The kitchen has always been known as the "heart" of the home. For a long time, exhaust gas, waste heat, soot, steam and odor caused by fuel and diet components have been flooded in residential kitchens, and harmful substances (such as CO, NxOy, respirable dust, and aromatic hydrocarbons) have spread to the air. The direct inhalation of the human body is harmful to the health of the body, and at the same time, some of the pollutants adhere to the surface of the indoor object to form dirt, which seriously affects the indoor environment. How to eliminate harmful substances in the kitchen in a timely and effective manner has become the key to improving the kitchen environment.
At present, China has been able to better solve the problem of pollution such as smoke exhaust and odor in multi-storey residential buildings (within 9 floors), but there is no fundamental solution to the problem of smoke exhaust from high-rise residential kitchens. This paper introduces the use of GBF flue system in a residential area in Beijing, in order to explore the problem of smoke exhaust in high-rise residential kitchens.
Characteristics and working principle of 1GBF flue system The flue system consists of a range hood, a secondary check valve, a single straight flue and a roof hood. The flue is made of fast-hard aluminate cement mortar, the wall thickness is (15Â±2)mm, and the lining glass fiber is added to the floor for a length of 2 7m. In order to reduce the resistance inside the flue, the inside of the flue is required. The surface is smooth and straight, and there must be no irregularities, honeycombs, pockmarks, cracks, etc. The fire endurance limit of the flue is more than 1h. The check valve and the anti-reverse fan blade are injection molded by ABS engineering plastic and PP plastic, and the anti-back fan blade can be taken out and cleaned at any time without disassembling the check valve. The roof hood adopts the traditional roofing method, the cover is made of C20 fine stone concrete, and the windshield is made of 6mm thick insulation board.
The GBF flue system features a check valve with double anti-reverse fan blades at the air inlet of each layer of flue. The check valve interface size is 150mm, and the exhaust pipe of the exhaust hood passes through the check valve. Connected to the flue. When the range hood is working, the double-stop counter-blade opens, and the flue gas flows into the flue through the check valve. Because the check valve plays a role of partial cross-section in the flue, a local low-pressure zone is formed in the vicinity of the interface of the upper flue due to the increase of the airflow velocity. â˜† Tan Xiaoping, male, born in September 1971, master of engineering, engineer has Conducive to the discharge of the upper layer of flue gas; if there is a large reverse pressure in the flue or a countercurrent flow of the flue gas, under the action of the reverse pressure and the gravity of the anti-reverse fan blade, the double-reverse fan blade is closed, and the reverse flue gas is blocked, Avoid smoke or odor in the flue.
Test results and analysis of 2GBF flue system The GBF flue system was adopted in a residential district in Beijing. The plot consists of 26~28-storey tower-type high-rises. During the test of the residential kitchen, according to the actual use of the residential flue, a CXW-170 range hood is installed on the kitchen flue corresponding to each floor. Performance parameters: maximum wind pressure 252Pa maximum air volume 660m3 / h, input power 250W), and select a set of test points in the middle section of each floor of the residential flue, install wind speed and wind pressure sensor, used to measure the speed and static pressure of the air flow. By simulating the various usage conditions in the residential kitchen, according to the different operating rates of the range hood, the working conditions of 16 types of range hoods were designed. Under each working condition, the wind speed and wind pressure at each flue interface of each layer and the test points in the flue are measured at the same time. The data signals are read by the data acquisition instrument, and the actual wind speed and static pressure are obtained after A/D conversion. The data is then sent to the computer for data aggregation to calculate the static pressure and air volume at each test point in the flue.
The analysis of the test data shows that: l1) The wind pressure of the flue gas outlet of the flue system is gradually increased under the operating rate of different exhaust hoods, and the air intake is gradually decreasing. When the operating rate is 40%, the wind pressure and air volume are abnormal, which is caused by the tight connection of the connecting hose between the range hood and the check valve. When the operating rate changes between 10% and 100%, the average air intake of each layer from 430m3 / h to 240m3 is increased from 130Pa to 230Pa when the operating rate is between 40% and 60%. At the time of starting, the average air inlet volume of each layer of the starting layer reaches 300m3/h or more, and the average inlet air pressure is within 200Pa.
The average wind pressure at the air inlet of each layer is greater than the wind pressure of the flue (see), indicating that the flue gas of each layer can be normally flowed to the flue; the average wind pressure of the air inlets of each layer is not in the case of various operating rates. They are very small, basically between -4~1Pa, which means that no matter the pressure in the flue, it will not affect the airflow at the outer interface of the check valve.
After the operating rate exceeds 30%, the air inlet pressure of some floors of the air inlet is higher (some close to 240Pa). For the normal result of the range hood, the flue is suitable for the exhaust hood with large wind pressure and large air volume.
3 Conclusions 3.1 The working condition of the flue system in the high-rise residential kitchen is basically the same under various working conditions. The performance of the flue itself can be kept stable in the change of external conditions, which can fully meet the smoke exhausting requirements in the normal use of the kitchen.
3.2 In most cases (operating rate is 45% ~ 60%), the static pressure distribution in the flue inlet and flue is reasonable; when the floor of the hood is opened, the static pressure of the flue inlet is higher than that in the flue. Static pressure is conducive to the positive flow of the flue gas; the floor of the flue hood is not opened, and the average air pressure of the flue air inlet is stable under different working conditions due to the function of the check valve. Therefore, in the range hood Under normal conditions of use, it is not easy to produce smoke or odor.
3.3 The maximum exhaust air volume of the flue system can reach 42m3/min, which meets the smoke exhaust requirements of the kitchen kitchen range hood.
3.4 Although the cross section of the flue is small, the internal flow field distribution is in full compliance with the discharge requirements of the range hood. Due to the double-reverse fan blades, the reverse flow velocity of the airflow is extremely small when the underfloor kitchen hood is shut down.
3.5 The recommended fan characteristics of the selected range hood are: maximum air volume
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