Case Study and Design of Kitchen Ventilation

Abstract

This chapter presents several typical cases of Chinese and European kitchen ventilation designs, including ventilation design for kitchens of the high-rise residential building and commercial building in China, the institutional school kitchen, and restaurant kitchen in Europe.

9.1 Design Calculation of Residential Centralized Exhaust System

For residential kitchen, the exhaust shaft is generally made of concrete and the corresponding cross-sectional area of the central flue can be determined by the following method. The total fume flow resistance ∆P of high-rise buildings with n storeys, the heat pressure ∆P_heat (see Sect. 8.8 Eq. 8.21), and the natural buoyancy ∆P_B of the fume are calculated as follows:

$$ \Delta P = \sum\limits_{i = 1}^{n} {\left( {\lambda \frac{{L_{i} }}{{d_{i} }} + \xi_{i} } \right)} \frac{{\rho v_{i}^{2} }}{2} $$

(9.1)

$$ \Delta P_{\text{B}} = hg\left( {\frac{1}{{0.77 + \frac{{t_{\text{w}} }}{353.20}}} - \frac{1}{{0.73 - \frac{{\bar{t}}}{366.03}}}} \right) $$

(9.2)

• where

• i = level of floor;

• t_w = outdoor air temperature, °C;

• $\bar{t}$ = average temperature of the fume, °C;

• n = number of operating fans.

When determining the cross-sectional area of the exhaust shaft by natural venting, the flow resistance of the exhaust system and the natural buoyancy generated by the combustion should satisfy Eq. (9.3):

$$ \Delta P_{\text{B}} \ge P $$

(9.3)

To mechanical exhaust, for calculation purposes the components are best regarded as calculation nodes, as shown in Fig. 9.1, and the shaft is treated in the same manner as components. This type of system representation has advantages when carrying out computer solutions of complex system.

Fig. 9.1

Node and component representation of the exhaust system

For mechanical exhaust system (Chen and Gong 2004), as shown in Fig. 9.1, energy equation of fume of ith floor from indoor kitchen into the central exhaust shaft (Sect. 9.1) is defined as Eq. (9.4):

$$ P_{{{\text{a}}i}} + \frac{{\rho_{\text{n}} \overline{{v_{\text{o,l}} }} }}{2}^{2} { + }\Delta P_{{{\text{h}},i}} = P_{i} + \frac{{\rho_{\text{n}} \overline{{v_{\text{l}} }} }}{2}^{2} + \left( {\lambda_{{{\text{b}},i}} \frac{{l_{{{\text{b}},i}} }}{{D_{{{\text{b}},i}} }} + \xi_{{{\text{b}},i}} \frac{{\rho_{\text{n}} }}{2} + \xi_{\text{c}} } \right)\left( {\frac{{q_{{{\text{v}},i}} }}{{A_{{{\text{b}},i}} }}} \right)^{2} $$

(9.4)

• where

• P_ai = indoor air pressure in the ith floor, Pa;

• ρ_n = fume density, kg/m³;

• $\overline{{v_{\text{o,l}} }}$ = average velocity of fume at hood range entrance, m/s;

• ∆P_h,i = total pressure of the range hood in the ith floor, Pa;

• P_i = pressure in the ith floor shaft, Pa;

• $\overline{{v_{\text{l}} }}$ = average velocity of fume at central exhaust shaft in the ith floor, m/s;

• λ_b,i = friction resistance coefficient of the branch exhaust flue;

• l_b,i = length of the branch exhaust flue, m;

• q_v,i = airflow rate of the range hood in the ith floor, m³/s;

• ξ_b,i = local pressure loss coefficient of the branch exhaust flue in the junction;

• ξ_c= resistant coefficient of the one-way damper, which can be obtained by experiment. The one-way damper performance has been measured by many researchers, for example, Chen and Gong (2002) concluded that the local resistance coefficient is 2.5 through experiment.

• D_b,i= equivalent diameter of the branch exhaust flue, m;

• A_b,i= cross-sectional area of the branch exhaust flue, m².

The energy equation of fume from ith floor of central exhaust shaft to the outlet of the exhaust cowl on the roof (Sect. 9.2) is defined as follows:

$$ \begin{aligned} & P_{i} + \frac{{\rho _{{\text{n}}} \overline{{v_{i} }} ^{2} }}{2} + gh(n - i)(\rho _{w} - \rho _{{\text{n}}} ) + ih\rho _{{\text{n}}} g = P_{{{\text{a,c}}}} + \frac{{\overline{{\rho _{n} v_{{{\text{co}}}} }} ^{2}}}{{2 }} + nh\rho _{{\text{n}}} g \\ & \quad + \left( {\sum\limits_{{j = 1}}^{n} {\lambda _{i} \frac{h}{{D_{i} }} + \sum\limits_{{j = i}}^{N} {\xi _{i} } } } \right)\frac{{\rho _{{\text{n}}} \overline{{v_{i} }} ^{2} }}{2} + \xi _{{\text{f}}} \frac{{\rho _{{\text{n}}} v_{{{\text{co}}}}^{2} }}{2} \\ \end{aligned} $$

(9.5)

• where

• h = floor height, m;

• g = gravity acceleration, m/s²;

• n = operating number of kitchen hoods;

• P_a,c= air pressure at the outlet of exhaust cowl, Pa;

• v_co = fume velocity at the outlet of exhaust cowl, m/s;

• D_i = equivalent diameter of ith central exhaust shaft, m;

• N = total number of high-rise residential building’s floors;

• λ_i = friction resistance coefficient of the central shaft;

• ξ_i = pressure loss coefficient of the central shaft in the junction;

• ξ_f= pressure loss coefficient of the exhaust cowl.

The continuity equation of fume in the exhaust system, see Eq. (9.6),

$$ \overline{{v_{i} }} A_{i} = \sum\limits_{j = 1}^{i} {q_{{{\text{v}},i}} } $$

(9.6)

where A_i is cross-sectional area of central exhaust shaft, m².

In summary, for a centralized exhaust system with n range hoods operating simultaneously in residential building, there are 4 × n unknowns in the entire exhaust system. They are the airflow rate, total pressure, fume pressure, and fume velocity of exhaust hoods in each floor. Each layer of kitchen exhaust shaft can be listed by using Eqs. (8.17), (9.4)–(9.6), so there are 4 × n equations to describe the exhaust system in total (Chen and Gong 2002, 2004; Zhou 2014).

In the process of design calculation (see Fig. 9.2), the following steps are suggested, but need to vary to suit individual system layouts. Design of flowchart is given as follows.

Fig. 9.2

Flowchart of the design procedures

Step 1:

The reasonable shaft cross-sectional area and components size are to be found and guess one according to the related kitchen standards.

Step 2:

If the airflow rate is unknown, estimate an airflow rate depends on the worst operating condition of cooking exhaust system. Alternatively, when it is more appropriate, to estimate a Reynolds number (default value 10,000) in order to select a friction coefficient or a component loss coefficient. As Reynolds numbers are usually high, friction and loss coefficients do not change greatly over quite a wide range of Reynolds numbers, so that a reasonably accurate guess can be made.

Step 3:

Divide up the system into sections, which are having constant shaft and components size. Determine the hood status and related loss coefficients at each node, and using Eqs. (8.17), (9.4)–(9.6) to obtain 4 × n nonlinear equations describing the whole exhaust system.

Step 4:

Solve the 4 × n nonlinear equations by using MATLAB software involving iterative solutions. Some representative unknown parameters can be obtained, such as the exhaust airflow rate and pressure distribution at central exhaust system.

Step 5:

With the results from step 4 as appropriate. If the airflow rate and cross-sectional area do not agree with estimated value or required values, repeat steps 1–4 with new values of flow rate and shaft size.

9.2 Ventilation Design for a High-Rise Residential Building

The project is a high-rise residential building with 32 floors above the ground as residential buildings and one floor underground as equipment room. The total construction area is 29,942 m², each floor height is 2.9 m, and the total height is 93.10 m. Each floor with eight apartments, there are 256 apartments in total. Building profile and typical floor plan are shown in Figs. 9.3 and 9.4. Design of this case aims to the kitchen ventilation system.

Fig. 9.3

Cross section of a high-rise residential building

Fig. 9.4

Typical floor plan of a high-rise residential building

Kitchen ventilation system design generally includes a comprehensive exhaust system (room ventilation), local exhaust system (range hood), and makeup air system of three parts. For residential kitchen because of its small kitchen area, generally less than 10 m², we can bring the makeup air by cracks of windows and doors. Thus, the comprehensive ventilation and air supplement in the residential kitchen cannot be considered only in the engineering application. This case focuses on the design and calculation of the exhaust fume system in the residential kitchen.

9.2.1 Design Procedures

This design is based on the following standards.

• (1) GB 50016-2014 Code for fire protection design of buildings.

• (2) GB 50736-2012 Design code for heating ventilation and air-conditioning of civil buildings.

• (3) GB 50368-2005 Residential building code.

• (4) GB 50096-2011 Design code for residential buildings.

• (5) GB 18483-2001 Emission standard of cooking fume.

• (6) JG/T 194-2018 Ventilating duct for residential kitchen and bathroom.

• (7) GA/T 798-2008 Vapor exhaust and fire resisting check damper.

• (8) GB/T 17713-2011 Range hood.

The key points of design procedures are as follows.

• a. Select the centralized exhaust shaft on basis of the building floors and the building codes and standards;

• b. Select the calculation parameters, including exhaust airflow rate, operating rate, shaft inner wall absolute roughness, and local loss coefficient;

• c. Check the centralized exhaust shaft size according to the calculated parameters.

9.2.2 Selection of Centralized Exhaust Shaft

• (1) Centralized Exhaust Shaft Type

At the present, the common exhaust flue used in the residence is the centralized exhaust shaft generally. It is easy to produce the backflow between the upper and lower floors because of the unbalance of the output pressure of exhaust hood among the floors. Therefore, the type of exhaust hood which can prevent the reflux of each layer should be used.

To prevent the reflux of vertical exhaust flue, the centralized exhaust system can be simply divided into two forms: One is to rely on the special structure of the flue, and the other is to rely on the one-way damper outside the shaft. Considering factors such as reducing the difficulty and weight of shaft production, current on-site construction management levels, system adjustment, and maintenance management, the current residential flue type is constant section centralized exhaust shaft with a reliable fireproof damper installed on the joint of exhaust hood hose and flue inlet. This kind of fireproof damper has the function of preventing string taste, fire resistance, small flow resistance, and regulating the balance of resistance between floors, and it is convenient to install, use, and maintain.

• (2) Centralized Exhaust Shaft Size

The centralized exhaust shaft size is selected according to the building floors and the building codes, and standards. The selection table for residential kitchen exhaust flue is given in Table 9.1.

Table 9.1 Selection table of residential kitchen exhaust flue size

• (3) Centralized Exhaust Shaft Cross-Sectional Size

The building consists of 32 layers, and the polymer cement fireproof exhaust flue is selected as centralized exhaust shaft. The section size of the concentrated exhaust flue is 500 mm × 400 mm.

9.2.3 Design Parameters

• (1) Exhaust Airflow Rate

The exhaust airflow rate relates to the effect of fume exhaust and the cross-sectional size of flue. There are a variety of calculation methods in the calculation of exhaust airflow rate, of which typical methods are reliable through a lot of experimental verification, as illustrated in Chap. 5, Table 5.19.

The layout of residential kitchen is shown in Fig. 9.11. All the kitchens adopt exhaust hoods, whose parameters are shown in Table 9.2. The calculation results of the exhaust airflow rate of different calculation methods are shown in Table 9.3.

Table 9.2 Kitchen and exhaust hood parameters summary

Table 9.3 Calculation results of exhaust airflow rate of different calculation methods

From Table 9.3, the calculation results of exhaust airflow rate of three calculation methods vary greatly, and the select exhaust airflow rate is related to the performance of the exhaust hood. In this design, the average operating rates of kitchen hoods are set as 60%.

Taking the high-rise building kitchen as an example, the exhaust airflow rate is selected to be 300 m³/h. It considers both the technical requirements for effective elimination of pollutants and the economic requirements for the shaft cross-sectional area. When the exhaust airflow rate is 300 m³/h, the air change rate for a 5 m² kitchen can reach 25 1/h, which is in line with the engineering design requirements. In this design, we selected a kitchen exhaust hood, of which the total pressure is 180 Pa when its exhaust airflow rate is 300 m³/h according to the performance curve. The principle diagram of the central exhaust system in high-rise residential building is shown in Figs. 9.5 and 9.6.

Fig. 9.5

Principle diagram of the central exhaust system in high-rise residential building

Fig. 9.6

Exhaust fume plan of standard kitchen of 32-story building (B-1, B-2)

9.2.4 Cross-Sectional Size Check of Centralized Exhaust Shaft

Central exhaust system resistance is calculated according to the cross-sectional size, exhaust airflow rate, operating rate, and local resistance coefficient of exhaust flue. If the total pressure provided by the exhaust hood can overcome the system resistance when the bottom users reach the rated exhaust airflow rate, the cross-sectional size of the selected flue meets the exhaust requirements.

The fumes excluded from the kitchen contain certain particulate matter. To remove it effectively, the exhaust fume velocity (Table 9.4) should be between 8 and 10 m/s.

Table 9.4 Exhaust fume velocity in shaft

For the selected exhaust hood, the total pressure is 180 Pa when its exhaust airflow rate is 300 m³/h. According to the previous calculation, this exhaust hood can meet the requirements of fume exhaust in this high-rise residential kitchen.

9.3 Ventilation Design for a Commercial Kitchen A in China

The kitchen of this case is located in a shopping mall, with a kitchen construction area of 170 m², with 14 workshops (cooking rooms), floor height of 3.6 m. The kitchen layout is shown in Fig. 9.7.

Fig. 9.7

Layout of the kitchen

Kitchen ventilation design generally comprised of a comprehensive exhaust system (air change rate), local exhaust system (range hood), and makeup air system. In this case study, only local ventilation and makeup air design is discussed.

9.3.1 Exhaust Airflow Rate

The calculation methods have been discussed in Sect. 5.2.4 in this case. The parameters of the kitchen and exhaust hood are shown in Table 9.5. The calculation results of the exhaust airflow rate of different calculation methods are shown in Table 9.6.

Table 9.5 Kitchen and exhaust hood parameters

Table 9.6 Exhaust airflow rate of kitchen workshops

In comparison with the three calculation results, the correlation $q_{v} = 3600 \cdot A_{\text{e}} \cdot v_{\text{h}}$ (see Sect. 5.2.4) is used to calculate the exhaust airflow rate. The layout of the exhaust system is shown in Fig. 9.8.

Fig. 9.8

Exhaust ventilation layout

9.3.2 Makeup Airflow Rate

Kitchen makeup air system can be divided into natural and mechanical makeup air systems. The mechanical makeup air system should be used when makeup air systems cannot meet the kitchen temperature or ventilation requirements.

It is recommended that air is released directly in kitchen, the air supply and the makeup airflow rate should be maintained 80–90% of exhaust airflow rate. The calculation results of makeup airflow rate in each workshop are shown in Table 9.7. The layout of the makeup air system is shown in Fig. 9.9.

Table 9.7 Makeup airflow rate in each kitchen workshop

Fig. 9.9

Makeup air system layout

9.3.3 Calculation Principle of Ventilation Duct and Vent Size

• (1) Kitchen Ventilation Duct

  • a. Kitchen exhaust duct: Kitchen exhaust fumes contain some particulate matter, and in order to effectively discharge it, air velocity of the exhaust duct should be increased appropriately. Air velocity in duct should be between 8 and 10 m/s, and the throat air velocity of exhaust duct joint should be in the range of 4–8 m/s.

  • b. Kitchen makeup air duct: The kitchen air supply duct is a positive pressure duct that conveyed the fresh air to the kitchen. When the air velocity is too high, the system resistance increases and the impact of ambient noise is aggravated. Therefore, the main duct air velocity should be 6–8 m/s, and the branch duct air velocity should be 3–5 m/s.

  • c. When the installation conditions permit, the aspect ratio of the rectangular duct should not be more than 4, and the maximum should not exceed 10.

• (2) Exhaust Hood and Diffusers

  • a. The plane size of the exhaust hood should be 100 mm larger than the size of the hearth, and the distance from the lower edge of the exhaust hood to the hearth should not be greater than 1.0 m, and the exhaust hood height should not be less than 600 mm.

  • b. The diffusers arrangement of makeup air system should avoid air outlet short-circuit phenomenon. The air supply vent should adopt the double shutter. The air velocity should be 2.5–4 m/s, generally, according to the requirement of noise, installation height and other factors, the makeup air vent velocity should be 2.0–4.5 m/s, and shielding rate of rainproof shutter can be 0.5.

• (3) Selection of Duct Material

  • a. The kitchen exhaust duct is made of 1.5 mm thick stainless steel plate with welding connection, and it needs to do 50 mm thick A-class fire insulation. The commercial kitchen centralized exhaust shaft should be lined with iron duct to ensure no air leakage.

  • b. Metal and composite materials can be used as makeup air duct to meet the technical requirements of corrosion resistance, fire resistance, and smooth surface.

9.3.4 Pressure Loss for Duct and Fan Selection

The calculation method of pressure loss for exhaust system can be found in Sect. 8.2.

This case is based on the summer meteorological parameters in Xi’an, China. Taking the selection of exhaust fan for terminal workshop (No. 07) as an example, the calculation result is given according to the exhaust system diagram (see Fig. 9.10) and the pressure loss calculation method.

Fig. 9.10

Exhaust system diagram

It can be obtained from the above calculation that the design airflow rate of workshop 07 is L₀₇ = 3834 m³/h, and the total pressure loss is P₀₇ = 238 Pa. The additional coefficient of air leakage in the ventilation system is 1.1, and the additional coefficient of the total pressure loss is 1.15, and therefore, the selection parameters of the exhaust fan of workshop 07 are shown in Table 9.8.

Table 9.8 Workshop (No. 07) exhaust fan type selection

Likewise, with the help of resistance calculation software, the fans used in this case are given in Table 9.9.

Table 9.9 Exhaust fans selection

9.4 Ventilation Design for a Commercial Kitchen B in China

This case mainly introduces the design of ventilation and air-conditioning system in a five-star hotel kitchen, with a total construction area of 1307 m² in the kitchen area of the hotel and a building height of 5.7 m. The kitchen is divided into two fire compartments, with an area of 334 and 973 m², respectively. The kitchen is located on the basement of the hotel, and the layout of various kitchen workrooms and the necessary equipment are given. The kitchen layout basically contains all the functional areas of the large catering kitchen, such as storage zone, rough processing zone, cold dish processing zone, flour pastry pantry zone, cooking zone, steaming zone, roasting zone, preparation area, dishwashing zone, waste sorting area, and staff rest area, as shown in Fig. 9.11.

Fig. 9.11

Equipment layout of a five-star hotel kitchen

Kitchen ventilation system design generally includes a general exhaust ventilation system (room ventilation), local exhaust system (range hood), and makeup air system. In this case, considering the function division and process flow of the star hotel kitchen, a comprehensive analysis and calculation of the ventilation system of a large catering kitchen are carried out.

9.4.1 Ventilation Categories in Kitchen

According to the kitchen division of functions and process flow, the ventilation system is divided as follows:

• (1) General exhaust ventilation

Although the stove and other equipment in kitchen do not work when the staff prepares for cooking, each area of the kitchen still has some heat and odor, and an exhaust system needs to be set up.

• (2) Local exhaust ventilation

Kitchen local exhaust system consists of two main types: One is the so-called exhaust fume ventilation system, which is used to exhaust and purify the kitchen fume and to eliminate the odor, and the other is the ventilation system, used to exhaust vapor and waste gas, which does not contain purification treatment.

• (3) Makeup air system

Kitchen makeup air system is the fresh air system, which can be divided into natural makeup air and mechanical makeup air according to the dynamic characteristics, can be divided into no cold air supply and cold air supply according to the treatment method. For large kitchens, in order to improve the thermal and humid environment of the workers, it is usually necessary to cool the fresh air in summer and to heat it in winter. The supply air should be controlled at 26–28 °C in summer and 12–15 °C in winter. In this design, the supply air temperature for the kitchen is 27 °C in summer and 15 °C in winter, and the fresh air in the rest zones is not treated.

9.4.2 Exhaust Airflow Rate

There are a variety of methods for the calculation of exhaust airflow rate. The three common methods used in this case are shown in Table 5.19 of Chap. 5.

The kitchen and exhaust hoods parameters are shown in Table 9.10, and the calculation results of exhaust airflow rate of different calculation methods are shown in Table 9.11.

Table 9.10 Summary of kitchen and exhaust hoods parameters

Table 9.11 Calculation results of exhaust airflow rate of different calculation methods

Comparing the results of the three calculation methods, the maximum of the three is adopted as design airflow rate of exhaust system. It should be noted that the exhaust hood size is the same in the steaming zone and cooking zone, and the exhaust hood of the steaming zone is set on both sides by the wall. Compared with the setting of the exhaust hood in the cooking zone, the exhaust airflow rate of the steaming zone should be calculated by the exhaust hood isobaric surface method. The calculation method of exhaust airflow rate for the dishwashing zone should be selected according to the requirements of the process. When the process cannot provide specific parameters, it should be calculated according to the exhaust hood area method.

According to the above analysis and design principles, the exhaust airflow rate value for kitchen workshop ventilation design is shown in Table 9.12, and the air duct plane diagram of the fume exhaust system is shown in Fig. 9.12.

Table 9.12 Exhaust airflow rate for kitchen workshop ventilation design

Fig. 9.12

Air duct plane diagram of the fume exhaust system

9.4.3 General Ventilation Airflow Rate

According to the function of kitchen workshops and the requirement of air change rate, the calculation results of the general exhaust ventilation of each zone are summarized as shown in Table 9.13. The air duct plan of general exhaust ventilation is shown in Fig. 9.13, and the makeup air system plan is shown in Fig. 9.14.

Table 9.13 Overall ventilation rate of the rooms in the kitchen area (except for the thermal workshops)

Fig. 9.13

Air duct plan of overall exhaust system

Fig. 9.14

Makeup air system plan

9.4.4 Makeup Airflow Rate

The overall ventilation system of the kitchen adopts outdoor air without cold and heat treatment. Table 9.13 gives the makeup airflow rate required for the general ventilation of the rooms. The ventilation system of the kitchen is a DC system. The makeup airflow rate should be 80–90% of the exhaust airflow rate and 80% is adopted in this design, and the rest of the required makeup air (20%) is taking from the surrounding area. The calculation results of the makeup airflow rate of kitchen thermal workshops are shown in Table 9.14.

Table 9.14 Makeup airflow rate of kitchen thermal workshops

9.4.5 Pressure Loss for Duct and Fan Selection

Calculation principle of ventilation duct and vent size can be seen in Sect. 9.3.3; the equation for calculating the loss of pressure of a duct system can be seen in Sect. 8.2.

Take exhaust system PYY-1 of roasting zone for example (see Fig. 9.15), the calculation result is given on the basis of the exhaust system and the calculation of pressure loss.

Fig. 9.15

Exhaust system PYY-1 of roasting zone

Similarly, we can get the design airflow rate of roasting zone is L = 13392 m³/h, and the total pressure loss is ΔP = 495 Pa. The additional coefficient of air leakage in the ventilation system is 1.1, and the additional coefficient of the total pressure loss is 1.15, and therefore, the selection parameters of the exhaust fan of roasting zone are shown in Table 9.15.

Table 9.15 Roasting zone exhaust fan type selection

Likewise, with the help of resistance calculation software, the fans used in this case are given in Table 9.16.

Table 9.16 Exhaust fans selection

9.5 Ventilation Design for an Institutional School Kitchen in Europe

The project describes an institutional kitchen ventilation design in European school kitchen. The school kitchen makes 1500–2000 meals for children and staff each day. The total food production area and dishwashing area of the kitchen area are 153 and 41 m², respectively. The height of the spaces is 2.6 m.

The school kitchen operates every weekday between 6:00 a.m. and 15:00 p.m. In the kitchen, there is working altogether six persons for cooking and serving the dishes. In Fig. 9.16, the kitchen appliance blocks and hoods are shown. In the kitchen, there are four hoods of which two dedicated in the food production area (Hoods 1 and 2), and two other hoods are installed in the dishwashing area (Hoods 3 and 4). In Table 9.17, direct heat load and the kitchen appliances are presented.

Fig. 9.16

Layout of an institutional school kitchen and the location of kitchen appliance blocks

Table 9.17 Kitchen appliances and block

The airflow rates of the food production area are calculated using the convection flow-based design method (see details of the design equations in Sect. 5.2.6). Table 9.18 presents the design parameters, the required exhaust airflow rates, and the dimensions of hood for the kitchen blocks 1 and 2.

Table 9.18 Exhaust airflow rates and the dimensions for kitchen appliance blocks

In this case, the installation height of the kitchen hood is 1.0 m over the appliances. The dimension of kitchen hood is 0.3 m larger than the appliance.

The hoods over the dishwashing area are designed to remove moisture of the washing machine. In the case kitchen, tunnel type of the dishwashing machine released average 13 kg/h of moisture, and the other smaller washing machine generates 10.4 kg/h. In this design by keeping the absolute humidity difference between the supply and exhaust air 6 g/kg, dry air, this means that the airflow rate of 0.5 and 0.4 m³/s are required, respectively.

Figure 9.17 presents the scheme of ventilation duct work and hood installation. The total exhaust airflow rate of four hoods is 4.0 m³/s. In the kitchen together with hood exhaust airflow rate, there is also general exhaust of 300 l/s to capture heat loads not captured with hoods. Thus, the total exhaust airflow rate is 4.3 m³/s in the kitchen. In this case, the total pressure drop of exhaust duct work and hood is 270 Pa.

Fig. 9.17

Scheme of hood installations and duct work of an institutional school kitchen

The supply airflow rate is 3.9 m³/s. The supply airflow rate is 90% of the exhaust airflow rate to keep the kitchen area slightly under pressure compared with the surrounding dining area. In this design solution, a part of the makeup air is supplied through supply unit integrated in the hoods. The rest of the makeup air is released from the ceiling diffusers.

9.6 Ventilation Design for a Restaurant Kitchen in Europe

The project describes a restaurant kitchen ventilation design in Europe. The total kitchen area is 55 m² (11 m (L) × 5 m (W)). The restaurant kitchen operates every day between 10:00 a.m. and 23:00 p.m. Figure 9.18 shows kitchen layout and the location of appliance blocks. Table 9.19 shows direct heat load and the kitchen appliances.

Fig. 9.18

Layout of a restaurant kitchen and the location of the kitchen appliance blocks

Table 9.19 Kitchen appliances and block

In the kitchen, there are four hoods of which three are dedicated in the food production area (Hoods 1–3), and one hood is installed in the dishwashing area (Hood 4). The airflow rates of the food production area are calculated using the convection flow-based design method (see details of the design equations in Chap. 5.2.6). Table 9.20 presents the design parameters, the required exhaust airflow rates and the dimensions of hood for the kitchen blocks.

Table 9.20 Exhaust airflow rates and the dimensions for kitchen appliance blocks

In restaurant kitchen, all appliances are assumed to be used in the same time. Thus, the simultaneous factor is 1.0. The dishwashing machine is a closed type, and the hood is designed based on the heat load. In this case, the installation height of the kitchen hood is 1.0 m over the appliances.

Figure 9.19 presents the scheme of ventilation duct work and hood installation. The total exhaust airflow rate of four hoods is 2.2 m³/s. In the kitchen together with hood exhaust airflow rate, there is also general exhaust of 200 l/s to capture heat loads not captured with hoods. Thus, the total exhaust airflow rate is 2.4 m³/s in the kitchen. In this case, the total pressure drop of exhaust duct work and hood is 250 Pa.

Fig. 9.19

Scheme of hood installations and duct work of a restaurant kitchen

The supply airflow rate is 2.16 m³/s. The supply airflow rate is 90% of the exhaust airflow rate to keep the kitchen area slightly under pressure compared with the surrounding dining area. In this design solution, a part of the makeup air is supplied through supply unit integrated in the hoods. The rest of the makeup air is released from the ceiling diffusers.