2. 1 Full ventilation
This is the most commonly used method to change the air quality of hotel kitchens in China. Most hotel kitchens use this method. Although this method can improve the air quality of the whole kitchen, the working environment of chefs who have been working in harsh conditions for a long time has not been fully improved.
2.2 Central air conditioning
In the design of some high-end hotels, from the perspective of improving the comfort of the kitchen, the air conditioning system of the kitchen is incorporated into the air conditioning system of the main building of the hotel. This way can really improve the comfort of the kitchen itself, but from the practical point of view, all the air conditioning systems in the kitchen with this air conditioning system have finally become furnishings and abandoned. The reason is that in the process of using this method, the oil fume produced in the kitchen "smells" through the air-conditioned room with the return air.
2.3 Local air supply plus comprehensive ventilation
Local air supply and total ventilation can completely improve the air quality in the kitchen and the working environment of chefs. Through such ventilation, the work area is covered with fresh air, and the chef inhales outdoor fresh air instead of air polluted by oil pollution. By local gas supply, operation can be reduced.
Body temperature and ambient temperature can reduce the discomfort caused by thermal radiation. Because it is local air supply, the blower needs small air volume, low energy consumption and small initial investment. The DC air conditioning system can ensure that the air conditioner will not be blocked by oil smoke. However, this air conditioning method, if not handled properly, will make the chef have a strong sense of blowing, causing discomfort and even serious occupational diseases.
In addition, too fast air supply speed will also affect the normal work of the fire site: the kitchen smoke exhaust system has not solved the smoke exhaust problem well, and the oil smoke pollution generated during operation is quite serious. The oil fume discharged into the kitchen not only pollutes the air and kitchen equipment in the kitchen, but also pollutes the air and decorative materials in other rooms such as adjacent restaurants. Some oil fume exhaust systems have defects in design and installation, which often cause great economic losses to operators. On the other hand, the exhaust air of some kitchens is too large, which solves the oil smoke pollution in the kitchen, but the power consumption, initial investment and operating cost of ventilation and air conditioning system are very large, resulting in unnecessary economic waste.
In addition, due to the working environment (operators are basically sweating during working hours), not only the efficiency of operating 1 is affected, but also the hygiene quality of dishes is easily polluted by the sweat of chefs. With the continuous development of social economy and the continuous improvement of people's living standards, the design of hotel kitchen ventilation system is not satisfied with simple ventilation design, but has gradually developed into an air conditioning form combining ventilation with air conditioning and refrigeration. Due to the large exhaust air volume of the kitchen stove in the hotel, the air conditioning system in the kitchen must supplement a large amount of air conditioning supply air volume. How to reasonably design the hotel's empty kitchen system and improve the working environment of the operating room can not only save the initial investment of the system, but also reduce the operating cost, which should be paid enough attention by the designers concerned.
Characteristics of air conditioning system in hotel kitchen
The hotel kitchen is a cooking room, and its indoor oil and steam are large, so the fan-coil system is not suitable. Otherwise, the oil filled in the kitchen is easily adsorbed on the surface of the coil, blocking the air circulation between fins, greatly reducing its heat transfer coefficient, and the air conditioning effect is getting worse and worse, so it needs to be cleaned in time and maintained frequently. Therefore, the air conditioning system of the hotel kitchen should adopt direct-flow air conditioning system, and the air source to be treated should all come from outdoor fresh air, generally not considering the same wind.
3. 1.2 Total theoretical air supply volume l
The total theoretical air supply of the hotel kitchen is the sum of the theoretical air consumption of the cooker, the air supply required by the operator and the air supply required to ensure the kitchen ventilation: L=L +L, +L (4).
3.2 Air supply system
The air supply system of hotel kitchen includes local air supply and comprehensive ventilation.
3.2. 1 Full ventilation
The purpose of designing comprehensive ventilation is to ensure that the chef's work area is covered by fresh air, and at the same time, it plays the role of supplementing air. Outdoor fresh air is sent to the vicinity of the chef's console in front of the stove through fresh air fans and ventilation pipes, and the location of fresh air should be appropriate. In the past engineering design, for the sake of the overall beauty of the kitchen, some ventilation pipes were often set in the oil fume hood, the height of fresh air outlet was flush with the lower edge of the oil fume hood, the air supply outlet was located directly above the chef's console, and the air supply direction was aimed at the chef's face (see figure 1). Because of long-term operation in such a working environment, the health of chefs is seriously affected, which will seriously cause occupational diseases of chefs. Therefore, the fresh air outlet should not be too close to the chef, and the height of the air outlet from the chef's head is generally 500 mm ~ 1000 mm (see Figure 2). In the design, diffusion guide vane tuyere is selected, d=200 1TIITI, and the diffusion angle of tuyere is 0=25. The air supply duct and static pressure box with the air outlet 2200 mm ~ 2700 mm away from the kitchen floor are made of inorganic composite materials or stainless steel plates. A fire damper shall be installed in the pipeline. When the temperature exceeds 70℃, the fire damper will automatically close in case of accident and interlock with the fan and air conditioning unit. In order to facilitate cleaning, the outer surface of the gas supply pipeline should be polished or coated. The common method is to spray a plastic layer with a thickness of 0.21titi ~ 0.41titi on the surface of steel plate.
3.2-2 Local air supply
Local air supply comes from fresh air units or combined air conditioners, and the air treated by air conditioners is sent to the kitchen through air ducts to adjust the air temperature in the kitchen and also play the role of air supply:
The author investigated the kitchens of some high-end hotels and restaurants in Wuxi, and the chefs responded well to the effect of local air supply and comprehensive ventilation system. But at the same time, some problems were found, mainly the placement of local air supply outlets. Considering the overall beauty and convenient installation of the kitchen, individual hotel kitchens will install local air supply outlets and comprehensive ventilation openings together (see Figure 3). In the actual use process, the temperature of the kitchen is often very high, but the chef feels uncomfortable because he is too close to the local air supply outlet and is affected by low temperature air supply for a long time, so he asks to stop the operation of the air conditioning unit, which affects the air conditioning effect of the kitchen.
Local air supply outlets should be arranged reasonably according to the specific situation of the hotel kitchen, and generally cannot be directly blown to the chef's head and back. Local air supply pipes should also be equipped with fire dampers, and anti-corrosion insulation layers should be made outside. Other requirements are the same as those of integrated ventilation pipes.
3-3 exhaust system
3-3. 1 Selection of oil fume hood The oil fume hood should be designed uniformly according to the technological requirements of the hotel kitchen, and it is generally made into an integral type, with an oil fume outlet above each cooker. This design is not only uniform and beautiful in appearance, but also easy to clean up oil stains, and more importantly, it has a good oil fume exhaust effect. If it is a single stove and a single range hood, the oil fume can easily spread from the gap between the two range hoods to the whole kitchen space. The outer edge of the smoke exhaust hood should not exceed the edge of the stove, the bottom edge of the hood should be1800 mm ~1900 mm+0900 mm from the ground, and an oil-water collection tank should be set around the hood. And at the lowest part of the groove, the pipe discharges into the sewer. The fume filter is arranged in the fume hood and should be easy to replace and clean, so as to prevent the fume from entering the exhaust fan after long-term operation and affecting its normal use. Generally, 8 = 2 mm ~ 5 mm steel plate is used for oil fume hood.
3-3.2 Calculation of minimum exhaust air volume L4 of range hood;
The minimum exhaust air volume of the fume hood is calculated according to the following formula: L~3600Fv (5) where F is the mouth area of the fume hood, m; According to literature [5], exhaust oil fume
Smoke hood suction speed v. Take 0.5 m/s.
Laying of exhaust pipeline
Defects in the design and installation of exhaust pipes often leave hidden dangers for the normal operation of hotel kitchens. If a large amount of grease accumulates in the exhaust pipe
It can't be discharged in time, and there are no proper cleaning measures. In hot summer, the oil dirt in the pipeline is prone to spontaneous combustion due to oxidation and high temperature, which may cause serious consequences. According to the author's investigation, a large amount of oil accumulated in the exhaust pipes of most hotel kitchens cannot be discharged, and there is no cleaning method. The exhaust pipe is generally welded with steel plate, with the thickness of 1.5 mm ~ 3 mm, and the horizontal exhaust pipe generally does not exceed 15 m, and has a slope of more than 2%. The oil fume hood is installed in the slope direction, and the movable flanges are used to connect the two ends of the horizontal pipeline and the appropriate position in the middle, so as to clean up the oil pollution in time (see Figure 4). The exhaust speed in the pipeline should be no less than10m/s, generally10m/s ~12m/s, so as to prevent the oil fume from easily adhering to the pipeline when the wind speed is low.
A valve is set at each exhaust port to control the exhaust air volume and ensure the exhaust effect of each stove. Brush the internal and external surfaces of the oil fume exhaust pipeline with antirust primer twice, then brush the internal surface with acid-resistant paint twice, and brush the external surface with gray enamel twice.
According to the above-mentioned improved design method, some existing hotel kitchens were reformed, and the owners generally responded well, basically solving the ventilation and working environment of the kitchen and achieving good results.
3.4 Hotel kitchen air conditioning design adopts direct evaporative cooling fan. The evaporative cooling ventilator has a simple structure. Reliable operation; Convenient maintenance and long service life; Low operation cost, energy saving and environmental protection. The air cooled by the direct evaporative cooling ventilator continues to be used as the air supply.
A large amount of ground is transported to the kitchen, and the kitchen fume is discharged to the outside. Its working principle is shown in Figure 5. When the direct evaporative cooling ventilator is selected as the cooling ventilation equipment in the kitchen, in order to eliminate the oil fume in the kitchen as much as possible, the exhaust air volume L4 of the range hood should be appropriately increased to improve the ventilation frequency in the kitchen. writing
[6] The minimum air exchange rate is 40 times /h, and according to the usage of Lianyungang Xugou Hualian Hotel, the minimum air exchange rate is 60 times/h.
More appropriate. The calculation method of the number of evaporative cooling ventilation units is as follows: n = VN/L (6), where JV is the number of units in unit; V is the volume of the hotel kitchen, m; N is the number of air changes, each time/h; L is the actual air volume of the selected unit, in m/h.
3.5 Air conditioning design of other auxiliary rooms in the hotel kitchen
Other auxiliary rooms without smoke emission can adopt fan-coil water system, which is more economical and energy-saving. For example, the air parameters of cold meat room, rough machining area, dish washing room and duty room can be determined according to their functions, different requirements of operation and heat load.
4 conclusion
In view of the bad influence of the cooking fume in the hotel kitchen on the kitchen staff, designers need to start from many aspects and design the kitchen air conditioning system reasonably. At present, the ventilation and cooling efficiency of most hotel kitchens is very low, so it is necessary to improve the efficiency through structural improvement, ensure the use function, and achieve the purpose of environmental protection and energy saving:
① The ventilation and cooling of the hotel kitchen should adopt local air supply plus comprehensive ventilation to make the air distribution more reasonable and effectively improve the working environment of the kitchen staff.
② When the direct evaporative cooling ventilator is selected as the cooling ventilation equipment in the kitchen, the minimum ventilation times required by the design should be met.
③ When selecting the capacity of the exhaust fan, it should be considered that the exhaust air volume exceeds the supplementary air volume, so that the kitchen can maintain a certain negative pressure and prevent the kitchen fume from "smelling" into other air-conditioned rooms.
(4) Reasonable design of exhaust duct to eliminate potential safety hazards.
I hope this helps.