Finding out the actual field performance of room air conditioners is of great significance to improve its control strategy and reduce operational energy consumption and cost. Firstly, systematically summarizes the current situation and development of field performance measurement technology, and points out that the compressor energy conservation method (CEC method) is a practical and feasible long-term online performance measurement method that can meet the requirements of non-intrusive, non-interference, and appropriate accuracy. Aiming at the contradiction between the fixed sensor position and the dynamic change of refrigerant state parameters, and the compressor performance degradation and long-term high-precision measurement in the CEC method, the implementation of the "all-condition refrigerant flow method" that based on the dynamic correction of the CEC method is analyzed. The domestic and foreign online performance measurement standards for air conditioners are summarized, and the calibration method of domestic online performance measurement instrument accuracy is mainly introduced. On this basis, the online performance measurement results of air conditioners are given through several typical cases, and the operating characteristics, energy efficiency status and development trend of online performance measurement technology are analyzed.

Energy saving, carbon emission reduction, thermal comfort and health are the inevitable way of the development of room air conditioner. Based on the goal of reducing the climate impact of air conditioner by 80% set by the Global Cooling Prize committee, a 5200 W ultra-efficient air conditioner with smart evaporative cooling ventilation and PV was developed. It is composed of high efficiency gas-injected vapor compression cycle with relay cooling, evaporative cooling fresh air system, photovoltaic system and automatic control system, which take R152a as the refrigerant. The simulated simulation annual power consumption is 585 kW•h in New Delhi, India, which is 80.2% less than the basic prototype with R22 as refrigerant and EER = 3.5. According to the test progress of IS 1391, the tested rating EER is 6.28 and ISEER reach 8.43. Moreover, in the 10-day lab test to simulate year-round performance, the total energy saving reached 82.8%. The results of 31 days field test show that the air conditioner can stably control the indoor temperature and humidity (room temperature ≤ 27 °C, relative humidity ≤ 60%). The calculated comprehensive electricity saving rate is 84.1%, equivalent to 85.7% reduction in climate impact.

Room air conditioners are one of the largest power-consuming devices in residential buildings. With people's pursuit of quality of life, the number and total energy consumption of air conditioners will continue to increase. Therefore, improving the energy efficiency of air conditioners is an important measure to save energy, reduce emissions, and accelerate the construction of ecological civilization. In view of the special climate and users' demand for air-conditioning in the Yangtze River Basin, analyzes the operating characteristics of room air conditioners with independent compression cycle of suction and supplement gas using R32 refrigerant. And obtains the key parameters of air conditioner design, matching and operation control. Aiming at the best energy efficiency, the air conditioner product has been developed. The experimental results show that: Compared with the room air conditioner with single-stage compression, the room air conditioner with independent compression of suction and supplement gas can increase the APF by 6%, increase the cooling (heating) capacity of high temperature and low temperature conditions by 5%, and reduce the exhaust temperature by 2~7℃.

The V-type segmented heat exchanger is commonly used in the second generation of fan coil air conditioner. The uniform distribution of fin shape and enhanced surface makes the heat transfer potential under non-uniform airflow field hardly fulfills. The C-type heat exchanger is designed and Taguchi method is used to optimize the fin surface enhancement in the high and low air velocity region, respectively. Five schemes are selected for simulation comparatively, and condensed water drainage of zones with different bridges are simulated. Optimal scheme is determined and tested experimentally. Results show that the performance reaches the best with 1.4 mm bridge width, 0.6 mm bridge height and 4 bridges in low air velocity region, but 1.2 mm bridge width, 0.6 mm bridge height and 2 bridges in high air velocity region. The heat transfer enhancement of the C-type fin and the airflow field matches accurately with favorable drainage performance, when the fin surface structure is enhanced by segment, upper and lower parts of the fin are arranged asymmetrically, and the tube spacing is unequally designed. Compared with the V-type one, APF is 6.4% higher while the cost is 14.5% lower on average for the optimized C-type heat exchanger.

Parallel flow heat exchanger has the advantages of small size, high heat transfer coefficient and less refrigerant charge in the system. It has a great application prospect in room air conditioner. A parallel flow indoor heat exchanger applied to 5 hp cabinet machine is designed. Through experimental test, the performance of air conditioner with parallel flow heat exchanger and ordinary tube fin heat exchanger is compared and analyzed, and the heating performance of air conditioner with parallel flow heat exchanger is optimized. The results show that compared with the ordinary tube fin heat exchanger, when the parallel flow heat exchanger is used, the refrigerating capacity is increased by 10.2%, but the heating capacity is reduced by 5.7%. After adding a flash evaporator in the system, its heating performance is slightly higher than that of tube fin heat exchanger.

Through the questionnaire survey of 746 residential buildings and the on-site survey of 110 residential buildings, the main installation form of the current air conditioner outdoor unit-the groove with louvers and its characteristic dimensions were found. Based on the research results to restore its usage scenarios, in the air-enthalpy difference laboratory, a large number of comparative tests were carried out on a 1 HP room air conditioner using the refrigeration performance test method of GB/T 7725-2004. The results show that the commonly used louver grooves will cause the cooling energy efficiency ratio of air conditioners to be reduced by 36%, and the ventilation dimensions that affect its performance are the front, left, top, rear, and right spacing in order, and there is an optimal value for the spacing of the louver grille which is related to the inclination direction and angle of the grille. On this basis, the recommended value of the minimum ventilation size of the groove space where the cooling energy efficiency ratio of 1 HP air conditioner attenuation is less than 4% is given.

Two-stage capacity Air conditioner can save more energy by improving SEER, through reducing compressor on/off frequency at low load conditions. By installing a 2-stage capacity compressor in an air conditioner unit, testing the performance and calculating the SEER according to the Indian climate temperature bin hours and ISO 16358-1-2013 standard, concluded that the SEER of the air conditioner unit as 2-stage capacity air conditioner can be improved approximately 15% higher than that of the unit as fixed single capacity air conditioner.

Enhanced vapor injection (EVI) method can effectively improve the heat capacity and high discharge temperature of air source heat pump in low ambient temperature. The control method of electronic expansion valve (EEV) in flash tank EVI heat pump air heater system is experimentally studied. The result shows the EEV before the flash tank can preferably use discharge superheat as its control target parameter, and the EEV after the flash tank can use suction superheat as its control target parameter. In addition, for the very experiment system and the very ambient temperature, the best discharge control value 43℃ and the best suction control value 0℃ is obtained by this experimental study.

Frosting has the most significant impact on the heating capacity and thermal comfort of heat pump air conditioners. Developing dynamic model of air conditioners under frosting condition is an effective solution to optimize control strategy to improve the heating capacity and thermal comfort of heat pumper air conditioners. A dynamic model of air conditioners under frosting condition is established, where the frost accumulation is calculated by the difference of air humidity through heat exchanger based on the heat exchanger surface temperature at first, and then a relation is built between the frost accumulation and air flow rate to couple the frosting and heat and mass transfer in air conditioning system. The experiment validations show that the new dynamic model can predict the attenuation of air flow rates and the attenuation of heating capacities under the frosting condition, where the maximum real-time deviation of air flow rates are less than 5%, and the calculation error of cumulative heat capacities are less than 5%.

In order to study the influence of range hood on the thermal efficiency of domestic gas stove. Through the analysis of experimental data, it's concluded that the thermal efficiency of domestic gas stove decreases with the increase of airflow, and the CO content in flue gas increases slightly, but the change is not significant. With the decrease of the installation height of range hood, the greater impact on the performance of domestic gas stove. CFX is used to simulate the air velocity and heat distribution around the gas stove. The results show that the convection heat transfer between the high-temperature flue gas of the domestic gas stove and the cooking utensils is weakened.

In order to solve the problem that the error between simulated and actual value calculated of range hood in the case of high pipeline pressure based on the FLUENT steady-state algorithm, a decompression cylinder model is proposed to be provided at the outlet of simulation model, and pipeline pressure is added by adjusting the area of outlet. Aerodynamic performance, noise and lampblack exhausting of range hood under high pipeline pressure is studied with focus on the error between simulated and actual value. The research results show that the optimization of simulation model has great corrections to simulation data of range hood under high pipeline pressure. The error of simulated aerodynamic performance is 7%, the error of simulated noise is about 10%, and the simulated lampblack exhausting is corresponding to actual situation. The research results have guiding significance for simulated platform construction and performance optimization of range hood.

The electromagnetic noise generated by AC asynchronous motor will seriously affect the user experience, need to focus on the solution. First of all, through the listening method, frequency spectrum analysis method, the suddenly loses power, audio function analysis of the fault prototype of the two high and one low abnormal noise diagnosis, identify the different sounds for the electromagnetic different sound of 1033 Hz and 400 Hz. Then, through mechanism analysis and theoretical frequency calculation, the noise caused by the harmonic interaction between stator and rotor teeth and the noise caused by the interaction between fundamental magnetic field and power supply harmonics are determined. According to the noise types, the solutions of optimizing the ratio of stator and rotor slots and the i-shaped rubber pad are proposed respectively. Finally, through spectrum analysis and listening test, it is proved that the solution is effective.

Range hoods have now become one of the indispensable household appliances in modern households. By comparing the difference between the national standard and the IEC standard test method for the air volume of range hoods through tests. It is found that due to the limitation of the public flue, the excessive air volume of ordinary residences not only cannot exert a better smoke exhaust effect, but also affects the cooking time. The flow direction of the generated oil fume is disturbed. There are some differences between the national standard and the IEC standard for the test method of the air volume of the range hood. When the range hood products are exported to Europe, it is necessary to pay attention to the difference in the product performance standards, and also provide a reference for the subsequent formulation of the standard test method.

The start-up transient of the air-conditioning constant speed scroll compressor will produce a large starting torque, which will cause a large stress on the piping. Identifying the starting torque of the compressor is of great significance for predicting and reducing piping stress. Firstly, simplify the complicated compressor and piping system into a single degree of freedom torsion model. Secondly, based on the modal test at different positions of the compressor, the compressor torsion transfer function is calculated. Finally, according to Duhamel's integral and load function, the starting torque of the compressor is identified, maximum error 20%, which provides load for subsequent simulation.

According to the standard GB 21455-2019 "Minimum allowable values of the energy efficiency and energy efficiency grades for room air conditioners", the energy efficiency rating index for fixed frequency heat pump type room air conditioners is APF (Annual Performance Factor). In order to improve the test quality, it is particularly important to evaluate the uncertainty of the APF. The air enthalpy method was used to test the performance of the air conditioners, and the calculation, measurement and uncertainty evaluation of APF were analyzed, and the relative expanded uncertainty of APF was 1.96%. Among them, and the uncertainty component introduced by the rated cooling capacity was the largest, accounting for 75.11%. Taking the rated cooling conditions as an example, the measurement parameters that had a greater impact on the rated cooling capacity were the indoor side inlet air bulb temperature and the indoor side outlet rheumatic bulb temperature, and the uncertainty components accounted for 51.99% and 36.42%, respectively.

As the key core component of air conditioner, the efficiency of fan directly affects the energy efficiency of air conditioner. Improving fan efficiency and correct blade design and selection are the key means to improve the energy efficiency of air conditioner. Based on an outdoor enclosure, three-dimensional Navier-Stokes equations and k-ζ turbulence model is adopted to achieve unsteady flow solving to obtain the characteristic data of the blades and the SIMPLE algorithm is selected to solve the pressure-velocity combinations. The working point data of fan is predicted with the help of the motor characteristic curve and the wind resistance curve of air conditioning outdoor unit. The results show that the predicted data coincide with experimental data, the deviation is less than 5%, which can effectively guide the selection and design of fan blade.

The requirement of single-rotor compressor application on floor-standing air conditioner continues to grow. However, the severe vibration of single-rotor compressor always occurs with its inherent attribute, especially at low speed with unsuitable control, and it will aggravate the stress of pipe, so the extensive application is impeded. The scheme of four-way valve pipes and one control method of vibration reduction was designed. After comparing the stress of suction pipe and exhaust pipe with the target stress, the results show that the single-rotor compressor can apply to 2P floor-standing air conditioner. The scheme can provide support to the application research on floor-standing air conditioner with single-rotor compressor.

The air conditioner filter has the function of filtering dust and preventing pollution inside the air conditioner. Dirty filters can easily breed bacteria and affect the health of users. At the same time, the reduced air volume of the air conditioner causes insufficient cooling. When the air conditioner filter is dirty and blocked, the air pressure on both sides will change. Combining the inherent fan characteristic curve and the system resistance curve of the wall-mounted air conditioner cross flow fan, a method for detecting the cleanliness of the air conditioner filter using a differential pressure measurement device is proposed. Analyze the influence of air-conditioning air volume, data sampling time, distance between air-conditioner and ceiling, angle of air-conditioning baffle, position of differential pressure measuring device on the evaporator and other factors on the pressure difference between the two sides of air-conditioning filter, and test and research. The results indicate that the higher the air-conditioning wind speed, the more obvious the pressure difference between the two sides of the filter, and the angle of the air-conditioning baffle and the air outlet position of the differential pressure measuring device will affect the data gradient of the pressure difference on both sides of the air-conditioning filter.

Under extremely cold weather conditions, the starting performance of the motor decreases sharply due to the influence of resistance torque such as fan load and internal lubricating oil, which is very easy to lead to starting failure. This is a difficult problem that restricts the normal operation of air conditioner under low temperature conditions. Through the analysis of the force on the shaft system at the moment of motor starting, it is discussed in detail from two aspects: increasing the motor starting torque and reducing the resistance torque. It is concluded that the starting problem of motor under low temperature can be solved by increasing the starting current of DC motor and adopting new low temperature resistant lubricating oil and motor bearing, and the effectiveness of the solution is verified by experiments.

Air conditioning refrigerant substitution technology in high temperature operating areas has become a challenge for the global air conditioning industry, R290 refrigerant is one of the best choices at present, but R290 has some problems, such as performance degradation and insufficient filling capacity. Based on the mechanism analysis, an R290 large displacement single cylinder compressor suitable for high temperature condition is designed. In this compressor, suction heat isolation is adopted to minimize the performance decay, and the damper, the foundation and the balance weight are all improved to cope with the noise and vibration problem, which support the design of the upcoming compressors.

Based on the problem of the broken pins of the intelligent power module used in air conditioning device controllers, the failure mechanism research of automobile electronic components was carried out by the method of combining experiment and simulation. First, through the vibration durability test analysis of the electronic controller assembly, the failure of the intelligent power module was reproduced, and the failure was consistent with the failure of the fault sample. Secondly, the method of combining dynamic test and CAE simulation was adopted. The failure of the intelligent power module is mainly caused by the stress, which is caused by the first-order modal resonance of the printed circuit board, and the weak point of the electronic controller assembly is located. Then by adding the screw fixing position of the printed circuit board to the electronic controller assembly, the vibration response characteristics of the printed circuit board are optimized. It is verified by CAE simulation that the stress of intelligent power module is reduced from 301.3 MPa to 51.8 MPa. After the vibration durability test, the function of the electronic controller assembly is normal. The intelligent power module is also checked by X-ray, and the pin of the intelligent power modules were not damaged. Finally, the solution was used to complete the modification design, and provided design guidance for the subsequent reliability design of air conditioning device controllers.

For common household electrical appliances with spring or thin film touch buttons, because the working voltage of the buttons are not high, they are easy to be ignored in the product structure design and safety test, and fail in the test of electric strength, material, creepage distances and clearances and so on. Through the summarizing of actual cases, analyzing the reasons for fail and suggestions for improvement measures that can be adopted, so as to provide effective reference for product designers and safety test engineers.

The 24 V vehicle air conditioner is a new product that has only appeared in recent years, it is mainly used on Engineering vehicle and trucks. It is usually in the form of backpack on the vehicle like the traditional residential split air conditioner. Vehicle air conditioners are popular among truck drivers, and the market share is getting higher and higher. The reliability appears to be particularly important, especially the reliability related to the electrical safety. At present, rain, temperature rise, and burning are the three most important factors affecting product reliability, but the qualification conditions of the three factors are mutually restrictive. The optimal solution is found successfully through theoretical analysis, software simulation, and experimental testing. The final verification found that the wind field, the position of the electric control, the form of the bracket, and even the sticking position of the sponge will have a certain impact on electrical safety.