The sales of fresh air conditioners are increased year by year with the the development of urbanization and the demand of comfort health and aesthetics. It has attracted more and more attention from consumers of the fresh air volume and the fresh air noise, and it has become increasingly prominent of the troubles caused by fresh air aerodynamic analysic. Therefore, in order to improve the aerodynamic performance and noise value of multi-blade centrifugal fans, the research conducted a full-parameter optimization design of a single arc blade based on a combination of CFD numerical simulation and experiments. It is used by the response surface design method to perform parameterized design on the blade's inlet installation angle βb₁, outlet installation angle βb₂, blade inner diameter D₂, and blade number Z. The relationship between blade parameters, air volume and power were obtained after multiple sets of scheme calculations. The results show that by adjusting the impeller parameters, the flow field distribution in the blade flow channel is improved, the work capacity of the blade is effectively improved and the fan noise performance is reduced. Compared with the prototype, the measured noise at the same air volume is reduced by 0.8 dB(A) and the power is reduced by 11.8%.

In order to explore the optimization direction of using R290 as a substitute for R32 in residential split air conditioners, conducted comparative analysis, including thermal property analysis, thermodynamic cycle calculation, and testing analysis of the two refrigerants on the same platform. The results of the system cycle calculations showed that the theoretical Carnot cycle performance of R290 is superior to R32. The results of the whole machine testing show that the rated refrigeration energy efficiency ratio of R290 decreased by 16.8%, and the rated heating energy efficiency ratio decreased by 5.6%. The main reason for the decrease in the overall efficiency of the R290 system is the poor stability of the saturation temperature of R290 with pressure fluctuations. Therefore, reducing the pressure loss on the low-pressure side becomes the key direction to improve the efficiency of the R290 system.

As the ambient temperature rises, the cooling capacity requirement of air conditioner is also gradually increase. The inner chip will not be dissipated well and damaged due to the high power of inverter module. Reducing compressor frequency is command method to ensure the safety of the inverter module, but the disadvantage of this method is that the higher the temperature, the worse the cooling capacity. In order to solve this weakness, a bionic tree-shaped phase change unidirectional cycle heat transfer method is proposed and this type heat sink is developed. Through the enthalpy laboratory tests, when the ambient temperature is 62℃, the temperature of the inverter power module can be reduced more than 8℃ which will avoid the cooling capacity attenuation due to the forced frequency reduction of compressor.

The axial flow fan, distinguished by its high efficiency and substantial flow rate, emerges as a viable selection for indoor air conditioning applications. Nonetheless, certain categories of axial flow fans could potentially exhibit issues related to noise levels and sound quality during operation. To mitigate these concerns, the employment of a fluid-structure interaction simulation was necessitated for the analysis of stress and deformation in the axial flow fan. The findings revealed a requisite optimization of the blade tip's cross-section, particularly those with significant deformation. Subsequent results indicated that the novel design of the axial flow fan, incorporating reinforced components, substantially diminished the deformation at the blade tip. This effectively led to a reduction in the noise level and the Overall Level difference of the axial flow fan, thereby enhancing its operational efficiency.

As a natural working medium, R290 has become important alternative refrigerant in the field of room conditioning due to its good environmental performance. Compared the thermal performance of R290 and R32, and verified the ability and energy efficiency of two variable frequency air conditioners with the same configuration of heat exchangers by experimental comparison. The results show that when the charging amount of R290 is only 54% of R32, the R290 air conditioner can achieve the same ability and the same level of energy efficiency with R32 air conditioner by debugging. Proved R290 refrigerant can be a good substitute for R32 refrigerant.

As an important device in frequency converter, the life of electrolytic capacitor directly determines the service life of air conditioning. Ripple current of electrolytic capacitor is also the key parameter that affects its life. The feed-forward control of compressor current is carried out by ripple suppression technology, which can reduce ripple current of electrolytic capacitor and prolong the service life of capacitor. Firstly, the mathematical model of the control system is established, and the stability of the system is analyzed according to the Bode diagram to determine the control parameters; The mathematical model of feedforward system is established and the influence of feedforward control on the stability of the system is analyzed. Secondly, the feasibility of the control scheme and algorithm is confirmed by simulation, and the robustness of the control loop is guaranteed. Finally, the experimental results show that the ripple current of electrolytic capacitor decreases by 13.6% after increasing the control strategy, which can effectively prolong the service life of the electrolytic capacitor. The results show that the control technology can meet the requirements of limit test and the control strategy is safe and reliable.

Portable air conditioners (PACs) hold significant market potential due to their high flexibility and exceptional localized cooling capabilities. To address the issue of water shutdown in high-humidity environments, water-wheels can be installed at the bottom of the condenser of the PAC. Investigated the impact of different water-wheel positions on the performance of PAC under high-humidity environments. The results showed that the position of the water wheel had a great influence on the performance of the PAC. Among the four water wheels at different positions, the better the effect of the water wheel that could drive condensate into the high temperature area of the condenser, the higher the PAC’s EER, the strongest condensate removal ability. With the enhancement of the water splash effect of the water wheel, the evaporation pressure and condensation pressure of the PAC both decreased and the cooling capacity increased. Because the condensation pressure dropped more significantly than evaporation pressure, the input power got a decrease. What’s more, the higher the relative humidity of indoor air, the lower the sensible heat ratio of the PAC.

In recent years, the demand for AC (Air conditioner) with ventilation system in the market has gradually increased, but the high manufacturing cost has limited its widespread use. In order to reduce the cost of AC with ventilation system, a new design scheme is proposed, in which ventilation system unit share a motor with AC. Theoretical analysis and experiment are conducted on the wheel diameter, revolution, power, air volume and noise of the ventilation system. The results show that the scheme has obvious cost advantage, little effect on Annual Performance Factor (APF), and the air volume of ventilation system is 20 m³/ h, so the scheme is highly potential.

The low-frequency noise problem is a very common type of complaint in the refrigerator market. The main cause of this problem is the resonance between the compressor and the refrigerator base. The excitation source of this resonance is mostly the unbalanced inertia force generated during the operation of the compressor. By optimizing the dynamic balance of reciprocating compressors, the unbalanced inertia force during operation can be significantly reduced, thereby improving the low-frequency noise of the refrigerator system. Based on a certain fixed-frequency reciprocating compressor, simplifies its crank-connecting rod-piston system into a crank-connecting rod mechanism, conducts dynamic analysis of the mechanism, derives the theoretical formula of unbalanced inertia force, and explains the inertia force characteristics in the reciprocating direction and the nameplate direction. Based on the theoretical formula of unbalanced inertia force, a dedicated reciprocating compressor dynamic balance design software is developed. The software can calculate the reciprocating inertia force curve of different balancing schemes and calculate the optimal balancing mass. For this software, propose a dimensionless factor method to benchmark the calculated values with experimental values, and the results show that the error level between the two meets the requirements of engineering applications.

Due to the structural of the integration cooking appliances, steam oven modular’s tank is often flat and long, resulting in poor temperature uniformity, which is more obvious when the baking tray is used as the food carrier. The internal temperature of the steaming oven module is simulated by using the grill and the baking pan as the food carrier, and it is found that the internal temperature field of the steaming oven module is poor when the baking pan is used as the food carrier. Through the optimization of fan speed and baking pan structure, it is found that when the rotation speed of the circulating fan is increased from 800 r/min to 1500 r/min, and 10 through-hole schemes with a total area of 2606.27 mm² are added to the handles on both sides of the baking pan, the temperature uniformity of the baking pan is increased from 23.3℃ to 5.3℃. The results of this study provide theoretical value and data basis for the subsequent technical research and new product development of steamed and baked products.

The safety of flammable refrigerant air conditioners is a key concern in the industry, and one of the urgent issues to be solved for the safety of air conditioners using flammable refrigerants is how to design potential ignition sources as non-ignition sources to ensure that there is no risk of ignition in the event of flammable refrigerant leakage. IEC 60335-2-40:2022 provides the conditions for potential ignition sources in flammable refrigerant air conditioners to be considered as non-ignition sources by listing, summarizing, and analyze and interpret these conditions using methods such as analysis, and provide validation test methods to facilitate the industry to better understand and digest standards, and design flammable refrigerant air conditioning products that meet the requirements based on the standards

In order to improve the simulation precision of nonlinear materials, focuses on the Mooney-Rivlin model constants, aiming to compare the simulation accuracy obtained by defining nonlinear materials using engineering stress data and real stress data. Firstly, make a standard tensile spline, conduct tensile tests on the spline, and obtain the deformation tension curve of the spline. Secondly, the experimental data was processed to obtain the engineering stress-strain curve and the true stress-strain curve of the rubber. Then input the obtained stress-strain curve into ANSYS for curve fitting, and obtain the two parameter Mooney-Rivlin model constants C10 and C01. Finally, a nonlinear simulation analysis is conducted to compare the stress-strain curve obtained from the simulation with the test results to verify the accuracy of the model. The research results show that the fitting results obtained by using the real stress-strain curve are more in line with the actual situation, can guide the definition and simulation of subsequent nonlinear models.

At present, the high-frequency noise problem of refrigerator compressor is prominent, and the poor hearing of high-frequency noise is easy to cause user complaints. It is urgent to identify the high-frequency noise problem of refrigerator compressor and optimize it. In view of the high-frequency noise problems that are easy to occur in the current refrigerator compressor, takes a certain type of fixed-speed compressor as an example to study the noise source and transmission path. The high-frequency noise problems such as 2500 Hz, 4000 Hz and 5000 Hz of a certain type of fixed-speed compressor are deeply analyzed and optimized. The test results show that the optimization scheme can significantly improve the high-frequency noise problem, which provides relevant ideas and theoretical basis for the improvement of the high-frequency noise problem of the refrigerator compressor, and has certain guiding significance for the subsequent product design.

Noise research and control has gradually become one of the key factors in the development of large rotor compressor with displacement over 7 HP. Different types of noise excitation sources in rotor compressors are analyzed, of which the main factors are improved and validated by experiments. For large displacement rotor compressor with high load, the crankshaft system stability optimization is very important. 3D model of the compressor is established for CAE simulation. Optimization is done on thickness of the cylinder head ring slot to achieve the contact pressure between the cylinder head and crankshaft reduction by 2% and the crankshaft deformation reduction by 1%. This significantly improves the shaft system stability during operation. Experiments also show a very positive effect on noise improvement with overall 6 dB improvement on OA value.

The suction muffler of reciprocating compressor has a great influence on the noise and performance of the compressor. Therefore, a three-dimensional sound field model and internal flow field model of the suction muffler are established. The acoustic finite element model and FW-H aeroacoustics model are used to calculate its acoustic characteristics respectively. At the same time, the outlet flow of the muffler is monitored based on fluid mechanics transient calculation. The optimal scheme of the suction muffler of a reciprocating compressor is established by using the multi-physical field numerical analysis method and the simulation results are verified by experimental tests finally. The results show that the measured noise of the optimized scheme is better in the 400 Hz~1250 Hz and 2500 Hz~6300 Hz frequency bands, the maximum optimized amplitude is 4 dB(A) and the total noise is reduced by 2 dB(A). The performance test results are also greatly improved compared with the original scheme, the cooling capacity is increased by 7.8 W (about 5%) and the COP is increased by 0.021, which effectively verifies the accuracy of the sound power level, aerodynamic noise and CFD numerical analysis model of the suction muffler. Therefore, the comprehensive analysis method can better guide the forward design and optimization of the suction muffler.

In the field of home appliances, reducing carbon emissions and improving the energy efficiency level of products have been the development trend in recent years. Dishwasher products are mainly heated by electric heating due to the requirements of washing temperature and drying dishes, and the energy consumption value is high. Based on the working characteristics of a platform electric dishwasher product, a one-dimensional thermal simulation model is established and the heat transfer process and energy distribution in the washing cycle are described, and the total energy consumption prediction error is less than 4%, and the characteristic parameter characterizing the degree of dishwashing from the perspective of heat absorption of tableware—washing factor is proposed. The energy consumption of the dishwasher is further optimized according to the NLPQL optimization algorithm, and it is found that the energy consumption can be reduced by 6% with the same washing level, and the findings are of reference value for balancing energy consumption and washing efficiency in dishwasher product design.

In the integrated steaming and baking machine, traditional methods such as steaming or baking were often used to thaw food, which not only takes a long time but also leads to uneven thawing of food. Therefore, the combination of steaming and baking thawing method, which is different from traditional methods, was used to thaw pork mince. At the same time, the influence of traditional steaming or baking thawing methods on the thawing rate and over ripening rate of pork mince was compared. Then, standard and non-standard ingredients, as well as multiple machine models, were used to verify and determine the optimal steaming and baking combination thawing method. The results showed that 60℃+medium humidity and 50℃ nutrient steaming could be the best way to thaw minced pork. The standard ingredients, non-standard ingredients and a variety of machine validation results showed that 60℃+medium humidity thawing conditions had the strongest compatibility and were suitable for thawing a variety of food ingredients.

The process of using a range hood to remove indoor oil smoke and gas particle mixtures is mainly divided into three stages: collecting oil smoke, sucking oil smoke, and discharging oil smoke. The ability to collect oil smoke is the primary guarantee for the smoke exhaust effect of the range hood. Research has found that the heat generated by the stove during the heating process forms a temperature gradient between the stove head and the smoke exhaust port of the range hood. The temperature gradient oil smoke particles generate upward thermal buoyancy, and under the effect of thermal buoyancy, the speed at which the mixture of oil smoke particles rises and diffuses also varies. Analyze from two dimensions: simulation and real machine testing, due to the different heating principles and heat conduction methods of gas stoves and electromagnetic stoves, using gas stoves and electromagnetic stoves separately to verify the impact of different temperature gradients on the smoking effect of range hoods. Analysis found that gas stoves increase the diffusion speed of the mixture of oil smoke and particles by about 2 times compared to electromagnetic stoves, and the capture rate of oil smoke decreases by about 12%. By using temperature as a judgment criterion, the smoking effect can be ensured without increasing energy consumption.

Aimto enhance the operability of the testing methods from the standard and improve the traceability of the testing record in inspection process, studying the testing methods of some testing items in the standard GB 4706.1—2005 Household and similar electrical appliances-Safety-Part 1: General requirements, IEC 60335-1 standard and relevant CTL resolutions. Investigate the standard clauses, pretreatment, operational procedures, precautions and used cases of the testing items in different cases from the household electrical appliance testing original records written by different inspectors. Taking the symbol wiping test and the power cord tension torque test as examples, and analyzes in depth the influencing factors and solutions of personnel, equipment, material, method, environment, and other aspects from the perspective of quality control. It also summarizes the traceability control methods that can be applied to the testing process of household appliances.