Municipal solid waste (MSW) generation continues to increase exponentially, leading to the need for better disposal methods. Approximately 50% of the MSW is landfilled in the United States (US). Landfilling is known for its negative effects on the environment and human health. The objective of this study was to conduct a life cycle assessment (LCA) of some of the most common waste treatment methods and propose an alternative and environmentally friendly integrated waste management method (IWM). The LCA was conducted using OpenLCA. Replacing landfilling, incineration, and composting with recycling, gasification, and anaerobic digestion (IWM) reduced the global warming potential from 899 kg CO2 eq to −14.6 kg CO2 eq. The same trend was observed for acidification (from 0.21 kg SO2 eq to −1.1 kg SO2 eq), ecotoxicity (from 2363.8 CTUe to 1.22 CTUe), eutrophication (from 0.5 kg N eq to 0.3 kg N eq), smog formation (from 4.4 kg O3 eq to 1.85 kg O3 eq), ozone depletion (from 2.1 × 10−5 kg CFC-11 eq to 0 kg CFC-11 eq), respiratory effects (from 2.8 × 10−3 kg PM2.5 eq to −7.25 × 10−3 kg PM2.5 eq), cancer (from 2 × 10−5 CTUh to 1.2 × 10−7 CTUh), and non-cancer effects (from 6 × 10−5 to 1.4 × 10−5 CTUh). The results show that an integrated waste management approach with recycling, gasification, and anaerobic digestion can dramatically reduce the environmental and health impacts of municipal solid waste disposal. Policy reforms, technical innovation, economic investment, and social engagement are needed to change waste management paradigm.

This study aims to examine the membrane wetting of a porous cylindrical surface in comparison with dense cylindrical surfaces. Droplets of distilled water, ethyl alcohol, and 35 g/L NaCl solution with an average volume of 5 mu l were deposited on a hydrophobic polypropylene (PP) cylindrical membrane with micropores, a dense polypropylene (PP) cylindrical membrane, and a stainless-steel cylinder, to investigate their temporal wettability behavior. The diagnostics consisted of backlight imaging using a high-speed camera. The droplet spreading was characterized in terms of the droplet base length and the droplet contact angle as a function of time. The study found that the temporal evolution of the contact angle of droplets on dense and porous surfaces is connected to the dynamics of the droplet base. The droplet base undergoes three stages: expanding base, constant base, and finally shrinking base. The study found that for a porous PP membrane, the contact angle decreased exponentially in the initial stage and then linearly over time, indicating the initial dominance of absorption followed later by evaporation. In contrast, dense surfaces exhibit a linear decrease in contact angle, emphasizing pure evaporation with no absorption. A theoretical model for the temporal evolution of the contact angle due to evaporation was developed and the model was successful in correlating the experimental data during the second and third stages. The present study also developed simplified linearized correlations for the temporal evolution of droplets for all three stages. The findings for the time-dependent wetting behavior of PP membranes with micropores demonstrated that even hydrophobic porous materials can become wet due to the liquid's infiltration on the hydrophobic porous surface.

This paper presents the primary breakup of liquid sheet under the influence of crossflow. The atomization of liquid sheets is important for many applications, e.g., agricultural sprays, fuel atomization, and spray coatings, among others. The aerodynamic effects on the liquid breakup process is investigated experimentally to identify the breakup regime transitions. A subsonic wind tunnel was used to simulate the crosswind effects on flat fan nozzle spray. Two flat fan nozzles sizes were tested in this study. High-speed digital imaging technique was used to measure the breakup regime transitions, the location of the end of the liquid core, the breakup time, the location, and size of droplets at onset of breakup and the spray trajectory. The results were correlated using phenomenological analyses. The aerodynamic effects were responsible for initiating bag breakup and reducing the droplet sizes which are susceptible to drift. This would be problematic for spraying herbicides in windy conditions.

This paper focuses on a a solar energy-based project aimed at water desalination and purification. The project's objective is to establish an economically viable and sustainable approach to water heating and desalination, offering benefits to global communities. The project team has devised a solar heating system utilizing a Fresnel array-inspired setup, intended to complement a desalination system employing membrane distillation, which necessitates water heating. The primary focus has been on designing an efficient solar receiver to absorb solar energy for water heating. Moreover, the team has developed equations for concentrator mirror angles across various days, generating charts indicating optimal mirror angles and spacing between mirror rows for different solar times. Project outcomes involve applying heat transfer loss theory via conduction across individual receiver layers, conducting experiments to assess coating efficiency and receiver performance. The team successfully assembled the system with four parallel mirror rows, spaced at 1.5 feet intervals to minimize shadow casting. The solar receiver features two glass tubes, air gaps held by 3D-printed end caps, and an internal mesh turbulator to enhance heat transfer through flow turbulence. The ultimate objective was to heat water sufficiently for membrane distillation (around 40°-70°C). Experimental testing on a windy day with clouds resulted in a final water temperature of 38°C after 3 hours. Receiver efficiency, calculated by comparing solar energy incident on the pipe to energy transferred to water, was 17.5%. While not within the desired range, these promising results, considering surrounding conditions, deem the project successful in creating an efficient heating system for membrane distillation. Recommendations and improvements are possible, confirming the project as a successful proof of concept.

Refrigeration accounts for 20% of the world's overall electricity consumption, and the global demand for refrigeration could more than double by 2050. 1 Improvements to the refrigeration cycles are needed to offset the increase in energy consumption. This article quantifies the effect of heat transfer between the compressor and the expander on the coefficient of performance (COP) of the conventional mechanical vapor compression cycles.

The injection of choked gaseous jets into the still air is investigated experimentally motivated by many industrial applications including flares and burners. The objective is to study the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into the still air, seeded with water fog. The computational methods consisted of 7.7 x 10(6) cells simulation using star ccm+. The test conditions include injection angles of 0 deg, 15 deg, and 30 deg. The results including mean and fluctuating velocities and the flow vorticity are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

Advancements in lean premixed combustion have increased the efficiency and reduced the amount of greenhouse gas emissions, but they have led to increased noise emissions due to higher turbulence and mixing fluctuations. This study used an external sensor (microphone) to validate the simulation of the combustion noise of a confined space. An experimental facility with a laboratory-scale furnace was used to carry out the measurement, and the simulation of the confined flame noise was conducted in OpenFOAM. The simulation utilized the Partially Stirred Reactor (PaSR) and a hybrid computational aeroacoustics (CAA) approach using the large eddy simulation (LES)/the Ffwocs Williams–Hawkings (FWH) method. Additionally, unsteady Reynolds-averaged Navier–Stokes (URANS)/the FWH method was tested for a comparison with the LES prediction. A sensor which was placed outside the enclosure for ease of access was then used to validate the results of the numerical model. The sensor data agreed with the LES/FWH results including the amplitude and frequency of the primary combustion peak and the overall sound pressure level (OASPL). This suggested that a sensor which was placed outside the enclosure could serve as a validation tool for the simulation of the confined flames despite the sound reflections from the walls.

The air-assisted atomization of a micro liquid jet injected from beveled needle point style injector is studied experimentally motivated by its potential applications in biomedical devices. The primary breakup mechanism is investigated using doubled pulsed shadowgraphy. The results include the intact core length, the location of the onset of liquid jet breakup, size of drops at onset. The results are interpreted using phenomenological analysis, and relevance of the findings to biomedical applications are discussed.

The injection of choked gaseous jets into the still air is investigated experimentally motivated by many industrial applications including flares and burners. The objective is to study the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air, seeded with water fog. The computational methods consisted of 7.7 million cells simulation using Star CCM+. The test conditions include injection angles of 0 degrees, 15 degrees, and 30 degrees. The results including mean and fluctuating velocities and the flow vorticity are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

The objective of this research project is to eliminate the spray drift caused by crosswind. Spray drift is an important problem for the agricultural industry. Some herbicides (e.g. Dicamba) can cause serious damage if it drifts to nearby crops that are not genetically modified to withstand those herbicides. Our hypothesis is that the nozzle geometry and the injection angle can be actively/passively controlled to compensate for the crosswind velocity and effectively deliver the herbicides to the target area. The measurements include the breakup regime transitions, the droplet sizes, and the droplets trajectory as function of the wind speed and the injection angle. The current results show that the crosswind modifies the primary breakup mechanism from sheet breakup regime (i.e. thinning and fragmentation of the liquid sheet into ligaments) to bag breakup regime (i.e. the formation bags along the downstream side of liquid sheet) resulting in smaller drop sizes and an increased drift flux. Techniques to eliminate the bag breakup regime are presented.

The injection of choked gaseous jets into still air is investigated computationally and experimentally. The objective is to compare the performance of three turbulence models – Realizable k-e, SST k-w and Reynolds Stress Transport to resolve the effect of injection angle on the jet mixing with ambient air. The experimental methods consist of particle image velocimetry (PIV) using pulsed Nd:YAG lasers of a choked gas jet, seeded with aluminum oxide particles, injected into still air that has been seeded with water fog. The test conditions include injection angles of 0° and 15°. The results including jet velocities and the vorticity field are presented. The flow field is not symmetric along the injection axis due to the asymmetric triggering of expansion fans at the jet exit due to the inclined injection plane. Moreover, the numerical simulation reveals the complex interaction mechanism of the expansion fans and shockwaves within the injection port.

More than one billion people worldwide still lack access to electricity. Rural electrification via gasification has the potential to satisfy electricity access and demand. This study conducts an economic evaluation of rural electrification through gasification of biomass and municipal solid waste (MSW) using a 60 kW downdraft gasifier, developed at Oklahoma State University. The effects of feedstock cost, electricity selling price, feed-in-tariff, tipping fee, tax rate, and the output power are evaluated using major financial parameters: the net present value, internal rate of return, modified internal rate of return, simple payback period, and discounted payback period, and sensitivity analysis. Results show that the downdraft gasification power system offers a payback period of 7.7 years, while generating an internal rate of return, modified internal rate of return, and net present value of 10.9%, 7.7%, and $84,550, respectively. Results from a sensitivity analysis indicate that the feed-in-tariff has the greatest positive contribution to the project’s net present value. Using MSW, the gasification power system potentially reduces carbon dioxide, nitrogen oxides, and sulfur dioxide emissions as compared to direct combustion and landfill. The technology provides a promising future for rural electrification utilizing biomass and MSW whilst offering economic and environmental benefits for local communities.

The objective of this research is to design a human-powered desalination unit that can provide safe drinking water for a typical household in developing countries. The hypothesis of our study is that a human-powered machine operating on a Mechanical Vapor Compression (MVC) cycle can provide economically- and technologically-affordable drinking water without the use of expensive RO membranes. Thermodynamic analysis for human-powered MVC cycle with minimized pressure difference and small surface area is conducted. The design space included the following limitations: (i) only one compressor and only pump could be used, (ii) evaporation mass ratio was less than 0.7, and (iii) the water had to reach the minimum temperature required to inactivate bacteria, viruses, and protozoa. The effects of the concentration of salt in the waste brine were considered. The flow rate of clean water generated was calculated as a function of the required heat exchanger surface area; the primary cost factor in the design; as well as the compressor isentropic efficiency. The effect of the isentropic efficiency of the compressor on the unit performance was also investigated. The point of maximum efficiency in term of mass flow rate per unit surface area was calculated.