Abstract
The baking process demands a high amount of energy, but only one-third of the total energy supply to the baking oven is actually used for baking, while the rest is dissipated to the environment. This implies that the energy input to the baking process can be significantly reduced, e.g., by enabling a more efficient heat transfer to the product, compared to commercially available ovens. Application of highly radiative, gas-fired heat sources, with a wide power modulation range, such as porous volumetric ceramic burners (VCB), can lead to a reduction in both the baking time and the energy input to a baking oven. In order to optimize energy input to a wide variety of baking products, the role of individual mechanisms in heat transfer between a heat source and a baking product needs to be determined. In the scope of this work, the analysis of the heat transfer within a baking oven model, heated by porous VCBs, was conducted. Contribution of heat transfer mechanisms (heat conduction, convection, thermal radiation) to the total heat transfer was determined by the difference method, where two aluminum cubes of different surface characteristics were used as target objects. Further, the influence of water, commonly added to the baking chamber in form of steam or aerosol, on the heat transfer characteristics within the oven was investigated. Without water addition, the heat transfer between the porous VCBs and the test object occurred mainly through thermal radiation (~45%), followed by heat conduction and convection (~27.5% each). Compared to the reference, commercially available electrical deck baking oven, the share of thermal radiation in the model oven was increased (+ 10%), whereas the share of heat conduction was reduced (−20%). With water addition, the heat transfer to the test object through heat conduction, convection, and thermal radiation declined, as an additional heat transfer through condensation took place. Results of this research provide necessary understanding of the heat transfer mechanisms within the novel baking oven, heated by porous VCBs. They are the base for optimization of the heat transfer from the VCBs to different baking goods, through changing the VCB's operating parameters.
Highlights
The annual energy use of the food industry in Germany is ∼58 TWh, out of which some 6 TWh is used for pastry production (Blesl and Kessler, 2017)
The temperature in the center of the black cube (BCI, Black painted Cube on the baking Plate (BCP)) was higher compared to the temperature of the polished one (PCI, Polished Cube on the baking Plate (PCP)), due to the additional heat transfer by thermal radiation
A very small temperature difference between BCP and Black painted Cube on the Insulation layer (BCI), as shown in Figure 5A, indicates that the heat transfer through heat conduction was negligible compared to heat transfer through thermal radiation
Summary
The annual energy use of the food industry in Germany is ∼58 TWh, out of which some 6 TWh is used for pastry production (Blesl and Kessler, 2017). The most energy-intensive step within the pastry production is the baking, with the average energy demand of 7 MJ per kg of bread (Fellows, 1996). The energy-saving potential of the baking industry is correspondingly high, whereas the energy efficiency of baking ovens is the key factor for energy management within this food production branch. Besides an extremely wide regulation range in terms of thermal power (1:20 or more) and, in terms of temperature, the radiation-to-convection heat transfer between this burner type and a heated object is high, compared to state-of-the-art ovens, with a positive effect on the baking process, e.g., preserved product quality at reduced baking time
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
