Noise pollution is one of the problems that need to be solved in today's society. Excessive noise will cause different degrees of harm to people's hearing and non-hearing health. Traditional noise control methods mainly aim at reducing sound energy. However, from the perspective of auditory perception, the ultimate goal of noise reduction is to reduce the negative effects of annoyance. Therefore, another approach to reduce the annoyance, namely Audio Injection Method (AIM). Were proposed compared with the traditional noise control methods, AIM has obvious advantages such as simple implementation and low cost, and has wide application prospects in various fields, especially in the field of home appliances.Summarized the research progress on AIM at home and abroad. First introduces the comprehensive parameters and attribute parameters of product sound quality evaluation. After that, the formation and evaluation of the cancellation effect in AIM are introduced, including the principle and related terms of AIM, the determination method of controllable sounds, experimental method, etc. Finally, the practical cases of AIM in improving the sound quality of outdoor and household appliances are given.

To gain a deep understanding of the emission mechanism of kitchen fume particles and to achieve precise control, it is essential to quantitatively characterize the emission process of the kitchen fume particles. Therefore, a review of the methods for testing the emission rates of kitchen fume particles is presented. The common principles and methods of quantitative testing of particle emission rates are systematically reviewed first. Then, the necessity of new test methods for measuring the dynamic emission rate is elucidated. Finally, the example of particle mass emissions is used to illustrate the new testing method of the dynamic particle emission rate. The results show that the traditional test method has limitations, such as difficulty in controlling test conditions and producing accurate and consistent results. On the basis of addressing the above issues, the new dynamic test method can also realize the real-time test of kitchen particle emission rate, which is worth further in-depth research and optimization. It is of great significance to analyze and sort out the technological progress of the test methods for the emission rate of kitchen fume particles, to further quantitatively characterize the emission process of kitchen fume particles and clarify its dynamic emission law.

In order to meet people's growing thirst for a better life, intelligent household appliances and smart home technology are developing rapidly. Intelligent household appliances are gradually improving and systematizing along intelligent single products, intelligent scenes, and smart homes. Human-machine-environment systems engineering studies human, machine, and environmental characteristics, and the relationships of human-machine, human-environment, and machine-environment, as well as the totality of human-machine-environment systems. In recent years, artificial intelligence technologies such as large models, generative artificial intelligence, and knowledge graphs have provided strong technical support for the technological upgrading of this round of intelligent household appliances. Combined with the current status of intelligent household appliances, summarized the development history of the technology, products and technology status of intelligent household appliances, and analyzes the future development trend of intelligent household appliances technology in combination with the development of artificial intelligence technology.

The performance improvement of the heat pump dryer needs to take into account the needs of increasing the air volume of the fan and reducing the noise of the fan. However, the increase of the air volume is usually accompanied by the increase of the aerodynamic noise of the fan, which makes it difficult to meet these two needs at the same time. By changing the structural parameters of the fan impeller that affect the air volume and the aerodynamic noise of the fan, the air volume and aerodynamic noise are simulated and analyzed, and the influence law of the structural parameters of the fan impeller on the air volume and noise is found respectively. Based on this law, an optimized fan impeller structure design method that takes into account both air volume increase and noise reduction is proposed. The results show that the most important factors affecting air volume and noise are impeller width and impeller inlet angle. The air volume increases with the increase of impeller width and impeller inlet angle. The noise increases with the increase of impeller width and the decrease of inlet angle. Compared with the original structure, the air volume of the proposed optimized structure increases by 14.2 m³/h, and the noise of the monitoring point decreases by 2.08 dB(A) on average. The optimization design method of fan impeller considering the demand of air volume and noise is proposed, which provides guidance and reference for the design of fan structure with high air volume and low noise in the actual operation of dryer.

Under the background of the dual-carbon strategy, both international and domestic environmental policies and regulations are gradually reducing the quotas of fluorinated refrigerants. Therefore, the research on environmentally friendly refrigerants as substitutes is urgent. Water, as a pure natural working fluid (R718), can achieve nearly zero carbon emissions throughout the entire life cycle of refrigerants. It is an ideal refrigerant from the perspectives of environmental protection and safety, and it also has good refrigeration performance. According to reports, the energy efficiency level of R718 compression cycle refrigeration systems is comparable to that of refrigerants such as R134a and R290. Developed countries such as Denmark, Germany, Japan, and the United States are at the forefront of research and promotion of water vapor compression cycle refrigeration technology. However, China is still in the theoretical research stage, and there have been no reports of practical applications of water vapor compression cycle refrigeration systems in China. With the vigorous development of China's HVAC industry and the continuous restriction of HFC refrigerants, the environmentally friendly, safe, and good-performing R718 refrigerant will have broad development prospects.

With the miniaturization and high-speed development of rotary compressors, the velocity of the fluid within the compressor significantly increases. The high-speed refrigerant is prone to carrying away a large amount of lubricating oil, resulting in a high oil circulation rate. This can lead to decreased energy efficiency and even wear failure due to insufficient lubrication. Conducting numerical simulations to analyze the internal flow field behavior of a compressor with a high oil circulation rate, we found that positioning the outlet on the side of the muffler is the main reason for this phenomenon. Subsequent analysis of different outlet positions of the muffler revealed that a muffler with a top exhaust port can significantly increase the stator edge backflow, experiments confirmed that this design significantly reduces the oil circulation rate. Numerical simulations and experiments have both confirmed the significant effect of the muffler on the oil circulation rate, and optimizing the muffler is an effective method to reduce the oil circulation rate of the compressor.

Regarding how to effectively evaluate the performance of the intelligent toilet odor removal device, three odor removal test schemes are proposed: "cabin odor removal rate", "instantaneous odor removal rate", and "odor clean air volume"; Three odor removal life test schemes: "long term determination of odor removal and purification effect", "pollutant holding capacity", and "accumulated odor purification capacity"; Conduct experimental research on different schemes, including simulating the sensory experience of actual toileting. Experiments have shown that selecting ammonia, hydrogen sulfide, and methyl mercaptan as characteristic pollutants, the three testing methods of "instantaneous odor removal efficiency", "cumulative odor purification amount", and "odor sensory experience" are the best. The difficulty of experimental construction, maturity of analysis methods, and reliability of evaluation methods can better reflect the odor removal effect of the deodorization device.

The quality of milk froth includes aroma, luster, flavor, taste, etc. In order to clarify the relationship between steam performance and the quality of milk froth, the effects of steam performance on the quality of milk froth were investigated by comparing 6 different brands of expresso coffee machines. It was found that the steam performance of espresso coffee machines significantly affected the quality of milk froth. When the foaming time was short, the water content of steam was low, and the precision was low, the quality of milk froth was at a high level. Among 6 espresso coffee machines, the steam performance of foreign brand F was the best. In foreign brand F, the foaming time is 57 s, the water content of steam is 9.50%, and the precision is 1.40. Besides, the milk froth made by foreign brand F had the best quality with 87.08% stability, 46 s milk density, and the highest score in subjective evaluation. In addition, there was no significant difference between domestic brand D and foreign brand F in terms of steam performance and milk froth quality.

The optimal charge amounts of R-410A and R-454B in Air Handler Unit (AHU) were compared through experimental studies, and the differences in various performance parameters under A_full and B_full conditions were analyzed. The feasibility of replacing R-410A with R-454B in AHU was also assessed. The results indicated that the optimal charge amounts for R-410A and R-454B are 3 kg and 3.65 kg, respectively. Compared to R-410A, R-454B showed a capacity reduction of 2.22% and 2.64% under A_full and B_full conditions, respectively, with an EER2 increase of 2.76% and 1.41%. Additionally, the discharge temperature decreased by 3.9 °C and 4.7 °C, the suction temperature decreased by 6.0 °C and 5.2 °C, the condensing pressure decreased by 6.35% and 5.70%, and the evaporating pressure decreased by 2.10% and 2.14% under the same conditions. These results suggest that R-454B can generally meet the capacity and energy efficiency requirements of current R-410A systems. Moreover, R-454B imposes lower high-temperature protection and strength requirements on system components compared to R-410A, indicating that R-454B can be directly used in existing R-410A systems, a reference for the mass transition of refrigerants in AHU was provided.

In the ordinary air fryer on the addition of water spray DC pump and oil spray electromagnetic pump, developed a dual-jet function of the air fryer. The content of vitamin C in cowpeas were determined by fluorescence method after cooking through different cooking medium, the effects of air-frying with water or oil or only air on the cooking effect of cowpeas and their vitamin C were analyzed objectively, to verify the feasibility and effectiveness of the dual-jet functional design. Cowpeas had better cooking effect under air-frying condition with water/oil as medium, and the content and retention rate of vitamin C were higher, the content were (5.19±0.122) mg/100 g and (5.04±0.097) mg/100 g respectively, the retention rates were 29.34%±1.513% and 28.38%±0.985% respectively. The effect of cowpeas cooked under air-frying with only air as medium was poor, the content of vitamin C was only (3.33±0.118) mg/100 g, and the retention rate was only 17.75%±0.992%. This is closely related to the physical and chemical effects of water and oil on food during cooking.

Currently, the indoor unit of the domestic floor standing air conditioner commonly adopts the cylindrical appearance, and the products are constantly developing to miniaturization and high energy efficiency. Focuse on the indoor heat exchanger design of the cylindrical floor standing air conditioner, the L-type structure is used for the heat exchanger, the angle of the heat exchanger is determined by CFD simulation, the Midea Heat Exchanger simulation software is used to select a suitable refrigerant circuitry and finally a heat exchanger sample for overall performance comparison with the prototype machine is produced. Results show that when the angle of L-type heat exchanger is 80°, there is both higher air volume and sufficient heat exchange area to ensure higher heat transfer capacity. Among the different refrigerant circuitry, the circuitry with 6 branches has the highest capacity, and the uniformity of refrigerant distribution and airside temperature distribution are the best. Compared with the prototype, the air volume flow rate of L-type heat exchanger under rated cooling condition increases by 13.4%, and that under rated heating condition increases by 10.8%. The APF of the overall system increases by 0.146.

The mineral materials physical ordered dishwasher uses pure natural mineral materials and processes washing water through physical means to achieve the cleaning effect on tableware. In order to evaluate the effectiveness of this type of dishwasher, a study was conducted on the testing methods of mineral materials physical ordered dishwashers from two aspects: cleaning performance and rinsing performance. The testing method for washing performance has been modified based on the national standard, and the technical requirements for rinsing performance are more stringent. Experimental verification shows that mineral materials physical ordered dishwashers without detergent have similar cleaning effects compared to regular dishwashers with detergent, and there is no residue of anionic surfactants in their drainage and tableware surfaces. The research on mineral materials physical ordered dishwasher inspection methods will provide technical support for the development of new dishwashers, and help regulate market behavior, protect the legitimate rights and interests of dishwasher manufacturing enterprises and consumers.

With the increasing popularity of water purifier and people's attention to drinking water safety, the microbiological safety out of water purifier has become one of the problems which must be solved. Usually, RO water purifiers can effectively remove bacteria. However, there is a potential safety risk of microbial breeding in the pipeline after pure water coming out of membrane to nozzle. To solve this problem, proposes a step-by-step hot water sterilization technology for cold boiled water system of commercial water purifiers made for school. By heating, insulation, heating, and cooling the drinking water pipeline, using relatively less hot water to extend the time of effective sterilization temperature. At the same time, the structure of the outlet solenoid valve is optimized to solve the sterilization blind spots. Through testing and verification, the outlet bacterial colony can be controlled below 5 CFU/100 mL all day, effectively solving the problem of excessive outlet bacterial colonies and ensuring the safety.

Unlike household scenarios, the vehicle refrigerator compressor operating in a mobile environment can cause a deterioration in oil discharge, which can have adverse effects on the system. A study was conducted on the effect of a muffler on the oil discharge volume, as the refrigerant oil enters the cylinder through the muffler during inclined operation of the compressor. The oil volume with 65 mL is firstly determined as the research object to study the influence of the muffler on the oil discharge for vehicle refrigerator compressor. Based on the experimental analysis of horizontal and inclining at the different structures, the effect and mechanism of the muffler oil leakage hole are further revealed with numerical simulation. The results show that there is negative pressure inside the muffler during the suction process, and the oil would be sucked in quickly when the leakage hole touches the oil surface. The maximum oil discharge could reach 25.8 mL/h, and the amount of oil discharge decreases to zero after the leakage hole is removed. Ultimately got the best solution for the oil discharge problem of the vehicle refrigerator compressors wnder study.

In order to achieve the requirement of high volume rate of refrigerators, frequency conversion reciprocating compressors are becoming more and more miniaturized. If the excitation source is not balanced or the vibration isolation measures are improper, it will cause problems such as large vibration of the compressor at low speed. By analyzing the vibration excitation source and transmission path, it is found that the unbalanced force is the main reason for the low-speed jitter of the compressor. It is clear that the components such as the inner exhaust pipe, the seat spring and the foot pad play an important role in the transmission of vibration. The insufficient lateral stiffness of the compressor foot pad can easily lead to large vibration of the compressor at low speed. Through dynamic balance optimization and pad optimization design, the vibration of X, Y and Z directions at low speed meets the customer test standards. At the same time, in the X direction with large amplitude, the vibration at low speed decreases by 31.8%~55.9%. The problem of large vibration of compressor at low speed is successfully solved, and the adaptability of miniaturized frequency conversion compressor to refrigerator system at low speed is improved.

The drop damage of air conditioner products is the key and difficult problem in the development of air conditioners. It is difficult for air conditioner products to successfully pass the drop test at one time, the rectification period is long, and the research and development cost is high. Based on material test research, firstly obtains the real stress-strain curve of air conditioner packaging and plastic materials to provide accurate material parameters for simulation calculation, and then studies the numerical calculation method of drop of air conditioner hanger packaging with the help of computer CAE simulation tools, simulates the drop behavior of the product during transportation, and analyzes the impact deformation of various parts of the product under different drop conditions. Taking a 1.5 P product as an example, the numerical calculation model of air conditioning drop was established, and the simulation theoretical calculation was compared with the test results. The results showed that the theoretical research method could accurately identify the weak points of product packaging and structural design, and the simulation theoretical calculation was basically consistent with the test trend, and the strength optimization of the machine strength drop problem was guided to improve the machine strength reliability. The application of computer simulation technology to the research and development of air conditioning products can greatly shorten the product development cycle, improve product quality, and enhance the competitiveness of enterprises.

The residual moisture inside the air conditioner after cooling creates a high humidity environment, which is the main cause of odor, bacteria, and mold production in the air conditioner. Heat pump drying technology is a necessary means of preventing bacteria and mold inside air conditioners to ensure their healthy use. Based on the innovative design of fresh air conditioning, an internal exhaust system has been developed, which can discharge the water vapor inside the air conditioner to the outside without affecting the user's comfort experience during use. Firstly, it is theoretically analyzed that the moisture content in the air conditioner after drying should be less than or equal to the moisture content before cooling and drying. Then, an orthogonal experiment is designed to determine the main factors affecting the residual water content in the air conditioner. Finally, based on the results of the drying experiment, the calculation formula for the drying rate of the air conditioner unit is inferred. The conclusion is that the air conditioner unit should maintain low humidity (≤ 70%) for a sufficient period of time after drying, with a continuous decreasing trend and a drying rate of ≥ 99%. This serves as the basis for judging the drying of the air conditioner unit and provides technical reference for subsequent research on heat pump air conditioning drying technology.

In the process of developing a 1.5 HP room air conditioner, the refrigerant was changed from R32 to R410A. Under the condensation condition, there were small water droplets on the left side of the air duct of the indoor unit, which formed into large water droplets and drips. The theoretical analysis and experimental verification showed that the same evaporator diverting flow path, using different refrigerant, diverting uniformity was different. In the case of not changing the diverting flow path of the indoor evaporator of the mass production model, the circulation amount of R410A refrigerant in the system can be increased by reducing the target exhaust temperature to increase the opening of the electronic expansion valve during the system operation, and the uniformity of the diverting flow of the indoor evaporator can be improved by reducing the dryness of the evaporator inlet, so as to effectively solve the condensation problem. The research provides a feasible solution for solving similar problems in practical engineering, and plays a certain guiding role for refrigerant change and system optimization in the subsequent development process of cost reduction.

As one of the main components of air conditioner, heat exchangers play an important role in improving energy efficiency. Based on the limitation of performance or manufacturing to Ф 5mm heat exchangers and microchannel heat exchangers used as outdoor unit heat exchangers, a new heat exchanger is proposed to improve the energy efficiency of Variable Refrigerant Flow (VRF) air conditioner. By reducing tube pitch of Ф7 mm copper round tube heat exchangers and thus increasing tubes quantity in each row, the new heat exchanger structure can simultaneously enhance the heat transfer capacity inside the tubes (by increasing the heat transfer area inside the tubes) and the heat transfer capacity outside the tubes (by increasing the maximum air velocity at the narrowest to enhance the air side heat transfer coefficient). Based on simulation and performance testing, a comprehensive analysis and verification were conducted to the new heat exchanger. Compared with the prototype Ф7 mm heat exchanger, simulation shows that at same air flow resistance (13.6 Pa), the air side KA value (which represents heat transfer capacity that equal to the product of heat transfer coefficient K and corresponding heat transfer area A) of the new Ф7 mm heat exchanger is 20.7% higher than that of the prototype Ф7 mm heat exchanger, and the correspond total KA value of the heat exchanger is 12.02% and 9.11% higher, respectively; The performance test results of the VRF air conditioner show that the new heat exchanger has improved energy efficiency by 1.9%, 1.8%, and 1.5% in the standard cooling, the standard heating, and low-temperature heating, respectively.

A new type of skirting wire heater with a fan system was proposed. In response to the pain point of slow room temperature rise caused by existing skirting wire heaters, a scheme was designed to add a fan system to the existing skirting wire heater, and a dedicated room for experimental testing was built and temperature testing points were arranged. Relevant experimental research was conducted to test the effect of the fan system on the temperature rise speed of the skirting wire heater under different air volumes. The results show that in the first 30 minutes, the temperature rise rate is faster for those with higher air volume under the same power. However, after 30 minutes, the temperature rise is relatively stable. From the test curve, it can be seen that under the same operating conditions, the larger the air volume, the faster the temperature rise rate. Therefore, the fan system has a significant impact on the temperature rise rate of the baseboard heater, especially in the first half hour after startup. The fan system can accelerate the distribution of hot air through forced convection, allowing the heat inside the body to dissipate as soon as possible, thereby accelerating the rise speed of room temperature.