In this thesis, heat and moisture transfer between supply and exhaust air streams are investigated for a run-around system in which the coupling material is a desiccant coated solid that is transported between two exchangers. The finite difference method is used to solve the governing partial differential equations of the cross-flow heat exchangers in the supply and exhaust ducts. The outlet air properties are calculated for several inlet air operating conditions and desiccant properties. The accuracy of the heat transfer model is verified by comparing the simulations with well-known theoretical solutions for a single cross flow heat exchanger and a liquid coupled run-around system. The difference between the analytical predictions and the numerical model for sensible effectiveness for each exchanger and the run-around system were found to be less than 1% over a range of operating conditions. The model is also verified by modifying the boundary conditions to represent a counter flow energy wheel and comparing the calculated sensible, latent, and total effectiveness values with correlations in the literature. <p>Using the verified model for energy exchangers and the run-around energy recovery system, the sensible, latent and overall effectiveness are investigated in each exchanger and the run-around system during simultaneous heat and moisture transfer. The overall effectiveness of the run-around energy recovery system is dependent on the air flow rate, the solid desiccant flow rate, the desiccant properties, specific surface area, the size of each exchanger, and the inlet air operating conditions. The run-around system can achieve a high overall effectiveness when the flow rates and exchangers properties are properly chosen. Comparisons between the solid desiccant and salt solution run-around system effectiveness (Fan, 2005 and Fan et al, 2006) shows they are in good agreement. In a sensitivity study, the thickness of desiccant on the fibre is investigated in the solid run-around system. It was found that good performance is obtained with very thin desiccant coatings (1 or 2 micron). During the practical use of this system, a desiccant coated fibre could be inserted into very porous balls or cages that protect the desiccant coated fiber from mechanical wear. The performance sensitivity for this kind of run-around system is demonstrated.

In this thesis, several possible liquid desiccants (aqueous solutions of LiCl, LiBr, MgCl2 and CaCl2) are investigated to find the most appropriate working fluid to be used in a run-around membrane energy exchanger (RAMEE). The liquid desiccant is one of the main components of the RAMEE and indirectly conditions the outdoor ventilation air by using the energy of the exhaust air, significantly reducing the building energy consumption.<p> Numerical simulations, in this thesis, show that the total effectiveness of the RAMEE changes less than 0.5% when different salt solutions are used. However, the capital and operational costs of the RAMEE are significantly different for different desiccants. MgCl2 is the most inexpensive among the selected salt solutions and is followed by CaCl2, LiBr and LiCl. The price of a LiCl solution in the RAMEE is almost 20 times more than the price of MgCl2 solution. Different thermo-physical properties of the salt solutions result in different pumping energy consumptions for each specific salt solution. For example, the pumping energy consumption for a MgCl2 solution is 3.5 times more than for a LiBr solution in the RAMEE. The change in the volume of the liquid desiccant throughout a year is another characteristic which depends on the thermo-physical properties of the salt solution. Solutions with larger volume expansion require larger storage tanks and will experience longer transient delays. The difference between the volume expansions of different salt solutions is less than 5% of the total solution volume. MgCl2 solution expands more than 17% throughout a yearly operation of the system in Saskatoon.<p> Crystallization of the salt solution is another important parameter in the selection of the liquid desiccant. Simulations show that, for a specific indoor and outdoor operating condition the risk of crystallization is greatest for MgCl2, followed by CaCl2, LiCl and LiBr. The risk increases as the supply or exhaust airstreams become dryer. For a cross flow RAMEE with a total effectiveness of 55% (NTU=10 and Cr*=3) operating in a building with indoor RH of 50%, the critical outdoor humidity below which crystallization will begin to occur is 28% RH for MgCl2, 20% for CaCl2 and 0%RH for LiCl and LiBr. According to the simulations, all four investigated salt solutions can be used in North America (except the states of Nevada, Arizona, New Mexico and parts of Texas) with no risk of crystallization when the indoor humidity is 50% RH. However, with indoor humidity of 30% MgCl2 and CaCl2 solutions will have risk of crystallization for a large number of hours in a year in most of the central western United States. A mixture of 50% LiCl and 50% MgCl2 solution is suggested to be used when the cost-effective MgCl2 solution cannot be used due to crystallization issues. The price of this newly suggested mixture is 30% less than that of a pure LiCl solution and can be used in all North American climates with very small risk of crystallization.

In this study, a pilot-scale Regenerative Thermal Oxidizer (RTO) was used to test its performance for volatile organic compound (VOC) destruction and degree of thermal energy conservation. The RTO is electrically heated and contains two 0.5 m ¡Ñ 0.5 m ¡Ñ 2.0 m (L ¡Ñ W ¡Ñ H) columns both packed with gravel particles of 1.0 cm in diameter to a height of 1.4 m. The bed has a void fraction of 0.415. The purpose of this study is to establish the influencing operating conditions and to improve the technique for further applications. Experiments include two phases: (1) energy conservation test with no VOC in the influent air stream , and (2) VOC destruction test with influent air streams containing one of the three VOCs: isopropyl alcohol, acetone, and xylene. Phase 1 experiments were conducted in the maximum gravel temperatures (Tmax) of 402-704 oC, superficial gas velocities (Ug, evaluated at ambient temperatures of 25-30 oC) of 0.15-0.50 m/s, and bed shift times (ts) of 0.5-2.0 min. Results indicate that the temperature raise (

The work was concerned with the design, analysis and basic demonstration of a novel hydraulically assisted fixed geometry turbocharger system intended to help overcome some of the transient issues associated with current automotive boosting technologies. The novel system was based upon use of relatively lightweight parts, where kinetic energy is recovered during vehicle braking, stored in a simple hydraulic accumulator and then used later on to rapidly accelerate the engine's turbocharger. The turbocharger is fitted with a replacement centre housing enclosing a small impulse turbine, rigidly mounted to the turbocharger shaft and powered by a jet of oil. The aim is one of helping the engine to accelerate the vehicle while operating in a region of much higher brake efficiency due to the reduction in exhaust backpressure when compared with competing variable geometry and/or compound boosting technologies. The specific tasks involved concept design and computational analysis, including specification of the turbine type and geometry together with the associated hydraulic parts. A production turbocharger was reverse engineered to confirm the feasibility of packaging the hydraulic turbine system into the centre housing of a typical fixed geometry design. Finally an experimental rig was designed and manufactured to allow basic demonstration of the system, with speeds of up to ~90000 rpm @ 200 bar pressure from the pump via the accumulator achieved in ~0.8 seconds and clear potential for further optimisation. This hydraulic boosting system is capable of attaining 70% efficiency (a product of 0.85 from the oil pump, 0.95 from the hydraulic accumulator and 0.88 of Pelton wheel). The system has higher power density at low cost compared to the main competitor ‘E Boosting - with efficiency in the region of 90%’. The cost of E boosting and need for 48 volt battery makes it less favourable compared to the hydraulic turbine system. The concept has been shown to offer significant potential to assist a turbocharger to spool up via a Novel Hydraulic Kinetic Energy Recovery System approach.

A gestão dos resíduos sólidos está se tornando prioridade tanto no sistema público como no privado. Considerando o tripé da sustentabilidade (social, ambiental e econômico), as indústrias vêm adotando a transformação dos resíduos em coprodutos como um negócio estratégico. Um exemplo é a indústria do aço. Na produção do aço em usina semi-integrada, utiliza-se pelo menos 70% de sucata de ferro e aço como matéria-prima. O grupo das sucatas de pós-consumo é o mais utilizado, devido à maior disponibilidade no mercado. Entretanto, este grupo de sucata possui alto teor de impurezas. A remoção destas impurezas geralmente é feita em um equipamento chamado Shredder , uma máquina trituradora de sucata. Os metais não ferrosos separados neste beneficiamento tem alto valor de mercado e são comercializados, e sobram os resíduos não metálicos que são chamados de Resíduos da Shredder. O foco deste trabalho foi a caracterização físico-química e a classificação de periculosidade destes resíduos, para identificação de aplicações viáveis. O trabalho foi realizado em uma Shredder situada no município de Iracemápolis, no Estado de São Paulo. No período de setembro a março de 2014, foram geradas, em média, 4.928,32t/mês de Resíduo da Shredder. Pelas características apresentadas, os Resíduos da Shredder são divididos em Fluf da Shredder e em Terra da Shredder. A Terra da Shredder apresentou características para potencial aplicação na construção civil, e o Fluf para recuperação energética, principalmente devido ao alto poder calorífico. O poder calorífico médio encontrado para o Fluf foi de 4.527,48 Kcal/Kg (PCI E PCS). Este valor é equivalente a combustíveis consolidados, como o carvão mineral brasileiro. Entretanto, devem ser tomadas precauções no gerenciamento desses resíduos para mantê-los classificados como não perigosos, bem como deve ser estudada tecnologia para remoção de organoclorados. / The waste management in Brazil and Worldwide is becoming a priority in any management system either private or public. Considering the triple bottom line (social, environmental and economical), the industry has adopted the transformation of wastes into byproducts as a strategic business. An example is the steel industry. Mini-mill process uses at least 70% of iron and steel scrap as its raw material. Iron and steel scrap post-consumer is the most widely used due to greater availability in the market. However, this kind of scrap contains high levels of impurities. The removal of these impurities is usually done in a device called Shredder. The nonferrous metals removed are commercialized because of high market value and the non-metallic remains are called the Shredder Residue. The focus of this work was the physicochemical characterization and the classification of hazards these wastes poses in order to identify possible applications. This work was performed in a Shredder located in Iracemápolis City, State of São Paulo. In the period of this work were generated in average 4.928, 32t/month of Shredder Residue. Due to the characteristic found this waste was divided in Fluff of Shredder and Sand of Shredder. The Sand of Shredder showed features for potential application in civil construction and Fluff for energetic recovery mainly because of its high heat value. The average heat value found was 4.527,48 Kcal/Kg (between HHV and LHV). This heat value is equivalent to consolidated fuel such as Brazilian mineral coal. But, precautions should be taken in the management of such wastes to keep them classified as non-hazardous as well as studies should be performed on ways of removing organochlorine compounds.

Waste-heat-to-power (WHP) recovers electrical power from exhaust heat emitted by industrial and commercial facilities. Waste heat is available in enormous quantities. The U.S. Department of Energy estimates 5-13 quadrillion BTUs/yr with a technical potential of 14.6 GW are available and could be utilized to generate power by converting the heat into electricity. The research proposed here will define a system that can economically recover energy from waste heat through a thermal regenerative electrochemical system. The primary motivation came from a patent and the research sponsored by the National Renewable Energy Laboratory (NREL). The proposed system improves on this patent in four major ways: by using air/oxygen, rather than hydrogen; by eliminating the cross diffusion of counter ions and using a dual membrane cell design; and by using high concentrations of electrolytes that have boiling points below water. Therefore, this system also works at difficult-to-recover low temperatures. Electrochemical power is estimated at 0.2W/cm2, and for a 4.2 M solution at 1 L/s, the power of a 100 kW system is 425 kW. Distillation energy costs are simulated and found to be 504 kJ/s for a 1 kg/s feed stream. The conversion efficiency is then calculated at 84%. The Carnot efficiency for a conservative 50% conversion efficiency is compared to the ideal Carnot efficiency. Preliminary work suggests an LCOE of 0.6¢/kWh. Industrial energy efficiency could be boosted by up to 10%. Potential markets include power stations, industrial plants, facilities at institutions like universities, geothermal conversion plants, and even thermal energy storage.

Microbial electrolysis cell (MEC) system is a potential technology that could treat wastewater while simultaneously generating H2 (green energy). MEC's electroactive bacteria (EAB) are essential microbes responsible for oxidizing organic pollutants (such as acetate) in wastewater using an electrogenesis process. Since EABs comprise the core of MECs, they are essential for maintaining functional stability (Coulombic efficiency (CE), current density, and pollutant removal) of MECs. The cause of EAB becoming dominant at the anode of MECs fed with wastewater is still unclear. Furthermore, efficient EAB are typically not detected in wastewater, and when they are present their abundance is low, which affects their early colonization on the anode and subsequent growth into a mature biofilm. This study investigated bioaugmentation as a strategy to drive the assembly of functionally redundant anode EAB biofilms to improve MEC performance. Two bioaugmentation strategies (Conditions 2 and 3) with known EABs (G. sulfurreducens and D. acetexigens) were tested during the startup of MECs. Meanwhile, control MEC reactors (Condition 1) were operated with only wastewater as the sole source of inoculum to compare the anodic biofilm assembly and system performance with the bioaugmented reactors. Equal number of G. sulfurreducens and D. acetexigens cells were added to the wastewater-fed MEC (10% inoculum at 2.1E+07 live cells/mL). In Condition 3, anodic-biofilm colonized G. sulfurreducens and D. acetexigens was used as anode in wastewater fed MECs. Using single-chambered MEC reactors, the bioaugmented MECs (Condition 2 and 3) performed more efficiently than the non-bioaugmented (Condition 1) MECs. Current generation, CE and gas production were different between the three conditions tested (Condition 3 > Condition 2 > Condition 1). Analysis of 16S rRNA gene sequencing of anodic biofilm indicates revealed that the bacterial communities was not affected between the tested conditions. However, the relative abundance of EABs, mainly G. sulfurreducens and D. acetexigens, was markedly influenced by bioaugmentation compared to the control reactor. The highest peak current generation (~ 1500 mA/m2), CE (70.3 ± 9%), and gas production (0.04 m3/m3/day) was observed in Condition 3. Collectively, these results provide a framework for engineering the anode microbial communities in MECs for wastewater treatment.

Yes / Energy saving is an important consideration in process design for low cost sustainable production with reduced environmental impacts (carbon footprint). In our earlier laboratory scale pilot plant study of catalytic wet air oxidation (CWAO) of phenol (a typical compound found in wastewater), the energy recovery was not an issue due to small amount of energy usage. However, this cannot be ignored for a large scale reactor operating around 140–160 °C due to high total energy requirement. In this work, energy savings in a large scale CWAO process is explored. The hot and cold streams of the process are paired up using 3 heat exchangers recovering significant amount of energy from the hot streams to be re-used in the process leading to over 40% less external energy consumption. In addition, overall cost (capital and operating) savings of the proposed process is more than 20% compared to that without energy recovery option.

Heat pipe is a passive heat transport device, engineered to harness latent heat of vaporization of contained working fluid to efficiently transfer sensible energy of one fluid stream to another. Heat pipes have observed applications in HVAC, electronics cooling, space equipment cooling, etc. due to their high effective thermal conductivity. Heat pipe heat exchanger (HPHE) employs finned heat pipes for performance enhancement. A mathematical model was developed into a Mathcad based tool for properly sizing and optimizing gravity-assisted HPHE designs. A charging station was setup to fabricate heat pipes under deep vacuum using a liquid nitrogen cold trap. A wind test tunnel was constructed to conduct experiments on a HPHE prototype. The thermal performance testing resulted in 11.4 kW of heat duty with 54% effectiveness of the HPHE. Parametric studies were also conducted for varying input heat and air flow rates, followed by the result comparison with program predictions.

There is a growing awareness of the valuable nutrients (nitrogen and phosphorus) being lost in conventional wastewater treatment systems. Although the removal of these nutrients has been well addressed, efforts for nutrient recovery have seen little development. As the emphasis on sustainability in the wastewater treatment industry increases, conventional wastewater treatment processes are being re-evaluated and new treatment systems developed. A possible nutrient recovery mechanism is the precipitation of magnesium ammonium phosphate hexahydrate (MgNH4PO4·6H2O), commonly known as struvite. Human urine has been identified as a rich source of nutrients in wastewater; hence the separate collection of urine is considered a viable method of enabling struvite recovery. Since dilution of urine to a certain degree is inevitable, reconcentration of urine beyond the solubility limit of struvite is critical. Currently available methods for reconcentration (e.g., evaporation, freeze-thaw, reverse osmosis and electrodialysis) are relatively expensive with high energy demand. Thus, the research here aims to demonstrate nutrient reconcentration from diluted urine and simultaneous organic removal by using the principles of microbial desalination cells (MDCs), where energy released from organic oxidation is partially used for the separation of nutrient ions. With reduced energy demand, a sustainable method for the utilization of source-separated urine is examined. The performance of bioelectrochemical systems relies on the activity of exoelectrogenic bacteria to transfer electrons to the anode. An examination of exoelectrogen sensitivity at various wastewater treatment conditions (i.e. ammonia and oxygen) is an important component of this research. Methanogenesis is considered the greatest challenge in achieving practical applications in anaerobic bioelectrochemical systems. An electrolytic oxygen production method is suggested for effective control of methanogenesis in a feasible and cost-effective manner. / Thesis / Master of Applied Science (MASc)