, a soothing function test method suitable for household appliances is developed. In the experiment, the Trier Social Stress Test (TSST) was used to stimulate the subjects' anxiety. The subjects sat in two separate environments with and without the aromatherapy air conditioner, and waited to restore calm. After that, the time spent by the subjects in stable mood under the condition of with or without aromatherapy and soothing function was compared, and the electrical skin value was used as the measurement index during the test. The test results show that when the aromatherapy air conditioner is turned on, the emotional stabilization time of the subjects is shorter, and there is a significant difference compared with the situation when the aromatherapy air conditioner is not turned on. Therefore, it is proved that the soothing function of the air conditioner is effective and the test method is also proved to be effective and feasible.

The new air conditioner air duct technology is used to change the internal flow field of the traditional floor standing air conditioner into an independent dual airflow field for cooling and heating, which realizes the return air from the lower air inlet during cooling, the air supply from the upper air outlet, and the return air from the upper air inlet during heating, the air from the lower air outlet during heating. The thermal air can be directly sent to the position below the knee of the human body to improve the thermal comfort of the human body. The new air duct can reduce the supply air temperature difference by 1.5℃, effectively improve the uniformity of the indoor temperature field, thereby improving the indoor air quality, and can achieve the purpose of energy saving.

In order to solve the problem of high frequency noise in the compressor of household variable frequency air conditioning, the noise source and transmission path are studied. In terms of noise source, studied the mechanism of high frequency noise based on the pulse width control technology and harmonic theory of motor air gap magnetic field, recognized that 5000 Hz noise were mainly caused by the interaction between controller's carrier frequency and rotor's magneto motive force which formed a harmonic electromagnetic wave. Then conducted an experimental verification on correlation of 5000 Hz noise and carrier frequency. In terms of the transfer path, recognized that the shell resonance caused by the weak rigidity in the upper cavity area of the motor was the core reason that leaded to the high noise of the compressor at 5000 Hz. As a result, two optimization schemes of adding a separator in the upper cavity region of the motor and reducing the upper cavity of the motor were proposed through the acoustic radiation simulation analysis method .Then verified the effectiveness of above two optimization schemes that reduced 5.8 dB(A) and 6.9 dB(A) at 5000 Hz noise respectively and provided a theoretical basis and guidance for the improvement of high frequency noise in the compressor of household variable frequency air conditioning.

High quality air is the guarantee of national health. In the domestic environment, problems such as poor ventilation and insufficient lighting often lead to the generation and accumulation of harmful substances in the indoor environment, which not only reduces the air quality, but also directly or indirectly damages people's health. Taking hydrogen sulfide gas as the odor source, through the method of sensory evaluation, experiments are designed to compare the current common odor removal technology on the market, and their advantages and disadvantages are summarized. The research results show that the effect of photocatalyst and activated carbon on odor removal is obvious, and the speed of anion removal is relatively slow. Plasma can produce by-products while removing odor, which needs to balance the relationship between odor removal effect and by-product control. The results can provide reference for the development of home appliances.

Expansion muffler is a widely used component in air conditioner to improve the transmission sound of compressors. The acoustic finite element method is applied to study the transmission loss of air-conditioning discharge pipes equipped with mufflers. It is found that two additional constriction mufflers can be formed in the pipeline, and the overall sound attenuation is much greater than that of the expansion muffler. Therefore, reasonable design of muffler position and pipe length can achieve the effect of muffler and make the cost more economical.

Pyroelectric infrared sensors are widely used in air conditioning, and the decorative materials have a great influence on the actual detection distance. The infrared transmittance of the material was characterized by the characteristic infrared (9.5 µm) of human body radiation, and compared with the actual infrared detection distance of the sensor. High density polyethylene (HDPE) was used as the main material to prepare the covering film of the sensor. The lower the transmittance of the material at 9.5 μm wavelength, the shorter the actual detection distance of the sensor. Infrared transmittance can effectively evaluate the infrared penetration performance of materials, which has a good guiding significance for the development of infrared penetration materials.

The design of blowers integrates a variety of structural relationships, and the design by experiment lacks regularity and has high design costs. The parameters of blower structural determine its performance. By using the method of computational fluid dynamics, the influences of three different parameters on the wind speed at the outlet of blower are analyzed, such as the axial distance between fan and motor, the clearance between fan and blower, and the axial length of blower. Basis on the univariate analysis, Box-Behnken test design was carried out, the regression equation was obtained by using Response Surface Methodology (RSM), and the optimal structural parameters of blower performance were obtained by taking the maximum outlet wind speed as the optimization objective.

With the rapid development of the household electrical appliances industry, innovative technologies emerge one after another, and the rapid iteration of new products, consumers have certain difficulties in purchasing products. The basic rules in the market are quality-based pricing, and it is the common demand of the industry, enterprises and consumers to improve the quality grading standards and system for household electrical appliances. Taking the quality grading of household electrical appliances as the research object and analyzing the current standards of product quality grading, this paper discusses the establishment basis, technical index setting and grade division of the quality grading standard. By establishing the corresponding standards and building a standard system, it can promote the improvement of product quality and promote the high-quality development of the industry.

Baking household appliances with Nickel-chromium alloy heating tube have slow heating speed and mediocre baking effect. Graphite can solve these problems from the heat source itself with fast heating rate and short wavelength. Firstly, the graphite sheet with thickness of 170 μm~200 μm was obtained by controlling the calendering process. Then, graphite resistors from 7.94 Ω to 9.26 Ω were prepared by theoretical calculation. Finally, the graphite heating tube obtained by optimizing the packaging and gas filling process can shorten the oven baking time by about 30%, and improve the color and aroma of food. Because the infrared radiation wavelength of graphite heating tube is better matched with food and the heating tube heats up faster.

Refrigerator, as one of the household appliances used in the family and running continuously, its power consumption occupies a large proportion of the electricity consumption in the residents' daily life. In the context of China achieving carbon peak by 2030 and carbon neutral by 2060, the energy saving of refrigerators is of great significance. At the same time, people have higher and higher requirements for food preservation, and the frozen storage temperature is getting lower and lower. In order to meet the demand of lower temperature, greater cooling capacity and lower power, compared the cooling capacity, power consumption and COP of R600a, R290 and their mixture, and found that the introduction of appropriate R290 into R600a can optimize the overall COP of the system, increase the cooling capacity and meet better user requirements.

Capillary is applied as the throttling component in most dehumidifiers. When the dehumidifier leaks refrigerant, the dehumidifier is prone to frost which reduces the energy efficiency. Based on experiments to study the frosting situation and defrosting protection of the R32 refrigerant leakage process in the dehumidifier. The results indicate that The R32 refrigerant dehumidifier defrosting protection program will fail when overlooked the refrigerant leak conditions. When other conditions remain constant, the indoor dry bulb temperature is linearly negatively related to the frosting area and frosting time of the evaporator, and the refrigerant leakage rate of the dehumidifier is non-linearly related to the frosting time of the evaporator. The subsequent defrosting protection program can adjust the defrosting time and the fan's speed to decrease defrosting energy consumption base on the previous study. The inner distribution of the evaporator is affected significantly by the refrigerant leakage rate and indoor dry bulb temperature. The later defrosting protection program can set the defrosting protection enter temperature and the position of the temperature-sensing element to improve the accuracy of defrosting protection.

Recently noise reduction has been a research hotspot in the field of refrigerators and other home appliances. In this paper, a non-bottom-mounted condenser refrigerator is tested by the method of sealing the compressor cabin in order to explore the realization of the no-noise refrigerator. The experimental results show that the radiated noise of the compressor is the main source of noise; the method of sealing compressor cabin can effectively reduce the radiated noise of the compressor, and the average sound power of the refrigerator is reduced by 4.3 dB(A); the power consumption is increased by 0.8% at ambient temperature of 32℃. It provides a solution for realizing the no-noise refrigerators.

Internal flow field characteristics of air fryer are important for food processing. However, it is difficult to accurately measure and predict the distribution of the flowfield due to the complex internal structure of air fryer. Based on Reynolds time-mean equation and k-ε turbulence model, Fluent software was used to conduct three-dimensional numerical simulation of the flow field in an air fryer, and the detailed information of velocity, turbulent kinetic energy and vorticity distribution in the air fryer was obtained. The simulation results reveal the flow field movement law in the air fryer, the generation and development process of vortex structure, and the influence of the internal structure of the fryer on the flow field. The analysis results can guide the design of related structure and heating system of air fryer, and can also be used as a reference for the design and development of related small household appliances.

The oil superheat is currently adopted as the criterion of the reliability for rotary compressors in air-conditioning systems. It is generally acknowledged that the viscosity of the oil increases monotonously with oil superheat. Experimentally studied the relationship between the solubility characteristics of refrigerant in oil, the oil superheat and the oil viscosity. The results showed that the dissolved refrigerant levels were almost the same at various positions within the oil pool, and the saturation state was not reached. Therefore, the oil viscosity in positions with high temperature was rather low, and for a fixed position within the oil pool, the oil viscosity could decrease when the superheat raised in some testing conditions, which indicated that viscosity is not monotonously related with oil superheat. The experiment results proved the limitation and irrationality of the current methodology which utilized oil superheat as a standard for compressor reliability, to a certain extent. It is also recommended to use oil viscosity as a more reasonable criterion.

SQ flat wire common mode choke are commonly used in black household appliances such as TVs. This type of inductor has the advantages of high production automation, good consistency, and high-frequency interference suppression, but it has not been used in inverter refrigerator products. While in inverter refrigerators using SQ flat wire common mode choke with the same size and inductance as the commonly used toroidal common mode choke, the inductance fails, resulting in abnormally high disturbance voltage in the low frequency band. Studies the failure cause of SQ flat wire common mode choke being inductor core saturation. Core saturation is due to SQ common-mode choke owning the smaller core cross-sectional area and larger leakage inductance compared to toroidal common mode choke, and compared to TVs and other black household appliances, inverter refrigerators have larger peak operating currents and larger inverter carrier leakage. Therefore, the SQ flat wire common mode choke is prone to saturation and failure under the combined action of common mode current and differential mode current. The method of increasing the magnetic core area and reducing the number of winding turns is proposed to reduce the magnetic density in magnetic core, can avoid the saturation failure of the magnetic core, so that the SQ flat wire common mode choke can be used in inverter refrigerator products.

The water temperature often fluting up and down is the gas water heater user pain point. Due to the shower switched off ,the burner stop to work, but there are still cold water keep inner pipe not to be heated, so if the shower switched on again, beginning is hot water, then the cold water follow out. So how to control the outlet water temperature is the core issue. There some research updated the control algorithm software to get better result, utilize the before feedback and after feedback method, perfect the temperature in advanced. By referring to the TRIZ solution, try the structural hardware solutions, try to solve it from the two aspects: ①Object field (add inner recycling pipe) method; ②Solution to technical conflict (add the water pot), set up the solution model and try to test them one by one or combine two of them together. After many times test and date analysis, evaluate both the cost and result, choose the water pot and inner recycle solution. It can efficiency reduce the temperature vibrating and shorten the recovery time.

Saudi Arabia has proposed a new standard for air conditioning energy efficiency, SASO 2663-2021. Saudi Arabia has set new technical requirements for air conditioners coming into its market. By introducing the relevant content, including air conditioning energy efficiency standards, energy efficiency testing methods, the impact of the new standards on air conditioning energy efficiency and the influence factors of SEER of fixed and variable air conditioners. It is compared with the standard ISO 16358-1:2013/A1:2019, and then the reader will have a more comprehensive understanding of Market access for air conditioning in Saudi Arabia, which provides a reference for the relevant air conditioning design and development personnel.

The thermocouple is a low-cost, sturdy and durable temperature sensor. In the comprehensive testing equipment part of the temperature measurement that does not require high test accuracy, thermocouples are usually used as sensors. Thermocouples are usually combined with extension cords and display instruments to form a set of measurement systems. In order to reduce the cost and cabinet installation design, sometimes it is necessary to introduce a relay to achieve the purpose of separate measurement. The addition of electrical components to the measurement system will affect the measurement accuracy and uncertainty. Analyze the principle of thermocouple temperature measurement and the working principle of relay structure. Analyze the influence of adding an electromagnetic relay in the thermocouple measurement system on the design of the signal conditioning circuit, and verify the influence of different circuit designs on the uncertainty of the measurement system through experiments, and give a set of suitable circuit design schemes. The test results show that there are two schemes: no relay connection in the measurement system and 1 relay normally open contact in the measurement system, and the measurement uncertainty is U<1℃. This research provides reference for the design of the subsequent thermocouple measurement system.