What are the key points in hotel kitchen exhaust design?

1. Overview

The main reasons for problems in kitchen ventilation are, on the one hand, insufficient coordination between the kitchen technology design profession and the ventilation design profession; on the other hand, due to the The design lacks experience and the design is not reasonable.

2. Calculation of kitchen ventilation volume

The ventilation volume of the kitchen consists of two parts, namely the local exhaust volume and the comprehensive exhaust volume. The local exhaust volume should be determined based on the selected stove and kitchen exhaust hood, and the overall exhaust volume is generally determined by calculation.

1. Calculation of ventilation volume

The ventilation volume of mechanical ventilation should be calculated through heat balance calculation. The calculation formula is:

L=Q/0.337( tp-ti) (1)

In the formula, L - necessary ventilation volume, m3/h;

tp - indoor exhaust air calculation temperature, the following values ??can be used: 35 degrees Celsius in summer, 15 degrees Celsius in winter;

ti——calculated temperature of indoor ventilation, degrees Celsius;

Q——total heat (sensible heat) in the kitchen, W;

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Q＝Q1＋Q2＋Q3＋Q4(2)

In the formula, Q1--the heat dissipation of kitchen equipment is calculated according to the data provided by the process. If there is no information, please refer to the literature;

Q2--Heat dissipation of the operator, W;

Q3--Heat dissipation of lighting fixtures, W;

Q4--Cooling load of the indoor outer enclosure structure, W.

2. Local exhaust volume

The local exhaust volume is calculated based on the suction wind speed of the exhaust cover. The minimum exhaust volume is L=1000P·H

In the formula, L - the exhaust volume of the exhaust hood, m3/L;

P - the perimeter length of the hood (the length of the side against the wall is not included), m;

H——The distance from the cover to the stove surface, m.

3. Estimation of kitchen ventilation volume

Based on summarizing the engineering design and use, designers can estimate the ventilation volume as follows:

Chinese kitchen n =40-50h-1;

Western kitchen n=30-40h-1;

In the estimated ventilation volume, the local exhaust volume is considered to be 65%, and the overall exhaust volume is considered The air volume is considered as 35%.

3. Local exhaust locations and requirements

In Chinese kitchens, the cooking heat and smoke exhaust volume are generally large, and the exhaust volume is also large, so an exhaust hood is generally used. Range hood. To reduce the impact of oil fume on the environment, a disinfectant fume hood can be used.

Cooking room: The requirements for fresh air in this room are low, but the exhaust effect must be good. Otherwise, steam will fill the entire workroom and affect the work of the chef. The exhaust is mainly water vapor, so it does not need to be used. And purification device, discharge directly.

Western kitchen: The cooking volume is not very large, but it requires many and complete equipment, and the exhaust volume is smaller than that of a Chinese kitchen.

Dishwashing room: requires a larger exhaust volume.

IV. Requirements for supplementary air in the kitchen

In kitchen ventilation, a certain amount of fresh air must be supplemented, and the air supply volume should be considered as 80%-90% of the exhaust air volume.

It is unfavorable for the negative pressure value in the kitchen to be greater than 5Pa. Because the negative pressure is too large, the furnace will be drafted. Therefore, it is possible to adjust the speed of both the supply fan and the exhaust fan. 30% of the supplementary air volume can be used as post air supply, and the air supply outlets are directly and evenly arranged above the front side of the exhaust hood. The kitchen air supply can directly use outdoor fresh air, and only a coarse-efficiency filter is installed. In addition, in order to improve the working environment of cooks, partial or comprehensive cooling devices should be installed according to conditions. The relationship between the heat emitted by kitchen appliances and the air conditioning cooling load can be calculated by the following formula:

When the heat source of the stove is gas: qc=qeF1F2≈0.1qe.

(3)

In the formula, qc——cooling load of kitchen air conditioner, kW;

qe——heat dissipation of kitchen equipment, kW;

F1——equipment The simultaneous use coefficient is taken as 0.5;

F2 - the proportion of surface radiant heat in the equipment input power, taken as 0.32;

F3 - the exhaust heat dissipation coefficient, taken as 1.6.

When the heat source of the stove is electricity and steam: qc=qeF1F2/F3≈0.16qe(4)

To avoid odor transfer from the kitchen to the restaurant, 60% of the air supply volume can be It is sent to the dining room and then flows from the dining room to the kitchen. In view of the large amount of ventilation in the kitchen, such a large amount of supplementary air flows to the kitchen through the dining room. From the aspects of energy saving and duct layout, this method is not advisable.

V. System layout

1. The air supply system should be DC mode. The kitchen ventilation system should use variable speed fans or associated fans for air supply and exhaust.

2. Arrangement of air supply and exhaust vents

The arrangement of air supply and exhaust vents in the kitchen should be considered according to the specific location of the stove. Do not let the air supply jet disturb the exhaust performance of the stove. Pass. When determining the outlet wind speed of the air supply outlet, the regional wind speed is about 2m above the ground