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Experimental Evaluation of Innovative Catalytic Heat Exchangers for Energy-efficient Amine-based Post-combustion CO₂ Capture Processes
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Process Systems Engineering, University of Regina. xxv, 185 p.This PhD research focused on enhancing CO2 desorption performance in post-combustion
carbon capture processes by developing and optimizing catalytic heat exchangers. The guiding
principle was to address challenges, including operational complexity and high energy
consumption, while minimizing costly modifications to existing piping and infrastructure in pilot
plants.
The feasibility of novel aqueous piperazine-based biphasic solvents was initially investigated
to reduce solvent flow rates and optimize heat exchanger size. Although these solvents
demonstrated promising absorption and desorption performance, challenges such as high
viscosities, suboptimal phase split ratios and low amine concentrations in the rich phase limited
their applicability in the catalytic heat exchanger system.
An innovative agitated jacket vessel with a coil heat exchanger (JVC-EX) was developed and
experimentally validated. Compared to the conventional fixed catalyst bed desorber, the JVC-EX
using benchmark MEA solvent and solid acid catalyst HZSM-5 achieved approximately 30%
catalytic enhancement, a 50% reduction in catalyst demand, and a 22% decrease in energy
consumption while maintaining excellent operational stability and flexibility. However, concerns
emerged regarding catalyst durability due to mechanical stirrer-induced attrition, highlighting the
need for further mechanical optimization.
To address this limitation, a spouted bed and jet-flow catalytic heat exchanger (SBJ-EX) was
introduced as a non-agitated alternative. The SBJ-EX demonstrated a 70% improvement in heat
transfer efficiency compared to traditional plate heat exchangers and delivered excellent CO2
desorption performance at lower operating temperatures. Its spouted design effectively minimized
catalyst attrition, ensured system stability, and enabled faster catalyst replacement, significantly
reducing maintenance downtime. Both catalytic heat exchangers showed strong adaptability for
integrating existing and new industrial-scale carbon capture systems.
Overall, this thesis provided valuable insights into the design, operation, and optimization of
novel catalytic heat exchangers, emphasizing their potential to drive the adoption of catalysts in
commercial-scale carbon capture applications.Studentye
Emotion Regulation Under Pressure: The Impact of Cognitive Reappraisal and Expressive Suppression on Stress Responses
No full textA thesis Submitted in Partial Fulfillment of the Requirements For the Degree of Bachelor of Science (Honours) in Psychology, University of Regina.Acute social stress, a common type of stress faced in situations of intense pressure and social evaluation, induces both psychological and physiological responses. When these responses are prolonged or poorly managed, they can have detrimental effects on one’s health. Emotion regulation, the capacity to control and modulate one’s emotional responses, is a central mechanism that shapes how individuals experience and recover from stressors. This study examined how two prevalent emotion regulation strategies, cognitive reappraisal (CR) and expressive suppression (ES), influence acute social stress responses. Participants (N=58) completed the Emotion Regulation Questionnaire as part of an online survey to assess their use of each strategy. They then participated in the Trier Social Stress Test (TSST) and control version of the TSST (C-TSST) in a counterbalanced design. Physiological markers (heart rate [HR], heart rate variability [HRV], and skin conductance level [SCL]), along with subjective stress ratings, were collected through both tasks. Through a manipulation check, it was concluded that the TSST successfully induced more stress than the C-TSST. Multiple linear regression analyses and linear mixed-effects models assessed associations between emotion regulation strategies and stress responses. ES was significantly associated with higher perceived threat and showed a slight trend towards slower HR recovery. CR was not found to be significantly linked to physiological or subjective stress markers, although slight trends were present. These findings highlight the potential impact of emotion regulation on stress reactivity. By gaining a deeper understanding of adaptive and maladaptive emotion regulation strategies, interventions that promote healthier coping mechanisms can be implemented
Optimization of heterogeneous bio-based catalysts and synthesis of inorganic equivalent for large-scale biodiesel production
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Process Systems Engineering, University of Regina. xix, 189 p.This research focuses on optimizing the production of biodiesel to reduce overdependence on fossil fuels by utilizing waste resources. In recent years there have been concerns on the use of fossil fuels in the increasing demand of energy and its drawbacks. Fossil fuels, unlike biodiesel, are carbon rich and hence on combustion, releases excessive amounts of CO2, NOX and SOX leading to global warming.
In this research, waste cooking oil (WCO) and ethanol were used as the main raw materials to produce biodiesel known to have net zero carbon emission potential to meet Canada’s commitment to attain net zero carbon emissions by 2050. In providing alternative use for waste resources, waste eggshells, cow bones, fish scales and banana peels were investigated, characterized and optimized to manufacture high performing Lewis base catalysts to obtain high biodiesel yield in a transesterification reaction.
Initially eggshell, fish scale and cow bone catalysts all of which are primarily calcium based were studied and optimized by varying mix procedure, mix ratio as well as impregnating 1%, 5% and 10% by weight of potassium promoters. Physical mixing, 1:6:3 (ES: FS:CB) mix ratio, 10% potassium impregnation were the obtained optimum and a 75% biodiesel yield was obtained when 1:6:3 + 10% K catalyst was used.
Due to the low biodiesel yields obtained there was a need to investigate other biobased materials with Lewis base potential. This led to the shift to potassium based biobased material, banana peels for optimization and use as transesterification catalyst. The banana peels were calcined at 600℃ (BP600), 800℃ (BP800), 900℃ (BP900) and 1000℃ for optimization. The yield on calcining at 1000℃ was not
enough to carry out a reaction. BP900 had the best performance yielding up to 96.16% biodiesel.
An inorganic replica of the optimum biobased catalyst BP900 was prepared using inorganic precursors due to the drawbacks of the biobased catalyst (low calcination yield of 10%, not available in large commercial quantities) via co-impregnation (BPIn1) and coprecipitation methods (BPIn2). BPIn 2 had a biodiesel yield of 84.58% and was used for further studies.
The effect of reaction time, temperature, catalyst amount and ethanol to oil ratio (E:O) on the biodiesel yield were checked and the optimum conditions were 6 hours, 70℃, 2wt%, 21:1 respectively. The viscosity, acid value and density were determined according to ASTMD, and results were within acceptable standards. TGA, XRD, SEM/EDS, N2 Physisorption and CO2 TPD analysis were performed on catalysts to determine their characteristics. Kinetic data was obtained for BPIn2 catalyst by varying the E:O, reaction time and reaction temperature for 2wt% catalyst dose runs to obtain various biodiesel yields. NLReg software was used to regress the data to obtain an activation energy (Ea) of 39.07kJ/mol, collision factor (k0) of 1.5*106 /gcat.h. mol5.6, an order with respect to ethanol (e) of 3, and an order of reaction with respect to oil (o) of 2.Studentye
Regina Energy Futures Survey 2025: Measuring support for the City of Regina’s Energy and Sustainability Framework Goals and Supportive Policies
No full textThe Regina Energy Futures Project acknowledges funding support
from the City of Regina
Illness or immorality?
No full textA Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Bachelor of Arts (Honours) in Psychology, University of Regina. 45 p.People prone to feelings negative emotions in response to contaminants (e.g., disgust) tend to have distinct moral views. But how do these people feel about the morality of those who are a potential source of contamination, such as those who appear ill? The current study was designed to explore the relationships between predispositions to contaminants and moral judgement of those displaying signs of illness. Undergraduate participants (N = 170) completed measures of obsessive-compulsive contamination symptoms, disgust propensity, disgust sensitivity, and purity-based morality. Participants then read a vignette depicting a person displaying signs of illness. After reading the vignette, participants rated that ill person's level of immorality and their own feelings of contamination. Greater levels of obsessive-compulsive contamination symptoms, disgust propensity, disgust sensitivity, and purity-based morality, and feelings of contamination were associated with harsher moral judgement of the person displaying signs of illness. Moreover, obsessive-compulsive contamination symptoms mediated the relationship between feelings of contamination and moral judgement of the person with signs of illness. These findings illuminate the importance of morality for individuals that often experience intense feelings - especially feelings that pertain to contamination. Moral psychology researchers have focused on how affects like disgust influence people's general moral principles. However, focusing on abstract principles overlooks the concrete behaviours that are relevant to people's moral lives. Clinical psychology researchers can improve understanding of mental health by exploring how individuals prone to intense affect react to relevant and provocative real-world situations
An exploration of conceptual similarity in multiple target visual search
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Experimental and Applied Psychology, University of Regina. iv, 66 p.Visual search studies generally suggest that multiple target visual search is more difficult
and less efficient than traditional single target search, with costs to both RT and accuracy.
Typically, these studies use dual target trials and abstract stimuli. A study by Laderoute
(2021) using varying target set sizes and naturalistic stimuli found better performance for
many-target search, with per-item RTs that decreased as target set size increased.
Interestingly, increasing the perceptual similarity of the targets had no effect on search
performance. However, in that study, regardless of the perceptual similarity condition, all
targets within a trial were always the same type of item. It is possible that this high
degree of conceptual similarity between targets facilitated search performance. The
present study further explores the many-target benefit and assesses the possibility of a
conceptual similarity effect. Participants searched naturalistic scenes for 2, 6, or 18
targets. On each trial, targets were either variations of the same item, items belonging to
the same specific category, or items belonging to the same general category (e.g., hair
ties, hair accessories, toiletries). Performance was best in the same-item 18-target
condition. Mean per-item RT decreased as target set size increased, with little to no effect
on accuracy. Search performance was best for same-item targets, and worse for samecategory
and similar-category targets, with very similar performance in the two
“category” conditions. The effect of conceptual similarity decreased as target set size
increased. This study provides additional information about the factors that enhance and
impair multiple target visual search performance, and has relevance for both professional
and non-professional searchers.Studentye
The Macdonald group
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Science in Mathematics, University of Regina. v, 113 p.Given α ∈ Z, the Macdonald group G(α) is defined by
G(α) = ⟨ A,B | A[A,B] = Aα, B[B,A] = Bα ⟩.
It is known that G(α) is finite if and only if α ̸= 1, in which case the prime factors of |G(α)|
are those of α − 1. It is also known that G(α) is nilpotent in certain cases. We show that
G(α) is always nilpotent, so that for α ̸= 1, G(α) is the direct product of its Sylow subgroups.
In the first third of the thesis, we determine the order, upper and lower central series, nilpotency
class, and exponent of each of these Sylow subgroups.
For the remaining two thirds of the thesis we concentrate on the Sylow 2-subgroup J = J(α)
of G(α), so we assume that α = 1 + 2mℓ, where m ≥ 1 and ℓ is odd. We show that J has
presentation
J = ⟨ x, y | x[x,y] = x1+2mℓ, y[y,x] = y1+2mℓ, x23m−1
= 1 = y23m−1⟩,
order 27m−3, and nilpotency class 5 if m > 1 and 3 if m = 1.
In the middle third of the thesis, we determine the automorphism groups of the 2-groups J,
H = J/Z(J) and K = H/Z(H), where |H| = 26m−3 and |K| = 25m−3. Explicit multiplication,
power, and commutator formulas for J, H, and K are given, and used in the calculation
of Aut(J), Aut(H), and Aut(K).
In the final third of the thesis, we consider the infinite family of finite 2-groups {J(α)}α̸=1
and settle the following isomorphism problem: given α ̸= 1 ̸= α′ ∈ Z, when are J(α) and
J(α′) isomorphic?Studentye
Prophet time series modeling of waste disposal rates in four North American cities
No full textThis version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1007/s11356-024-33335-5In this study, three different univariate municipal solid waste (MSW) disposal rate forecast models (SARIMA, Holt-Winters, Prophet) were examined using different testing periods in four North American cities with different socio-economic conditions. A review of the literature suggests that the selected models are capable to handle seasonality in a time series, however, their ability to handle outliers are not well understood. The Prophet model generally outperformed the Holt-Winters model and the SARIMA model. The MAPE and R2 of the Prophet model during pre-COVID-19 were 4.3%–22.2% and 0.71–0.93, respectively. All three models showed satisfactory predictive results, especially during the pre-COVID-19 testing period. COVID-19 lockdowns and the associated regulatory measures appear to have affected MSW disposal behaviors, and all the univariate models failed to fully capture the abrupt changes in waste disposal behaviors. Modeling errors were largely attributed to data noise in seasonality and the unprecedented event of COVID-19 lockdowns. Overall, the modeling errors of the Prophet model were evenly distributed, with minimum modeling biases. The Prophet model also appeared to be versatile, and successfully captured MSW disposal rates from 3,000 to 39,000 tonnes/month. The study highlights the potential benefits of the use of univariate models in waste forecast.The research reported in this paper was supported partly by a grant from the Natural Sciences and Engineering Research Council of Canada (RGPIN-2019-06154) to the corresponding author at the University of Regina
Hydrothermal liquefaction of pulp and paper mill residues for renewable biocrude production
No full textA Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Process Systems Engineering, University of Regina. xvii, 193 p.The climate change challenge has prompted global governments and international organizations to implement measures aimed at reducing greenhouse gas emissions and mitigating their impact on the ecosystem. The pulp and paper industry, a major contributor to global waste generation, often lacks efficient waste disposal methods despite the energy-rich nature of its waste products. Consequently, there is a pressing need to intensify research efforts on valorizing and utilizing pulp and paper waste residues thereby checking the inordinate disposal of effluents from this sector, hence this thesis.
The objective of this research is to investigate the effects of reaction parameters such as temperature, residence time, feed concentration and catalysts on the yield of biocrude from the Hydrothermal Liquefaction (HTL) of pulp and paper mill residues. These reaction parameters were taken through non-catalytic and catalytic optimization. While Central Composite Design (CCD) was used in the design of experiments, Response Surface Methodology (RSM) was utilized in optimization. The optimum parametric conditions obtained are temperature: 340oC, residence Time: 56min and feed concentration: 5%. Zeolite (HZSM-5), gamma-alumina (γ-Al2O3), activated carbon and potassium carbonate (K2CO3) were utilized as catalysts and their performances with respect to biocrude yield improvement were evaluated. The order of catalytic effect on biocrude yield is potassium carbonate (K2CO3) > gamma-alumina (γ-Al2O3) > zeolite (HZSM-5) > activated carbon. However, due to the hygroscopic nature of potassium carbonate it cannot be recovered and re-used. As a result of this deficiency, gamma-alumina was adopted as the best (recyclable) catalyst in this study. Catalyst Characterization, such as N2 Physisorption Analysis (BET), Fourier-Transform InfraRed (FTIR) Spectroscopy, Powder X-ray Diffraction (XRD), Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDS), and Temperature-Programmed Desorption (TPD). were performed on the fresh and spent catalysts to study their properties and make informed inferences on their impacts on biocrude yield. Finally, an intrinsic kinetic model was developed to derive a rate equation that could be easily integrated with generalized equations for rates of physical transport processes. This integration would enable the development of a reactor model that is capable of extrapolating across a spectrum of reactor operating circumstances. Limitations to mass transport were initially eliminated to establish the kinetic limited region. From the kinetic study, a first-order equation was proposed. The activation energy and pre-exponential factor of the reaction are 15.981 KJ/mol and 0.254 s-1 respectively. The average absolute deviation (3.40%) of the kinetic model showed that the model is an excellent fit for the hydrothermal liquefaction process. Based on the findings from this research, it was concluded that γ-alumina is an appropriate catalyst precursor to efficiently convert pulp and paper mill residues into biocrude, producing the highest biocrude yield of around 26%, which may be attributed to its selectivity, high level of crystallinity, and acidity. Further investigations into hydrothermal liquefaction are recommended, with an emphasis on varying factors such as pressure, feed mass to catalyst ratio, and reactor stirrer speed.Studentye
Let's Normalize Breastfeeding in Public
No full textBreastfeeding is vital for infant's brain development. Breastmilk is clean, safe and prevents infants from a variety of illnesses. Breastfeeding in public is often stigmatized in public that leads to discontinuation of breastfeeding. Let's normalize breastfeeding in public to provide a healthy start to young children