Darin W. Nutter

A Ground Resistance for Vertical Bore Heat Exchangers With Groundwater Flow

A new ground resistance was developed for use in existing vertical bore heat exchanger (VBHE x ) design algorithms. The new ground resistance accounts for the added heat transfer mode of convection due to groundwater flow by using as its foundation the solution for a moving line heat source. The combined ground resistance is presented in terms of the dimensionless Fourier and Peclet parameters. Results show that significant convection heat transfer may occur within a variety of hydrogeological regimes, particularly when the Peclet number is larger than 0.01. Since the new model captures the influence of groundwater flow, the resulting ground resistance differs markedly from the conduction-only ground resistance currently used in many vertical borehole heat exchanger design algorithms.

Invited review: Environmental impacts of dairy processing and products: A review

The objective of this review is to summarize research efforts and case studies to date of the environmental impacts from dairy processing. The pervasiveness of greenhouse gas emission, water use, consumer waste, and other environmental impacts of dairy are described. An outline of the method of choice, the life cycle assessment, for conducting research and deciding appropriate allocation of the impacts is provided. Specific research examples in dairy processing highlight how the representative final product is associated with environmental impacts to air, water, and land. The primary conclusion from the study was the usefulness of life cycle assessment methodology and the need for further research due to limited studies, variable data, and the magnitude of environmental impact.

Computer simulation of energy use, greenhouse gas emissions, and process economics of the fluid milk process1

Energy-savings measures have been implemented in fluid milk plants to lower energy costs and the energy-related carbon dioxide (CO2) emissions. Although these measures have resulted in reductions in steam, electricity, compressed air, and refrigeration use of up to 30%, a benchmarking framework is necessary to examine the implementation of process-specific measures that would lower energy use, costs, and CO2 emissions even further. In this study, using information provided by the dairy industry and equipment vendors, a customizable model of the fluid milk process was developed for use in process design software to benchmark the electrical and fuel energy consumption and CO2 emissions of current processes. It may also be used to test the feasibility of new processing concepts to lower energy and CO2 emissions with calculation of new capital and operating costs. The accuracy of the model in predicting total energy usage of the entire fluid milk process and the pasteurization step was validated using available literature and industry energy data. Computer simulation of small (40.0 million L/yr), medium (113.6 million L/yr), and large (227.1 million L/yr) processing plants predicted the carbon footprint of milk, defined as grams of CO2 equivalents (CO2e) per kilogram of packaged milk, to within 5% of the value of 96 g of CO 2e/kg of packaged milk obtained in an industry-conducted life cycle assessment and also showed, in agreement with the same study, that plant size had no effect on the carbon footprint of milk but that larger plants were more cost effective in producing milk. Analysis of the pasteurization step showed that increasing the percentage regeneration of the pasteurizer from 90 to 96% would lower its thermal energy use by almost 60% and that implementation of partial homogenization would lower electrical energy use and CO2e emissions of homogenization by 82 and 5.4%, respectively. It was also demonstrated that implementation of steps to lower non-process-related electrical energy in the plant would be more effective in lowering energy use and CO2e emissions than fuel-related energy reductions. The model also predicts process-related water usage, but this portion of the model was not validated due to a lack of data. The simulator model can serve as a benchmarking framework for current plant operations and a tool to test cost-effective process upgrades or evaluate new technologies that improve the energy efficiency and lower the carbon footprint of milk processing plants.

Mitigation of greenhouse gas emissions in the production of fluid milk.

Global climate change, driven by the buildup of greenhouse gas (GHG) emissions in the atmosphere, is challenging the dairy industries in the United States and throughout the world to develop sustainable initiatives to reduce their environmental impact. The U.S. dairy industry has committed to lowering the GHG emissions, primarily CH(4), N(2)O, and CO(2), in each sector of the fluid milk supply chain which extends from the farm, to the processing plant, and to distribution of the packaged product, where it is refrigerated by the retailer and then the consumer. This chapter provides an overview of the life cycle analysis (LCA) technique and its use in identifying the GHG emissions in each sector of the fluid milk supply chain, from cradle to grave, and the best practices and research that is currently being conducted to reduce or mitigate GHG emissions in each sector. We also discuss the use of on-farm and off-farm process simulation as tools for evaluating on-farm mitigation techniques, off-farm alternative processing scenarios, and use of alternative energy management practices.

Computer simulation of energy use, greenhouse gas emissions, and costs for alternative methods of processing fluid milk1

Computer simulation is a useful tool for benchmarking electrical and fuel energy consumption and water use in a fluid milk plant. In this study, a computer simulation model of the fluid milk process based on high temperature, short time (HTST) pasteurization was extended to include models for processes for shelf-stable milk and extended shelf-life milk that may help prevent the loss or waste of milk that leads to increases in the greenhouse gas (GHG) emissions for fluid milk. The models were for UHT processing, crossflow microfiltration (MF) without HTST pasteurization, crossflow MF followed by HTST pasteurization (MF/HTST), crossflow MF/HTST with partial homogenization, and pulsed electric field (PEF) processing, and were incorporated into the existing model for the fluid milk process. Simulation trials were conducted assuming a production rate for the plants of 113.6 million liters of milk per year to produce only whole milk (3.25%) and 40% cream. Results showed that GHG emissions in the form of process-related CO₂ emissions, defined as CO₂ equivalents (e)/kg of raw milk processed (RMP), and specific energy consumptions (SEC) for electricity and natural gas use for the HTST process alone were 37.6g of CO₂e/kg of RMP, 0.14 MJ/kg of RMP, and 0.13 MJ/kg of RMP, respectively. Emissions of CO2 and SEC for electricity and natural gas use were highest for the PEF process, with values of 99.1g of CO₂e/kg of RMP, 0.44 MJ/kg of RMP, and 0.10 MJ/kg of RMP, respectively, and lowest for the UHT process at 31.4 g of CO₂e/kg of RMP, 0.10 MJ/kg of RMP, and 0.17 MJ/kg of RMP. Estimated unit production costs associated with the various processes were lowest for the HTST process and MF/HTST with partial homogenization at

Environmental Sustainability of Fluid Milk Delivery Systems in the United States

0.507/L and highest for the UHT process at

Measurement and Verification of Industrial Equipment: Sampling Interval and Data Logger Considerations

0.60/L. The increase in shelf life associated with the UHT and MF processes may eliminate some of the supply chain product and consumer losses and waste of milk and compensate for the small increases in GHG emissions or total SEC noted for these processes compared with HTST pasteurization alone. The water use calculated for the HTST and PEF processes were both 0.245 kg of water/kg of RMP. The highest water use was associated with the MF/HTST process, which required 0.333 kg of water/kg of RMP, with the additional water required for membrane cleaning. The simulation model is a benchmarking framework for current plant operations and a tool for evaluating the costs of process upgrades and new technologies that improve energy efficiency and water savings.

The effects of barometric relief dampers on internal static pressure, air quality, and energy consumption for a typical large-scale retail building

Beverage producers in the United States choose packaging based on cost and consumer preference. Monolayer high†density polyethylene (HDPE) and gable†top carton containers have long dominated the U.S. fluid milk market, but pressure for more sustainable packaging is increasing. We present a broad discussion on environmental sustainability of 18 fluid milk containers through life cycle assessment. Because different container types require unique milk processing, distribution, and disposal and incur or avoid milk losses, fluid milk delivery systems (FMDSs) are evaluated, rather than containers in isolation. By assessing FMDSs, a complete measure of containers’ environmental sustainability was obtained. Despite conservative assumptions about milk losses, differences in container size, milk processing, distribution, and container recycling, pair†wise cradle†to†grave comparisons of FMDSs show there are no superior FMDSs. But, 500†to 1,000†milliliter FMDSs are potentially superior to ≥half gallon if they prevent milk losses. Thus, the future of FMDSs in the United States depends on the industrys ability to prevent distribution (12%) and consumption milk losses (20% to 35%). Farm†gate†to†grave comparisons showed that chilled HDPE FMDSs are superior to other plastic and chilled paperboard FMDSs for climate†change impact, but the result is inconclusive for chilled HDPE to ambient (unrefrigerated) paperboard or plastic pouch FMDS comparisons. Plastic pouch FMDSs show potential to reduce nonrenewable fossil energy, but need to be recyclable. Ambient FMDSs are superior to chilled FMDSs for water depletion. Eight†ounce paperboard FMDSs are superior to 8†ounce plastic FMDSs. Thus, alternative FMDSs may improve environmental sustainability of the U.S. postfarm fluid milk supply chain.

Maintenance-cost modeling for a refrigerated-trailer fleet

ABSTRACTMeasurement and verification (M&V) of energy efficiency projects is an important activity for energy managers, government agencies, building owners, and utility representatives. Misapplication or misunderstanding of M&V protocol requirements can cause significant error in energy savings calculations. Additionally, incomplete knowledge of how common data loggers function can create confusion around the measurements being taken and the results being reported. This article seeks to further the understanding of data collection intervals, M&V costs, and M&V plan uncertainty. Additionally, a detailed description of how several types of electrical data loggers function is presented, showing the advantages and potential disadvantages of each.

Curriculum restructure to answer critical needs in packaging for energy efficiency/renewable energy systems, wireless, and mixed-signal systems areas

In order to prevent building over-pressurization, many roof-top units on large-scale retail buildings are equipped with barometric relief dampers. In this study, the effects of barometric relief dampers on internal static pressure, indoor air quality, and heating and cooling energy consumption for a typical large-scale retail building were investigated. The airflow characteristics of barometric relief dampers (i.e., the relationship between pressure drop and airflow rate) were first determined and incorporated into a building simulation model, which consisted of several thermal zones. The integration of building thermal simulation, multizone network method, and computational fluid dynamics was employed to perform the analysis. From the simulation results, it was found that the barometric relief dampers reduced building internal excess pressure by up to 7%. The CO2 concentrations were decreased up to 3% in the heating season, and the decrements were much less during the cooling season. This was primarily due to the additional fresh air infiltration entering the front entrance doors, caused largely by the presence of barometric relief dampers. Finally, for ASHRAE Climate Zone 4A, annual heating energy consumption was increased by 2%; however, the effect on annual cooling energy consumption was negligible.