Tunnel ovens typically consist of a series of open-ended baking chambers that are connected with a metal belt that passes through them. Also available are tray ovens, which consist of a rigid baking platform that is carried on a chain belt. Products baked using a tunnel oven can either be baked directly on the hearth or within a pan.
Tunnel ovens can be divided into two general categories: direct gas fired tunnel and indirect gas fired tunnel. Direct gas fired tunnel ovens bake products using air turbulence. This method of baking takes a shorter amount of time, and it also ensures that the product is baked uniformly and that they have strong side walls. Direct gas fired tunnel ovens feature a set of thermocouple sensors that provide zoned temperature controls and regulate the baking chamber’s overall temperature. The ovens also feature a hearth that is either made from steel, stone, or mesh, the latter of which allows for air circulation and an even patterning on the underside of the product. Direct gas fired tunnel ovens feature a set of ribbon burners that are located both above and below the hearth, and evenly distribute heat. With all of these features, the oven’s operator is able to bake the product with more accuracy and precision.
Within an Indirect gas fired tunnel oven, the burners can function with the use of oil, propane, or gas. The burners fire into a combustion chamber, which supplies the heat that radiates throughout the baking chamber. This system allows the product to bake within heated ambient air as opposed to direct exposure to the heat of the burners. Like their direct gas fired counterparts, Indirect gas fired tunnel ovens feature a mesh hearth that enables air to circulate throughout the chamber and uniformly bake the bottom of the product as it moves across the conveyor. Other features that can be found in an Indirect gas fired tunnel oven include steam zones, and upper and lower zones that allow for more precise baking control.
There are other types of tunnel ovens available, including:
- Hybrid, which allow for the combination of heating technologies, which allows for more than one heating method to be used within a single machine. Common combinations include any combination of direct gas fired, indirect gas fired, and impingement.
- Dual fuel, which features two heating systems that work independently from one another, such as electric and fuel oil, for example. One source can make up for another source if it is unavailable. Because dual fuel ovens are equipped with a backup heat source, they can minimize downtime, product waste, and turnaround times, especially in facilities with inconsistent energy sources.
- Electric, which serves as the perfect alternative to a gas-based source if it is not available.
- Thermal oil, which is the recommended tunnel oven choice for baking products with radiant heat with static air. The oven heats the oil and the heat is circulated throughout the chamber, creating a soft and evenly distributed radiant heat.
- Radiant tube, which utilizes a set of ducts that are fired into by a burner. The heated gases travel through the tubes, enabling the oven to generate heat throughout the chamber.
- Infrared, which delivers infrared heat across the oven, and is ideal for applications such as surface browning, melting product toppings, drying, and other high-temperature applications.
- Air impingement, which breaks through a product’s thermal boundaries using hot air that is forced over the surface of the product at a high speed. These ovens are highly energy efficient and keep operating costs low.
There are many benefits to using a tunnel oven. A tunnel oven allows for a continuous production cycle of items, especially food. They also require little to no turnaround time between batches. They are often found in the food industry and are used to bake food items ranging from breads to meats. They are also used in the automotive industry, such as the curing of materials for automotive parts. Many companies who manufacture tunnel ovens offer the option of customization by analyzing the desired dimensions, capacity, resources, and the size conditions of the facility to ensure that the customer’s requirements are met. They also offer different types of baking surfaces as well as additional features that allow for humidity and temperature control, which will help you accurately regulate the application’s color, moisture content, and surface temperature. Manufacturers will assist you in finding the right tunnel oven that will enable you to fabricate products of better quality with a fast turnaround time, all at a low production cost.
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