a KitchenExhaust is a Kitchen Hood Exhaust calculation software designed for Android phone OS.  It is specially engineered by a professional engineer for design mobility & quick calculations.

Aim: creating a mobile design environment for the practising engineers & designers in today's mobile world.

Results: Instant solutions at your fingertips.

Highlights:

• calculate kitchen exhaust airflow rate for various built-in hood configurations in accordance to Singapore Standard SS 553 (formerly CP 13)

• grease filter sizing

• louvre opening sizing

• built-in data, guides

• in SI-IP units

see aKitchenExhaust explained

Software design features: practical. . . 

The software is designed to be user friendly and flexible with built-in guides and explanations. The built-in hood configurations for ease of calculations are:

• island hood

• 1-side wall-mounted

• 2-side wall-mounted

• 3-side wall-mounted  

Methods: Calculating Exhaust AirFlow Rate. . . 

There are many methods available to calculate the required exhaust airflow rate, namely:

• Capture / Face Velocity Method

• Linear Extract

• Thermal Convection/Heat Load Method

• Appliance Power Input

• Air Changes                                           

Every country has its own local code of practice to calculate the required exhaust airflow rate. The exhaust flowrate calculation presented in aKitchenExhaust software is based on SS 553 (formerly CP 13). SS 553 uses the Capture (Face) Velocity Method. CIBSE and Australian Standard AS 1668.2 adopt the similar approach, but not exactly the same.

The governing parameters used in determining the exhaust flowrate are:

• capture (face) velocity

• perimeter of hood (open sides)

• distance from stove top to hood bottom

The exhaust flowrate in SS 553 is as follows:

Q = 1.4*Vel*2(L+W)*H*F . . . for island hood

where Q = exhaust flowrate (m3/s)

            Vel = capture velocity (m/s)

                L = hood length (m)

              W = hood width (m)

               H = distance of hood to emitting surface (m)

                F = factor

Comparisons between SS 553 (formerly CP 13) and AS 1668.2 . . . 

The exhaust flowrate calculations of SS 553 (formerly CP13) vs AS 1668.2 are presented below:

SS 553 (formerly CP 13)  

Q (m3/s) = [1.4 x Vel x Factor] x Perimeter x Height

Q = [0.294 to 0.42] x P x H (based on Vel = 0.3 m/s)

AS 1668.2  

Q (m3/s) = [Vel factor/1000] x Perimeter x Height 

Q = [0.15 to 0.75] x P x H

Understanding the Capture (Face) Velocity Method in SS 553 (formerly CP 13)  . . . 

An important point to note is that in SS 553, the capture (face) velocity is based on the vertical face area of hood open sides as illustrated in Sketch A. It is not based on the hood base area as shown in Sketch B. Therefore, the distance from stove top to hood bottom, i.e., H and the number of hood open sides will greatly affect the exhaust airflow required.

To account for the different type of cooking, a multiplying Factor is employed in SS 553 for simplicity in calculation. For heavy duty cooking, a Factor of 1 is used. For light and medium duty cooking, a Factor of 0.7 is applied. Indirectly, this can be translated to design face velocity varying from 0.21 m/s (for low/medium duty cooking) to 0.3 m/s for heavy duty cooking.