In response to the common problem of uneven double-layer baking in integrated stove oven, a CFD simulation tool was used to analyze the flow field of the existing structure, and a preliminary optimization plan for the external guidance method was proposed to shorten the distance required for air supply and reduce flow resistance. Based on response surface methodology, experimental design is carried out on the three parameters of position dimension L, diversion angle θ, and diversion height H of the preliminary scheme, and a response surface mathematical model is obtained, to solve for appropriate optimization parameters. The results indicate that the standard deviation of double-layer wind speed σ is most sensitive to changes in the position L of the air outlet of the hot air hood, and the diversion angle θ becomes more sensitive to the standard deviation σ as the position L increases. When the position L approaches 135 mm, the diversion angle is 79.4°, and the diversion height is 3 mm, the standard deviation has a minimum value. The standard deviation σ of the upper and lower layers of the optimization scheme has decreased from 0.389 in the original structure to 0.250, and the uniformity of double-layer baked toast alices and egg tarts have been improved.

In order to study the performance of air fryer cooking French fries, while taking into account the intuitive visual feelings of consumers, and scientifically evaluate the cooking performance of air fryer, based on the shade chart developed by the Dutch Potato Processing Industry Association (V.A.V.Ⅰ), according to CIELab color space and GB/T 7921—2008 "Uniform color space and color difference formula", the color of French fries cooked in air fryer was studied. The relationship between color card and color value is established by color ability index, the overall color situation is reflected by color uniformity, and the sensory color is transformed into numerical expression. The results show that the coloring ability of most air fryer cooking fries can reach more than 75%, and the coloring ability of some air fryer cooking fries can approach 90%. The overall color uniformity of fries cooked in air fryer is about 90%. The indexes of color ability and color uniformity are easy to be understood by consumers, and lay a foundation for color evaluation of the cooking performance of air fryer, and provide a reference for related research fields.

To explore the degreasing effect and quality evaluation of meatloaf under different baking modes. By measuring the cooking loss rate, degreasing rate and sensory score of six different baking modes and taking optical photos, the optimal baking mode was selected by comparing with competing products. The optimal baking mode and steam-assisted baking were adopted to improve the degreasing rate, and the effects of steam-assisted baking on the quality indexes such as nutrient composition, color difference and texture of the patty were studied. The results shows that the degradability of the top double-ring heating + fan and annular hot air + bottom heating modes was 38.97% and 38.36%, respectively, and the sensory scores were 78.75 and 80.07 points. When steam assisted baking was used, the degreasing rate was the highest (47.33%), the protein content was the highest (65.78%) (dry base), the overall effect of texture and color was the best, and the overall baking result was the best. The results provide a theoretical basis for evaluating the effects of different baking modes on meat products, providing quantifiable requirements for heating effects, and improving the heating performance of oven products and developing intelligent programs.

Investigates the effects of baking with varying oxygen levels mediated by hot steam on the quality of three food items: eggplant, broccoli, and chicken. The research reveals that as the oxygen content increases, the concentrations of polyphenols, anthocyanins, chlorophyll, and vitamin C in the foods gradually decrease. Consequently, the DPPH (1,1-diphenyl-2-picrylhydrazyl) antioxidant activity diminishes, and the degree of dehydration and carbonization on the food surfaces intensifies. Furthermore, the sensory evaluation scores for eggplant and broccoli also gradually decline with rising oxygen levels. Under 0% oxygen conditions, the baked eggplant and broccoli exhibit optimal characteristics in terms of appearance, antioxidant content, antioxidant activity, and sensory attributes. As for baked chicken, with increasing oxygen content and decreasing hot steam, the hardness gradually increases, reaching its lowest point at 0% oxygen. Concurrently, the oil loss rate rises, while the peroxide value of the oil decreases. However, indicators such as the a value, color score, and total sensory evaluation score of baked chicken initially increase and then decrease with rising oxygen content. At 5% oxygen, the baked chicken achieves the highest appearance and sensory scores, but the highest oil loss rate per unit and the lowest peroxide value are observed at 0% oxygen.

Proper cooking methods and controlled conditions can effectively retain nutrients in food. In traditional cooking methods, steaming shows more significant advantages in the retention of food nutrients. In modern heating technology, radio frequency heating greatly reduces the exposure time of food to high temperature through high-frequency electromagnetic waves, reduces the loss of heat-sensitive vitamins and effectively inhibits the maillard reaction, and steam heating effectively maintains the color, taste and vitamins of food and other nutrients. In addition, other cooking technologies and combinations such as hot air heating, radiation heating, and microwave heating have been gradually developed and applied in food processing. With the progress of science and technology, home appliances are expected to achieve more breakthroughs and innovations in the emerging cooking technology and a variety of cooking method combination technology in the future, the use of diversified cooking technology to better retain the nutritional value of ingredients, promote digestion and absorption. The personalization and integration of household appliances are used to promote the development of healthy cooking concepts and better serve people's healthy life.

Using cucumbers as experimental subjects, investigates the differences in the effect of induction cooker and open-flame stove on their color, texture, microstructure, aroma components, and free fatty acid composition in terms of edible quality. The results indicated that compared to induction cookers, cucumbers cooked on the open-flame stove were heated more evenly, resulting in more uniform changes in color and texture structure. The main aroma components of cooked cucumbers were aldehydes and thioether compounds, and the total aroma component content (5745.66 μg/kg) of cucumbers cooked on the open-flame stove was much higher than that of cucumbers cooked on the induction cooker (3017.13 μg/kg). The main free fatty acids produced in cooked cucumbers were palmitic acid, oleic acid, linoleic acid, and linolenic acid, which were also more abundant in cucumbers cooked on the open-flame stove. In summary, compared to induction cooker, cooking on the open-flame stove can give cucumbers better edible quality and is a better cooking method.

Making dried fruits is another important use of a steam oven, second only to baking and barbecue. Improving the effect of using a steaming oven to make dried fruits will promote the user experience and have significant implications for improving product quality. The dehumidification performance of a steam oven is the main influencing factor on the cooking effect of dried fruits. By comparing eight common fruits, it was determined that lemon would be used as a moisture wicking performance test load for steam oven products. Providing an overview of the current technical status of lemon slice drying and the parameter indicators that affect the drying quality of lemon slices. Physical indicators such as dry base moisture content, color difference, and cooking time, which are easy to test and quantify, are selected to study the testing method for the dehumidification performance of steam oven products. The requirements for the dehumidification performance level of steam oven products are also provided.

Air fryer is a popular product favored by young customers in recent years. Compared to traditional frying cooking methods, air fryer use high-temperature air as the cooking medium to heat ingredients, which has the advantages of low fat, light oil, and health. However, at the same time, air fryer have pain points such as poor cooking uniformity, requiring users to flip the ingredients during use, which affects the user experience. Therefore, it is significant to study the cooking performance of air fryer. Builds a CFD model that simulates flow filed in the air fryer under load condition. Through experiments and simulations, this research digs into the heating mechanism, analyses flow pattern of high temperature air flow in the air fryer and ultimately explains the reason of poor heating uniformity. Results show high consistency between simulation results and experimental results. Results also points out that heating uniformity is highly related to the air speed at the surface of the food and changing the flow pattern can highly improve the heating uniformity.

Air fryer is a leading cooking tool for kitchen innovation, proposed a calculation method of mass and heat transfer in a propane air fryer, the law of heat transfer and air flow in an air fryer with air return structure was studied, a calculation model considering steady-state heat transfer and fluid dynamics was established and the influence of three-dimensional structure of air fryer on internal temperature and fluid velocity was analyzed. The analysis shows that the temperature of the heating plate is transmitted to the air, and the temperature is transmitted to the food through the air flow. In the velocity field analysis, the velocity distribution diagram of different sections is shown, the influence of the inlet on the air velocity is clarified, and the change of the direction and velocity of the air flow with the spatial position is shown. The temperature heat transfer and air flow inside the air fryer are deeply analyzed, compared with experiments, it was found that the air fryer with an air recirculation structure has higher cooking efficiency and better quality for food, which provides important reference and theoretical support for optimizing the design and improvement of the air fryer.

In order to improve the uneven cooking of a heating tray type electric rice cooker, the influence of side heater power on the quality of rice is investigated by heat convection in the pot, moisture content, uneven rate of cooking rice and sensory evaluation. Verified on an ordinary 5 L rice cooker body (P=750 W bottom power + different side heater power), the experiment shows that the uniformity of rice is the best at 6.85% when the side heater power is 40 W; the uniformity of rice when the side heater power is 20 W is similar to that when it is 40 W, which is 7.96%; when the side heater power is 20 W and 40 W, the smoothness of each point in the heat convection test pot is the best; when the side heater power is 80 W, the rice sample scored the highest in sensory evaluation. The results show that for a rice cooker with 5 L body and 750 W bottom power, matching 20 W~40 W side heater has the best effect on rice quality improvement.

A range hood is a type of household appliance that uses a fan as the core component to transport air, and plays an important role in purifying the smoke generated during the cooking process in the kitchen. Noise is an important factor that affects the user experience of products and is also a key aspect that consumers pay attention to when making purchases. Computational Fluid Dynamics (CFD) technology has been widely used in the home appliance industry for fluid mechanical design and optimization simulation of fan duct flow fields. Using computational fluid dynamics to optimize an export vehicle mounted range hood using axial flow impellers, and design a guide ring structure on the outer edge of the axial flow blades. Through numerical simulation, it was found that adding a guide ring structure can block the leakage of airflow along the radial path from the blade tip gap, reduce the impact and disturbance of radial leakage airflow on the mainstream airflow (axial intake), reduce the cutting of radial airflow by the blade tip, improve airflow leakage, and increase the airflow, efficiency, and turbulent noise of the fan blades. The experimental test results show that adding a guide ring structure to the axial flow fan blades of the vehicle mounted range hood contributes approximately 2.89 dB(A) to the overall noise reduction.

There are three types of noise in rotary compressors: mechanical noise, aerodynamic noise, and electromagnetic noise. Among them, aerodynamic noise contributes significantly to compressor noise, and it mainly occurs during the exhaust process of the compressor. Currently, setting up a resistant muffler at the compressor exhaust port is a common method to reduce aerodynamic noise in engineering. Therefore, designing a muffler with good noise reduction effect is of great practical significance. The industry generally uses transmission loss to measure the noise reduction effect of adversarial silencers, but the method can’t consider the pulsating noise of the fluid inside the silencers. Firstly, the noise reduction effect of two different types of silencers is evaluated using the commonly used transfer loss curve in the industry. Then, the CFD commercial software is used to simulate the pressure pulsation inside the muffler for pulsation noise evaluation. Finally, the muffler effect of two kinds of structure muffler is verified on a certain type of compressor. The simulation and experimental results indicate that the fluid dynamic noise inside the muffler cannot be ignored, the transfer loss curve cannot measure the pulsating noise and it is feasible to use CFD software to simulate pressure pulsation and evaluate pulsating noise. The research results provide certain reference value for the design optimization of built-in silencers in rotary compressors.

The feasibility of internally threaded Al round tube coil applied in 4HP outdoor unit (ODU) of in residential Variable Refrigerant Flow (VRF) heat pump was studied by simulation and test, which aims to establish a design methods and improvements for replacing internally threaded copper round tube heat exchanger based on the performance and cost. The simulation and test results show that under the same operating conditions, directly replacing Φ7 mm Cu tube coil by Φ7 mm Al tube coil with the same rows (keeping other structural not be changed, such as the tube spacing, row spacing, fin spacing, flow paths, etc.), the cooling energy efficiency is reduced by 2.2% on average, and the heating energy efficiency is reduced by 1.8% on average, which can be improved by increasing its heat exchanger area, adjusting the flow path design, and improving its expansion tube process or modifying its internal thread profile.

Currently, the smoking effect is a technical direction that needs further optimization when users use the range hood in practice, and the design of a multi-flow field on the front end has an important impact on the smoke absorption effect of the entire machine. Computational fluid dynamics have far-reaching consequences on the research of the technical direction of range hood, used for the design and optimization of its fan system (scroll casing, impeller, motor), air ducts, and front-end flow channels. Range hoods are easily affected by crosswinds or other complex environments in existing kitchen environments, which can lead to a decrease in smoke absorption effectiveness, causing some smoke to escape into the kitchen and increasing the difficulty of cleaning the kitchen due to strong odors and smoke. Uses numerical simulation, comparative analysis, and experimental verification to design a special-shaped double air inlet that can expand the coverage of the negative pressure zone, reduce the negative pressure value directly above the pot smoke, improve the range hood's ability to capture smoke produced by the pot, and reduce smoke flow leakage. At the same time, due to changes in the flow of air at the front end, the noise level of the entire machine's semi-anechoic chamber is reduced by approximately 0.6 dB(A).

The refrigerator compressor has and wear due to the poor lubrication of the crankshaft, and the power of the compressor lubrication system comes from the crankshaft, so it is very important to optimize the design of the crankshaft. Based on the geometric factors on the oil shaft of the compressor and the distance and the wall of the spiral pump on the oil is calculated. The calculation show that the smaller this distance, the higher the oil on the crankshaft. The calculation results are verified by experiments, and the calculation results and experimental results maintain good consistency, which provides guidance and reference for the analysis and optimization of the crankshaft.

At present, many electric fan products can simulate natural wind, but there is a lack of unified testing methods to determine whether the processed wind of the natural wind function of electric fans is close to natural wind. Researchers have found through extensive experiments and research that turbulence intensity can characterize the characteristics of airflow turbulence, and the pulsation characteristics of natural wind are determined by its own 1/f turbulence characteristics. The commonly used indicators for assessing the thermal comfort of indoor environments are the blowing sensation index and the expected average thermal sensation index, which are highly related to electric fan products. This study investigates the use of the blowing sensation index and the expected average thermal sensation index to test the thermal comfort of natural wind gears in electric fan products, and verifies the results through testing multiple electric fan samples. After testing and verification, the thermal comfort of electric fan products that meet the requirements of natural wind is significantly better than that of electric fan products that do not meet the requirements of natural wind.

In recent years, there have been many safety accidents at home and abroad involving R32 flammable refrigerant air conditioners, where improper installation and maintenance operations caused blockage on the high-pressure side, resulting in compressor explosions. Relying on the temperature measurement technology of inverter compressor windings, the explosion scenarios of R32 air conditioning systems under extreme conditions will be simulated and restored through experiments to obtain the motor winding and exhaust temperatures at the instant of compressor explosion. Based on the winding temperature measurement technology, the temperature difference ΔT parameter between the calculated value of winding temperature and the measured value of exhaust temperature is fitted. It is proved that the ΔT parameter can represent the degree of danger of explosion of the compressor operating under extremely dangerous conditions, providing a key determination index for the safety protection control of flammable refrigerant air conditioning systems.

In order to reduce the aerodynamic noise of a fan, takes a certain axial flow fan as the research object and proposes a noise reduction method based on genetic algorithm, which takes the minimum turbulent kinetic energy on the blade surface as the optimization objective. The noise reduction mechanism and aerodynamic performance of the optimized blade profile are analyzed. Firstly, by parameterizing the blade structure, automatic control of spatial size and shape was achieved. Secondly, with the constant air volume as the constraint objective, three structural parameters are selected, namely the axial bending parameter, the angle between the tangent and chord of the leading and trailing edge points, and combined with sensitivity factor analysis, the response relationship between the turbulent kinetic energy on the blade surface and the blade structural parameters is established. Finally, the NSGA-II genetic algorithm was used to determine the optimal blade structure, and the differences in aerodynamic performance and noise levels before and after optimization were compared to verify the feasibility of the method. The results showed that: (1) Different axial bending shapes have different weights on the impact of air flow and noise; (2) Two optimization schemes were selected: blade #1 can achieve noise reduction by reducing the rotational speed, while ensuring that the air volume is level with the original blade; Compared to the original blade, the air volume of blade #2 is basically the same, and the maximum noise reduction reaches 1.6 dB(A) while ensuring constant speed; (3) Through experimental verification, it was found that the impact of air volume on noise is greater than that of rotational speed. Under the premise of ensuring constant air volume, the effect of noise reduction through blade shape is better than that of reducing rotational speed.

In order to improve the reliability of the compressor for the room air conditioner, the assembly of the motor for the compressor is analyzed. Through theoretical research, the optimal design method of motor assembly coordination is determined: the minimum interference of motor assembly which meets the requirements of drop test is controlled to meet the requirements of motor force and torque, and the maximum interference of fit is determined according to GB/T 1801 to meet the design requirements of no plastic deformation. The drop test verification of the product using this design method shows that when the actual interference between the motor stator and the cylinder is 13.0 μm, the measured maximum output force is 8680 N, which is consistent with the theoretical calculation results, which proves that it meets the reliability requirements of the product.