Year: 2013
Type: dissertation
Abstract: The aim of this project was to benchmark energy utilisation of bread manufacturing and to provide methodologies and results with the aim of improving efficiency in \ncommercial bakeries. The bread industry is an important provider of staple food products across the world. Owing to the large energy use in bread manufacturing, bakeries have come under increased scrutiny to reduce their environmental impact. \n \nThe proving process exposes dough to heat and humidity in order to encourage yeast activation. Provers (responsible for 5 % of carbon emissions in bakeries) are \nover-engineered to the extent that energy costs impact upon performance. The industry standard practices that use large volumes of airflow to maintain food safety have not been scientifically justified. Experimentally validated \nComputational Fluid Dynamics (CFD) simulations showed the residence time distribution profiles for different numbers of air changes. The results have indicated \nthat it is possible to reduce airflow by 33 % and electricity demand by over 70 %. \n \nA system-level thermodynamic analysis was developed in order to measure and model heat streams in industrial bread ovens. The model was subjected to a sensitivity analysis to ensure the calculations could be trusted to give suitably \naccurate results. A number of measurement techniques were employed and the methodology was designed to increase the potential for industry-wide use to assess the efficiency of ovens. The results showed that between 40 and 49 % of heat is wasted in industrial ovens. The model has been successfully distributed to industry. \n \nExperimental measurements of heat transfer for a range of regimes used in baking ovens were undertaken. The results were validated by previous correlations \npublished in literature. Investigation focussed on three particular novel research areas. Firstly, comparisons between nozzle types showed that rows of circular jets \ncould be approximated as slot nozzles for mean heat transfer. Secondly, the ratio of convective to radiative heat transfer was investigated. Thirdly, the prevalence of \nsecondary peaks in local heat flux profiles was compared for two nozzle sets. These unique results can be used to help design baking ovens with energy efficient \noperating conditions.
Author: Joe Paton
Language: English
Field: Energy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1565949986