Design of Experiments Modeling of a Heat Tunnel

There are many factors that contribute to heat losses in tunnels used in processing and this is an attempt to understand the factors that are significant in reducing the heat losses, with the long term goal of making design improvements to increase the efficiency of the equipment to provide value to the customer. Retaining the heat in a process heat tunnel is important for several reasons. Temperature settings, safety, environmental pollution and energy conservation are the major ones. As energy prices continue to escalate, economic benefits of energy conservation should be examined. State and federal teams are now pushing standards for ovens to gain energy efficiency; but many manufacturers feel that the upgrading of heat tunnel energy efficiency would affect their bottom line adversely. Heat tunnels present further challenges as they all incorporate openings to allow the conveyor and products to enter and exit the oven. These 'product apertures' require measures to reduce the escape of heat from the tunnel and the consequential increase in operating costs. The most common method in fast production lines is the use of curtains. The present study was performed to understand the direction that a designer should concentrate to maximize the process settings such as curtain design, temperature, conveyor speed, heat generation levels and insulation thickness. This was achieved by constructing a Design of Experiments (DOE) model to investigate the factors that affect heat losses at high (+) and low (-) levels.