Since the word has been heated up, people have increasingly found that air quality is related to physical health. As the air that needs to be touched every moment, together with water and food, it forms the three cornerstones of health and wellness.
From the perspective of people's life scenes, the air environment in contact is mainly divided into two categories: indoor air environment and outdoor air environment. The air quality of the outdoor atmosphere requires the attention of the whole society and the global community to improve together. This is a long-term process that requires a large amount of capital investment and the establishment of a system. On average, people spend more than 80% of their time indoors. For individuals and families, it is also necessary to improve indoor air quality. The indoor environment here refers to the generalized indoors, not only to the family residence, but also various public service places such as offices, various types of vehicles and vessels, hotels, hospitals, etc.
The source of indoor air pollution mainly comes from three aspects: cooking fumes, harmful gases, and various biological sources of pollution. Cooking fumes are a large number of thermal oxidative decomposition products produced by cooking oil and food under the conditions of temperature. The fumes contain at least 300 kinds of harmful substances, such as a large number of hydrocarbons, alkanes, gaseous pollutants such as S02, N02, CO and CO 2 and PM2.5, PM10 and other particulate pollutants. These harmful substances have lung toxicity, immunotoxicity and genotoxicity. According to the survey of Shanghai Second Medical University, cooking for one hour at home is equivalent to every first: Han Jian (1978. 3~), female, graduated from Qingdao University in engineering management, and is currently the technical innovation manager of Qingdao Haier Dishwashing Co., Ltd. Mainly engaged in the technological innovation of kitchen electric range hoods, stoves, disinfection cabinets, ovens and smart kitchens and the work of pre-research in the next 3 to 5 years.
Two cigarettes are smoked in the day, and it can be seen that the oil smoke has serious harm to the cardiopulmonary respiratory system, the cardiovascular and cerebral circulatory system and the immune system.
For the other two sources of pollution: harmful gases (formaldehyde, VOC, TVOC, etc.) and biological sources of pollution (aphids, infectious diseases, etc.), there are currently solutions, mainly various types of air purifiers and disinfection cabinets. The air purifier is based on HEPA filtration, combined with formaldehyde treatment module, electret module, photocatalyst technology, etc. to reduce harmful gases to a lower level. The disinfection cabinet uses high temperature and ultraviolet technology to achieve sterilization and disinfection purposes. This article will focus on how to reduce the pollution problems caused by cooking fumes indoors.
2 Related concepts and theoretical basis 1 Related concepts 1.1 Deep cavity frequency conversion Haier Group's core technology of the new range hood is mainly composed of two elements "deep cavity" + frequency conversion.
The deep cavity refers to changing the structural design of the oil filter net in the traditional range hood, and changing the "convex" to "concave" as shown. The depth of the collecting chamber is deepened from 50mm to 120mm, which increases the area of ​​the smoke chamber and the effect of the smoke, and solves the problem of the fumes of the flat smoke machine. The soot absorbs faster and more cleanly.
The structure of the deep cavity hood machine deep cavity frequency conversion hood is frequency conversion means that the motor used in the new range hood is a motor with frequency conversion function. The advantage of frequency conversion is that the speed adjustment and start and stop selection can be automatically performed according to the size of the soot. In order to achieve timely suction and discharge and energy saving and noise reduction.
1.2 Inhalation factor compares the hazards of various sources of pollution from the perspective of human health, and proposes the concept of pollutant inhalation factor (intakefraction), referred to as IF, defined as the amount of pollutants in the body that is ultimately inhaled or digested by the human body in the total emissions. The ratio of the pollutants directly relates to the measurement of pollutants directly to human health, and the degree of harm to health is evaluated. For example, for automobile exhaust, the introduction of the inhalation factor measurement index can more accurately define the degree of damage to pedestrians caused by automobile exhaust.
The specific calculation method is: where s represents the inhalation factor, / is the total inhalation (g) of the pollutant to the human body, and E is the total emission (g) of the pollutant. The calculation of the total emissions is generally performed on the unit. The integral of the emission is calculated by e(1)(g/s), and the calculation of the total amount of inhalation is more complicated, because the factor of population 6, exposure concentration Q, and rate of inhalation are involved. In principle, the total inhalation should be equal to the above three. The product of the factors.
2.2.1 Euler-Euler model The Euler-Eulerian model is characterized by the fact that the dispersed phase and the continuous fluid phase are considered as continuous media, and the movement of the dispersed phase and the continuous fluid phase is also investigated in the Euler coordinate system. This model is suitable for the volume concentration of the particles is not large, and the difference between the fixed volume of the particles studied and the total volume of the flow field is not large, because the original continuous medium hypothesis will fail in this case and will result in Large calculation error, so this model is mainly used in applications where the concentration of the dispersed phase is high.
There are three main types of Euler-Eulerian models: homogeneous model, small slip model, and two-fluid model. The two-fluid model is divided into a particle pseudo-fluid model and a two-fluid model of gas-liquid two-phase flow, gas-liquid two-phase flow. The two-fluid model is the most common.
For the two phases of gas and liquid, respectively, the equations of mass, momentum and energy are simulated and combined with the heat, mass and stress transfer equations between the two-phase interfaces. The equation of the Euler-Eulerian model is: dC breathing model is Refers to the person's natural physiological respiratory rate and air breathing, as shown.
The respiratory model has an average breathing cycle of about 6 seconds, wherein the inhalation is 2.5 seconds, the inhaled gas volume is about 0.6L, the interval is 0.5 seconds, and then the exhalation is 2.5 seconds, and the exhaled gas volume is about 0.6. L, after another 0.5 second interval, enter the next cycle. The total circulating breathing gas volume is 0.6 L. The measurement calculation of the inhalation factor will be performed in conjunction with the present breathing model.
3 deep cavity frequency conversion range hood and ordinary smoke machine suction and discharge effect improvement comparison table 3 deep cavity frequency conversion range hood cooking process PM2. 5 collection data two hood cooking full course PM2.5 agricultural degree change comparison two hood cooking full PM10 concentration The change comparison shows that the PM2. soot particle concentration in the breathing zone of the common hood is significantly larger than the corresponding value of the deep cavity inverter hood. Ordinary hood.
Percentage contribution of six plant oils to soot particle size The standard deviation analysis of the soot particle size data of six plant oils showed that the standard deviation was small and the consistency was good, indicating that the volume distribution of soot had little relationship with the type of vegetable oil. Among them, the most frequent particle 3 inhalation factor is determined by taking a cycle of the breathing model for a total of 6 seconds, first calculating the total amount of inhaled air in the breathing cycle. Adult lung capacity calculation formula: vital capacity index = vital capacity + body surface area, body height (cm) weight (kg) - 0.1329. Guidance: normal adults 24 hours of oxygen is about 500L, g sucking air is 2200L or so. Calculate the total amount of soot particles per person to be calculated as the population P, the exposure concentration C; and the product of the three factors of the inhalation rate based on the time integral, assuming that the cook is 1 person, and in addition, the concentration of the soot particles is concentrated in 2 5um, take the peak concentration of PM2. 5 in the stage of blasting, ignoring the contribution of PM10. Inhalation rate=152.8/6=25.47ml/S, calculated according to Table 7. Table 7 common range hood and deep cavity inverter smoke machine single breathing cycle inhalation soot particle mass (unit: mg) deep cavity frequency conversion ordinary PM2.5 total Inhalation quality Finally, the total soot emissions in the period were calculated. It is also assumed that in the stage of the popping, the total amount of soot released during the breathing cycle is calculated according to the measured air volume combined with the soot particle concentration as shown in Table 8.
Table 8 general range hood and deep cavity variable frequency hood single breathing cycle suction exhaust soot particles total (mg) deep cavity frequency conversion common soot particles total release amount, calculate the deep cavity frequency conversion and ordinary hood high wind stall stir In the state, the respective inhalation factors are shown in Table 9.
Table 9 ordinary range hood and deep cavity variable frequency hood single breathing cycle inhalation factor contrast deep cavity frequency conversion common inhalation factor from the above analysis can be concluded that deep cavity variable frequency hood can reduce the inhalation factor by about 6.5% compared with ordinary hood Under long-term use conditions, it can effectively reduce the concentration and quantity of people suffering from pathogenic soot hazards, improve the health index, and reduce the probability of disease induction.
4 Improvement effect analysis Using the Euler-Eulerian model, CFD simulates the concentration field of human breathing area under the working condition of ordinary hood and deep cavity variable frequency hood. In order to maintain, it can be seen that the concentration field around the breathing area of ​​the user of the deep cavity variable frequency hood is lower than that of the ordinary hood, and in addition, as the air volume increases, the concentration of the breathing area of ​​the user can be improved.
In addition, by comparing the power consumption and noise of the reference operating conditions, the comparison values ​​of the two are shown in Table 10.
Table 10 Comparison of power consumption and humming value of common hood and deep cavity inverter hoods. Comparison of deep cavity frequency conversion common noise (A) power consumption W 6 Conclusion In summary, deep cavity frequency conversion technology can effectively improve the suction and discharge effect of range hoods. Under the same working conditions, the inhalation factor is reduced, and the environmental protection and energy saving purposes can be achieved. In this paper, based on the original fixed-point measurement of soot concentration, two main improvements are made: first, the research target is specifically concentrated in the human mouth and nose breathing area, combined with the human respiratory model for measurement; second, the inhalation factor method is used to determine the absorption of the fumes in the body. Or the proportion of the amount of digestion, not the total amount of emissions, but the amount of inhalation. Based on the above two points, the inhalation factor of deep cavity frequency conversion and ordinary hood is studied.
After the consistency of the smoke distribution of the six different vegetable oils, respectively, the total amount of smoke emitted per unit time and the total amount of the inhalation were measured, and the deep-cavity frequency conversion was 6.5% lower than that of the conventional smoke machine. In addition, the power consumption and noise of the range hood can be significantly reduced, and it has a wide range of promotion value.
(Finish)
Desk Riser
Manual, gas lifting and electric desk riser. Customize colors and size desk adjuster can transform any desk into a comfortable workstation that suitable for your needs at any time. It gets you out of your chair to relieve muscle tension, improve blood circulation, reduce stress, and increase productivity and that's the best sit and standing workstation and a minimalist and an affordable & feasible solution for sitting or standing at work.
Different models of stand up Desk Converter and monitor riser:
Spacious two-tier desktop: Add up to 2 monitors on the roomy top tier plus a keyboard and mouse or laptop on the lower tier. The ergonomic two-tier design provide you perfectly for ideal studying and working space.
Convenient gas spring lift and single-handle design let you smoothly switch from sitting to standing. Freely height adjustment -- Once you find your ideal height, our smart height locking mechanism locks the desk in place.
These series of desk riser have a sturdy and stable steel frame. Our durable and heavy-duty steel frame provides maximum stability at every level. No matter sitting or standing, you can safely work with confidence.
We have many series of computer standing desks to help point you in the right work direction. Whether you want something that`s high-end and elegant, affordable, high quality or a Gaming Desk, laptop desks, there`s something on our products list to suit your comfort and wellness needs. We offer the best compuer desk, movable laptop table, office chairs, Laptop Desk, Sit Stand Desk, office exercise bike and an under-desk treadmill to make your work experience healthier.
Ergonimic desk riser, Standing desk converter wood, Adjustable desk desk converter, Computer desk riser, Desk adjuster
Foshan Hollin Furniture Co.,Ltd , https://www.chnhollin.com