With the higher requirements of the majority of users for the comfort of air conditioning, the noise problem of air conditioning outdoor unit has become increasingly concerned, and the research on noise problem is also the key to improving the performance index of air conditioning. Therefore, with the goal of reducing the operating noise value of the axial fan of the air conditioner, from the point of weakening the vortex of the blade tip and the leakage vortex of the blade top on the surface of the fan, on the basis of the existing axial fan, combined with the shape of the wings in the biological world, a sawtooth bionic fan structure with blade top was designed, and the original and bionic fans were simulated by using the STAR-CCM simulation tool. The simulation results show that the broadband noise of the bionic fan is reduced by about 2~4 dB(A) compared with the original model, and the noise reduction mechanism of the gradual bionic sawtooth at the top of the blade is revealed in multiple dimensions. The analysis shows that the designed biomimetic structure effectively changes the strength and development trajectory of the blade tip vortex and the blade tip leakage vortex and has a positive impact on the noise reduction of axial fans.

The refrigerator compressor is one of the most important components in the refrigerator cooling system, and it is also the main source of noise in the refrigerator system. To improve the noise problem of the refrigerator system, both the compressor itself and the refrigerator system need to be optimized. Therefore, it is especially important to study the transmission path of the refrigerator system. In order to seek methods to reduce compressor noise and optimize compressor structure design, it is necessary to analyze the two important transmission paths of noise in the refrigerator system, structural and air transmission paths. The matching relationship between the compressor and refrigerator system, as well as the formation mechanism and control methods of the two propagation paths, were investigated to support the subsequent optimization and improvement of refrigerator system noise. Through TPA transmission path analysis, the noise contributions of the five paths were investigated, and the evaluation results of the contribution of each transmission path were ranked.

The popularity of range hood in the domestic market is getting higher and higher, and customers' standards for the selection and purchase of range hood are also gradually improved. The pursuit of product quality is not limited to high suction, more and more users pay more attention to the sound quality experience of range hood. The sound quality optimization of range hood has become a new track to improve the competitiveness of products. Analyzed a range hood with typical "abnormal noise" problem, and the "abnormal noise" hearing is quantified by the psychoacoustic parameter "noise adjustment ratio". The structure of the machine is optimized by sound radiation test, structural modal test and structural modal simulation, and the abnormal noise is eliminated successfully.

In order to improve the user's negative experience of high noise and poor listening sensation in the operation of range hoods, a working noise test room was established in combination with relevant industry standards, and a pressure adjustable back pressure system was added to simulate the actual usage conditions of users. Taking the sound quality of the actual working state of the range hood as the research object, multiple linear regression was used to fit the psychological acoustic parameters of the noise sample with the subjective evaluation results, and an objective evaluation model for the sound quality of the range hood considering working back pressure was obtained. The sound quality evaluation model can effectively capture the abnormal resonance noise generated by AC motors, improving the evaluation accuracy by 17%, and ultimately achieving an objective evaluation accuracy of 94.6%. In the early stage of product development, the sound quality level of the range hood during operation was used as a key indicator to measure the quality of the product, which improved the ability of R&D, quality, and production chains to identify abnormal noise, unified evaluation standards, and improved the level of quality control.

In response to the eddy current noise problem in a certain type of horizontal refrigeration cabinet compressor chamber, analyzes the composition of the compressor chamber sound source, the mechanism of eddy current noise generation, and fluid and acoustic simulation to obtain the source of eddy current noise in the horizontal refrigeration cabinet compressor chamber, and further improves and optimizes the overall machine noise. The results indicate that: (1) The vortex noise of the horizontal freezer is caused by the axial flow fan in the compressor chamber, and amplified through the compressor chamber. (2) Eddy current noise is related to the effective ventilation area of the inlet and outlet of the compressor chamber. Experiments have shown that by increasing the inlet by 30% and reducing the outlet area by 10%, the overall noise is reduced by 3.0 dB(A).

An energy-efficient control method for air conditioners based on adaptive network constraints and Q-learning is proposed to reduce the high energy consumption of air conditioners under traditional integral differential control. First, the reward matrix is constructed by using the expert system and the Reward function, and the air conditioner operating parameters corresponding to its elements are divided into data sets A and B. Next, the Radial Basis Function (RBF) neural network model is initialized, the constructed network is trained using dataset A as training data, and the network constraint model is validated using dataset B until the accuracy rate reaches more than 90%. Finally, the network constraint model is combined with the Q-learning algorithm to realize the optimal strategy selection for air conditioning energy saving. Experiments show that the algorithm is able to achieve energy saving effect compared to traditional air conditioning control logic without sacrificing user comfort.

In order to reduce labor costs, while improving production efficiency and increasing output, in the refrigerator compressor industry, the requirements for intelligent manufacturing are getting higher and higher. Takes a certain type of compressor as an object, analyzes its bracket deformation during the bending and calibrating process in intelligent manufacturing, and considers the whole process as a quasi-static system according to the actual load. According to the actual loading of the bracket, the whole process is regarded as a quasi-static system. Based on ANSYS Workbench software to establish the finite element model of each process, calculate the stress and deformation results of the bracket. Then targeted improvement programs are proposed. In addition, the evaluation criterion of the stress result of the bracket is also established, and the concepts of stress coefficient S and maximum stress σ_MAX are introduced, so as to evaluate the risk of load and deformation of the optimization scheme in various different processes and give a definite conclusion. At the same time, mold processing was carried out for the improvement plan, and online verification was carried out, effectively improving the deformation problem of the base.

With the rapid expansion of new refrigerants and new fields, and the increasingly stringent customer conditions, the reliability requirements of rotary compressors are getting higher and higher, but there is no mature wear prediction method for friction pairs in the industry. Aiming at a R290 heat pump compressor, taking the friction pair of vane-blade groove as an example, starting with the basic models of boundary lubrication, mixed lubrication and fluid lubrication, integrating the influencing factors such as load, oil-refrigerant mixture properties and speed during the operation of the compressor, the classical Archard model is adopted. A theoretical model for predicting the wear of the friction pair of the rotary compressor is established, and the simulation results are consistent with the wear data after the long-term reliability test; The establishment of the method is helpful for the rapid reliability prediction of the rotary compressor and the improvement of the development speed.

Wet weather is a weather phenomenon characterized by high humidity levels that can affect people's lives and health. Weather forecasts do not directly report on wet weather, which makes it difficult for people to prevent it. The scarcity of data on wet weather in the research field also poses a challenge to its prediction. Constructed, an artificial dataset for predicting wet weather and a wet weather prediction algorithm based on a hybrid expert system was proposed, which can predict wet weather for the next 24 hours. Based on the prediction results, a wet weather scene mode was designed to proactively send warning messages to users and recommend that they activate the autonomous intelligent humidity control mode to actively regulate indoor air. The test results show that this technology can effectively predict wet weather and provide intelligent humidity control strategies based on the prediction results, improving users' living comfort and health.

A specific model of air source heat pump air conditioner, after operating in low ambient temperatures from 0℃ to -20℃ in the north for 2 to 5 heating seasons, test shows there is a problem of condenser branch pipe leakage. After investigation, it was found that the contact between the condenser branch pipe and the condenser tube plate was worn, resulting in refrigerant leakage. Siemens vibration testing equipment was used to collect vibration data of heat pump air conditioners with refrigerant leakage. Combined with finite element analysis, it was found that the cause of condenser branch pipe wear and leakage was the vibration impact generated during the four-way valve switching under the defrosting condition of the heat pump air conditioner. It was transmitted to the condenser branch pipe through the copper pipe, and relative vibration was generated at the interference fit of the flipping hole between the condenser branch pipe and the condenser tube plate. In cold winter conditions, the rate of frost formation in the condenser is fast, and the heat pump air conditioning frequently enters the defrosting condition. The frequent switching of the four-way valve accelerates the wear of the condenser branch pipe, ultimately leading to leakage. A new vibration damping rubber block was designed to address this issue. The rubber block was installed at the position where the amplitude of the gas collection pipe and condenser branch pipe was the highest, reducing the vibration caused by the impact of the four-way valve on the branch pipe. After experimental testing, the amplitude was reduced by more than 50%. Before the rectification, there were 767 after-sales cases caused by condenser branch pipe leakage in the previous heating season, with a direct loss of 900500 yuan. After the rectification the following year, there were 58 after-sales cases caused by condenser branch pipe leakage in the same heating season, the direct loss amount is 66400 yuan, and the reduction in after-sales cases after rectification is about 92%.

The feasibility of aluminum capillary tubes replacing copper capillary in refrigerator system has been discussed from processing technology, product performance and application difficulties and measures. The results show that aluminum capillary tubes are feasible in forming process, the mechanical properties, pressure resistance, corrosion resistance and bending properties of aluminum capillary tubes can meet the needs of return pipe components. Compared with copper capillary tubes, the average daily power consumption of the refrigerator with aluminum capillary tubes increased by 10.20%. The average daily power consumption of refrigerators using fluted aluminum return pipe assemblies with aluminum capillaries increased by 1.113%.

In the low-temperature heating capacity experiment of the production verification test (PVT) phase of a certain household air-conditioning outdoor unit project, the frequency reduction phenomenon because of high exhaust temperature caused by the expansion valve flux deviation at the same opening value occurred. Combing linear regression analysis with air conditioner experiments, when the expansion valve with the current flow control level was tested on the whole machine, the lower limit of the initial opening without exhaust frequency reduction was 150 B. However, because the system parameters were set at 140 B, the exhaust temperature was too high during the open-loop stage and frequency reduction occurred. The flow deviation of the expansion valve is the main reason for the occurrence of frequency reduction. To solve this problem, an optimization plan was proposed for the manufacturer to screen the lower limit of flow rate and increase the system expansion valve opening setting to 160 B. The peak exhaust temperature dropped by 17.3%, and there was a margin of more than 3℃ from the frequency reduction temperature. It has been fully verified by experiments that this solution can effectively solve the problem of exhaust frequency reduction under low-temperature heating conditions.

The bended separating plate channel has certain advantages for oil fume filtration in range hoods, but its oil filtration characteristics and aerodynamic performance have not yet been explored. Based on the basic principles of aerodynamics, the bended separating plate channel was redesigned, and its oil filtration characteristics and aerodynamic performance with different channel widths were studied using computational fluid dynamics methods combined with a multiphase model. The results show that the bending channel has a good filtering effect on larger oil particles, but the capture rate is not high for oil particles with a diameter less than 5 μm; with the channel width decreases, the oil fume filtration performance further enhances, but the pressure drop (flow resistance) first decreases and then increases. By improving the channel structure through adding pressure balancing holes, the oil fume filtration performance was effectively enhanced, but it also led to an increase in the pressure drop.

Under low-temperature operating conditions, frost layer is easy to appear on the evaporator coil surface of the refrigerated dehumidifier, thus its dehumidification performance is deteriorated. In order to improve the dehumidification performance of the refrigerated dehumidifier under low-temperature conditions, a variable-frequency dehumidifier performance test system was builded. The effect of the electronic expansion valve opening on the operating parameters, dehumidification performance, and frost phenomenon of the dehumidification system was experimentally investigated under low-temperature operating conditions with different combinations of compressor frequency and fan speed. The following conclusions were drawn: the increase in the electronic expansion valve opening can increase the evaporating temperature, so that the lowest temperature point of the evaporator is postponed to the second half of the process, and the frost layer appears first in areas with sparse condensate distribution, alleviating the frost phenomenon and improving the dehumidification performance. When the evaporating temperature reaches near -4℃, the frost covering rate is close to 100%, and the evaporator coil surface is seriously frosted, at the same time the suction pressure is abnormally lowered to 0.2 MPa. The experimental results shows, the evaporating temperature of -4℃ and the suction pressure of 0.2 MPa can be used as a general criterion for the start of defrosting. The research results can provide optimization direction and reference basis for the dehumidification performance enhancement of refrigerated dehumidifier under low-temperature operating conditions.

There is a "breathing effect" in the refrigerating operation of refrigerator, and the air between the inside and outside of the refrigerator will exchange heat and mass with the "breathing effect". Through the method of pressure difference experiment, studies the influence of the switch of fan, damper and compressor and the change of refrigerator penetration state on the formation mechanism of differential pressure during the refrigeration process of single-cycle frost-free refrigerator. It has been proved that by closing the frost drain pipe, the way of the outside high temperature and high humidity air entering the refrigerator can be changed, the air intake volume of the refrigerator can be increased, and the path of the outside air entering the refrigerator can be extended, so as to improve the relative humidity of the refrigerator room, which is beneficial to the freshness preservation of vegetables and fruits, and at the same time, energy saving and emission reduction.

Automatic ice making and water dispensing functions have become important features of high-end household refrigerators. In overseas markets, primarily in Europe and America, products equipped with ice and water systems account for a significant proportion of their refrigerator products. In recent years, the refrigerators with ice and water function has become increasingly popular in domestic and foreign markets, and various refrigerator manufacturers have also increased their investment in the development of ice water function. However, there is still lack of related industry standards, especially in terms of user experience. To solve this problem, this study summarizes the various factors that affect the user experience of refrigerators with door-mounted ice and water dispensing functions, such as ice dispensing speed, water dispensing speed, ice splashing amount, water dispensing temperature, and water dripping amount. And proposes detailed experimental methods and criteria for various performance parameters. This solution fills the gap in the current industry in terms of experimental and evaluative standard for the user experience of ice and water functions. It has certain reference significance for the research on automatic ice making and water systems in refrigerators.

In order to improve the simulation precision of nonlinear materials, the simulation accuracy of different constitutive models of rubber was studied, and compares the errors of using Neo-Hookean model, Mooney-Rivlin model, Yeoh model, Ogden model, Polynomial model, and Arruda-Boyce model to define materials for simulation. Firstly, conduct axial compression tests on standard compression specimens to obtain stress-strain data under axial compression. Secondly, input the data into the simulation software, use different constitutive models for data fitting, obtain model parameters, and define rubber materials. Then simulate the compression test and compare the obtained stress-strain results with the experimental data to obtain the accuracy of each model. Finally, simulation was conducted on the outdoor chassis foot pad of the air conditioner, and the most suitable constitutive model for defining the foot pad was selected. The results show that using Mooney-Rivlin two parameter model to define rubber materials for simulation has a minimum error of 3.2% compared to the test results, providing accuracy assurance for subsequent nonlinear simulation.

Starting from the perspective of the solubility characteristics of refrigerants and oil, compares and studies the differences in oil surface changes during low-temperature heating start-up under different solubility characteristics conditions, and analyzes the changes in the solubility of refrigerants in oil during low-temperature heating start-up, and a solution for the low-temperature start characteristics of oil was proposed. During the low-temperature start-up process, oil with a slow increase in refrigerant solubility with temperature (insoluble oil) show a decrease of about 17% in refrigerant solubility. The time for the oil temperature to rise to stability is about 600 seconds, indicating a more stable oil level. Oil with a steep increase in refrigerant solubility with temperature (soluble oil) show a decrease of about 34% in refrigerant solubility during low-temperature start-up, and the time for oil temperature to rise to stability is about 300 seconds. Compared with slow rise oil, the solubility change is greater, the oil temperature rises faster, and the refrigerant quickly separates from the oil due to the decrease in solubility, resulting in a phenomenon similar to "flash evaporation". The oil is discharged from the compressor in large quantities with the refrigerant, it may even cause oil shortage on the compressor side. Based on the difference between rapidly increasing and slowly increasing refrigerant solubility oil, a solution for the phenomenon of oil shortage in rapidly increasing refrigerant solubility oil is proposed: reduce the rate of solubility change and the rate of oil temperature rise, thereby avoiding the refrigerant from evaporating and carrying oil away from the compressor.

At present, the exhaust holes in the internal cavity of the common integrated stove oven on the market are set near the bottom of cavity, lower than the exhaust holes position on the external air intake box. After long-term use, it is easy to cause the sewage reflux from the internal exhaust holes of the steaming and roasting cavity, which seriously affects the customer experience. In order to completely solve this customer pain point, it is necessary to move the internal exhaust hole position of the cavity up and the upper exhaust hole position of the external intake box down to ensure that its position is higher than the intake box exhaust hole position, forming a "high inside and low outside". The steaming and roasting performance of the integrated stove and the cooking effect of the food were compared and tested before and after the change of the exhaust holes position of the integrated stove. The results showed that the steaming and roasting performance of the integrated stove oven became worse on the micro level after the change of the exhaust holes position of the integrated stove, but there was little difference on the cooking effect on the macro level. After the change of the position of the exhaust holes of the independent integrated oven, the microcosmic steaming and roasting performance became better, and there was almost no difference in the macrocosmic cooking effect. Therefore, in order to solve the problem of sewage reflux in the internal cavity of the integrated stove, the position of the exhaust hole can be adjusted.