Mechanical and Materials Engineering, Department of
Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research
First Advisor
Bruce I. Dvorak
Committee Members
Robert Williams, Qilin Guo
Date of this Version
8-2025
Document Type
Thesis
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Mechanical Engineering and Applied Mechanics
Under the supervision of Professor Bruce I. Dvorak
Lincoln, Nebraska, August 2025
Abstract
This thesis examines the economic and environmental effects of electric and steam shrink-wrapping tunnels used in beef packaging processes, paying particular attention to the indirect refrigeration loads caused by the heat and humidity that each system releases. Traditional sustainability evaluations frequently ignore these indirect impacts, which are especially important in meat processing facilities where 45–55% of electricity use is attributed to refrigeration. Life cycle assessment (LCA), field measurements, and thermodynamic modeling are all used in this work to offer a thorough analysis of both tunnel types.
The case study facility in Nebraska operates both steam and electric shrink tunnels to process the same mass of meat, allowing direct comparison. The electric tunnel consumed an estimated 57,600 kWh of electricity per year, while the steam tunnel used 4,644 kWh (excluding steam production). However, the steam tunnel utilized 4,800 MMBTU of natural gas per year. Furthermore, the electric tunnel only increased refrigeration demand by 0.50 kWh/hr, but the steam tunnel increased it by 14 kWh/hr due to greater heat loss and moisture emissions.
From a life cycle perspective, considering the current Nebraska electricity grid, the electric tunnel outperformed the other in the majority of environmental impact areas linked to air emissions, such as respiratory impacts, smog generation, and global warming potential. The increased environmental burden resulting from its manufacture, especially in areas linked to human health- non-carcinogenic and ecotoxicity, partially offsets these advantages. The electric tunnel's operational benefits were further enhanced when the extra refrigeration energy needed to control heat and humidity was considered. An additional scenario using a decarbonized electricity grid, such as the French grid, was also assessed. Results indicate that electric tunnels performed better than steam tunnel across all the environmental categories as electricity becomes cleaner. Overall, the LCA results show that, when both direct and indirect energy usage are considered, the electric tunnel has reduced environmental consequences in the most policy-relevant impact areas. Cost research showed that the electric tunnel offers a shorter payback period and cheaper yearly utility expenses, even after accounting for the additional need for refrigeration. According to the findings, electric shrink tunnels may be a more economical and environmentally friendly choice, especially when indirect refrigeration effects are considered.
Advisor: Bruce I. Dvorak
Comments
Copyright 2025, Segun Samuel Oladipo. Used by permission