Problem 1: In the kitchen ventilation project, the power consumption of smoke exhaust fan and lampblack purification equipment is large, and the ventilation effect of fan is poor. Cause: All exhaust hood pipes of the overall kitchen are finally concentrated into a large air duct system, and a large lampblack purification equipment and a large fan are used for air exhaust. As a result, as long as the kitchen has a stove to use, the exhaust fan and the lampblack purifier must be turned on. In this way, not only the ventilation effect of the fan is not good, but also the power consumption is large. In high-end hotels, the annual electricity consumption for kitchen ventilation accounts for 2.8% of the total annual consumption.
Solution: Divide into two or three systems according to the specific situation, or use variable speed fans, which are fully open at peak load. The peak time for the use of kitchen stove is about 4-5 hours, while the rest of the time is for processing and preparation or sanitation, so no large exhaust volume is required.
Question 2: The air supply system of the hotel kitchen adopts the following methods:
1. Partial return air is used for air treatment;
2. Fan coil unit is adopted;
3. There is no air supply system in the kitchen, but a single air cooler. The efficiency is greatly reduced after less than a year of use, making the kitchen temperature too high. Cause: These devices are equipped with water-cooled surface coolers or direct evaporative surface coolers. The air in the kitchen is in direct contact with the cooler, and the oil mist will soon pollute and block the clearance between the fins on the surface cooler, reducing its air volume, resulting in too high temperature in the kitchen and poor effect.
Solution: return air cannot be used in the fresh air supply system of the kitchen. Only DC system can be used. DC air conditioning system or DC air supply system can be used according to outdoor conditions. Window type or cabinet type air conditioners should not be used in the kitchen.
Problem 3: The kitchen fan coil fails to cool down. The kitchen is equipped with stove exhaust system, fresh air supplement system and fan coil cooling system. When it was just put into production, the effect was very good. One year later, the temperature could not be lowered, sometimes reaching more than 35 ℃, which was intolerable to the staff. Cause: Through inspection, it is found that the oil mist and water vapor in the kitchen are large, especially the oil smoke after the gas combustion attaches to the coil surface, which greatly reduces its heat transfer coefficient and makes the cooling effect worse and worse.
Solution: plug the fan coil unit at the return air inlet in the kitchen, and then use the pipe to lead the air in the dining room as the return air of the fan coil unit in the kitchen, while reducing the amount of outdoor air. (Fan coil system cannot be used in kitchen design)
Problem 4: The fire of the kitchen gas range sprays outside the kitchen door, affecting normal use. Cause: The proportion of air intake and exhaust in the kitchen is improper, resulting in high negative pressure in the kitchen.
Solution: For kitchens with mechanical ventilation system, supplementary air intake shall be considered. The negative pressure value of the kitchen shall not be greater than 0.5mm water column. If the negative pressure is too large, the stove will be downdraft, that is, the inflammation vaccine will spray out. In order to achieve this purpose, the air supply volume shall be 85%~95% of the exhaust volume in general.
Question 5: The questions between the kitchen operation room and the dining room. The kitchen is adjacent to the dining room, which makes people feel uncomfortable, and makes the environment quality of the high-end dining room not fragrant and elegant enough. Cause: The air flow in the kitchen and dining room is not well organized. It should be the kitchen negative pressure and the dining room positive pressure. Sometimes, because the kitchen has opened a window, the air in the kitchen flows into the dining room, which makes the two smell everywhere.
Solution: To prevent kitchen odor from pouring back, in addition to the corridor transition between the kitchen and the dining room, 60% of the kitchen exhaust air volume should be supplemented by the dining room. That is, 60% of the make-up air volume in the kitchen is sent to the dining room, and then flows from the dining room to the kitchen. However, it should be noted that the wind speed when the air flows from the dining room to the kitchen through the food port should not be greater than 1m/s.
Problem 6: The meeting hall of a high-end hotel has the smell of cooking in the kitchen. Cause: The exhaust outlet of the kitchen is close to the outdoor air inlet of the air conditioner, and the air inlet is located in the downwind direction of the exhaust outlet. As a result, the air intake is not clean, so that the smell of the kitchen is sent into the building, resulting in "smell".
Solution: The fresh air inlet should be set at a place with clean air, and should be set at the windward side of the air outlet, which should be lower than the air outlet. In civil buildings, the air inlet shall not be set in the same direction as the kitchen exhaust.
Problem 7: There is water in the kitchen exhaust fan casing, which causes ice formation and affects the use. Cause: In cold and cold areas, the exhaust fan of the kitchen is set outdoors. In winter, the water vapor and oil mist in the exhaust will condense and freeze at night. The exhaust fan cannot be started when the kitchen is working the next day. Even when the stove is in use, not only cannot exhaust, but also water drops.
(1) Pay attention to the rotation direction of the fan, and try to select the centrifugal fan with horizontal outlet. If the fan at the upper outlet must be selected, a drain pipe shall be installed at the bottom of the fan housing, and the water collection shall be drained at the same time. The outdoor part of fan and air duct shall be insulated.
(2) The horizontal pipe shall have a slope of more than 2% towards the exhaust hood.
(3) The velocity in the exhaust pipe is generally about 10m/s.
(4) The fan should preferably not be located outdoors, but in the exhaust fan room.