Rack Oven Direct-Fire Heating With Flame-Protected Gas Recirculation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Commercial rack ovens waste heat and energy due to inefficiencies in heat exchange between combustion gases and cooking air, leading to reduced efficiency in heating the cooking chamber and food products.
Innovation Solution
A rack oven design that recirculates gases from the cooking chamber past a burner with a flame protector to prevent gas extinguishment, allowing direct use of combustion exhaust gases for heating, and includes a blower to circulate gases at varying rates depending on oven size, with a pre-mixer and mesh structure burner for efficient combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If combustion exhaust gases are circulated through heat exchange tubes to heat cooking air, then the cooking chamber is heated, but significant heat and energy are lost in the heat exchange process
Solution Approach 1:
The patent extracts the harmful heat loss from the traditional heat exchange system by eliminating the heat exchange tubes and direct combustion gas circulation. Instead, it uses a flame protector to prevent combustion gases from directly contacting and extinguishing the burner flame, while still allowing the burner to heat the cooking chamber efficiently through direct radiation and convection from the flame itself.
Solution Approach 2:
The flame protector acts as an intermediary element that allows the system to benefit from both combustion gas flow (for atmosphere and moisture control) and efficient heating (through protected direct flame contact with the cooking chamber). It mediates between the conflicting requirements of gas circulation and flame stability.
2Productivity
If combustion gases are circulated at high rates to improve heating, then heating efficiency increases, but the burner flame may be extinguished by the gas flow
Solution Approach 1:
The flame protector serves as a physical barrier and intermediary structure that shields the burner flame from the high-velocity combustion gases. This allows the system to maintain high gas circulation rates for improved heating productivity while the flame protector ensures flame stability by preventing direct gas impingement on the flame.
Solution Approach 2:
The flame protector can be implemented as a mesh structure or screen that allows gas passage while providing sufficient protection. The mesh or screen structure acts as a flexible barrier that maintains flame stability while permitting the necessary gas flow for heating and atmosphere control.
3Reliability
If a flame protector is added to prevent burner extinguishment, then flame stability is maintained, but device complexity increases
Solution Approach 1:
The flame protector is implemented as a relatively simple mesh structure or screen rather than a complex mechanical system. This mesh implementation provides effective flame protection while adding minimal structural complexity to the overall oven system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances energy efficiency by utilizing wasted heat from combustion gases, maintaining a stable flame, and optimizing airflow to improve heating efficiency across different oven sizes, reducing energy loss and improving cooking performance.
Implementation Method 1
delivering gaseous fuel and oxygen to a burner in a combustion zone
Implementation Method 2
moving gases along a circulation flow path from the cooking chamber past the burner to pick-up heat and combustion gases
Implementation Method 3
utilizing a flame protector in the circulation flow path upstream of the burner such that gases moving past the burner do not extinguish the burner
Data Source
AI summary
A rack oven includes a cooking chamber accessible via a door and a rack rotating mechanism within the cooking chamber. A combustion chamber is separated from the cooking chamber by at least one wall, the combustion chamber including a burner. A circulation flow path is provided for delivering gases from the cooking chamber into the heating chamber and past the burner in the combustion zone to pick-up heat and combustion gases for delivery back to the cooking chamber to heat the cooking chamber. A flame protector located in the heating chamber in the circulation flow path upstream of the burner prevents gases moving past the burner from extinguishing the burner.